Immunostimulant activity of the extracts and bioactives of the fruits ofMorinda citrifolia

The present investigation evaluates the immunostimulant effects of the extracts and the bioactive fractions, namely, polysaccharides, anthraquinones, and alkaloids, of the fruits of Morinda citrifolia Linn. (Rubiaceae). The extracts and the fractions were evaluated for their effect on in vitro phagocytosis of Candida albicans spores by neutrophils obtained from pooled human blood. The maximum activity was demonstrated by the hydroalcoholic extract (79.25% at 1.0 mg mL−1, p < 0.05) and the polysaccharide fraction (60.0% at 0.2 mg mL−1, p < 0.05) obtained from the fruits of the plant. The hydroalcoholic extract and the polysaccharide fraction were evaluated for their effect on serum interleukin-6 (IL-6) levels in rats sensitized by intraperitoneal injection of Bacillus Calmette Guerin (BCG) vaccine I.P. The hydroalcoholic extract (910.82 pg mL−1 at 200 mg kg−1, p < 0.05) and the polysaccharide fraction (556.82 pg mL−1 at 40 mg kg−1, p < 0.05) significantly increased serum IL-6 levels in the antigenically challenged rats as compared to the vehicle control group (75.04 pg mL−1) and standard reference herbal drug, Withania somnifera (L. Dunal) (Solanaceae) (396.38 pg mL−1). The studies indicated the potential of Morinda citrifolia as an immunostimulant herbal drug.