In vitro and in vivo antiplasmodial activity of extracts and isolated constituents of Alstonia congensis root bark

Medicinal plants used in Gabon for prophylaxis and treatment against COVID-19-related symptoms: an ethnobotanical survey

Background: Gabon faced COVID-19 with more than 49,000 individuals tested positive and 307 recorded fatalities since the first reported case in 2020. A popular hypothesis is that the low rate of cases and deaths in the country was attributed to the use of medicinal plants in prevention and treatment. This study aimed to document the plants used for remedial and preventive therapies by the Gabonese population during the COVID-19 pandemic and to pinpoint specific potential plant species that merit further investigation. Methods: An ethnobotanical survey involving 97 participants was conducted in Libreville. Traditional healers and medicinal plant vendors were interviewed orally using a semi-structured questionnaire sheet, while the general population responded to an online questionnaire format. Various quantitative indexes were calculated from the collected data and included the relative frequency of citation (RFC), use value (UV), informant consensus factor (ICF), relative importance (RI), and popular therapeutic use value (POPUT). One-way ANOVA and independent samples t-test were used for statistical analyses. p-values ≤0.05 were considered significant. Results: The survey identified 63 plant species belonging to 35 families. Prevalent symptoms treated included fever (18%), cough (16%), fatigue (13%), and cold (12%). The demographic data highlighted that 52.58% of male subjects (p > 0.94) aged 31-44 years were enrolled in the survey, of which 48.45% (p < 0.0001) and 74.73% (p < 0.99) of informants had university-level education. In addition, the results indicated that a total of 66% of the informants used medicinal plants for prophylaxis (34%), for both prevention and treatment (26%), exclusively for treatment (3%), and only for prevention (3%) while suffering from COVID-19, against 34% of the participants who did not use plants for prevention or treatment. Annickia chlorantha, Citrus sp., Alstonia congensis, Zingiber officinale, and Carica papaya emerged as the most commonly cited plants with the highest RFC (0.15-0.26), UV (0.47-0.75), and RI (35.72-45.46) values. Most of these plants were used either individually or in combination with others. Conclusion: The survey reinforces the use of traditional medicine as a method to alleviate COVID-19 symptoms, thereby advocating for the utilization of medicinal plants in managing coronavirus infections.

Antimalarial Efficacy and Safety of Senna occidentalis (L.) Link Root Extract in Plasmodium berghei-Infected BALB/c Mice

Background

Emergence of Plasmodium resistance to antimalarial drugs presents a major drawback in efforts to control malaria. To address this problem, there is an urgent and continuous need for the development of new and effective antimalarial agents. Senna occidentalis (L.) link extract has exhibited in vitro antiplasmodial activity in many pharmacological studies. To our knowledge, data on its in vivo antimalarial efficacy is still very limited. A recent study demonstrated that polar extracts from the plant roots inhibit Plasmodium berghei proliferation in a mouse model. This study further describes the efficacy and safety of a methanolic root extract of the plant as an antimalarial agent by demonstrating its effect on hematological, biochemical, and histological parameters of Plasmodium berghei-infected BALB/c mice.

Methods

Rane's test, a curative approach, was used to evaluate the antimalarial efficacy of Senna occidentalis methanolic root extract in Plasmodium berghei-infected BALB/c mice. The effect of the extract on both hematological and biochemical parameters was evaluated using automated analyzers. Kidney, liver, lung, spleen, and brain tissues were harvested from euthanized mice and examined for changes in organ architecture.

Results

This study demonstrates that methanolic root extract of Senna occidentalis significantly inhibited Plasmodium berghei parasitemia in BALB/c mice (p < 0.01). Infected mice that were treated with the extract depicted a significantly low level of total leucocytes (p < 0.01), red blood cell distribution width (p < 0.01), and a significantly high hemoglobin concentration (p < 0.001) compared to the infected animals that were administered with the vehicle only. The infected animals that were treated with the extract exhibited a significantly low level of urea, creatinine, bilirubin, and alkaline phosphatase (p < 0.05), compared to the infected animals that were given the vehicle only. The level of sodium, potassium and chloride ions, lymphocytes, granulocytes, hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration, total protein, albumin, aspartate aminotransferase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), total platelets, mean platelet volume (MPV), and platelet distribution width of the infected animals treated with the extract was not significantly different from those of the infected animals that were given the vehicle only (p > 0.05). The extract alleviated organ pathological changes in the infected mice. The extract did not induce any remarkable adverse effect on the growth, hematological, and biochemical parameters of uninfected animals (p > 0.05). In addition, administration of the extract did not alter the gross appearance and histological architecture of the organs, implying that the extract was well tolerated in mice.

