Crude aqueous extracts were prepared from freshly gathered leaves of Vitex negundo (lagundi), Tamarindus indicus (sampalok) and Psidium guajava (bayabas). The effects of the extracts on human complement-mediated hemolysis were determined for both the alterantive and classical pathways using in vitro microtiter plate assays. The effects of these extracts on chemotaxis and phagocytic activity of human peripheral blood leukocytes were also assessed in vitro. A modified Boyden chamber method using Escherichia coli bacterial chemotactic factor (BCF) and zymosan-activated human serum (ZAS) as chemoattractants was employed for the chemotaxis assay whereas microscopic observation of the engulfment of Staphylococcus aureus was used in the assessment of phagocytosis.
All data were analyzed using ANOVA and Tukey's multiple range test at a 0.05 level of significance. For all the extracts, the degree of complement mediated hemolysis was lower compared with negative controls to which no extract had been added. A significant reduction in hemolysis by Tamarindus and Psidium extracts with respect to the negative controls for both the classical and alternative complement pathways was observed, Tamarindus being associated with the greatest reduction in hemolysis. The chemotactic index was significantly lower in the presence of Vitex extract with respect to the negative controls using either BCF or ZAS as chemoattractants. In the presence of Tamarindus extract, the chemotactic index was significantly higher for BCF-directed chemotaxis with respect to the control, whereas for ZAS-directed chemotaxis it did not differ significantly from the control. Of the three extracts, only Tamarindus yielded counts of phagocytosed bacteria significantly different (lower) with respect to the negative control. The apparent anti-complementary effects of Tamarindus indicus and Psidium guajava leaf extracts, the reduction in leukocyte chemotactic activity in the presence of Vitex negundo leaf extracts and the reduction of leukocyte phagocytosis associated with Tamarindus indicus leaf extracts may offer at least a partial explanation for their value as remedies for inflammatory disorders. (Author)