Assessing African medicinal plants for efficacy and safety: pharmacological screening and toxicology

Sub-acute toxicity, antinociceptive and anti-inflammatory effects of Mucuna pruriens L. leaves in experimental rodents

ETHNOPHARMACOLOGICAL RELEVANCE

Mucuna pruriens L is a wild and cultivated leguminous plant which have been used as an aphrodisiac, diuretic, nerve tonic, and antiarthritic agent.

AIM

To evaluate the toxicity, antinociceptive, and anti-inflammatory activities of M. pruriens (EEMP) ethanol extract in experimental models.

METHODS

M. pruriens dried leaves were extracted using aqueous ethanol (30:70). Tests for acute and subacute toxicity were conducted on rats and mice. Mice were used in hotplate, acetic acid, and formalin models to test the antinociceptive activity of EEMP. The anti-inflammatory properties of EEMP (25, 100, and 400 mg/kg) were assessed egg albumin, carrageenan, and formalin-induced oedema models. The study examined the anti-inflammatory mechanism of EEMP (25-400 mg/kg) in rats with an air pouch caused by carrageenan. Air pouch exudates were tested for total leucocytes and differential cell counts, TNF-α, IL-6, myeloperoxidase activity, malondialdehyde, nitrites, and reduced glutathione (GSH).

RESULTS

The acute oral toxic dose of EEMP is greater than 2000 mg/kg. There were no significant behavioral, hematological or biochemical alterations seen after 14-days repeated administration of EEMP (200, 400 and 800 mg/kg) in mice. The EEMP demonstrated significant antinociceptive activity in hotplate, acetic acid and formalin-induced nociception in mice. The EEMP significantly and dose dependently reduced paw oedema at 2, 4 and 96 h in the egg-albumin, carrageenan- and formalin-induced paw oedema, respectively. Exudates volume, inflammatory cell counts, TNF-α, IL-6, myeloperoxidase, malondialdehyde and nitrites were significantly reduced, while GSH increased in carrageenan-air pouch of EEMP-treated rats.

CONCLUSION

Mucuna pruriens leaves ethanol extract demonstrated good safety profile as well as antinociceptive and anti-inflammatory activity through mechanisms related to inhibition of oxidative stress and pro-inflammatory cytokines as well as lysosomal membrane stability.

Antimicrobial activity of Southern African medicinal plants on Helicobacter pylori and Lactobacillus species

ETHNOPHARMACOLOGICAL RELEVANCE

Numerous medicinal plants have been used traditionally in South Africa for gastric ulcer treatment. Helicobacter pylori is known for causing inflammation and the onset of gastric ulcers. While several studies explored medicinal plants against H. pylori, investigation of medicinal plants used for gastric ulcers has been neglected, as well as the effects these plants would have on bacteria occurring naturally in the gut microbiome.

AIM OF THE STUDY

This study aimed to investigate Southern African medicinal plants used traditionally for treating gastric ulcers against H. pylori , as well as the effects that these plants have when combined with Lactobacillus species and tested against H. pylori.

METHODOLOGY

Based on evidence from the ethnobotanical literature, 21 plants were collected. Their antimicrobial activity was assessed against five clinical H. pylori strains, and in combination with each of three Lactobacillus species, using the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) broth microdilution assays. Toxicity was assessed using the brine shrimp lethality assay.

RESULTS

Noteworthy activity was observed against at least one H. pylori strain for 12 plant species. The lowest mean MICs were from organic extracts of Carissa edulis Vahl (0.18 mg/mL) and Chironia baccifera L. (0.20 mg/mL), and aqueous extracts of Sansevieria hyacinthoides (L.) Druce (0.26 mg/mL) and Dodonaea viscosa Jacq. (0.30 mg/mL). Aqueous extracts of the investigated plants were combined with Lactobacillus species, and the majority of combinations showed increased antimicrobial activity compared with the extracts alone. Combinations of Lactobacillus rhamnosus with 18 of the 21 aqueous plant extracts showed at least a two-fold decrease in the mean MBC against all H. pylori strains tested. Lactobacillus acidophilus combined with either Protea repens L., Carpobrotus edulis (L.) L. Bolus or Warburgia salutaris (Bertol.f.) Chiov. aqueous extracts had the best anti-H. pylori activity (mean MBCs of 0.10 mg/mL for each combination). Only four organic and one aqueous extract(s) were considered toxic.

CONCLUSION

These results highlight the potential of medicinal plants to inhibit H. pylori growth and their role in traditional treatments for the management of ulcers. The results also indicate that aqueous extracts of these plants do not hinder the growth of bacteria that occur naturally in the gut microbiome and play a role in maintaining gut health, as well as show the potential benefit of including Lactobacillus species as potentiators of H. pylori activity.

In vitro Safety Assessment of Extracts and Compounds From Plants as Sunscreen Ingredients

This work investigated the safety of extracts obtained from plants growing in Colombia, which have previously shown UV-filter/antigenotoxic properties. The compounds in plant extracts obtained by the supercritical fluid (CO2) extraction method were identified using gas chromatography coupled to mass spectrometry (GC/MS) analysis. Cytotoxicity measured as cytotoxic concentration 50% (CC50) and genotoxicity of the plant extracts and some compounds were studied in human fibroblasts using the trypan blue exclusion assay and the Comet assay, respectively. The extracts from Pipper eriopodon and Salvia aratocensis species and the compound trans-β-caryophyllene were clearly cytotoxic to human fibroblasts. Conversely, Achyrocline satureioides, Chromolaena pellia, and Lippia origanoides extracts were relatively less cytotoxic with CC50 values of 173, 184, and 89 μg/mL, respectively. The C. pellia and L. origanoides extracts produced some degree of DNA breaks at cytotoxic concentrations. The cytotoxicity of the studied compounds was as follows, with lower CC50 values representing the most cytotoxic compounds: resveratrol (91 μM) > pinocembrin (144 μM) > quercetin (222 μM) > titanium dioxide (704 μM). Quercetin was unique among the compounds assayed in being genotoxic to human fibroblasts. Our work indicates that phytochemicals can be cytotoxic and genotoxic, demonstrating the need to establish safe concentrations of these extracts for their potential use in cosmetics.

NANOPARTICLE-BASED formulation of dihydroartemisinin-lumefantrine duo-drugs: Preclinical Evaluation and enhanced antimalarial efficacy in a mouse model

Artemisinin-based combinations (ACTs) are World Health Organization-recommended treatment for malaria. Artemether (A) and lumefantrine (LUM) were the first co-formulated ACT and first-line treatment for malaria globally, artemether is dihydroartemisinin's (DHA's) prodrug. Artemisinins and LUM face low aqueous solubility while artemisinin has low bioavailability and short half-life thus requiring continuous dosage to maintain adequate therapeutic drug-plasma concentration. This study aimed at improving ACTs limitations by nano-formulating DHA-LUM using solid lipid nanoparticles (SLNs) as nanocarrier. SLNs were prepared by modified solvent extraction method based on water-in-oil-in-water double emulsion. Mean particle size, polydispersity index and zeta potential were 308.4 nm, 0.29 and -16.0 mV respectively. Nanoencapsulation efficiencies and drug loading of DHA and LUM were 93.9%, 33.7%, 11.9%, and 24.10% respectively. Nanoparticles were spherically shaped and drugs followed Kors-Peppas release model, steadily released for over 72 h. DHA-LUM-SLNs were 31% more efficacious than conventional oral doses in clearing Plasmodium berghei from infected Swiss albino mice.

A Review of the Potential of Poly-(lactide-co-glycolide) Nanoparticles as a Delivery System for an Active Antimycobacterial Compound, 7-Methyljuglone

7-Methyljuglone (7-MJ) is a pure compound isolated from the roots of Euclea natalensis A. DC., a shrub indigenous to South Africa. It exhibits significant promise as a potential treatment for the highly communicable disease tuberculosis (TB), owing to its effective antimycobacterial activity against Mycobacterium tuberculosis. Despite its potential therapeutic benefits, 7-MJ has demonstrated in vitro cytotoxicity against various cancerous and non-cancerous cell lines, raising concerns about its safety for consumption by TB patients. Therefore, this review focuses on exploring the potential of poly-(lactide-co-glycolic) acid (PLGA) nanoparticles as a delivery system, which has been shown to decrease in vitro cytotoxicity, and 7-MJ as an effective antimycobacterial compound.