Conclusions

Senna occidentalis methanolic root extract exhibited good antimalarial activity against Plasmodium berghei and may be safe in mice.

Senna occidentalis (L.) Link root extract inhibits Plasmodium growth in vitro and in mice

BACKGROUND

Senna occidentalis (L.) Link has been used worldwide in traditional treatment of many diseases and conditions including snakebite. In Kenya, a decoction from the plant roots taken orally, is used as a cure for malaria. Several studies have demonstrated that extracts from the plant possess antiplasmodial activity, in vitro. However, the safety and curative potency of the plant root against established malaria infection is yet to be scientifically validated, in vivo. On the other hand, there are reports on variation in bioactivity of extracts obtained from this plant species, depending on the plant part used and place of origin among other factors. In this study, we demonstrated the antiplasmodial activity of Senna occidentalis roots extract in vitro, and in mice.

METHODS

Methanol, ethyl acetate, chloroform, hexane and water extracts of S. occidentalis root were tested for in vitro antiplasmodial activity against Plasmodium falciparum, strain 3D7. Cytotoxicity of the most active solvent extracts was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the curative potency in Plasmodium berghei infected mice evaluated by Rane's test.

RESULTS

All of the solvent extracts tested in this study inhibited the propagation of P. falciparum, strain 3D7, in vitro, with polar extracts being more active than non-polar ones. Methanolic extracts had the highest activity (IC50 = 1.76) while hexane extract displayed the lowest activity (IC50 = 18.47). At the tested concentrations, methanolic and aqueous extracts exhibited high selectivity index against P. falciparum strain 3D7 (SI > 10) in the cytotoxicity assay. Further, the extracts significantly suppressed the propagation of P. berghei parasites (P < 0.05) in vivo and increased the survival time of the infected mice (P < 0.0001).

CONCLUSIONS

Senna occidentalis (L.) Link root extract inhibits the propagation of malaria parasites in vitro and in BALB/c mice.

Chemistry, bioactivity, biosynthesis, and total synthesis of stemmadenine alkaloids

Covering: up to July 2022Stemmadenine alkaloids are a restrictive sub-group of monoterpene indole alkaloids, represented by two congeners: stemmadenine and vallesamine. Their skeleton is defined by the cleavage of the C-3-C-7 bond of the Strychnos group's pentacyclic scaffold in monoterpene indole alkaloids. The parent alkaloid stemmadenine acts as a key intermediate in the biosynthesis of several major monoterpene indole alkaloid families, including regular Strychnos alkaloids, Aspidosperma alkaloids, and Iboga alkaloids. In this review, a complete coverage of the stemmadenine alkaloids, from the early reports till the present day at 2022, are presented, and their diverse biological activities are briefly described. Moreover, the biosynthetic proposal for stemmadenine and the proposed biogenetic conversion of stemmadenine-type alkaloids into vallesamine-type congeners are discussed in detail. Moreover, the successful synthetic strategies to access the strained stemmadenine scaffolds are fully reviewed.

Chemical Composition and Lipoxygenase Inhibitory Activity of the Essential Oil of Alstonia Angustiloba

This study was aimed to investigate the chemica l compositions and lipoxygenase inhibitory activity of the essential oil from Alstonia angustiloba growing in Malaysia. The essential oils were obtained by hydrodistillation and fully characterized by gas chromatography and gas chromatography-mass spectrometry. Analysis of the A. angustiloba essential oil resulted in the identification of twenty-five chemical components, attributed 90.8% of the total oil. The most abundant components of A. angustiloba oil were linalool (21.2%), 1,8-cineole (16.8%), α-terpineol (9.5%), terpinene-4-ol (8.5%), β-caryophyllene (6.2%), and caryophyllene oxide (5.2%). The essential oil displayed moderate activity towards lipoxygenase activity with IC50 value of 45.8 μg/mL.

