Phytochemical investigation of Aloe pulcherrima roots and evaluation for its antibacterial and antiplasmodial activities

A critical review on the active anti-viral metabolites of bioprospecting traditionally used plant species from semi-arid regions of the subcontinent

Plants are crucial medicinal resources, with 80 % of people relying on them for primary healthcare. The search for natural antiviral compounds is increasing, especially in semi-arid ecosystems where abiotic stress promotes the production of beneficial secondary metabolites. This review highlights semi-arid plants with the potential as functional foods to combat viral diseases and other illnesses. Literature was searched in databases like ScienceDirect to gather information on novel compounds from stress-tolerant semi-arid plant species. These compounds have potential uses in treating viral infections and other health issues such as diabetes and high blood pressure. The review screened 61 semi-arid plants known for their antiviral metabolites. Eight plants were identified with novel antiviral compounds. Key metabolites include agathisflavone, pectic arabinogalactan, azadirachtin, aloin, aloe-emodin, aloesaponarin I, allicin, terpenoids, chlorogenic acids, curcumin, chromones, β-sitosterol, lupeol, oleuropein, carissol, β-amyrin, and ∆-9-tetrahydrocannabinol. Stress-tolerant semi-arid plants are significant sources of metabolites for treating infectious diseases and boosting immune systems. Further research on these metabolites in animal models is needed to verify their efficacy for treating human diseases during endemic and pandemic outbreaks, such as COVID-19.

Antibacterial and Antioxidant Compounds from the Root Extract of Aloe debrana

This study was conducted to isolate and identify the chemical compounds from the roots of Aloe debrana (L.) and evaluate their antioxidant and antibacterial activities. From the acetone (99.5%) extract of the roots of this plant, four anthraquinones, such as chrysophanol (1), asphodeline (2), aloesaponarin I (5), and laccaic acid D-methyl ester (6), and a new catechol derivative, 5-allyl-3-methoxybenzene-1,2-diol (3), were isolated and elucidated by different chromatographic and spectroscopic methods together with linoleic acid (4), respectively. Compounds 2, 3, and 4 were reported here for the first time from this plant and compound 3 from the genus Aloe. The compounds were evaluated for their antioxidant activity using H2O2 and DPPH assays and bactericidal activity against S. aureus and E. coli. Compounds 3 and 6 showed highest antioxidant activities with IC50 values of 19.38 ± 0.64 and 32.81 ± 0.78 μg/mL in DPPH, and 28.52 ± 1.08 and 27.31 ± 1.46 μg/mL in H2O2, respectively. The isolated compounds also demonstrated considerable activity towards S. aureus. Among these compounds, compound 3 exhibited the highest activity (91.20 ± 0.12% and 9.14 ± 0.93 mm at 1.0 mg/mL) against this bacterium. The overall results suggest that the isolated compounds may be considered as potential sources of the bioactive agents to be used in the pharmacological, food, and other industries. Moreover, their high sensitivity against S. aureus may also support the use of A. debrana plant in the traditional medicine to treat wounds. Therefore, the isolated compounds are responsible for medicinal properties of this plant.

New opportunities and perspectives on biosynthesis and bioactivities of secondary metabolites from Aloe vera

Historically, the genus Aloe has been an indispensable part of both traditional and modern medicine. Decades of intensive research have unveiled the major bioactive secondary metabolites of this plant. Recent pandemic outbreaks have revitalized curiosity in aloe metabolites, as they have proven pharmacokinetic profiles and repurposable chemical space. However, the structural complexity of these metabolites has hindered scientific advances in the chemical synthesis of these compounds. Multi-omics research interventions have transformed aloe research by providing insights into the biosynthesis of many of these compounds, for example, aloesone, aloenin, noreugenin, aloin, saponins, and carotenoids. Here, we summarize the biological activities of major aloe secondary metabolites with a focus on their mechanism of action. We also highlight the recent advances in decoding the aloe metabolite biosynthetic pathways and enzymatic machinery linked with these pathways. Proof-of-concept studies on in vitro, whole-cell, and microbial synthesis of aloe compounds have also been briefed. Research initiatives on the structural modification of various aloe metabolites to expand their chemical space and activity are detailed. Further, the technological limitations, patent status, and prospects of aloe secondary metabolites in biomedicine have been discussed.

Quinones: Biosynthesis, Characterization of 13 C Spectroscopical Data and Pharmacological Activities

Quinones are natural products widely distributed in nature, which are involved in stages of several vital biological processes, with mostly having a variety of pharmacological properties. The main groups comprising most of these compounds are benzoquinones, naphthoquinones, anthraquinones, and phenanthraquinones. Quinone isolation has been a focus of study around the world in recent years; for this reason, this study approaches the junction of natural quinones identified by 13 C Nuclear Magnetic Resonance (NMR) spectroscopic analytical techniques. The methodology used to obtain the data collected articles from various databases on quinones from 2000 to 2022. As a result, 137 compounds were selected, among which 70 were characterized for the first time in the period investigated; moreover, the study also discusses the biosynthetic pathways of quinones and the pharmacological activities of the compounds found, giving an overview of the various applications of these compounds.

Antibacterial activities of anthraquinones: structure-activity relationships and action mechanisms

With the increasing prevalence of untreatable infections caused by antibiotic-resistant bacteria, the discovery of new drugs from natural products has become a hot research topic. The antibacterial activity of anthraquinones widely distributed in traditional Chinese medicine has attracted much attention. Herein, the structure and activity relationships (SARs) of anthraquinones as bacteriostatic agents are reviewed and elucidated. The substituents of anthraquinone and its derivatives are closely related to their antibacterial activities. The stronger the polarity of anthraquinone substituents is, the more potent the antibacterial effects appear. The presence of hydroxyl groups is not necessary for the antibacterial activity of hydroxyanthraquinone derivatives. Substitution of di-isopentenyl groups can improve the antibacterial activity of anthraquinone derivatives. The rigid plane structure of anthraquinone lowers its water solubility and results in the reduced activity. Meanwhile, the antibacterial mechanisms of anthraquinone and its analogs are explored, mainly including biofilm formation inhibition, destruction of the cell wall, endotoxin inhibition, inhibition of nucleic acid and protein synthesis, and blockage of energy metabolism and other substances.