Neuropathological profile of the African Giant Rat brain (Cricetomys gambianus) after natural exposure to heavy metal environmental pollution in the Nigerian Niger Delta

Pollution by heavy metals is a threat to public health because of the adverse effects on multiple organ systems including the brain. Here, we used the African giant rat (AGR) as a novel sentinel host to assess the effect of heavy metal accumulation and consequential neuropathology upon the brain. For this study, AGR were collected from distinct geographical regions of Nigeria: the rain forest region of south-west Nigeria (Ibadan), the central north of Nigeria (Abuja), and in oil-polluted areas of south Nigeria (Port-Harcourt). We found that zinc, copper, and iron were the major heavy metals that accumulated in the brain and serum of sentinel AGR, with the level of iron highest in animals from Port-Harcourt and least in animals from Abuja. Brain pathology, determined by immunohistochemistry markers of inflammation and oxidative stress, was most severe in animals from Port Harcourt followed by those from Abuja and those from Ibadan were the least affected. The brain pathologies were characterized by elevated brain advanced oxidation protein product (AOPP) levels, neuronal depletion in the prefrontal cortex, severe reactive astrogliosis in the hippocampus and cerebellar white matter, demyelination in the subcortical white matter and cerebellar white matter, and tauopathies. Selective vulnerabilities of different brain regions to heavy metal pollution in the AGR collected from the different regions of the country were evident. In conclusion, we propose that neuropathologies associated with redox dyshomeostasis because of environmental pollution may be localized and contextual, even in a heavily polluted environment. This novel study also highlights African giant rats as suitable epidemiological sentinels for use in ecotoxicological studies.

Effect of glyphosate-based herbicide roundup on hemato-biochemistry of Labeo rohita (Hamilton, 1822) and susceptibility to Aeromonas hydrophila infection

In the present study, comprehensive research was executed to investigate the salient toxic effects of glyphosate herbicide in static water system by evaluating the haemato-biochemical profiles of Labio rohita. A challenge study against Aeromonas hydrophila was conducted to determine disease susceptibility of the fish, treated to varying concentrations of commercial-grade glyphosate herbicide. A static range finding bioassay and definitive test revealed that the 96-h LC50 value of glyphosate was 10.16 mg L-1. The experimental fish were subjected to three sub-lethal concentrations of 2.06, 1.03, and 0.63 mg l-1 for 28 days and changes were documented bi-fortnightly to study haemato-biochemical alterationsin the fish. Significantly (p < 0.05) low values in red blood corpuscles (RBC), hemoglobin (Hb), and hematocrit value (Hct) were documented. In contrast, a significant (p < 0.05) escalation in white blood corpuscles (WBC) was documented in comparison to the control. Biochemical and stress markers such as blood glucose, total protein, and alkaline phosphatase (ALP) were significantly (p < 0.05) low, whereas serum glutamate pyruvate transaminase (SGPT) and serum glutamate oxaloacetate transaminase (SGOT) escalated significantly (p < 0.05). Chronic exposure to glyphosate, on the other hand, had the least effect on the Na+ and K+ ions. Further, a challenge assay against A. hydrophila at three sub-lethal glyphosate concentrations demonstrated a synergistic impact that reduced the fish survivability. The findings conclude that persistent low glyphosate concentrations in aquatic ecosystems show significant pathophysiological changes in L. rohita, with increased vulnerability to infections. Altogether, our findings indicate the need to further study the possible assessment for a sustainable bio-remediation technique, mitigation of the detrimental effects of glyphosate exposure in fish, and recommendation of an acceptable residue concentration of the glyphosate in aquatic ecosystem.

GC-ToF-MS Profiling and In Vitro Inhibitory Effects of Selected South African Plants against Important Mycotoxigenic Phytopathogens

The harmful effects following the ingestion of mycotoxin-contaminated food include the induction of cancers, mutagenicity, immune suppression, and toxicities that target organs of the digestive, cardiovascular, and central nervous systems. Synthetic fungicides are generally associated with a high toxic residue in food and the development of excessive fungal resistance. This study aimed to determine the antifungal activities against mycotoxigenic fungi of selected South African plant leaves and potentially develop plant-derived bio-fungicides, and, furthermore, to explore the in vitro antioxidant activity and the phytochemical spectra of the compounds of the selected medicinal plant extracts. The extracts were tested for antifungal activity against phytopathogenic strains using a microdilution broth assay. Bauhinia galpinii extracts exhibited the lowest minimum inhibitory concentration (MIC) against C. cladospoides and P. haloterans at 24 h incubation periods. C. caffrum had good antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) with 50% inhibitory concentration (IC50) values of 0.013 mg/mL while B. galpini had IC50 values of 0.053 against free radicals of 2,2'-azinobis (3-ethylbenzthiazoline-6-suphonic acid (ABTS). The antimycotoxigenic and antioxidant activity exerted by both B. galpinii and C. caffrum may well be attributed to high TPC. In the GC-ToF-MS analysis, all the selected medicinal plants exhibited the presence of Hexadecanoic acid at varying % areas, while both B. galpinii and C. caffum exhibited the presence of lupeol at % area 2.99 and 3.96, respectively. The compounds identified, particularly the ones with higher % area, may well explain the biological activity observed. Although the selected medicinal plants exhibited a notable biological activity, there is a need to explore the safety profiles of these plants, both in vitro and in vivo.

Simultaneous Estimation of Quercetin and trans-Resveratrol in Cissus quadrangularis Extract in Rat Serum Using Validated LC-MS/MS Method: Application to Pharmacokinetic and Stability Studies

Cissus quadrangularis is a nutrient-rich plant with a history of use in traditional medicine. It boasts a diverse range of polyphenols, including quercetin, resveratrol, β-sitosterol, myricetin, and other compounds. We developed and validated a sensitive LC-MS/MS method to quantify quercetin and t-res biomarkers in rat serum and applied this method to pharmacokinetic and stability studies. The mass spectrometer was set to negative ionization mode for the quantification of quercetin and t-res. Phenomenex Luna (C18(2), 100 A, 75 × 4.6 mm, 3 µ) column was utilized to separate the analytes using an isocratic mobile phase consisting of methanol and 0.1% formic acid in water (82:18). Validation of the method was performed using various parameters, including linearity, specificity, accuracy, stability, intra-day, inter-day precision, and the matrix effect. There was no observed significant endogenous interference from the blank serum. The analysis was completed within 5.0 min for each run, and the lower limit of quantification was 5 ng/mL. The calibration curves showed a linear range with a high correlation coefficient (r² > 0.99). The precision for intra- and inter-day assays showed relative standard deviations from 3.32% to 8.86% and 4.35% to 9.61%, respectively. The analytes in rat serum were stable during bench-top, freeze-thaw, and autosampler (-4 °C) stability studies. After oral administration, the analytes showed rapid absorption but underwent metabolism in rat liver microsomes despite being stable in simulated gastric and intestinal fluids. Intragastric administration resulted in higher absorption of quercetin and t-res, with greater C_max, shorter half-life, and improved elimination. No prior research has been conducted on the oral pharmacokinetics and stability of anti-diabetic compounds in the Ethanolic extract of Cissus quadrangularis EECQ, making this the first report. Our findings can provide the knowledge of EECQ's bioanalysis and pharmacokinetic properties which is useful for future clinical trials.

Comprehensive chemical profiling of Bassia indica Wight. aerial parts extract using UPLC-ESI-MS/MS, and its antiparasitic activity in Trichinella spiralis infected mice: in silico supported in vivo study

BACKGROUND

Trichinellosis is a public health threat infected both animals and humans as a result of eating undercooked meat. It caused by Trichinella spiralis that has widespread drug resistance and even developed many sophisticated strategies for their survival, this increases the demand in searching for new anthelmintic drugs from natural source.

METHODS

Our objectives were to test the in vitro and in vivo anthelmintic activity of Bassia indica BuOH frac., and to characterize its chemical composition using UPLC-ESI-MS/MS. Besides an in silico molecular docking study with the prediction of the PreADMET properties.

RESULTS

In vitro investigation of B. indica BuOH frac., showed severe destruction of the adult worm and larvae, marked cuticle swelling, areas with vesicles, blebs and loss of annulations. This was assured via in vivo study, which revealed a significant reduction (P < 0.05) in the mean adult worm count with efficacy of 47.8% along with a significant decrease (P < 0.001) in the mean larval count per gram muscle with efficacy 80.7%. Histopathological examinations of the small intestine and muscular sections showed marked improvement. In addition, immunohistochemical findings demonstrated that B. indica BuOH frac. depressed the proinflammatory cytokines expressions of TNF-α, which was obviously upregulated by T. spiralis. Precise chemical investigation of the BuOH frac. using UPLC-ESI-MS/MS resulted in the identification of 13 oleanolic type triterpenoid saponins; oleanolic acid 3-O-6´-O-methyl-β-D-glucurono-pyranoside (1), chikusetsusaponin-IVa (2) and its methyl ester (3), chikusetsusaponin IV (4) and its methyl ester (5), momordin-Ic (6) and its methyl ester (7), betavulgaroside-I (8), -II (9) -IV (10), -X (11), licorice-saponin-C₂ (12) and -J₂ (13). In addition, 6 more phenolics were identified as syringaresinol (14), 3,4-di-O-caffeoylquinic acid (15), 3-O-caffeoyl-4-O-dihydrocaffeoylquinic acid (16), 3,4-di-O-caffeoylquinic acid butyl ester (17), 3,5-di-O-galloyl-4-O-digalloylquinic acid (18) and quercetin 3-O-(6´´-feruloyl)-sophoroside (19). The auspicious anthelmintic activity was further ascertained using in silico molecular docking approach that targeted certain protein receptors (β-tubulin monomer, tumor necrosis factor alpha (TNF-α), cysteine protease (Ts-CF1), calreticulin protein (Ts-CRT)), all the docked compounds (1-19) fit into the binding site of the active pocket with binding affinities noteworthy than albendazole. In addition, ADMET properties, drug score and drug likeness were predicted for all compounds.