Chemical Composition and In Vitro Antiplasmodial Activity of the Ethanolic Extract of Cyperus articulatus var. nodosus Residue

Cyperus articulatus L. is popularly known as priprioca. Its rhizomes are used as a medicine in the treatment of malaria in traditional medicine. Since priprioca oil is extracted for commercial purpose, we evaluated if the components from the priprioca residue can be a source of antiplasmodial active molecules. This study aimed to determine the in vitro antiplasmodial and cytotoxicity activities of the ethanolic extract of C. articulatus as an in vitro antiplasmodial agent. From the solid residue of the plant rhizomes, 40 g samples were removed and subjected to hot extraction using a Soxhlet extractor. The in vitro antiplasmodial activity was determined using the W2 and 3D7 strains of P. falciparum. The phytochemical study identified the following main compounds: corymbolone (14.25%), cyclocolorenone (9.75%), and cadalene (8.36%). The extract exhibited moderate IC₅₀ (inhibitory concentration) against the two strains of P. falciparum: 1.21 ± 0.01 against the W2 strain and 1.10 ± 0.06 µg/mL against the 3D7 strain. Our results show the therapeutic potential of priprioca residue as a low-cost antiplasmodial agent.

Antiplasmodial and Genotoxic Study of Selected Ghanaian Medicinal Plants

Results

Five out of the eight plants, A. boonei stem bark, S; siamea Lam root, M. lucida Benth leaves, P. niruri, and A. hispidum DC whole plants, showed varying degrees of antiplasmodial activity against the asexual stage of the parasite. The most active extract against chloroquine-sensitive (3D7) and chloroquine-resistant (Dd2) P. falciparum strains is the A. hispidum extract which yielded a mean inhibitory concentration at 50% (IC₅₀) of 3.66 µg/ml and 3.71 µg/ml for 3D7 and Dd2, respectively. This was followed by S. siamea Lam with 3.95 µg/ml for 3D7 and 4.47 µg/ml for Dd2. The IC₅₀ values of the A. boonei extract against 3D7 and Dd2 P. falciparum parasites were 5.13 µg/ml and 3.62 µg/ml, respectively. For the M. lucida Benth extract, the least IC₅₀ value was 6.46 µg/ml. All five extracts exhibited dose-dependent antiplasmodial activity. Assessment of the genotoxic effects the A. hispidum extract by the comet assay revealed substantial damage to P. falciparum DNA.

Conclusion

This study demonstrates that the crude extract of A. hispidum DC, one of the plants used traditionally to treat malaria, inhibits the growth of P. falciparum in vitro and could be a potential source of antimalarial drug. The report has highlighted genotoxic and cytotoxic effects of the selected plant extracts on human leukocytes as well.

A review on antimicrobial botanicals, phytochemicals and natural resistance modifying agents from Apocynaceae family: Possible therapeutic approaches against multidrug resistance in pathogenic microorganisms

Accelerated emergence of drug- resistant pathogenic microbes, their unbeatable virulence and a gradual loss of efficacy of currently used antimicrobial agents over the last decade, have expanded the scope of herbal medicine to combat this emerging challenge to have a wide spectrum of activity to develop effective medicines with lesser untoward side effects. Plant-based natural products should be of utmost interest to today's pharmaceutical industries since they are a primary source of new chemical entities directed at new drug targets. Apocynaceae or 'Dogbane' family has attained a global reputation as a source of some life-saving plant-derived products and novel compounds. Members of this family have also been extensively investigated against several nosocomial pathogenic microbes through in vitro and in vivo experimental settings. Several plant-derived components obtained from members of this family have also exhibited remarkable microbial growth inhibitory properties. Popular and widely accepted international databases such as PubMed, Science Direct, ResearchGate, Scopus, Google Scholar, JSTOR and more were searched using the various search strings such as Apocynaceae, antimicrobials, multidrug resistance, resistance modifying agents and pathogenic microorganisms were used in various combinations to retrieve several citations related to the topic. The current review encompasses recent developments in experimental studies and phytochemical analyses which correlates with antimicrobial efficacy of selected Apocynaceous plants along with synergistic mechanism and structural details. The present review recognizes and leverages the importance of Apocynaceae plants, which could be of significant interest in the development of more effective and less toxic antimicrobial drugs which may surmount multidrug resistance. Three different paradigm models harnessing clinical antimicrobial resistance (AMR) including the plant family Apocynaceae, Gram-positive and Gram-negative bacterial species have been broadly discussed in this review. In a nutshell, the present review represents a comprehensive account on the antimicrobials and resistance modifying agents obtained from the members of the plant family Apocynaceae and derived phytochemicals. It also gives an insight into the underlying mode of action of these phytochemicals against an array of pathogenic bacteria, their mechanism of antibiosis, plant parts from which the phytochemicals were isolated or the extracts was prepared with a critical discussion on the botanically-derived antibiotics as a template for antimicrobial drug development.