For synchronization, mostly ring stage parasites (10 to 12 h post-invasion) wen~ used. The parasite culture was centrifuged at 200g for 5min and the supernatant was discarded. To the pellet, 4 ml of 5% sorbitol was added, mixed gently and incubated for 15min at 37°C. The mix was shaken 2 or 3 times and centrifuged at 200g followed by washing 3 times in complete medium (list I). The culture was then maintained at 5% hematocrit in a 37°C incubator

orbitol-synchronization 0/ P./alciparum

All antisera were obtained from the reagent bank at National Institute of Immunology, New Delhi.

Antisera.

The procedure of Hagerman and Butler (1978) was used to estimate the tannin content in different tannin sources. Reagents: Bovine serum albumin (BSA) 1.0 mg/ml: 10.0 mg of bovine serum albumin was dissolved in 10.0 ml of 0.2 M acetate buffer, pH 5.0, containing 0.17 M sodium chloride. Sodium dodecyl sulfate (SDS)-triethanolamine solution: The solution contained 1.0% SDS and 5.0% (v/v) triethanolamine in distilled water. Ferric chloride reagent (0.01 M): 1.62 g of ferric chloride was dissolved in 1.0 L of 0.01 N hydrochloric acid.