Powders of C. violaceum (1000 g) were extracted with 95% ethanol (mass–volume ratio of 1:5) for 7 days at room temperature with appropriate ultrasonic treatment. The extraction procedure was repeated in triplicate for the same powder. The extracts were combined, filtered, and the obtained filtrates were concentrated under vacuum at 40 ◦C using a rotary evaporator . The dried crude ethanol extract was suspended in water and sequentially fractioned with solvents of increasing polarity to obtain petroleum ether (60–90 ◦C) fraction (PEF), chloroform fraction (CF), ethyl acetate fraction (EAF), n-butanol fraction (BF) and aqueous fraction (AF) . Then, the organic solvent fractions were concentrated by a rotary evaporator under vacuum at 40 ◦C and were then dried at 30 ◦C for 4 h in a vacuum oven for total solvent removal, and the AF was concentrated by a rotary evaporator and was then freeze–dried. The dried extract and fractions were kept in colored vials at 4 ◦C prior to analysis