Permeation of Phytochemicals of Selected Psychoactive Medicinal Plants across Excised Sheep Respiratory and Olfactory Epithelial Tissues

The intranasal route of drug administration offers an opportunity to bypass the blood-brain barrier and deliver compounds directly into the brain. Scientific evidence exists for medicinal plants (e.g., Centella asiatica and Mesembryanthemum tortuosum) to treat central nervous system conditions such as anxiety and depression. The ex vivo permeation of selected phytochemicals (i.e., asiaticoside and mesembrine) has been measured across excised sheep nasal respiratory and olfactory tissue. Permeation studies were conducted on individual phytochemicals and C. asiatica and M. tortuosum crude extracts. Asiaticoside exhibited statistically significantly higher permeation across both tissues when applied alone as compared to the C. asiatica crude extract, while mesembrine permeation was similar when applied alone or as M. tortuosum crude extract. Permeation of all the phytocompounds was similar or slightly higher than that of the drug atenolol across the respiratory tissue. Permeation of all the phytocompounds was similar to or slightly lower than that of atenolol across the olfactory tissue. In general, the permeation was higher across the olfactory epithelial tissue than across the respiratory epithelial tissue and therefore showed potential for direct nose-to-brain delivery of the selected psychoactive phytochemicals.

Ecology of Echinops giganteus A. Rich. in Sub-Saharan Africa: Distribution, Ecoclimatic Niche, and Phytosociology

Echinops giganteus A. Rich. is an aromatic and medicinal plant of the Asteraceae family exploited in Cameroon under the access and benefit sharing (ABS) standard. Despite its importance, little information exists on the ecology of E. giganteus. The aim of the present study was to contribute to a better understanding of its ecology for sustainable management in the Western Highlands of Cameroon. Occurrence data as well as stationary ecological information were collected in the field and from different databases. Bioclimatic data were extracted from the WorldClim database and processed using DIVA-GIS and Maxent software. The Braun-Blanquet quadrat method was used for the phytosociological study. Results showed that the distribution of E. giganteus in its wild state is restricted to sub-Saharan Africa. This distribution is likely conditioned by altitude (1000 m–2600 m), light, temperature, and rainfall. The bioclimatic variables that best explained this distribution were the mean annual temperature (Bio1: 38.8%) and the precipitation of the coldest quarter (Bio19: 24.9%), and their favorable ranges were between 2°C–32°C and 300 mm–1800 mm, respectively. E. giganteus is a heliophilic plant that prefers well-drained substrates and would not have a requirement for organic matter. The floristic analysis of the E. giganteus community identified 68 plant species in 59 genera and 28 botanical families, with the most represented family being the Asteraceae (49%). The average species richness per quadrat was 8 species, dominated by herbs. Species consistent with E. giganteus were Aspilia africana (Pers.) C. D. Adams and Imperata cylindrica (L.) P. Beauv. Chamaephytes and Phanerophytes were dominant among the biological types, while the phytogeographic types were dominated by Pantropical species (38.23%). The most represented diaspore types and modes of dissemination were pogonochores (35.85%) and anemochores (55.38%).

Evaluation of mutagenic, cytotoxic, mitochondrial dysfunction, apoptotic activity, and acute toxicity of ethanolic extract of Cissus quadrangularis

Recent studies have focused on exploring the efficacy of Cissus quadrangularis extract (EECQ) against various metabolic disorders involving the liver as the prime target organ, suggesting a considerable threat of hepatotoxicity in the person encountering it. Consequently, the current study was aimed to unravel the mutagenic, cytotoxic, mitochondrial dysfunction, apoptotic activity in HepG2 cells, and acute toxicity of EECQ. MTT, SRB, trypan blue dye exclusion, and lactate dehydrogenase (LDH) assay were performed in HepG2 cell lines to determine the cytotoxicity of the extract. The mutagenic potential was determined by the Ames test using various strains of Salmonella typhimurium. Acute toxicity was done at a dose of 2000 mg/kg in Sprague Dawley rats. MTT and SRB cytotoxicity assays demonstrated dose-dependent cytotoxicity of extract. The three highest noncytotoxic doses from the above assay, investigated by trypan blue dye exclusion and LDH assay, did not reveal cytotoxicity. Besides, mitochondrial dysfunction was determined by measuring cellular and mitochondrial ROS, ATP, NAD, mitochondrial membrane potential, Bax/Bcl2 ratio, mitochondrial and cytoplasmic cytochrome c, and apoptosis-inducing factor, were found to be equivalent in both extract exposed and unexposed cells. Moreover, the apoptotic cell morphology and the expression of pro-apoptotic mRNAs and proteins were equivalent in both the group. In acute toxicity, EECQ in rats did not cause any significant change in body weight, liver index, and liver function test. All-encompassing, the present study unraveled that EECQ is not mutagenic, cytotoxic, nor apoptotic in human hepatic cells, as well as neither acute toxicity.

Metabolic Profiling by GC-MS, In Vitro Biological Potential, and In Silico Molecular Docking Studies of Verbena officinalis

Verbena officinalis L. is a traditionally important medicinal herb that has a rich source of bioactive phytoconstituents with biological benefits. The objective of this study was to assess the metabolic profile and in vitro biological potential of V. officinalis. The bioactive phytoconstituents were evaluated by preliminary phytochemical studies, estimation of polyphenolic contents, and gas chromatography-mass spectrometry (GC-MS) analysis of all fractions (crude methanolic, n-hexane, ethyl acetate, and n-butanol) of V. officinalis. The biological investigation was performed by different assays including antioxidant assays (DPPH, ABTS, CUPRAC, and FRAP), enzyme inhibition assays (urease and α-glucosidase), and hemolytic activity. The ethyl acetate extract had the maximum concentration of total phenolic and total flavonoid contents (394.30 ± 1.09 mg GAE·g^-1 DE and 137.35 ± 0.94 mg QE·g^-1 DE, respectively). Significant antioxidant potential was observed in all fractions by all four antioxidant methods. Maximum urease inhibitory activity in terms of IC₅₀ value was shown by ethyl acetate fraction (10 ± 1.60 µg mL^-1) in comparison to standard hydroxy urea (9.8 ± 1.20 µg·mL^-1). The n-hexane extract showed good α-glucosidase inhibitory efficacy (420 ± 20 µg·mL^-1) as compared to other extract/fractions. Minimum hemolytic activity was found in crude methanolic fraction (6.5 ± 0.94%) in comparison to positive standard Triton X-100 (93.5 ± 0.48%). The GC-MS analysis of all extract/fractions of V. officinalis including crude methanolic, n-hexane, ethyl acetate, and n-butanol fractions, resulted in the identification of 24, 56, 25, and 9 bioactive compounds, respectively, with 80% quality index. Furthermore, the bioactive compounds identified by GC-MS were analyzed using in silico molecular docking studies to determine the binding affinity between ligands and enzymes (urease and α-glucosidase). In conclusion, V. officinalis possesses multiple therapeutical potentials, and further research is needed to explore its use in the treatment of chronic diseases.

Natural products for the treatment and management of diabetes mellitus in Zimbabwe-a review

Use of medicinal plants and herbs in the treatment and management of diseases, including diabetes mellitus and its complications remains an integral part of African tradition. In Zimbabwe, nearly one million people are living with diabetes mellitus. The prevalence of diabetes mellitus in Zimbabwe is increasing every year due to lifestyle changes, and has accelerated the use of traditional medicines for its treatment and management in urban areas. In addition, the high cost of modern medicine has led many people in rural parts of Zimbabwe to rely on herbal plant medicine for the treatment of diabetes mellitus and its complications. This review highlights a number of studies carried out to evaluate the antidiabetic properties of indigenous plants found in Zimbabwe with the goal of treating diabetes mellitus. Further, we discuss the mechanism of action of various plant extracts in the treatment and management of diabetes mellitus. Together, this review article can open pathways leading to discovery of new plant derived medicines and regularization of use of crude plant remedies to treat diabetes mellitus by the Zimbabwean government and others across Africa.

Indigenous Nigeria medicinal herbal remedies: A potential source for therapeutic against rheumatoid arthritis

Rheumatoid arthritis (RA) is a debilitating disease associated with locomotion impairment, and conventional therapeutic drugs are not optimal for managing RA. There is an avalanche of medications used for the management of RA. Still, studies have shown that they are associated with severe side effects, including hepatotoxicity, retinopathy, and cardiotoxicity disorders of the central nervous system (CNS), skin, blood, and infections. Complementary and alternative medicine (CAM) is currently gaining attention as a novel panacea for managing debilitating diseases, such as RA. Nigerian folk herbal remedies are replete with a plethora of curative medicine, albeit unvalidated scientifically but with seemingly miraculous provenance. Studies of the identification of bioactive compounds present in these botanicals using advanced spectral analytical techniques have enhanced our understanding of the role of Nigerian herbal remedies in the treatment and management of RA. Interestingly, experimental studies abound that the bioactive compounds present in the extracts of plant botanicals protected animals from the development of RA in different experimental models and reduced the toxicity associated with conventional therapeutics. Validated mechanisms of RA amelioration in human and animal models include suppression of the expression of NF-κB, IL-1β, TNF-α, IL-6, IL-8, IL-17, IL-23, chemokines, TGF-β, RANKL, RANK, iNOS, arginase, COX-2, VEGFA, VEGFR, NFATC1, and TRAP in the synoviocytes. Decreased ROS, NO, MDA, carbonyl groups, and PGE₂ in the synovial fluid increased the expression of PPARα/γ; antioxidant and anti-inflammatory molecules also improve RA etiology. In this mini-review, we discuss the global burden of RA, the novel role of plant-based botanicals as potential therapeutics against signaling pathways in RA. Also addressed is the possible repurposing/reprofiling of plant botanicals to increase their therapeutic index among RA patients that patronize traditional healers in Nigeria with a global projection.