The Chemical Space of Marine Antibacterials: Diphenyl Ethers, Benzophenones, Xanthones, and Anthraquinones

The emergence of multiresistant bacteria and the shortage of antibacterials in the drug pipeline creates the need to search for novel agents. Evolution drives the optimization of the structure of marine natural products to act as antibacterial agents. Polyketides are a vast and structurally diverse family of compounds that have been isolated from different marine microorganisms. Within the different polyketides, benzophenones, diphenyl ethers, anthraquinones, and xanthones have shown promising antibacterial activity. In this work, a dataset of 246 marine polyketides has been identified. In order to characterize the chemical space occupied by these marine polyketides, molecular descriptors and fingerprints were calculated. Molecular descriptors were analyzed according to the scaffold, and principal component analysis was performed to identify the relationships among the different descriptors. Generally, the identified marine polyketides are unsaturated, water-insoluble compounds. Among the different polyketides, diphenyl ethers tend to be more lipophilic and non-polar than the remaining classes. Molecular fingerprints were used to group the polyketides according to their molecular similarity into clusters. A total of 76 clusters were obtained, with a loose threshold for the Butina clustering algorithm, highlighting the large structural diversity of the marine polyketides. The large structural diversity was also evidenced by the visualization trees map assembled using the tree map (TMAP) unsupervised machine-learning method. The available antibacterial activity data were examined in terms of bacterial strains, and the activity data were used to rank the compounds according to their antibacterial potential. This potential ranking was used to identify the most promising compounds (four compounds) which can inspire the development of new structural analogs with better potency and absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties.

In vitro dual activity of Aloe marlothii roots and its chemical constituents against Plasmodium falciparum asexual and sexual stage parasites

ETHNOPHARMACOLOGICAL RELEVANCE

Aloe marlothii A.Berger (Xanthorrhoeaceae) is indigenous to southern African countries where its aqueous preparations are used in traditional medicine to treat several ailments including hypertension, respiratory infections, venereal diseases, chest pain, sore throat and malaria.

AIM OF THE STUDY

The aims of this study were as follows: (i) isolate and identify the antiplasmodial active compounds in A. marlothii roots. As the water extract was previously inactive, the dichloromethane:methanol (DCM:MeOH) (1:1) was used, (ii) examine the activity of the isolated compounds against Plasmodium falciparum asexual blood stage (ABS) parasites as well as for transmission-blocking activity against gametocytes and gametes, and (iii) to use in silico tools to predict the target(s) of the active molecules.

MATERIALS AND METHODS

The crude DCM:MeOH (1:1) extract of A. marlothii roots was fractionated on a reverse phase C8 column, using a positive pressure solid-phase extraction (ppSPE) workstation to produce seven fractions. The resulting fractions and the crude DCM:MeOH extract were tested in vitro against P. falciparum (NF54) ABS parasites using the malaria SYBR Green I based-fluorescence assay. Flash silica chromatography and mass-directed preparative high-performance liquid chromatography were utilised to isolate the active compounds. The isolated compounds were evaluated in vitro against P. falciparum asexual (NF54 and K1 strains) and sexual (gametocytes and gametes) stage parasites. Molecular docking was then used for the in silico prediction of targets for the isolated active compounds in P. falciparum.

RESULTS

The crude extract and two SPE fractions displayed good antiplasmodial activity with >97% and 100% inhibition of ABS parasites proliferation at 10 and 20 μg/mL, respectively. Following UPLC-MS analysis of these active fractions, a targeted purification resulted in the isolation of six compounds identified as aloesaponol I (1), aloesaponarin I (2), aloesaponol IV (3), β-sorigenin-1-O-methylether (4), emodin (5), and chrysophanol (6). Aloesaponarin I (2) was the most bioactive, compared to other isolated constituents, against P. falciparum ABS parasites exhibiting equipotency against the drug-sensitive (NF54) (IC₅₀ = 1.54 μg/mL (5 μM)) and multidrug-resistant (K1) (IC₅₀ = 1.58 μg/mL (5 μM)) strains. Aloesaponol IV (3) showed pronounced activity against late-stage (>90% stage IV/V) gametocytes (IC₅₀ = 6.53 μg/mL (22.6 μM)) demonstrating a 3-fold selective potency towards these sexual stages compared to asexual forms of the parasite (IC₅₀ = 19.77 ± 6.835 μg/mL (68 μM)). Transmission-blocking potential of aloesaponol IV (3) was validated by in vitro inhibition of exflagellation of male gametes (94% inhibition at 20 μg/mL). In silico studies identified β-hematin and DNA topoisomerase II as potential biological targets of compounds 2 and 3, respectively.

CONCLUSION

The findings from our study substantiate the traditional use of A. marlothii to treat malaria. To our knowledge, this study has provided the first report on the isolation and identification of antiplasmodial compounds from A. marlothii roots. Furthermore, our study has provided the first report on the transmission-blocking potential of one of the compounds from the genus Aloe, motivating for the investigation of other species within this genus for their potential P. falciparum transmission-blocking activity.

Medicinal plants used in traditional treatment of malaria in Ethiopia: a review of ethnomedicine, anti-malarial and toxicity studies

Background

Malaria is extremely common in Ethiopia, and it is one of the country's most serious public health and economic problems. Traditional medicines have long been utilized in Ethiopia by people of various ethnic groups. As a result, the goal of this study is to record the use of Ethiopian medicinal herbs that have been used to treat malaria. Also, a critical review of the literature on the therapeutic properties of these and other Ethiopian medicinal plants that have been tested against Plasmodium spp. parasites was conducted with the goal of highlighting neglected studies and fostering further research in this area.

Methods

A comprehensive literature search was performed in Scopus, Web of Science Core Collection, PubMed, Science Direct, Google Scholar, and Scientific Electronic Library Online (SciELO) from August 2021 to October 2021. The study databases included original articles published in peer reviewed journals covering anti-malarial plants, dated until October 2021.

