In order to evaluate the seasonal variation as well as cytotoxicity of different fractions of Alstonia scholaris R. Br. (ASE), the HeLa cells were treated with different doses of various fractions of ASE collected in monsoon, winter and summer. The exposure of HeLa cells to different extracts prepared from the stem bark collected in monsoon, winter and summer seasons resulted in a dose dependent increase in the cell killing effect of ASE and the highest cell killing effect was observed for the extract prepared from the summer collections. Similarly, treatment of HeLa cells with different doses of various fractions of the Alstonia scholaris extract viz. residue (ASERS), steroidal (ASEST), chloroform (ASECH), petroleum ether (ASEPE), diethyl ether (ASEDE), ethyl acetate (ASEEA), n-butanol (ASENB), aqueous (ASEAQ) and echitamine chloride (ECL) also resulted in a dose dependent decline in the cell viability, where the greatest cytotoxic effect was observed for residue (ASERS), followed by the whole extract (ASE) and chloroform (ASECH) fraction, while the least activity was observed for the steroidal (ASEST) fraction. The cytotoxicity declined ASERS > ASE > ASECH >ECL > ASEEA > ASEDE > ASEPE > ASENB > ASEAQ > ASEST in order. Our study demonstrates that the extract prepared from the summer collection, and the fractions containing the alkaloids were highly effective in cell killing. The extract of ASE was more powerful than the active principle echitamine present in ASE.
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