Immunostimulating effect of pule (Alstonia scholaris L. R.Br., Apocynaceae) bark extracts.

The immunostimulating effect of "Pule" (Alstonia scholaris (L.) R.Br., Apocynaceae) bark extracts was studied in BALB/c mouse. The extracts were administered orally, once a day for 7 consecutive days. The results showed that at the same doses (50, 100 and 200 mg/kg b.w.) the aqueous extract had higher phagocytic index (1.39-1.79) than the ethanolic extracts (0.81-0.93) in normal mice. The aqueous extract at 50 mg/kg b.w. also enhanced phagocytic activity of immunosuppressed mice significantly (P < 0.01). At 50 and 100 mg/kg b.w. the extract prevents the decrease of immune system induced by prednisone. The aqueous extract at 100 mg/kg b.w. increased lytic activity of peritoneal exudate cells against Escherichia coli significantly (P < 0.05). At the doses of 50 and 100 mg/kg b.w. the aqueous extract had no effect on primary antibody level. The aqueous extract at 50 mg/kg b.w. induced the cellular immune response while at 100 mg/kg b.w. inhibited the delayed type of hypersensitivity reaction.