Results

The review looked at 51 plant species (28 families) that have been used to treat malaria in Ethiopia. The most often used ethnobotanical plant species for the treatment of malaria were Allium sativum, Croton macrostachyus, Carica papaya, and Lepidium sativum. Leaves were used more frequently as a therapeutic preparation than other parts. Plant extracts were found to have very good, good, and moderate anti-malarial activity in mice with rodent Plasmodium species. The most active species were Ajuga remota and Capsicum frufescens, which suppressed parasitaemia by 77.34% and 72.65%, respectively, at an oral dose of 100 mg/kg and an LD50 of above 2000 mg/kg. The compound Aloinoside reported from Aloe macrocarpa leave latex was the most potent; it suppressed parasitaemia by 100% at 400 mg/kg oral dose of Plasmodium berghei infected mice, and its LD50 was above 2000 mg/kg. Toxicity was shown to be safe in 84% of the plant extracts.

Conclusion

In Ethiopia, medicinal plants have a significant part in reducing the severity of malaria due to their widespread use. As a result, more studies are needed to identify and develop effective novel drugs that could be employed in broader malaria eradication efforts.

Endemic medicinal plants of Ethiopia: Ethnomedicinal uses, biological activities and chemical constituents

ETHNOPHARMACOLOGICAL RELEVANCE

Around 80% of Ethiopians rely on traditional medicinal plants to treat a variety of ailments, and the country is home to a number of endemic plants, making it part of East Africa's hotspot of biodiversity. Despite widespread acceptance of endemic medicinal plants among the local community, comprehensive documentation of their therapeutic uses and phytochemistry is lacking. This review thus provides the first comprehensive appraisal of traditional use, pharmacological properties and phytochemistry of Ethiopian endemic medicinal plants. By storing and preserving indigenous and scientific knowledge about the medicinal benefits of the plants, such documentation generates information database for the future. It also aids the conservation of key medicinal plants along with translational research to accelerate the development of pharmaceuticals.

AIM OF THE REVIEW

The aims of this review are to collect and document current information on the ethnopharmacological uses, phytochemistry, and biological activities of Ethiopian endemic medicinal plants, identify research gaps, and provide perspectives and suggestions for future research on the plants as potential sources of pharmaceuticals.

MATERIALS & METHODS

A comprehensive literature review using electronic databases such as Medline, Web of Science, Google Scholar, ScienceDirect, SpringerLink, and Wiley Online Library was conducted for collecting relevant information. The World Flora Online (WFO) database and the International Plant Names Index (IPNI) were utilized to authenticate the taxonomic information of the plants. Chemical structures were drawn using ChemBioDraw Ultra 12.1 and verified via PubChem.

RESULTS

The present review has identified 412 Ethiopian endemic plants. Out of the 412 endemic plants species recorded for Ethiopia 44 are medicinally valuable to mitigate a myriad of diseases, and nine (27.3%) of them are endangered. Our literature survey also found out that a total of 74 compounds were isolated and characterized from the endemic plants, with phenolics accounting for the majority of them (66.2%). The plants exhibited antimalarial, antimicrobial, anticancer, anthelmintic, mosquitocidal, antidiabetic, antioxidant, and anti-inflammatory properties.

CONCLUSION

The work has resulted in an up-to-date inventory of Ethiopia's endemic flora, as well as the identification of species with traditional medicinal uses. The pharmacological activity and phytochemistry of numerous endemic plants with various traditional therapeutic claims are yet to be researched scientifically. Scientific validation of the herbal remedies, including evidence-based safety and efficacy studies are, therefore, crucial. The endangered medicinal plants must be conserved in order for local communities to have access to them in the future.

Aloe vera and Streptozotocin-Induced Diabetes Mellitus

Diabetes mellitus is defined as prolonged hyperglycemia, which can harm the eyes, kidneys, and cardiovascular and neurological systems. Herbal agents and their derived supplements have been used for treatment of diabetes mellitus as a part of integrated complementary medicine for centuries. Numerous studies have considered Aloe vera (L.) Burm.f, Xanthorrhoeaceae, as an alternative medicine due to its abundant bioactive chemicals, such as alkaloids, anthraquinones, and enthrones, with therapeutical properties including antioxidant, anti-inflammatory, neuro-protective, and anti-diabetic effects. Aloe vera has received considerable attention in traditional medicine for the treatment of several diseases including diabetes mellitus. Numerous studies have investigated the effects of herbal agents on diabetes mellitus using a streptozotocin-induced diabetic model. Thereby, this article reviews the effects of Aloe vera prescription on streptozotocin-induced diabetes mellitus to provide a clear insight into the role of this medicinal plant in several biological functions, such as antioxidant, wound healing, anti-inflammatory, anti-hyperglycemic, and anti-hyperlipidemic in diabetic models.

Pharmacological evaluation of medicinal plants with antidiabetic activities in Ethiopia: A review

Diabetes mellitus is a serious, chronic disease that occurs either when the pancreas does not produce enough insulin, or when the body can't effectively use insulin. Herbal medicines have been commonly used by diabetic patients for the treatment of diabetes mellitus. To include findings from different studies, publications related to in vivo and invitro antidiabetic activities of medicinal plants in Ethiopia were searched from different databases, such as Web of Science, Google Scholar, Medline, Scopus, and PubMed, using English key terms. Different medicinal plant parts were used experimentally for antidiabetic effects in Ethiopia. Among these, leaves (69%) were the most commonly investigated medicinal plant parts followed by roots (14%) and seeds (7%). Most of the investigations were completed with hydro-methanolic extracts to obtain a higher percentage of yield. Medicinal plants such as Thymus schemperi R, Thymus vulgaris L, Hagenia abyssinica, Aloe megalacantha baker, Aloe moticola Reyonolds, Aloe pulecherrima Gilbert & sebseb, Bersama abyssinica fresen, and Rubus Erlangeri Engl have shown in vitro α-amylase inhibitory activity. However, only Hagenia abyssinica, Thymus schemperi R, and Thymus vulgaris L have exhibited α-glucosidase inhibitory activity. Likewise, only the extract of Aloe pulecherrima Gilbert & sebseb posses’ maltase and sucrose inhibitory activity. In vivo antidiabetic activity were conducted for the extract of medicinal plants such as A. remota, S. rebaudiani, T. schemperi, T. vulgaris, H. abyssinica, C. aurea, D. stramonium, A. megalacantha, A. moticola, A.integrifolia, A. pulecherrima, B. grandiflorum, B. abyssinica, P. schimperiana, M. stenopetala, C. aure, J. schimperiana, T. brownie, C. macrostachys, I. spicata, O. integrifolia, C. abyssinica, R. Erlangeri, L. culinaris, A. camperi, A. polystachyus, A. ilicifalius, C. tomentosa, and C. Edulis. This review gives collective evidence on the potential antidiabetic activities of medicinal plants in Ethiopia. Moreover, further studies are recommended to substantiate the use of these medicinal plants as an antidiabetic agent.

