AIM OF THE REVIEW: The present review aims to compile an up-to-date review of the progress made in the continuous pharmacological and phytochemistry investigation of K. africana and the corresponding commercial and pharmaceutical application of these findings with the ultimate objective of providing a guide for future research on this plant.

METHOD: The scholarly information needed for this paper were predominantly sourced from the electronic search engines such as Google, Google scholar; publishing sites such as Elsevier, scienceDirect, BMC, PubMed; other scientific database sites for chemicals such as ChemSpider, PubChem, and also from online books.

RESULTS: Pharmacological investigations conducted confirm the anti-inflammatory, analgesic, antioxidant and anticancer activity of the extract of different parts of the plant. Bioactive constituents are found to be present in all parts of the plant. So far, approximately 150 compounds have been characterized from different part of the plant. Iridoids, naphthoquinones, flavonoids, terpenes and phenylethanoglycosides are the major class of compounds isolated. Novel compounds with potent antioxidant, antimicrobial and anticancer effect such as verbascoside, verminoside and pinnatal among others, have been identified. Commercial trade of K. africana has boosted in the las few decades. Its effect in the maintenance of skin has been recognized resulting in a handful of skin formulations in the market.

METHODS: Five groups of adult male rats were used in this experiment. Normal/control group; the rats were injected subcutaneously with 15 mg/kg of sterile normal saline once a week for two weeks, and orally administered with 10% Tween 20 (5 mL/kg). Carcinogen and treatment groups; the rats were injected subcutaneously each with 15 mg/kg body weight AOM once a week for 2 weeks and were continued to be fed for two months, respectively with 10% Tween 20, 500 and 250mg/kg body weight plant extracts. Reference group; the rats were injected subcutaneously with 15 mg/kg body weight AOM once a week for 2 weeks, and injected intraperitoneally with fluorouracil 35 mg/kg body weight for five consecutive days.

RESULT: Total ACF detected in methylene blue stained whole mounts of rat colon were 21, 23and 130 in rats fed with 500, 250 mg/kg body weight treatment and carcinogen groups, respectively. Treatment with high and low doses of the plant extract led to83.6% and 82.2% decrease in the total crypts in the groups fed 500 mg/kg and 250 mg/kg Gynura procumbens respectively compared to carcinogen group. Immunohistochemical staining of ACF showed suppressed azoxymethane induced colonic cell proliferation and Bcl-2 expression. Glutathione-S-transfarase and superoxide dismutase activities were higher in treated rats compared to carcinogen groups.

METHODS: The experimental approach in the present study was based on a bioassay-guided fractionation. The crude methanol and fractionated extracts (hexane, chloroform and water) from different parts of A. scabra (leaves, rhizomes, roots and pseudo stems) were prepared prior to the cytotoxicity evaluation against human ovarian (SKOV-3) and hormone-dependent breast (MCF7) carcinoma cells. The identified cytotoxic extracts were then subjected to chemical investigations in order to identify the active ingredients. A normal human lung fibroblast cell line (MRC-5) was used to determine the specificity for cancerous cells. The cytotoxic extracts and fractions were also subjected to morphological assessment, DNA fragmentation analysis and DAPI nuclear staining.

RESULTS: The leaf (hexane and chloroform) and rhizome (chloroform) extracts showed high inhibitory effect against the tested cells. Ten fractions (LC1-LC10) were yielded after purification of the leaf chloroform extract. Fraction LC4 which showed excellent cytotoxic activity was further purified and resulted in 17 sub-fractions (VLC1-VLC17). Sub-fraction VLC9 showed excellent cytotoxicity against MCF7 and SKOV-3 cells but not toxic against normal MRC-5 cells. Meanwhile, eighteen fractions (RC1-RC18) were obtained after purification of the rhizome chloroform extract, of which fraction RC5 showed cytotoxicity against SKOV-3 cells with high selectivity index. There were marked morphological changes when observed using phase-contrast inverted microscope, DAPI nuclear staining and also DNA fragmentations in MCF7 and SKOV-3 cells after treatment with the cytotoxic extracts and fractions which were indicative of cell apoptosis. Methyl palmitate and methyl stearate were identified in the hexane leaf extract by GC-MS analysis.