Prophylactic Use of Natural Products against Developmentally Programmed Metabolic Syndrome

Parental dietary choices and/or nutritional interventions in the offspring are critical to early life development, especially during the periods of active developmental plasticity in the offspring. Exposure to a high-fructose, high-fat diet during the fetal or neonatal period predisposes the affected individuals to the development of one or more features of metabolic syndrome, such as dyslipidemia, insulin resistance, diabetes, and associated cardiovascular diseases, later in their life. Owing to the increasing global prevalence of metabolic syndrome and multiple side effects that accompany conventional medicines, much attention is directed towards medicinal plants and phytochemicals as alternative interventions. Several studies have investigated the potential of natural agents to prevent programmed metabolic syndrome. This present review, therefore, highlights an inextricable relationship between the administration of medicinal plants or phytochemicals during the intrauterine or neonatal period, and the prevention of metabolic dysfunction in adulthood, while exploring the mechanisms by which they exert such an effect. The review also identifies plant products as a novel approach to the prevention and management of metabolic syndrome.

Antidepressant Effects of South African Plants: An Appraisal of Ethnobotanical Surveys, Ethnopharmacological and Phytochemical Studies

Globally, the search for safe and potent natural-based treatment for depression is receiving renewed interest given the numerous side-effects associated with many existing drugs. In South Africa, the use of plants to manage depression and related symptoms is fairly documented among different ethnic groups. In the current study, we reviewed existing ethnobotanical, ethnopharmacological and phytochemical studies on South African medicinal plants used to manage depression. Electronic databases were accessed for scientific literature that meets the inclusion criteria. Plants with ethnobotanical evidence were subjected to a further pharmacological review to establish the extent (if any) of their effectiveness as antidepressants. Critical assessment resulted in 20 eligible ethnobotanical records, which generated an inventory of 186 plants from 63 plant families. Due to the cultural differences observed in the definition of depression, or lack of definition in some cultures, most plants are reported to treat a wide range of atypical symptoms related to depression. Boophone disticha, Leonotis leonurus and Mentha longifolia were identified as the three most popular plants, with over eight mentions each from the ethnobotanical records. The dominant families were Asteraceae (24), Fabaceae (16), Amaryllidaceae (10), and Apocynaceae (10) which accounted for about 32% of the 186 plants. Only 27 (≈14.5%) of the plants have been screened for antidepressant activity using in vitro and in vivo models. Agapanthus campanulatus, Boophone disticha, Hypericum perforatum, Mondia whitei and Xysmalobium undulatum, represent the most studied plants. Phytochemical investigation on nine out of the 27 plants revealed 24 compounds with antidepressant-like effects. Some of these included buphanidrine and buphanamine which were isolated from the leaves of Boophone disticha, Δ⁹-tetrahydrocannabinol, cannabidiol and cannabichromene obtained from the buds of Cannabis sativa and carnosic acid, rosmarinic acid and salvigenin from Rosmarinus officinalis, A significant portion (≈85%) of 186 plants with ethnobotanical records still require pharmacological studies to assess their potential antidepressant-like effects. This review remains a valuable reference material that may guide future ethnobotanical surveys to ensure their robustness and validity as well as database to identify promising plants to screen for pharmacology efficacy.

Cytotoxicity of Cymbopogon citratus (DC) Stapf fractions, essential oil, citral, and geraniol in human leukocytes and erythrocytes

ETHNOPHARMACOLOGY RELEVANCE

Our recently published paper demonstrated that ethyl acetate fractions obtained from Cymbopogon citratus (DC.) Stapf (C. citratus) leaves, which are consumed as infusion in folk medicine due to their therapeutic properties, are rich in polyphenols and exhibit promising antioxidant activity by acting through different mechanisms in vitro. However, studies regarding the toxicity of these fractions are necessary to investigate their safe use in future biomedical applications.

AIM OF THE STUDY

This study aimed to investigate the toxicity of ethyl acetate (obtained in acidic and basic conditions and after the essential oil removal from the leaves) and chloroform fractions, essential oil, and its pure constituents, citral and geraniol.

MATERIALS AND METHODS

The toxicity of C. citratus samples was evaluated by using Artemia salina (A. salina) and human blood cells (leukocytes and erythrocytes).

RESULTS

The A. salina lethality assay demonstrated that C. citratus fractions were moderately toxic with LC₅₀ values ranging from 146.12 to 433.15 μg mL^-1, whereas the essential oil and isolated compounds were highly toxic with LC₅₀ lower than 100 μg mL^-1. Leukocyte viability decreased after incubation in the presence of the fractions obtained after the essential oil removal from the plant leaves, as well as in the presence of essential oil, citral and geraniol. The same samples increased the osmotic fragility of erythrocytes, and field emission gun scanning electron microscopy (FESEM) analysis revealed significant changes in cell morphology. Interestingly, our results suggest that the previous removal of essential oil from plant leaves facilitated the extraction of cytotoxic compounds from C. citratus.

CONCLUSIONS

It was demonstrated that C. citratus ethyl acetate and chloroform fractions, essential oil, as well citral and geraniol were considered toxic to A. salina, cytotoxic to human blood cells and showed to induce alterations in the erythrocyte membrane at higher concentrations. These fractions will be further investigated to identify the phytochemicals involved in the observed cytotoxic effects and explored using in vivo models.

Progress in Immunoassays of Toxic Alkaloids in Plant-Derived Medicines: A Review

Plants are the cradle of the traditional medicine system, assuaging human or animal diseases, and promoting health for thousands of years. However, many plant-derived medicines contain toxic alkaloids of varying degrees of toxicity that pose a direct or indirect threat to human and animal health through accidental ingestion, misuse of plant materials, or through the food chain. Thus, rapid, easy, and sensitive methods are needed to effectively screen these toxic alkaloids to guarantee the safety of plant-derived medicines. Antibodies, due to their inherent specificity and high affinity, have been used as a variety of analytical tools and techniques. This review describes the antigen synthesis and antibody preparation of the common toxic alkaloids in plant-derived medicines and discusses the advances of antibody-based immunoassays in the screening and detection of toxic alkaloids in plants or other related matrices. Finally, the limitations and prospects of immunoassays for toxic alkaloids are discussed.

Health benefits and biological activities of spiny monkey orange (Strychnos spinosa Lam.): An African indigenous fruit tree

ETHNOPHARMACOLOGICAL RELEVANCE

Spiny monkey orange (Strychnos spinosa Lam.) is an African endemic fruit tree that is widely consumed by humans and animals for its nutritional value. In folk medicine, different parts of S. spinosa are widely used for the management of the health and well-being of humans and livestock.

AIM

We provide a critical appraisal on the ethnobotanical uses, nutritional and pytochemical as well as the biological activities of S. spinosa.

METHODS

Articles were mined from online databases such as Google Scholar, PubMed, Science Direct, SciELO and SpringerLink. We captured research outputs that aligned with the scope of the review.

RESULTS

Strychnos spinosa remains a commonly consumed fruit due to its high nutritional (e.g. carbohydrates, crude protein and fats) content and energy. In folk medicine, different parts of S. spinosa are prescribed as remedy for diverse medical conditions especially for treating malaria, diabetes, snakebites, skin-related conditions and sexually transmitted infections in humans as well as sleeping sickness in livestock. Together with essential oils, more than 25 compounds have been profiled using Gas chromatography-mass spectrometry (GC-MS), and approximately 45 compounds have been isolated and structurally elucidated using diverse spectroscopic techniques such as UV-visible, Infrared (IR), Nuclear Magnetic Resonance (NMR) and mass spectroscopy (MS). Strychnos spinosa exerts varying degrees of biological activities against different microorganisms (bacteria and fungi) and parasites (plasmodia, trypanosomes and ticks) responsible for many diseases in humans and livestock. Furthermore, low to moderate enzyme-inhibitory effects of S. spinosa extracts suggest its ability to mitigate pains, inflammations and diabetics as well as snakebite venom. Increasing evidence from the in vivo studies support the use of the plant as a popular remedy for managing diabetics in folk medicine. The low cytotoxic effect of the plant extracts against different cell lines could be an indication of its relative safety.

CONCLUSION

Strychnos spinosa exhibits various health-promoting benefits due to its diverse nutritional and phytochemical constituents. Given that the majority of the existing evidence on these aforementioned therapeutic properties and safety are in vitro-based, the clinical significance of these results remain limited.