A review on hydroxy anthraquinones from bacteria: crosstalk's of structures and biological activities

Anthraquinones (AQ), unveiling large structural diversity, among polyketides demonstrate a wide range of applications. The hydroxy anthraquinones (HAQ), a group of anthraquinone derivatives, are secondary metabolites produced by bacteria and eukaryotes. Plant-based HAQ are well-studied unlike bacterial HAQ and applied as herbal medicine for centuries. Bacteria are known to synthesize a wide variety of structurally diversified HAQ through polyketide pathways using polyketide synthases (I, II & III) principally through polyketide synthase-II. The actinobacteria especially the genus Streptomyces and Micromonospora represent a rich source of HAQ, however novel HAQ are reported from the rare actinobacteria genera (Salinospora, Actinoplanes, Amycoloptosis, Verrucosispora, Xenorhabdus, and Photorhabdus. Though several reviews are available on AQ produced by plants and fungi, however none on bacterial AQ. The current review focused on sources of bacterial HAQ and their structural diversity and biological activities along with toxicity and side effects.

Antiplasmodial, antimalarial activities and toxicity of African medicinal plants: a systematic review of literature

BACKGROUND

Malaria still constitutes a major public health menace, especially in tropical and subtropical countries. Close to half a million people mainly children in Africa, die every year from the disease. With the rising resistance to frontline drugs (artemisinin-based combinations), there is a need to accelerate the discovery and development of newer anti-malarial drugs. A systematic review was conducted to identify the African medicinal plants with significant antiplasmodial and/or anti-malarial activity, toxicity, as wells as assessing the variation in their activity between study designs (in vitro and in vivo).

METHODS

Key health-related databases including Google Scholar, PubMed, PubMed Central, and Science Direct were searched for relevant literature on the antiplasmodial and anti-malarial activities of African medicinal plants.

RESULTS

In total, 200 research articles were identified, a majority of which were studies conducted in Nigeria. The selected research articles constituted 722 independent experiments evaluating 502 plant species. Of the 722 studies, 81.9%, 12.4%, and 5.5% were in vitro, in vivo, and combined in vitro and in vivo, respectively. The most frequently investigated plant species were Azadirachta indica, Zanthoxylum chalybeum, Picrilima nitida, and Nauclea latifolia meanwhile Fabaceae, Euphorbiaceae, Annonaceae, Rubiaceae, Rutaceae, Meliaceae, and Lamiaceae were the most frequently investigated plant families. Overall, 248 (34.3%), 241 (33.4%), and 233 (32.3%) of the studies reported very good, good, and moderate activity, respectively. Alchornea cordifolia, Flueggea virosa, Cryptolepis sanguinolenta, Zanthoxylum chalybeum, and Maytenus senegalensis gave consistently very good activity across the different studies. In all, only 31 (4.3%) of studies involved pure compounds and these had significantly (p = 0.044) higher antiplasmodial activity relative to crude extracts. Out of the 198 plant species tested for toxicity, 52 (26.3%) demonstrated some degree of toxicity, with toxicity most frequently reported with Azadirachta indica and Vernonia amygdalina. These species were equally the most frequently inactive plants reported. The leaves were the most frequently reported toxic part of plants used. Furthermore, toxicity was observed to decrease with increasing antiplasmodial activity.

CONCLUSIONS

Although there are many indigenous plants with considerable antiplasmodial and anti-malarial activity, the progress in the development of new anti-malarial drugs from African medicinal plants is still slothful, with only one clinical trial with Cochlospermum planchonii (Bixaceae) conducted to date. There is, therefore, the need to scale up anti-malarial drug discovery in the African region.

Antibacterial and Antifungal Activities of Ethiopian Medicinal Plants: A Systematic Review

Background: Podoconiosis and lymphatic filariasis are the most common causes of lower limb lymphoedema in the tropics. Many sufferers experience frequent painful episodes of acute bacterial infection. Plant based traditional medicines are used to treat infections in many countries and are culturally established in Ethiopia. Ethiopian medicinal plants found to have antibacterial and antifungal activities were reviewed with the aim of increasing information about the treatment of wound infections in patients with lymphoedema. Methods: This study collates data from published articles on medicinal plants with antibacterial and antifungal activities in Ethiopia. A systematic search of Scopus, EMBASE, PUBMED/MEDLINE and Google Scholar was undertaken. The Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines were followed. The protocol was registered on PROSPERO with registration number CRD42019127471. All controlled studies of in vitro antibacterial and antifungal activities were considered. All articles containing the descriptors published until June 28, 2019 were included. The outcome was measured as percent inhibition of microbial growth. For quality assessment of individual in vitro studies, OECD guidelines and the WHO-Good Laboratory Practice (GLP) handbook were used. Results: Seventy-nine studies met the inclusion criteria. A total of 150 plant species and three compounds had been tested against 42 species of bacteria, while 43 plant species had been tested against 22 species of fungus. Conclusion: Materials derived from several Ethiopian medicinal plants have been shown to have promising activity against a variety of bacteria and fungi. Those derived from Azadiractha indica A. Juss. and Lawsonia inerms L. are the most extensively studied against a wide range of gram-negative and positive bacteria, and fungal species.

