Cytogenetical studies on the effect of omnacortil on root tip cells of Allium cepa L

Abstract: Omnacortil is steroid, an allopathic drug commonly used as analgesic and suppressant in various diseases. In the present work, onion root tips were subjected with a series of omnacortil concentrations, ranging from 0.2 µg/ml, 0.4 µg/ml, 0.6 µg/ml, 0.8 µg/ml and 1.0 µg/ml for 24 hours for studying its effect on root mitosis in Allium cepa L. The roots were examined in permanent root tip squash preparations stained by the aceto-orcein. This work has confirmed that omnacortil have various effects on chromosomes and induced different mitotic abnormalities and structural aberration of chromosomes. Mitotic index (MI), relative division rate (RDR), relative abnormality rate (RAR) of treated material has been determined. Obtained results showed that all the concentrations of omnacortil showed higher MI and RDR, lower concentrations such as 0.2 µg and 0.4 µg showed higher values over rest of the concentrations and control. Among the subjected concentrations 0.8 µg concentration is most effective and showed highest RAR. Low concentrations of steroids act as stimulants while higher concentrations induced various chromosomal aberrations such as clumping and stickiness, fragmentation, C-mitotic effect, anaphase bridge, chromosomal condensation and contraction, dissolution of chromosome, which clearly showed the mutagenic, clastogenic, antimitotic and cytotoxic effect of omnacortil. This is the first report detailing the effects of omnacortil on chromosomes