Toxicity evaluation of in vitro cultures of freshwater cyanobacterium Microcystis aeruginosa: I. Hepatotoxic and histopathological effects in rats.

Laboratory cultures of freshwater cyanobacterium (blue-green alga) Microcystic aeruginosa PCC 7806 was evaluated for its hepatotoxic effects in rats. The lyophilized cell extract injected intraperitoneally at 1 and 2 LD50 (15.8 and 31.6 mg/kg, respectively) produced significant increase in liver-specific enzymes viz. plasma alkaline phosphatase, gamma-glutamyl transferase, lactate dehydrogenase with a concomitant decrease in hepatic glutamic pyruvic transaminase. A corresponding increase in liver body weight index and histopathological changes in liver (degeneration of hepatocytes, congestion and hemorrhage etc.) are indicative of a dose and time dependent hepatotoxic nature of the algal extract.