Identification of Potential SARS-CoV-2 Main Protease and Spike Protein Inhibitors from the Genus Aloe: An In Silico Study for Drug Development

Severe acute respiratory syndrome coronavirus (SARS-CoV-2) disease is a global rapidly spreading virus showing very high rates of complications and mortality. Till now, there is no effective specific treatment for the disease. Aloe is a rich source of isolated phytoconstituents that have an enormous range of biological activities. Since there are no available experimental techniques to examine these compounds for antiviral activity against SARS-CoV-2, we employed an in silico approach involving molecular docking, dynamics simulation, and binding free energy calculation using SARS-CoV-2 essential proteins as main protease and spike protein to identify lead compounds from Aloe that may help in novel drug discovery. Results retrieved from docking and molecular dynamics simulation suggested a number of promising inhibitors from Aloe. Root mean square deviation (RMSD) and root mean square fluctuation (RMSF) calculations indicated that compounds 132, 134, and 159 were the best scoring compounds against main protease, while compounds 115, 120, and 131 were the best scoring ones against spike glycoprotein. Compounds 120 and 131 were able to achieve significant stability and binding free energies during molecular dynamics simulation. In addition, the highest scoring compounds were investigated for their pharmacokinetic properties and drug-likeness. The Aloe compounds are promising active phytoconstituents for drug development for SARS-CoV-2.

Antimicrobial activity of medicinal plants used for urinary tract infections in pastoralist community in Ethiopia

BACKGROUND

Medicinal plants have wide medicament application used to prevent and management of many ailments. These plants are used for primary health care in pastoralist communities who are deprived of modern medical care. They possess extensive therapeutics bioactive coupled with varied chemical structures. However, scientific validation of efficacy and safety of plants used to treat the urinary tract infections haven't been fully exploited. The aim of this study was to evaluate antimicrobial activity and screening phytochemicals of medicinal plants used to treat urinary tract infections.

METHODS

In-vitro experimental study was carried out to evaluate the antimicrobial effect and screening phytochemical of Rumex abyssinicus, Cucumis pustulatus, Discopodium penninervium, Lippia adoensis, Euphorbia depauperata, and Cirsium englerianum. Against drug resistance microbes. 80% methanol was used for extraction of the plant parts. The susceptibility tests were investigated using disc diffusion and broth micro-dilution methods.

RESULTS

The majority of tested extracts showed antimicrobial activity on two or more drug-resistant bacteria with MIC value (1.0-128.0 μg/ml) and 9-27 mm inhibition zone in diameter. Extracts obtained from C.englerianum and E. depauperate showed more potent antibacterial activity on MRSA and Enterococcus faecalis with IZ 25 and 27 mm respectively. E. coli and K. pneumoniae were inhibited by those extracts with IZ ranging 9-25 mm and 11-27 mm respectively. E.faecalis and K. pneumoniae were more susceptible bacteria to the respective extracts. R. abyssinicus showed promising antifungal effect with had 21 mm IZ and MIC range 16-32 μg/ml on C.albicans. Alkaloids, flavonoids, phenolic and terpenoid were common phytochemical characterized in majority of screened plants.

CONCLUSION

Tested extracts exhibited significant antibacterial and antifungal activity. Hence, further structural elucidation of bioactive that inhibited the growth of microbes aforementioned plants may be used as precursors for the synthesis of new antibiotics in the future.

Pharmaceutical importance of some promising plant species with special reference to the isolation and extraction of bioactive compounds: A review

BACKGROUND

Active principles from natural sources, in the form of extracts and natural compounds, provide an infinite number of bioactive compounds with consummate disposal of chemical diversity. These compounds and active principles are of utmost importance in the discovery of drugs of biological origin particularly, from plants.

OBJECTIVE

Development of resourceful technology for the isolation and extraction of bioactive compounds of medicinal importance is considered as an important task for researchers. There are a number of extraction, isolation, and characterization techniques currently utilized; however, most are laborious and use toxic chemicals and huge quantities of raw materials with a very low output. There are a number of abiotic and biotic factors that affects the quality and the quantity of plants bioactive compounds. Considering this the objectives of the current review is to discuss the various extraction and characterization techniques used to isolate the essential bioactive compounds from three plant species and the biotic and abiotic factors that affects the quantity and quality of the plants secondary metabolites.

METHODS

Many advanced technologies have been developed and tested for extraction, characterization, and their capacity for high yield products, and those requiring less application of toxic solvents are investigated continuously.

CONCLUSION

In this context, the present review summarizes the different types of extraction and characterization techniques utilized commercially by the food, drug, and pharmaceutical industries for better output and environmentally- and healthbenefiting products with special reference to three industrially important plants: Leonotis leonurus (L.) R.Br. (Lamiaceae) and Santalum album L. (Santalaceae) and Aloe vera (L.) Burm. f. (Aloaceae or Asphodelaceae).

Evaluation of Antidiabetic Activity of the Leaf Latex of Aloe pulcherrima Gilbert and Sebsebe (Aloaceae)

The leaf latex of Aloe pulcherrima has been used as remedy for diabetes mellitus. This was carried out to determine in vitro and in vivo antidiabetic activities of the leaf latex of Aloe pulcherrima. Methods. Sucrase and maltase inhibitory activity of the leaf latex of A. pulcherrima was determined in glucose oxidase assay, and α-amylase inhibitory activity was determined in dinitrosalicylic acid assay. Normoglycemic, glucose-loaded, and streptozotocin-induced diabetic mice were treated orally to determine blood glucose lowering activity of the latex. Effect of the latex on serum lipid level and body weight was measured in streptozotocin-induced diabetic mice. Additionally, DPPH assay was used to determine free radical scavenging capacity of the latex. Results. Antioxidant activity of the latex was concentration dependent; the strongest inhibition was measured at 800 μg/ml (80.57%). The leaf latex of A. pulcherrima inhibited sucrase (IC₅₀ = 2.92 μg/ml), maltase (IC₅₀ = 11.81 μg/ml) and α-amylase (IC₅₀ = 14.92 μg/ml) enzymes. All doses of the leaf latex induced hypoglycemic effect after 4 h in normal mice, and low dose of the latex did not show significant effect after 6 h. Glucose reduction of the leaf latex of A. pulcherrima was significant (p < 0.05) in oral glucose-loaded mice compared to the vehicle control. Blood glucose level of diabetic mice was significantly (p < 0.05) reduced on week one and weak two in a streptozotocin-induced diabetic mouse model. Glucose reduction increased with increasing the doses of the leaf latex of A. pulcherrima on week one (p < 0.05 (200 mg/kg), p < 0.01 (400 mg/kg), and p < 0.001 (600 mg/kg)). Administration of the leaf latex of A. pulcherrima for two weeks significantly (p < 0.05) improved diabetic dyslipidemia and body weight of diabetic mice. Conclusion. The study confirmed that the leaf latex of the plant showed a significant antidiabetic activity justifying the traditional uses of the plant.