Potential Benefits of Antiviral African Medicinal Plants in the Management of Viral Infections: Systematic Review

Background: Viruses cause various human diseases, some of which become pandemic outbreaks. This study synthesized evidence on antiviral medicinal plants in Africa which could potentially be further studied for viral infections including Coronavirus disease 2019 (COVID-19) treatment.

Methods: PUBMED, CINAHIL, Scopus, Google Scholar, and Google databases were searched through keywords; antiviral, plant, herb, and Africa were combined using “AND” and “OR”. In-vitro studies, in-vivo studies, or clinical trials on botanical medicine used for the treatment of viruses in Africa were included.

Results: Thirty-six studies were included in the evidence synthesis. Three hundred and twenty-eight plants were screened for antiviral activities of which 127 showed noteworthy activities against 25 viral species. These, were Poliovirus (42 plants), HSV (34 plants), Coxsackievirus (16 plants), Rhinovirus (14plants), Influenza (12 plants), Astrovirus (11 plants), SARS-CoV-2 (10 plants), HIV (10 plants), Echovirus (8 plants), Parvovirus (6 plants), Semiliki forest virus (5 plants), Measles virus (5 plants), Hepatitis virus (3 plants), Canine distemper virus (3 plants), Zika virus (2 plants), Vesicular stomatitis virus T2 (2 plants). Feline herpesvirus (FHV-1), Enterovirus, Dengue virus, Ebola virus, Chikungunya virus, Yellow fever virus, Respiratory syncytial virus, Rift Valley fever virus, Human cytomegalovirus each showed sensitivities to one plant.

Conclusion: The current study provided a list of African medicinal plants which demonstrated antiviral activities and could potentially be candidates for COVID-19 treatment. However, all studies were preliminary and in vitro screening. Further in vivo studies are required for plant-based management of viral diseases.

Insights into the Protective Effects of Thymoquinone against Toxicities Induced by Chemotherapeutic Agents

The drugs used to treat cancer not only kill fast-growing cancer cells, but also kill or slow the growth of healthy cells, causing systemic toxicities that lead to altered functioning of normal cells. Most chemotherapeutic agents have serious toxicities associated with their use, necessitating extreme caution and attention. There is a growing interest in herbal remedies because of their pharmacological activities, minimal side effects, and low cost. Thymoquinone, a major component of the volatile oil of Nigella sativa Linn, also known as black cumin or black seeds, is commonly used in Middle Eastern countries as a condiment. It is also utilized for medicinal purposes and possesses antidiabetic, anti-cancer, anti-inflammatory, hepatoprotective, anti-microbial, immunomodulatory, and antioxidant properties. This review attempts to compile the published literature demonstrating thymoquinone's protective effect against chemotherapeutic drug-induced toxicities.

Phytodentistry in Africa: prospects for head and neck cancers

Background

Orthodox dentistry has undergone significant changes in recent times with the introduction of various omics and molecular targeted therapies both at the experimental/trial and clinical implementation level. Although, significant milestones have been achieved in the molecular dentistry field in the past decade, there remains a dearth of application of phytopharmacological innovation in personalized and targeted therapies for dental diseases.

Main body

From time immemorial, plant products have long been an integral aspect of dental practice ranging from chewing sticks/herbal kinds of toothpaste to dental/impression materials. The current era of precision medicine seeks to apply a multipronged molecular and bio-computational approaches to solve fundamental medical problems that have hitherto remained difficult. Remarkable changes in the molecular/omics era, have transformed empirical therapies into personalized/individualized ones. Furthermore, the combinatorial application and the widespread introduction of high-throughput molecular tools such as pharmacogenomics, phytopharmacology, metabolomics, mathematical modelling, and genetic engineering inter alia, has tremendously improved the diagnostic and therapeutic landscape of medicine. Additionally, the variable molecular epidemiology of diseases among different population and emerging molecular evidence warrants the use of customized novel theranostic techniques. Unfortunately, the footprint of such emerging application is sparse in dental diseases such as maxillofacial cancers.

Conclusion

Hence, this review seeks to evaluate the potential application of phytopharmacological approaches to head and neck cancers in a resource-limited environment, such as Africa.

A Review of Plant-Based Therapies for the Treatment of Urinary Tract Infections in Traditional Southern African Medicine

Urinary tract infections (UTIs) are amongst the most common bacterial infections globally, with ∼11% of the world's population contracting at least one infection annually. Several South African plants are used in traditional healing systems to treat UTIs, yet the therapeutic potential of these plants against bacteria that cause UTI remains poorly explored. This study documents southern African plant species used traditionally to treat UTIs. An extensive literature review was undertaken to document the southern African plant species that are used in traditional South African medicine to treat UTIs, thereby highlighting gaps in the current research that require further study. One hundred and fifty-three southern African plant species that are used to treat UTIs were identified. Eighty-five southern African plants were identified as having noteworthy inhibitory activity against the major UTI-causing bacteria. Few of those studies screened against all of the bacterial causes of UTIs, and none of those studies examined the mechanism of action of the plant preparations. Furthermore, many of those studies did not test the toxicity of the plant extracts, so an evaluation of the safety for therapeutic usage was lacking. Substantial further research is to determine their potential for therapeutic use.

Antimalarial, Antioxidant, and Toxicological Evaluation of Extracts of Celtis africana, Grosseria vignei, Physalis micrantha, and Stachytarpheta angustifolia

In many parts of the world, malaria undoubtedly poses a serious threat to health care systems. Malaria treatment has increasingly become complicated, primarily due to the emergence of widespread resistance of the malaria parasites to cheap and affordable malaria therapeutics. The use of herbal remedies to treat various ailments, including malaria and malaria-like ailments in Ghana is common. We herein report on the antiplasmodial and antioxidant activities as well as toxicological evaluation of four medicinal plants (Celtis africana, Grosseria vignei, Physalis micrantha, and Stachytarpheta angustifolia) commonly used to treat malaria in Ghana. Following Soxhlet extraction of plant samples in ethanol, extracts were screened against Plasmodium falciparum (3D7 strain) in an in vitro antiplasmodial assay. The phosphomolybdenum and DPPH (1, 1-diphenyl-2 picrylhydrazyl) assays were used to evaluate antioxidant activities while toxicity assessment was carried out in mice using the acute toxicity test and kidney and liver function tests. Extracts from Celtis africana and Physalis micrantha were very active towards the parasites with half-maximal inhibitory concentrations (IC50's) of 29.1 and 3.5 µg/mL, respectively. Extracts of Grosseria vignei and Stachytarpheta angustifolia were inactive, having IC50 values greater than 50 µg/mL. All extracts exhibited excellent total antioxidant capacities (>800 mg/g AAE) and good DPPH radical scavenging potential (IC50 range of 300-900 µg/mL). The median lethal dose (LD50) of all extracts in the toxicological evaluation was greater than 2000 mg/kg and there was no effect of extracts on the levels and activities of key biomarkers of liver and kidney function. The activities of these plants obtained in this study partly give credence to their folkloric use in herbal medicines and suggest that they could provide promising lead compounds for malaria drug discovery programs.

South Africa's Best BARK Medicines Prescribed at the Johannesburg Muthi Markets for Skin, Gut, and Lung Infections: MIC's and Brine Shrimp Lethality

Indigenous trade of medicinal plants in South Africa is a multi-million-rand industry and is still highly relevant in terms of primary health care. The purpose of this study was to identify today's most traded medicinal barks, traditionally and contemporaneously used for dermatological, gastrointestinal, and respiratory tract infections; then, to investigate the antimicrobial activity and toxicity of the respective extracts and interpret outcomes in light of pharmacokinetics. Thirty-one popularly traded medicinal barks were purchased from the Faraday and Kwa Mai-Mai markets in Johannesburg, South Africa. Information on the medicinal uses of bark-based medicines in modern commerce was recorded from randomly selected traders. The minimum inhibitory concentration (MIC) method was used for antimicrobial screening, and brine shrimp lethality was used to determine toxicity. New medicinal uses were recorded for 14 bark species. Plants demonstrating some broad-spectrum activities against tested bacteria include Elaeodendron transvaalense, Erythrina lysistemon, Garcinia livingstonei, Pterocelastrus rostratus, Rapanea melanophloeos, Schotia brachypetala, Sclerocarya birrea, and Ziziphus mucronata. The lowest MIC value of 0.004 mg/mL was observed against Staphylococcus epidermidis for a dichloromethane bark extract of E. lysistemon. The tested medicinal barks were shown to be non-toxic against the Artemia nauplii (brine shrimp) bioassay, except for a methanol extract from Trichilia emetica (69.52% mortality). Bacterial inhibition of bark extracts with minimal associated toxicity is consistent with the safety and valuable use of medicinal barks for local muthi market customers. Antimicrobial outcomes against skin and gastrointestinal pathogens are feasible because mere contact-inhibition is required in vivo; however, MIC values against respiratory pathogens require further explaining from a pharmacokinetics or pharmacodynamics perspective, particularly for ingested rather than smoked therapies.

