Quantification, Antibacterial Assay and Cytotoxic Effect of Combretastatin, an Anticancer Compound from Three Indian Combretum species

Abstract

Combretastatin A4 is a natural stilbenoid phenol derived from South African Bushwillow (Combretum caffrum). Combretum albidum, Crombretum densiflorum and Combretum roxburghii (Family: Combretaceae) are the unexplored medicinal plant in the Indian medicinal system. According to ethno-botanical information, the leaves, barks and fruits Combretum species have antimicrobial and anti-tumor activities and extensively used in the treatment of syphilis, abdominal pains, conjunctivitis, diarrhoea, toothache, peptic ulcer, dysentery, Jaundice, skin, heart and cancer diseases. The present study was undertaken to ascertain the presence of anticancer phyto-constituent in the Indian Combretum species and its further utilization in the treatment of tumor. The phyto-chem. constituents of the leaf and bark extracts were recognized with reference to standard on the same HPTLC plate. The leaf extracts exhibited higher quantity of combretastatins than the bark samples. The combretastatin content was recorded the highest (182 μg/g) in the leaf extract of C. albidum. Antibacterial activity was studied by disk diffusion assay against seven bacterial strains. The leaf extract of C. densiflorum resulted higher level of zone of inhibition against Bacillus subtilis (19 mm), Escherichia coli (18 mm), Salmonella enteric (18 mm), Streptococcus pneumoniae (16 mm), Staphylococcus aurius (13 mm), Pseudomonas aeruginosa (12 mm) and Mycococcus luteus (12 mm). Lower antimicrobial activities were recorded by the leaf and bark extracts of C. albidum. The carcinogenic effect of methanolic crude extracts on Allium cepa cells inducing chromosomal aberrations like chromosomal clumping, sticky bridge, laggard, early separation, late separation, chromosome break (fragmentation) and erosion (heavy fragmentation) were recorded. The methanolic leaf extract of Combretum albidum exhibited the highest percentage of chromosomal aberration such as sticky bridge in metaphase which demonstrated the strongest cytotoxic effect in the root meristem cells. These results suggest that the methanolic extract of Combretum species has antimicrobial and cytotoxic activities that support the ethano-pharmacol. and anti-tumor uses of these plants.