Evaluation of acute and sub-acute toxicity of selected traditional antiurolithiatic medicinal plant extracts in Wistar albino rats

Introduction

Achyranthes aspera, Chenopodium murale, Satureja punctata, Rumex abyssinicus and Aloe pulcherrima are traditionally used to treat urolithiasis in Ethiopia. However, there are limited reports on toxicity studies.

Objective

This study was intended to evaluate the acute and sub-acute toxicity effects of plants.

Materials and Methods

The crude extracts of A. aspera and C. murale leaves, S. punctata aerial parts, R. abyssinicus rhizomes, and A. Pulcherrima gel were prepared using 70 % ethanol. In acute toxicity, 125, 500 and 2000 mg/kg were tested in a stepwise manner; whereas 2000 mg/kg administrated to female rats using gavage during sub-acute toxicity. On day 14 and 28, blood samples were collected from retro-orbital sinus; liver and kidneys of each animal were collected under anaesthesia. Data were analyzed using one-way ANOVA, Dunnett's comparison test of the Graph Pad Prism.

Results

No mortality and significant weight loss for all extracts in both toxicity tests. In acute toxicity, C. murale extract significantly reduced hemoglobin and platelets (P < 0.01) compared with the control. Likewise, S. punctata (P < 0.05) and R. abyssinicus (P < 0.01) extracts revealed significant reduction in platelet count. An exposure to C. murale and R. abyssinicus extracts reduced the concentrations of platelet distribution width and platelet larger cell ratio (p < 0.05) during sub-acute toxicity test. The level of creatinine reduced due to A. aspera extract administrations(P < 0.05). Liver histopathological examinations revealed focal periportal hepatitis following sub-acute toxicity test of C. murale. Histopathological studies of liver demonstrated that R. abyssinicus, A. aspera and S. punctata extracts showed mild acute liver injury. A. pulcherrima was not associated with any toxicity.

Conclusion

C. murale extract showed hematological, and histopathological toxicity profiles in rats. Furthermore, chronic toxicity studies of A. aspera, S. punctata and R. abyssinicus extracts would be beneficial to ensure safety.

Evaluation of Antidiabetic and Antioxidant Potential of Hydromethanolic Seed Extract of Datura stramonium Linn (Solanaceae)

Background

Nature has gifted a variety of phytochemicals having a potential effect against diabetes mellitus. Datura stramonium has been used as a remedy for the treatment of diabetes mellitus. The study aimed to determine the in vivo antidiabetic potential of hydromethanolic seed extract of the plant.

Methods

Dried seeds of Datura stramonium were macerated in hydromethanol. Three doses (100, 200, and 400 mg/kg) of the seed extract were given orally to normoglycemic, glucose-loaded, and Streptozocin-induced diabetic mice. Diphenyl-1-picrylhydrazine (DPPH) assay was employed to determine antioxidant activity of the seed extract.

Results

All doses of hydromethanolic seed extract of D. stramonium were devoid of any significant hypoglycemic effect in normoglycemic mice compared to the negative control group. Acute glucose reduction was significant (P<0.05 at 100, P<0.01 at 200 and 400 mg/kg) with respect to negative control in oral glucose-loaded mice. All doses of seed extract significantly (P<0.0l) reduced blood glucose level on weeks 1 and 2 in STZ-induced daily-treated diabetic mice. The seed extract at the doses of 200 and 400 mg/kg significantly (P<0.05) improved the body weight of diabetic mice on weeks 1 and 2. A low (100 mg/kg) dose of the seed extract delayed and significantly (P<0.05) increased body weight of mice on week 2 compared to negative control. The finding showed that the antioxidant activity of the hydromethanolic seed extract was concentration dependent and comparable with ascorbic acid. IC50 of the seed extract and ascorbic acid was found to be 11.95 and 5.07 mg/mL, respectively.

Conclusion

The findings of the study showed that hydromethanolic seed extract of Datura stramonium endowed significant antihyperglycemic and antioxidant activity.

Anticoccidial Activity of Aloe debrana and Aloe pulcherrima Leaf Gel against Eimeria Oocysts

Avian coccidiosis is one of the serious infectious diseases that pose huge impact on the health and production of poultry, hence mainly controlled by regular use of prophylactic and therapeutic chemical drugs. Frequent use of anticoccidial drugs, however, has resulted in the development of resistance in the Eimeria species and concerns about drug residues which have stimulated the efforts to search for alternative. Aloe pulcherrima and Aloe debrana are some of the endemic Aloe species of Ethiopia which are traditionally used for the treatment of various infectious diseases. In this study, an in vitro trial was undertaken to evaluate the effect of Aloe debrana and A. pulcherrima leaf gel infusions on the inhibition of the sporulation of oocysts of mixed Eimeria species isolated from naturally infected chickens. In this assay, petri dishes containing unsporulated coccidian oocysts at a dose of 1500 oocysts/ml of fecal solution were randomly assigned to 10, 15, 25, and 30% w/v crude gel infusion of both aloe species in 1% potassium dichromate solution while Amprolium and distilled water served as control groups. The results of this study show that 10, 15, 25, and 3 0% w/v gel infusions at the tested concentrations have anticoccidial activity as evidenced by their ability to decrease significantly (P < 0.05) the sporulation of Eimeria oocysts relative to the control incubation. The efficacy of A. debrana was found significantly better (P < 0.05) than A. pulcherrima at different concentrations. However, A. debrana at 30% concentration showed significantly higher (P < 0.05) sporulation inhibition efficacy of 79.35% (CI: 75.99-83.21) compared to A. pulcherrima (69.17%, CI: 64.65-73.92) at similar concentration in relation to the control incubation, though this could not be compared to Amprolium which was more effective (P < 0.05) with an inhibition percentage of 90.54% (CI: 89.16-92.21). This study has shown that there is potential for use of Aloe debrana leaf gel for the control of avian coccidiosis and as a chemotherapeutic, though much research is needed to determine absolute concentration which will make it comparable to commercially available drugs in terms of efficacy.

