Bitter leaf consists of the fresh or dried leaves of Vernonia amygdalina .A shrub or small tree, 2-5 m high with striate pubescent branches, becoming glabrous on maturity; leaves alternate, obovate-lanceolate, entire or finely toothed. Bitterleaf is a highly appreciated vegetable in West and Central Africa and can be consumed in various dishes. Leaf decoctions are used to treat fever, malaria, diarrhoea, dysentery, hepatitis and cough, as a laxative and as a fertility inducer. One of the most common medicinal uses of Vernonia amygdalina is as a treatment against intestinal worms including nematodes. In Zimbabwe a root infusion is used to treat sexually transmitted diseases. The bitterness is caused by sesquiterpene lactones (e.g. vernodalin, vernolepin and vernomygdin) and steroid glucosides (vernoniosides). Some of these compounds have significant antiparasitic activity, especially vernodalin and vernonioside B1. Vernolepin showed platelet anti-aggregating properties. Vernodalin and vernomygdin have cytotoxic activity.Aqueous leaf extracts containing the peptides, edotides, have been found to be potent inhibitors of mitogen-activated protein kinases (MAPK), important agents for the growth of breast cancer cells; the anti-oestrogen drug, tamoxifen, is known to be an MAPK modulator (Atanaskova et al., 2002; Mandlekar and Kong, 2001). Leaf extracts showed inhibitory activity against Trichomonas vaginalis (Hakizamungu et al., 1992) and the aqueous leaf extracts caused reductions in blood sugar levels of normoglycaemic and alloxan diabetic rabbits (Akah andOkafor, 1992).
A small tree with smooth bark; opposite dark green, coriaceous and shiny leaves, obovate, with 3-5 basal nerves, up to 15 cm long and 10 cm broad; flowers unisexual, cream, in axillary and terminal panicles; fruit small drupe.
Studies have shown that the bark of the plant contains volatile oils, mucilage, calcium oxalate, tannins, and starch, all of which work synergistically to give the plant its appetizer, carminative, digestive and stomachic actions (Pamplona-Roger, 11998). C. zeylanicum promotes gastric and intestinal juice secretion and enhances gastric motility. The bark extracts have shown to be effective against fluconazole-resistant and -susceptible Candida isolates in vitro. A small scale clinical trial on AIDs patients showed the herb to be effective for treating oral candidiasis (Quale et al., 1996). Antibacterial actions have also been demonstrated in vitro (Azumi et al., 1997; Bruneton, 1995). C. zeylanicum‟s diterpenes have shown antiallergic activity (Nagai et., 1982). Aqueous extracts exhibited antiulcer effects (Akira et al., 1986). Cinnamon may have hypoglycaemic properties in vitro (Berrio et al., 1992). Its mild astringent action may be due to the tannins. The essential oils of C. zeylanicum, Ocimum gratissimum, Cymbopogon citratus, Eugenia uniflora, and Alpinia speciosa demonstrated inhibitory action against dermatophyte strains in vitro (Lima et al., 1993). The oil and leaf extracts have antiviral activity (Kato, 1975; Leung and Foster, 1996); the eugenol-containing leaf oil has demonstrated antiseptic and anaesthetic properties. Several studies have shown that cinnamaldehyde has hypotensive and spasmolytic effects. It also inhibits the enzymes cyclooxygenase and lipoxygenase and increases peripheral blood flow (Tahara et al., 1986; Harada and Yamazaki, 1981). Extracts have shown antioxidant activity in vitro and may be useful as food antioxidants (Mancini-Filho et al., 1998).