Search

Various parts of the plant, Sterculia setigera Delile, from the Malvaceae family are largely used in most African countries for medicinal purposes. In African traditional medicine, the plant is used to treat fever, bacterial infection, diarrhoea, epilepsy, anaemia, and hypertension. Due to its high therapeutic properties, it has become a highly sought-after plant by researchers for pharmacological properties aimed at validating or providing scientific backing for its traditional use. Additionally, efforts to obtain small natural molecules from the plant as scaffolds for the development of new drugs have been explored. Although it is extensively used in traditional medicine and its phytochemical composition and biological activity are widely studied, there is no review paper that systematically analyses its biological activities and phytochemical composition. Hence, this review provides a systematic overview of the biological activities, phytochemical constituents, and ethnomedicinal properties of the plant. The data show S. setigera is a promising medicinal plant with pharmacological potential and thus can be useful for the development of novel therapeutic agents.

Natural products have a long history of use in the treatment of various diseases particularly in developing countries. The use of compounds of natural origin as lead compounds for the development of conventional drugs is widely recognised. Natural product-based drug discovery efforts in developing countries mostly involve the use of crude extracts in in-vitro and/or in-vivo assays. There are limited efforts at isolating active principles for structure elucidation studies. Studies that isolate pure secondary metabolites and characterize their structures have limited bioactivity evaluations. In conventional drug discovery programs, molecular docking serves as a useful tool for predicting interactions of small molecules with drug target(s) to guide synthesis decisions. Medicinal chemists use this tool to predict and synthesize compounds likely to have pharmacological activity and thus save time and cost for drug discovery. Efforts have been made to incorporate molecular docking techniques into natural products-based drug discovery. The objective of this review is to discuss molecular docking in natural product drug discovery programs with the goal of providing easy-to-understand information to help beginners interested in incorporating molecular docking in their research. This is expected to enhance natural product screening programs by predicting which phytochemicals are likely to show success, especially in new disease situations such as COVID-19. Applications in the repositioning of plants for emerging conditions are also discussed.

The leaves of Manihot esculenta Crantz are used widely in traditional medicine to treat gastric ulcers. However, the safety and ethnopharmacological use of the plant as an anti-ulcer agent has not been validated in experimental studies. The study investigated the toxicity profile and anti-ulcer properties of ethanolic leaf extract of Manihot esculenta (MELE) in rats. A high dose of MELE (2000 mg/kg, p.o.) did not cause death in any of the rats. Moreover, no behavioural, haematological, or biochemical abnormalities could be attributed to the extract. The administration of acidified alcohol reduced rats’ luminal pH from 4.47 ± 1.39 (naïve control) to 1.95 ± 0.31 in the negative control rats. However, pre-treatment of rats with MELE (30, 100, and 300 mg/kg, p.o.) or omeprazole (10 mg/kg, p.o.) significantly (p < 0.05) elevated the luminal pH to 2.24 ± 0.19, 3.21 ± 0.18, 3.12 ± 0.40 and 2.63 ± 0.10 respectively. MELE (100 and 300 mg/kg) and omeprazole (10 mg/kg) caused a significant (p < 0.05) reduction in rats’ gastric ulceration with percentage inhibition of 71.05, 76.31 and 78.94% respectively. The extensive ulceration and erosion of the stomachs of rats in the negative control group were reversed by treatment with various doses of the extract and omeprazole. Elevated Ki67 immunoreactivity in the negative control group was also reduced by the MELE (30, 100 and 300 mg/kg) and the standard reference drug, omeprazole (10 mg/kg). The present study suggests that MELE produced no observed adverse effects and offered protection against acidified ethanol-induced gastric ulceration. Further studies should aim at isolating the active compounds responsible for the anti-ulcer effect as well as their possible mechanisms of action.

Buruli ulcer disease, a necrotising skin and subcutaneous tissue disease, is endemic to tropical Africa. People in endemic communities’ resort to topical and oral consumption of plant extracts which have not been validated. The present study focused on validating the antimycobacterial properties and toxicity of different solvent extracts of the stem bark of P. angolensis and establish pharmacognostic standards for quality control purposes. In vitro antimycobacterial activity of the aqueous, 70% hydro-ethanol and ethyl acetate stem bark extracts of P. angolensis against M. ulcerans (NM 203 strain) was done using the Resazurin Microtiter Assay and their cytotoxicity assessed on normal Chang liver cells via the Alamar Blue assay. Pharmacognostic parameters were also evaluated according to standard methods. The ethyl acetate extract of the stem bark showed considerable activity against the M. ulcerans (MIC = 256 µg/mL) but was less active than the reference drugs streptomycin (MIC = 0.25 µg/mL) and rifampicin (MIC = 0.125 µg/mL). The aqueous and hydroethanolic extracts showed no activity. The active ethyl acetate extract was not cytotoxic (CC50=383.9 ± 69.7 µg/mL). Micromorphological analysis of the leaf surface revealed stellate trichomes and schizogenous cavities. Stem bark powder microscopy showed abundant starch grains, prismatic calcium oxalate crystals and large striated stone cells with a wide lumen. Morphological features, physicochemical, chromatographic, and spectroscopic standards have been established to guarantee consistency in the quality of herbal products containing P. angolensis. The activity of P. angolensis extract against M. ulcerans substantiates the traditional use of P. angolensis stem bark for Buruli ulcer management and as a potential source of antimycobacterial agents.