The potential of anti-malarial compounds derived from African medicinal plants: a review of pharmacological evaluations from 2013 to 2019

Background

African Traditional Medicine (ATM) is used for the healthcare of about 80% of the rural populations of the continent of Africa. The practices of ATM make use of plant-products, which are known to contain plant-based secondary metabolites or natural products (NPs), likely to play key roles in drug discovery, particularly as lead compounds. For various reasons, including resistance of strains of Plasmodium to known anti-malarial drugs, local African populations often resort to plant-based treatments and/or a combination of this and standard anti-malarial regimens. Emphasis has been laid in this review to present the anti-malarial virtue of the most recently published phytochemicals or natural products, which have been tested by in vitro and in vivo assays.

Methods

The data was based on the current version of the African Compound Libraries, which are constantly being updated based on inputs from journal articles and student theses (M.Sc/Ph.D) from African University libraries. Emphasis was laid on data published after 2012. In order to carry out the original data collection, currently being included in the African Compounds Database, individual journal websites were queried using the country names in Africa as search terms. Over 40,000 articles “hits” were originally retrieved, then reduced to about 9000 articles. The retained articles/theses was further queried with the search terms “malaria”, “malarial”, “plasmodium”, “plasmodial” and a combination of them, resulting in over 500 articles. Those including compounds with anti-malarial activities for which the measured activities fell within the established cut off values numbered 55, which were all cited in the review as relevant references.

Results and discussion

Pure compounds derived from African medicinal plants with demonstrated anti-malarial/antiplasmodial properties with activities ranging from “very active” to “weakly active” have been discussed. The majority of the 187 natural products were terpenoids (30%), followed by flavonoids (22%), alkaloids (19%) and quinones (15%), with each of the other compound classes being less than 5% of the entire compound collection. It was also observed that most of the plant species from which the compounds were identified were of the families Rubiaceae, Meliaceae and Asphodelaceae. The review is intended to continue laying the groundwork for an African-based anti-malarial drug discovery project.

Anti-amebic effects of Chinese rhubarb (Rheum palmatum) leaves' extract, the anthraquinone rhein and related compounds

Entamoeba histolytica infects 50 million people worldwide and causes 55 thousand fatalities every year. Current anti-amebic drugs (e.g. paromomycin) work either at the level of the intestinal lumen (where trophozoites proliferate via cell divisions) or on the invasive trophozoites that have penetrated the gut or colonized internal organs (e.g. metronidazole). Some of these drugs are highly toxic to patients, have generated trophozoite resistance, or caused mutations and cancer in laboratory animals. Thus, alternative anti-amebic compounds need to be identified to minimize the side effects (on patients) or resistance (by amebas) to current treatments. The literature suggests that anthraquinones (chemicals found in medicinal plants) have antibacterial, antiparasitic, anti-inflammatory and antioxidant properties. Here we provide experimental evidence that Chinese rhubarb (Rheum palmatum) leaves' extract (rich in the anthraquinone rhein) inhibits E. histolytica trophozoite growth in vitro. In addition, from a set of ten isolated/synthetic anthraquinones (which we suspected to have anti-amebic properties), four analogs (rhein; AHHDAC = 1-amino-4-hydroxy-9, 10-dioxo-9, 10-dihydro-anthracene-2-carboxylic acid; unisol blue AS; and sennoside B) efficiently inhibited amebic growth at EIC50 concentrations comparable to metronidazole. The mechanism of action of these compounds still needs to be determined, although anthraquinones might enhance the production of toxic oxygen metabolites as it has been suggested for various protists (e.g. Leishmania, Plasmodium, Trypanosoma). Our research is the first to explore anti-amebic effects of Chinese rhubarb leaves' extract and isolated/synthetic anthraquinones on pathogenic Entamoeba.

Efficacy of Aloe-Vera Use for Prevention of Chemotherapy-Induced Oral Mucositis in Children with Acute Lymphoblastic Leukemia: A Randomized Controlled Clinical Trial

Oral mucositis can be caused by chemotherapy and can affect a patient's quality of life. Nowadays, to prevent chemotherapy-induced oral mucositis (CIOM) is a crucial point in palliative care centers. This trial aimed to assess the effectiveness of aloe-vera in that concept. The trial was accomplished at Hematology Department of Hospital of Children of Damascus University, Syria. Acute lymphoblastic leukemia (ALL) children were the population from which 26 children were enrolled in the study. They were aged between 3 and 6 years old and were randomly referred according to the intervention into two groups, Aloe-vera (AV) and sodium bicarbonate 5% (13 each). Spongeous sticks were used to help in applying the material on tongue, labial and buccal mucosa, lips, floor of the mouth, and hard palate. Two blinded external examiners evaluated oral mucosa weekly for up to 2 months using the World Health Organization grading scale. Mann-Whitney U test was used to analyze data. According to the observed findings, CIOM degrees were less severe in the aloe-vera group than in the sodium bicarbonate group. Statistically significant difference of occurrence of different CIOM degrees between groups was recorded in the 2nd, 3rd, 4th, and 7th weeks of follow-up period. Moreover, Mann-Whitney U test indicated that patients in the sodium bicarbonate group began CIOM sooner than those in the aloe-vera group with a statistically significant difference (p = .001). These findings show that topical application of aloe-vera solution is effective in the prevention of CIOM in ALL children.

Ethnobotanical survey of medicinal plants in central Abyan governorate, Yemen

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional medicinal plant knowledge in Yemen is still only passed on orally from one generation to another. A few studies, mostly very limited in scope, have been dedicated to this indigenous knowledge so far. This paper presents the results of the first extensive field study in southern mainland Yemen, undertaken in three communities in the central region of Abyan governorate. The study is aimed to preserve the heritage of this indigenous knowledge and to explore and select local medicinal plants that promise high pharmacological efficacy for further pharmacological and phytochemical investigations.

METHODS

356 indigenous informants (273 males, 83 females) were interviewed about the modes of application and uses of the medicinal plants in the region. The ethnobotanical data were recorded by semi-structured face-to-face interviews, substantiated by specimen collections and taxonomic identifications and quantitative data analysis including informant consensus factor (ICF) and number of use-reports.