Evidence on collaboration of traditional and biomedical practitioners in the management of antimicrobial resistance in sub-Saharan Africa over 15 years: a systematic review protocol

BACKGROUND

The overuse of prescribed antimicrobials, concurrent use of traditional medicine, and prescribed antimicrobials have led to antimicrobial resistance. The absence of collaboration between traditional health practitioners and biomedically trained healthcare professionals can contribute to antimicrobial resistance, treatment failure, overdose, toxicity, and misadministration. This scoping review explores the evidence on collaboration between traditional health practitioners and biomedically trained healthcare professionals to reduce antimicrobial resistance and treatment failure in bacterial and viral diseases.

METHODS

We will search for electronic databases such as Science Direct, Google Scholar, PubMed, and MEDLINE via EBSCOhost. We will also search reference lists of included studies. A two-stage mapping procedure will be carried out. Stage one (1) will consist of the title, abstracts, and full article screening, respectively. A pilot screening form guided by the defined eligibility criteria will be used. In stage two (2), data will be extracted from the included studies. Two reviewers will conduct parallel screening and data extraction. Mixed methods appraisal tool (MMAT) will be used to assess the quality of the included studies. NVIVO version 11 will be employed to aid pertinent thematic analysis. The outcomes of interest will be as follows: Primary outcome will be preventing and reducing antimicrobial resistance. The secondary effect is the effective collaboration between traditional healthcare practitioners and biomedically healthcare professionals.

DISCUSSION

This review anticipates uncovering pertinent publications reporting the evidence of collaboration between traditional health practitioners and biomedically trained healthcare professionals to reduce antimicrobial resistance in sub-Saharan Africa. The sum-up of evidence acquired from the included studies will help guide future research. The result of the study will be print and electronically exposed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, CRD42017072952.

Identification of Anxiolytic Potential of Niranthin: In-vivo and Computational Investigations

Anxiety is an unpleasant state, which can critically decrease the quality of life is often accompanied by nervous behaviour and rumination. Niranthin is a lignan isolated from various Phyllanthus sources. The literature survey on niranthin highlights wide ranges of the therapeutic potentials. In a present study, based on our previous investigations, we evaluated pure, isolated and characterized niranthin as an anxiolytic agent. The niranthin [6-[(2R,3R)-3-[(3,4-dimethoxyphenyl)methyl]-4-methoxy-2-(methoxymethyl)butyl]-4-methoxy-1,3-benzodioxole] was purchased from commercial source and further subjected for assessment of its anxiolytic potentials using popular animal models including Elevated plus-maze model/test (EPM) and Light & Dark Exploration test (L&D). GABA-A receptor mediation was evaluated by pretreating the mice with the GABA-A receptor antagonist Flumazenil before the EPM task. Molecular docking simulation studies (pdb id: 4COF) carried out by Vlife QSAR software showed that niranthin (docking score: - 62.1714 kcal/mol) have shown comparatively best docking score compared to the standard drug Diazepam (docking score: - 63.1568 kcal/mol). To conclude, Niranthin has probable potential in the management of anxiety disorder. Our in-silico and in-vivo analysis (indirectly) indicated the plausible role of GABA mediation for anxiolytic activity. Although, these studies are preliminary, future in depth experimental explorations will be required to use Niranthin as anti-anxiety drug in near future.

Potential Health Risks of Macro- and Microelements in Commercial Medicinal Plants Used to Treatment of Diabetes

Information on the content of medicinal plants used in the treatment of diabetes is scarce in the literature. The objectives of this study were to determine the levels of macroelements and microelements in three different medicinal plant species including the dry samples and teas from Bauhinia forficata, Eleusine Indica, and Orthosiphon stamineus and assess the human health risks of ingestion of the tea. The content of the dry samples and teas was obtained using the technique of inductively coupled plasma optical emission spectrometry (ICP OES) after microwave digestion procedure. The hazard quotient (HQ) method was used to access the human health risks posed by heavy metal through tea consumption. The results revealed the presence of K, Mg, Na, P, Al, Fe, Zn, Mn, Cu, Ni, and Se in dry samples and plant teas. The dry plants have high concentration of K and P. All dry plants contain Mg, Na, Al, Fe, Mn, Ni, Zn, and Cu above the limit permissible level set by the World Health Organization (WHO). All the hazard index (HI) values in plant teas were found to be within safe limits for human consumption (HI < 1). The plants may have possible action benefits when used in popular medicine. However, the ingestion through capsules prepared by enclosing a plant powder or teas can be harmful to the health of diabetics. The prescription of this plant for the treatment of diabetes should be treated with caution.

Antioxidant, Cytotoxicity and Cytoprotective Potential of Extracts of Grewia Flava and Grewia Bicolor Berries

Objectives

Accumulation of cellular reactive oxygen species (ROS) leads to oxidative stress. Increased production of ROS, such as superoxide anion, or a deficiency in their clearance by antioxidant defences, mediates cellular pathology. Grewia Spp fruits are a source of bioactive compounds and have notable antioxidant activity. Although the antioxidant capacity of Grewia Spp has been studied, there is very limited evidence that links the antioxidant activities of Grewia bicolor and Grewia flava to the inhibition of free radical formation associated with damage in biological systems.

Methods

This study evaluated the protective effects of Grewia bicolor and Grewia flava extracts against free radical-induced oxidative stress and the resulting cytotoxicity effect using HeLa cells. Antioxidant properties determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and total phenolic content (TPC) assays showed significantly higher (p < 0.05) antioxidant activity in Grewia flava (ethanol extract) than Grewia flava (water extract) and Grewia bicolor (ethanol and water extracts).

Results

Using 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide or MTT assay, cytotoxicity results showed that extracts of Grewia bicolor and Grewia flava were less toxic to HeLa cells at tested concentrations compared to the untreated control. This confirmed the low toxicity of these edible fruits at the tested concentrations in HeLa cells. Furthermore, hydrogen peroxide (H₂O₂)-induced cell loss was effectively reduced by pre-incubating HeLa cells with Grewia bicolor and Grewia flava extracts, with Grewia flava (ethanol extract) revealing better protection.

Conclusion

The effect was speculated to be associated with the higher antioxidant activity of Grewia flava (ethanol extract). Additional studies will warrant confirmation of the mechanism of action of such effects.

Comparative antimalarial, toxicity and mito-protective effects of Diospyros mespiliformis Hochst. ex A. DC. and Mondia whitei (Hook.f.) Skeels on Plasmodium berghei infection in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Diospyros mespiliformis Hochst. ex A. DC. and Mondia whitei (Hook.f.) Skeels are traditionally used in Africa for the treatment of malaria. However, scientific evidence to substantiate this folkloric claim and their effects on liver mitochondria during malaria treatment have not been reported.

AIM OF THE STUDY

This study investigated the efficacy of D. mespiliformis and M. whitei against chloroquine-sensitive and resistant strains of malarial parasites in mice. It also investigated the toxicity and protection against cellular organelles like mitochondria.

MATERIALS AND METHODS

Male Swiss mice were infected with a chloroquine resistant (ANKA) strain of Plasmodium berghei and were treated via oral gavage with methanol extracts of D. mespiliformis and M. whitei reconstituted in diluted dimethylsulfoxide as vehicle (DMSO, 5% v/v) for five consecutive days. Percentage parasite load and clearance were assessed by microscopy. The infected control was treated with the vehicle. Hematological indices were assessed using standard procedures. Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were determined using assay kits. Hepatic mitochondria were isolated via centrifugation, and their permeability transition (mPT), ATPase (mATPase) activity and lipid peroxidation (mLPO) were determined spectroscopically. Liver tissue histology was carried out by standard laboratory procedures. Phytochemical analysis of both extracts were performed using LC-MS to identify the most prominent compounds from each of the extracts.

RESULTS

After treatment on day 5, D. mespiliformis and M. whitei at 400 mg/kg decreased mean values for: percentage parasitemia (5.0 ± 1.0, 2.0 ± 0.2), increased Packed Cell Volume (PCV) (36.0 ± 1.4, 36.0 ± 0.0%) and platelets (2.0 ± 1.4, 2.0 ± 2.8 × 10⁵mm³) relative to the untreated control (20.0 ± 5.2; 30.0 ± 0.0%; 1.4 ± 1.4 × 10⁵ mm³, respectively). At the same dose, D. mespiliformis and M. whitei decreased ALT (8.0 ± 3.8, 24.2 ± 4.0U/L), AST (6.2 ± 0.8, 8.0 ± 0.9U/L) and ALP (56.0 ± 0.7, 51.0 ± 1.0U/L) activities compared to the infected control (77.0 ± 10.9U/L, 14.0 ± 0.7U/L and 76.0 ± 6.0U/L, respectively). Both D. mespiliformis and M. whitei reversed mPT opening, decreased mATPase enhancement and mLPO, relative to the control. Histopathology of the liver showed extensive hemorrhagic lesions and severe disseminated congestion in the infected control while both D. mespiliformis and M. whitei were well tolerated at the highest dose. The LC-MS analysis of D. mespiliformis showed the presence of betulinic acid, tocopherol and kaempferol with antimalarial and antioxidant properties while the M. whitei sample contained coumarin and chlorogenic acid that have antimalarial and hepato-protective properties.

