Maytenus ovatus (Schweinf.) of the family Celastraceous is a
shrub usually spiny with whitish flowers bearing reddish fruits
and is widespread in the savannah regions of tropical Africa .
Mountains and sub-mountainous regions of African countries,
viz., Ethiopia, Kenya, Tanzania, Uganda, Mozambique and others
are wild habitats for the species, Maytenus ovatus, M. serratus, M.
heterophylla and M. senegalensis . Maytansine, a benzo-ansamacrolide
(ansamycin antibiotic) is a highly potent microtubuletargeted
compound that induces mitotic arrest and kills tumor cells
at sub-nano-molar concentrations was originally isolated from the
Ethiopian shrub, Maytenus ovatus. Maytansine binds to tubulin
at the rhizoxin binding site. It inhibits microtubule assembly,
induces microtubule disassembly, and disrupts mitosis. Maytansine
exhibits cytotoxicity against many tumor cell lines and also inhibit
tumor growth in vivo . Since the discovery of Maytansine from
Maytenus ovatus in 1972 as a potent cytotoxic agent, further 53
more maytansinoids have been identified from wild plants, microorganisms
and mosses .