RESULTS

In total, 195 medicinal plant species (170 wild and 25 cultivated) belonging to 138 genera and 55 flowering plant families, were recorded for the treatment of 155 different ailments classified into 16 categories. Apocynaceae (25 species), Fabaceae (18 species), Euphorbiaceae (16 species) and Asteraceae (14 species) were the most frequently used plant families. Paste (86) followed by unprepared plant exudates (77) and decoction (55) were the most common herbal preparation modes. Dermal application (51.8%) was the most common administration route. The highest number of use reports and the maximum number of used medicinal plants were recorded for treatment of skin and gastrointestinal ailments. Forty-five species have never been reported in the ethnomedicinal literature before. Plant species with the most citations were Aloe vacillans Forssk. (malaria), Solanum incanum L. (tooth decay), Caralluma awdeliana (Deflers) A. Berger (diabetes), Tribulus terrestris L. (kidney stones), Aristolochia bracteolata Lam. (snake poison), Hydnora abyssinica A.Br. (stomach ulcer), Indigofera oblongifolia Forssk. (urine retention) and Chrozophora oblongifolia (Delile) A. Juss ex Spreng (haemorrhoids).

CONCLUSIONS

Significant traditional knowledge of the uses of local medicinal plant species was recorded for the first time for central Abyan in particular and southern Yemen in general. The study shows that the medicinal plants still play an important role in the primary health care in the study area. The ethnobotanical results provide a basis for further pharmacological, biological, pharmacognostical, and phytochemical investigations.

Aloe vera (L.) Webb.: Natural Sources of Antioxidants - A Review

Many studies have proved that bioactive components of Aloe vera have an anti-inflammatory effect and support lipid and carbohydrate metabolism, helping to maintain normal sugar and cholesterol levels in blood and normal body weight. When aloe is applied externally, it accelerates the regeneration of the damaged skin. Aloe contains antioxidants, which may increase the shelf-life and nutritional value of food; therefore, it is widely used in cosmetic, pharmaceutical and food industry. An antioxidant activity was shown for leaf's skin, flowers and gel of aloe. In this work the future of A. vera as effective antioxidants is primarily discussed and expected trends are summarised. Furthermore, the bioactive components and the health-promoting effects of A. vera are investigated.

Chrysophanol: a review of its pharmacology, toxicity and pharmacokinetics

OBJECTIVE

Chrysophanol is a natural anthraquinone, also known as chrysophanic acid and 1,8-dihydroxy-3-methyl-anthraquinone. It has been widely used in the food and pharmaceutical fields. This review is intended to provide a comprehensive overview of the pharmacology, toxicity and pharmacokinetic researches of chrysophanol.

KEY FINDING

Information on chrysophanol was collected from the Internet database PubMed, Elsevier, ResearchGate, Web of Science, Wiley Online Library and Europe PM using a combination of keywords including 'pharmacology', 'toxicology' and 'pharmacokinetics'. The literature we collected included from January 2010 to June 2019. Chrysophanol has a wide spectrum of pharmacological effects, including anticancer, antioxidation, neuroprotection, antibacterial and antiviral, and regulating blood lipids. However, chrysophanol has obvious hepatotoxicity and nephrotoxicity, and pharmacokinetics indicate that the use of chrysophanol in combination with other drugs can reduce toxicity and enhance efficacy.

SUMMARY

Chrysophanol can be used in many diseases. Future research directions include how the concentration of chrysophanol affects pharmacological effects and toxicity; the mechanism of synergy between chrysophanol and other drugs.

Chrysophanol: A Natural Anthraquinone with Multifaceted Biotherapeutic Potential

Chrysophanol is a unique anthraquinone having broad-spectrum therapeutic potential along with ecological importance. It is the first polyketide that has been reported to be biosynthesized in an organism-specific manner. The traditional Chinese and Korean medicinal systems provide evidence of the beneficial effects of chrysophanol on human health. The global distribution of chrysophanol encountered in two domains of life (bacteria and eukaryota) has motivated researchers to critically evaluate the properties of this compound. A plethora of literature is available on the pharmacological properties of chrysophanol, which include anticancer, hepatoprotective, neuroprotective, anti-inflammatory, antiulcer, and antimicrobial activities. However, the pharmacokinetics and toxicity studies on chrysophanol demand further investigations for it to be used as a drug. This is the first comprehensive review on the natural sources, biosynthetic pathways, and pharmacology of chrysophanol. Here we reviewed recent advancements made on the pharmacokinetics of the chrysophanol. Additionally, we have highlighted the knowledge gaps of its mechanism of action against diseases and toxicity aspects.

Antiplasmodial Anthraquinones from Medicinal Plants: The Chemistry and Possible Mode of Actions

Malaria killed nearly half a million people in 2015, and 70% of this victims were young children. Malarial chemotherapy makes use of several drugs, each with its own pharmacological limitations, and with parasite resistance being the most challenging. People of low income nations often rely on traditional medicine as a treatment due to limited access to modern healthcare services. Despite uncertainties present in the outcome of traditional medicine, ethnomedicine approach has yielded important lead candidates. The investigation of medicinal plants utilized in the malaria endemic region yielded many antiplasmodial compounds with anthraquinone moiety. This paper describes natural anthraquinones extracted from medicinal plants utilized in traditional medicine for the treatment of malaria. In addition, the insight on structure-activity relationship and their mode of actions are also elaborated.

Aloe Genus Plants: From Farm to Food Applications and Phytopharmacotherapy

Aloe genus plants, distributed in Old World, are widely known and have been used for centuries as topical and oral therapeutic agents due to their health, beauty, medicinal, and skin care properties. Among the well-investigated Aloe species are A. arborescens, A. barbadensis, A. ferox, and A. vera. Today, they account among the most economically important medicinal plants and are commonly used in primary health treatment, where they play a pivotal role in the treatment of various types of diseases via the modulation of biochemical and molecular pathways, besides being a rich source of valuable phytochemicals. In the present review, we summarized the recent advances in botany, phytochemical composition, ethnobotanical uses, food preservation, and the preclinical and clinical efficacy of Aloe plants. These data will be helpful to provide future directions for the industrial and medicinal use of Aloe plants.