CONCLUSIONS

D.mespiliformis and M. whitei show antimalarial effects against resistant Plasmodium berghei infection, enhanced cell viability, mito-protection and are not toxic in mice.

CdO/CdCO3 nanocomposite physical properties and cytotoxicity against selected breast cancer cell lines

Cadmium Oxide nanoparticles have the lowest toxicity when compared to nanoparticles of other semiconductors and they are not detrimental to human and mammalian cells, thereby making them candidates for targeting cancer cells. Synadenium cupulare plant extracts were used to synthesize CdO/CdCO3 nanocomposite using cadmium nitrate tetrahydrate 98% as a precursor salt. The resultant nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy, ultraviolet visible spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The nanoparticles were then screened for effect on breast cancer cell lines (MCF-7 and MDA MB-231) and Vero cell line to determine their growth inhibition effect. Cytotoxicity effect was evaluated using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. XRD showed the peaks of monteponite CdO and otavite CdCO3 nanoparticles. TEM results showed irregular and spherical particles of varying sizes, whilst SEM revealed a non-uniform morphology. FTIR results showed peaks of functional groups which are present in some of the phytochemical compounds found in S. cupulare, and point to the presence of CdO. Annealed CdO/CdCO3 NPs showed selectivity for MCF7 and MDA MB231 in comparison to Vero cell line, thereby supporting the hypothesis that cadmium oxide nanoparticles inhibit growth of cancerous cells more than non-cancerous cells.

Screening for toxicological and anti-diabetic potential of n-hexane extract ofTapinanthus bangwensisleaves

Health forecasters predict that cases of diabetes will double in 2030; hence proactive action is required to salvage this problem. Thus, this study was undertaken to evaluate the toxicological and anti-diabetic potential of n-hexane extract of T. bangwensis leaves on α-amylase and α-glucosidase activity. The phytochemical screening, antioxidant activity as well as the inhibitory effect of the plant extract was determined by UV-spectrophotometry method while brine shrimp and Allium cepa methods were used for the toxicity study. Preliminary phytochemical screening detected the presence of flavonoid, phenol, tannin, alkaloid and cardiac glycoside whereas phlobatanin, steroid, terpenoid and saponin were absent. The result also showed that flavonoid concentration was the highest compared to others. The 2,2-diphenyl-1-picrylhydrazine (DPPH) and nitric oxide (NO) results showed that the plant extract exhibited significant antioxidant activity particularly at the highest concentration (100 µg/ml). Brine shrimp lethality result showed that the highest mortality rate of nauplii and median inhibition concentration (IC50) are 97% and 7.46 ± 0.33 µg/ml respectively. Furthermore, the results also revealed that mitotic index, root growth length and mitotic division (cytotoxicity indicators) decreased as concentration increases. Finally, the results showed that the plant extract exhibited significant inhibitory effect on α-amylase and α-glucosidase activities at 100 µg/ml; nevertheless, the effect was higher on α-amylase than α-glucosidase activity. In summary, the significant antioxidant and inhibitory effects may be attributed to the presence of the phytochemicals mentioned above. It can therefore be concluded that T. bangwensis leaves may demonstrate potent anti-diabetic effect.

The traditional use of southern African medicinal plants for the treatment of bacterial respiratory diseases: A review of the ethnobotany and scientific evaluations

ETHNOPHARMACOLOGICAL RELEVANCE

Multiple plant species were used traditionally in southern Africa to treat bacterial respiratory diseases. This review summarises this usage and highlights plant species that are yet to be verified for these activities.

AIM OF THE STUDY

This manuscript reviews the traditional usage of southern African plant species to treat bacterial respiratory diseases with the aim of highlighting gaps in the literature and focusing future studies.

MATERIALS AND METHODS

An extensive review of ethnobotanical books, reviews and primary scientific studies was undertaken to identify southern African plants which are used in traditional southern African medicine to treat bacterial respiratory diseases. We also searched for southern African plants whose inhibitory activity against bacterial respiratory pathogens has been conmfirmed, to highlight gaps in the literature and focus future studies.

RESULTS

One hundred and eighty-seven southern African plant species are recorded as traditional therapies for bacterial respiratory infections. Scientific evaluations of 178 plant species were recorded, although only 42 of these were selected for screening on the basis of their ethnobotanical uses. Therefore, the potential of 146 species used teraditionally to treat bacterial respiratory diseases are yet to be verified.

CONCLUSIONS

The inhibitory properties of southern African medicinal plants against bacterial respiratory pathogens is relatively poorly explored and the antibacterial activity of most plant species remains to be verified.

Screening selected medicinal plants for potential anxiolytic activity using an in vivo zebrafish model

RATIONALE

Medicinal plants are used extensively in many countries to treat conditions related to the central nervous system (CNS), and there is renewed interest to explore natural products, which may exhibit CNS activity.

OBJECTIVE

In this study, seven plants were selected based on literature reports of their ethnopharmacological use in treating anxiety-related conditions and assayed in a zebrafish model.

METHODS

Crude extracts were prepared with solvents of different polarities, and the maximum tolerated concentration (MTC) of these crude extracts was established. The anxiolytic activity of the crude extracts was determined using 5-day post-fertilization (dpf) zebrafish larvae. General locomotor activity and reverse-thigmotaxis behavior (indicative of anxiolytic activity) were analyzed under continuous illumination and alternating light-dark challenges, which induced anxiety in the zebrafish larvae.

RESULTS

Of the 28 extracts tested, 13 were toxic according to the MTC values obtained. Larvae were subsequently treated with the 15 non-toxic extracts, at a dose determined in the MTC assay or with 1% DMSO as control. The anxiolytic activity (reverse-thigmotaxis) was demonstrated by an increase in the percentage time spent by the larvae in the central arena of the well. Of the 15 non-toxic extracts tested, the Sceletium tortuosum water extract exhibited the most promising anxiolytic activity.

CONCLUSIONS

The zebrafish model was effective in studying anxiety-related behavior. Thus, the study confirmed that S. tortuosum mitigates anxiety in zebrafish larvae, a step towards the full in vivo validation of the traditional use of the plant.

In Vitro Antidiabetic and Antioxidant Effects of Different Extracts of Catharanthus roseus and Its Indole Alkaloid, Vindoline

The Catharanthus roseus plant has been used traditionally to treat diabetes mellitus. Scientific evidence supporting the antidiabetic effects of this plant's active ingredient-vindoline has not been fully evaluated. In this study, extracts of C. roseus and vindoline were tested for antioxidant activities, alpha amylase and alpha glucosidase inhibitory activities and insulin secretory effects in pancreatic RIN-5F cell line cultured in the absence of glucose, at low and high glucose concentrations. The methanolic extract of the plant showed the highest antioxidant activities in addition to the high total polyphenolic content (p < 0.05). The HPLC results exhibited increased concentration of vindoline in the dichloromethane and the ethylacetate extracts. Vindoline showed noticeable antioxidant activity when compared to ascorbic acid at p < 0.05 and significantly improved the in vitro insulin secretion. The intracellular reactive oxygen species formation in glucotoxicity-induced cells was significantly reduced following treatment with vindoline, methanolic and the dichloromethane extracts when compared to the high glucose untreated control (p < 0.05). Plant extracts and vindoline showed weaker inhibitory effects on the activities of carbohydrate metabolizing enzymes when compared to acarbose, which inhibited the activities of the enzymes by 80%. The plant extracts also exhibited weak alpha amylase and alpha glucosidase inhibitory effects.

Evaluation of Toxicity and Antihyperlipidemic Activity of Spondias Mombin l. Leaves Methanolic Extract in Laboratory Rats

AIMS

To study the toxicological profile and anti-hyperlipidemic effects of Spondias mombin leaves methanolic extract in experimental rats.

BACKGROUND

Preventing high levels of lipids or its recurrence is currently one of the key aims of clinical and experimental studies.

OBJECTIVE

This study was carried out to investigate the toxicological profile and anti-hyperlipidemic effects of methanolic extract of leaves of Spondias mombin.

METHODS

The acute toxicity study was carried out where the limited dose of 2000 mg/kg body weight was administered to five rats at 48 h intervals. The interpretation was prepared and recorded for 24 h. In the sub-acute toxicity study, rats were treated with 250, 500, and 1000 mg/kg doses of the extract every 24 h for 28 days. The hematological, biochemical, and histopathological tests of treated animals were carried out at the end of the test. The anti-hyperlipidemic activity of plant extract (100, 200 mg/kg) was studied on Triton-X-100 induced hyperlipidemia in rats. Histopathological changes in the liver of rats were examined.

RESULTS

For acute and subacute treatment, the extract did not reveal any signs of toxicity or mortality, or any significant effects on hematological, biochemical parameters, and histopathology of organs. The extract demonstrated an important anti-hyperlipidemic result by decreasing the serum levels of cholesterol, TGs, LDL, VLDL, and enhancing HDL.

CONCLUSION

Taking up the evidence of the experimental study, we can conclude that the methanolic extract of Spondias mombin leaves helps in declining hyperlipidemia in rats and it can be safely used for a period of 28 days to treat hyperlipidemia.

