Effects of crude ethanolic extract of Gloriosa superba L. tuber, on root growth and root tip mitosis, of Allium sativum L.

Colchicine is an alkaloid produced by some members of the Liliaceae family which include Gloriosa superba L. Apart from its other medicinal uses, it is used for both cytological and plant breeding studies. Absence of pure colchicine in Nigeria has retarded research progress in the above-mentioned areas of research. In this study, the genotoxic and cytotoxic effect of ethanolic crude extract of G. superba tubers, obtained by freeze-drying method, on Allium sativum meristematic roots were examined; to explore the possibility of using it, in research, in the absence of pure colchicine. The mitotic index of the roots treated with aqueous crude extract concentrations of 500mg/L, 1000mg/L and 2000mg/L for 3, 6, 12 and 24 hours, showed that there was significant reduction in the number of dividing cells with time. There were evidences of disturbed mitotic phases, C-metaphase, precocious chromosome movement and anaphase bridges, which increased as concentration and duration of treatment increased. Distilled water and 8-hydroxyquinoline were used as negative and positive controls. A. sativum roots exposed to the crude extract concentrations for 3, 6, 12, 24, 48 and 72 hours showed significant inhibition of root growth which increased with concentration and duration of treatment. The results obtained from this study indicate that the crude colchicine contained in G. superba, is an effective tubulin binder, which can arrest cells at the metaphase stage and is therefore recommended for cytological studies in Nigeria and other underdeveloped economies, in the absence of pure colchicine.Keywords: Root growth, root tip, mitosis, Gloriosa superba, Allium sativum, colchicin