Toxicological studies on the leaves of Avicennia marina (mangrove) in rats.

Haematological, biochemical and pathological effects in rats produced by the salt-tolerant plant Avicennia marina given at oral doses of 1 or 4 g kg(-1) for three consecutive days or 0.5 g kg(-1) day(-1) for 28 consecutive days are reported. No overt behavioral changes, moribundity or mortality were seen in either of the two experiments. A dose of 1 g kg(-1) did not affect significantly either body or liver weights. However, at a dose of 4 g kg(-1) the extract reduced both body and liver weights. The extract at both doses significantly increased leucocyte (mainly neutrophil) counts but did not affect significantly erythrocyte counts, haemoglobin concentration or the haematocrit. Except for a slight, but statistically significant, decrease in plasma glucose concentration and an increase in Na, Ca, Cu, Mg and cholesterol concentrations and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, the extract exerted no significant effects on plasma biochemistry. The treatment produced dose-related mild cellular degeneration in the liver and congestion in the central veins. There were also prominent Kupffer's cells and monocellular infiltrations. In the kidneys there was shrinkage and cellular degeneration of glomeruli and patches of medullary haemorrhage. In the spleen a slight activation of the germinal centre in the white pulp was noted. Subchronic treatment with the extract did not affect significantly the body and liver weights, the water intake, faecal and urinary output, leucocyte and erythrocyte counts, haemoglobin or haematocrit. There was a significant decrease in the number of platelets and an increase in the number of neutrophils. No significant changes in plasma biochemistry were observed, except for a 15% increase in AST activity. Subchronic treatment produced a significant reduction in glutathione concentration, amounting to about 20%. Histopathological findings after the subchronic treatment were similar in nature but milder than those seen after the acute treatment.