Neurobehavioral responses in swiss albino mice induced by an aqueous leaf extract from a medicinal plant named Heliotropium incanum Ruiz & Pav

It is of interest to examine the adverse neuro-behavioural responses on mice treated with the aqueous crude extract of Heliotropium incanum (AEHI), which were evaluated using various behavioral paradigms. On the basis of median lethal dose value, doses of AEHI were chosen to be 150mg/kg and 440mg/kg for further experiment. Four groups comprising of five mice each were divided for the 14 days experiment. Group I, the control group, received distilled water; Group II and III received AEHI (150 mg/kg body weight and 440 mg/kg body weight) respectively; Group IV received standard drugs, Diazepam/Fluoxetine, administered orally. On administration of AEHI, it was revealed that dose 440 mg/kg showed less exploration activity in the hole board test; decrease in the number of squares crossed in locomotory test, time period in the open arm in the plus maze test was significantly reduced and the immobility time was significantly extended in comparison to control and standard drugs. The microscopic study of brain revealed damaged hippocampus along with nerve cells degeneration. Consequently, the results concluded that the outcome of the AEHI produced evidences for the anxiogenic activity in mice.

Acute and sub-chronic toxicity evaluation of the crude methanolic extract of Diospyros mespiliformis hochst ex a. Dc (ebenaceae) and its fractions

•

The oral toxicity effect of crude methanolic extract (CMX) of Diospyros mespiliformis hochst ex a. Dc (ebenaceae) was studied.

•

Crude methanolic extract of D. mespiliformis has an LD50 higher than 5 g/kg post oral treatment in rats, thus relatively safe.

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The leaf and bark ethyl acetate fractions of D. mespiliformis were relatively safe post 28-days repeated treatment in rats.

Diospyros mespiliformis, commonly called Jackal berry or African ebony, belongs to the plant family, Ebenaceae. The roots, barks and leaves have been used traditionally to treat wide varieties of conditions, however, there is limited information and literature reports concerning the toxicity and safety of this plant. The present study was conducted to evaluate the acute and sub-chronic toxicity of the crude methanolic extract of Diospyros mespiliformis and its fraction in Wistar rats. Diospyros mespiliformis was extracted by methanol 96 %. The crude methanolic extract was then fractionated into low, average and high polar compounds using hexane, ethyl acetate and butanol respectively. For the acute toxicity study, the revised limit Dose Test of “Up and Down” procedure according to the OECD guideline was used to determine the median lethal dose (LD₅₀) of the crude methanolic leaf and bark extracts using a single fixed dose (5 g/kg) of the extracts administered by oral-gavage sequentially to 5 female Wistar rats. The rats were observed for instant death and toxicity signs for 24 h and then daily for 14 days. In the sub-chronic toxicity study, the bark and leaf ethyl acetate fractions (extract) was administered orally at doses of 250, 500 and 750 mg/kg bw /day respectively for 28 days to healthy Wistar rats. At the end of the experimental period, body weight, certain haematological, serum biochemical and histopathological parameters were evaluated. Results showed that acute oral administration of crude methanolic extract of Diospyros mespiliformis (5 g/kg bw) produced neither mortality nor visible changes in behavior or any other physiological activities and indicated that the LD₅₀ of crude methanolic leaf and bark extract was greater than 5 g/kg bw in Wistar Rats. In the 28-days repeated dose oral toxicity study, no significant toxic effects was detected in any of the parameters evaluated. In conclusion, the crude methanolic extract was found safe in the acute toxicity study and the ethyl acetate fraction of Diospyros mespiliformis in the sub chronic study in rats could be safe for therapeutic purposes over a period not exceeding 28 days.

Botanical Products in the Treatment and Control of Schistosomiasis: Recent Studies and Distribution of Active Plant Resources According to Affected Regions

Schistosomiasis, a parasitic disease caused by trematodes of the genus Schistosoma, is the second most prevalent parasitic disease in the world. It affects around 200 million people. Clinical treatment, prophylaxis, and prevention are performed in countries susceptible to schistosomiasis. In the pharmacological treatment for an acute form of schistosomiasis, the use of antiparasitics, mainly praziquantel, is more common. As an alternative way, prevention methods such as reducing the population of intermediate hosts (mollusks) with molluscicides are important in the control of this disease by interrupting the biological cycle of this etiological parasite. Despite the importance of pharmacological agents and molluscicides, they have side effects and environmental toxicity. In addition, they can lead to the development of resistance enhancing of parasites, and lead to the search for new and effective drugs, including resources of vegetal origin, which in turn, are abundant in the affected countries. Thus, the purpose of this review is to summarize recent studies on botanical products with potential for the control of schistosomiasis, including anti-Schistosoma and molluscicide activities. In addition, species and plant derivatives according to their origin or geographical importance indicating a possible utility of local resources for countries most affected by the disease are presented.

Bioprospecting for Antibacterial Drugs: a Multidisciplinary Perspective on Natural Product Source Material, Bioassay Selection and Avoidable Pitfalls

Bioprospecting is the exploration, extraction and screening of biological material and sometimes indigenous knowledge to discover and develop new drugs and other products. Most antibiotics in current clinical use (eg. β-lactams, aminoglycosides, tetracyclines, macrolides) were discovered using this approach, and there are strong arguments to reprioritize bioprospecting over other strategies in the search for new antibacterial drugs. Academic institutions should be well positioned to lead the early stages of these efforts given their many thousands of locations globally and because they are not constrained by the same commercial considerations as industry. University groups can lack the full complement of knowledge and skills needed though (eg. how to tailor screening strategy to biological source material). In this article, we review three key aspects of the bioprospecting literature (source material and in vitro antibacterial and toxicity testing) and present an integrated multidisciplinary perspective on (a) source material selection, (b) legal, taxonomic and other issues related to source material, (c) cultivation methods, (d) bioassay selection, (e) technical standards available, (f) extract/compound dissolution, (g) use of minimum inhibitory concentration and selectivity index values to identify progressible extracts and compounds, and (h) avoidable pitfalls. The review closes with recommendations for future study design and information on subsequent steps in the bioprospecting process.

Oxidative Stress Modulation by Cameroonian Spice Extracts in HepG2 Cells: Involvement of Nrf2 and Improvement of Glucose Uptake

Oxidative stress plays a relevant role in the progression of chronic conditions, including cardiometabolic diseases. Several Cameroonian plants, including spices, are traditionally used as herbal medicines for the treatment of diseases where oxidative stress contributes to insulin resistance, like type 2 diabetes mellitus. This study evaluated the antioxidant capacity and the effects on oxidative-stress-induced impairment of glucose uptake of 11 Cameroonian spice extracts. H₂O₂-induced reactive oxygen species (ROS) production by human HepG2 cells was significantly reduced by 8/11 extracts. The most effective extracts, Xylopia parviflora, Echinops giganteus, and Dichrostachys glomerata, showed a concentration-dependent ROS-scavenging activity, which involved Nrf2 translocation into the nucleus. Xylopia parviflora, Tetrapleura tetraptera, Dichrostachys glomerata, Aframomum melegueta, and Aframomum citratum extracts showed the highest antioxidant capacity, according to oxygen radical absorbance capacity (ORAC) (2.52-88 μM Trolox Eq/g of extract), ferric-reducing antioxidant power (FRAP) (40.23-233.84 mg gallic acid Eq/g of extract), and total phenol (8.96-32.96% mg gallic acid Eq/g of extract) assays. In HepG2 cells, glucose uptake was stimulated by 4/11 extracts, similarly to insulin and metformin. H₂O₂-induced oxidative stress reduced glucose uptake, which was rescued by pretreatment with Xylopia aethiopica, Xylopia parviflora, Scorodophloeus zenkeri, Monodora myristica, and Dichrostachys glomerata extracts. The ROS-scavenging ability of the spice extracts may reside in some secondary metabolites observed by phytochemical profiling (reverse-phase high-performance liquid chromatography coupled to a diode array detector (HPLC-UV-DAD)). Further studies are needed to better clarify their biological activities and potential use to control oxidative stress and promote insulin sensitivity.

Impact of Natural Compounds on Neurodegenerative Disorders: From Preclinical to Pharmacotherapeutics

Among the major neurodegenerative disorders (NDDs), Alzheimer’s disease (AD) and Parkinson’s disease (PD), are a huge socioeconomic burden. Over many centuries, people have sought a cure for NDDs from the natural herbals. Many medicinal plants and their secondary metabolites are reported with the ability to alleviate the symptoms of NDDs. The major mechanisms identified, through which phytochemicals exert their neuroprotective effects and potential maintenance of neurological health in ageing, include antioxidant, anti-inflammatory, antithrombotic, antiapoptotic, acetylcholinesterase and monoamine oxidase inhibition and neurotrophic activities. This article reviews the mechanisms of action of some of the major herbal products with potential in the treatment of NDDs according to their molecular targets, as well as their regional sources (Asia, America and Africa). A number of studies demonstrated the beneficial properties of plant extracts or their bioactive compounds against NDDs. Herbal products may potentially offer new treatment options for patients with NDDs, which is a cheaper and culturally suitable alternative to conventional therapies for millions of people in the world with age-related NDDs.