In vitro and in vivo immunomodulatory activities of iridoids fraction from Barleria prionitis Linn.

Ethnopharmacological Relevance: Barleria prionitis Linn. (Family: Acanthaceae), one of the important Ayurvedic medicinal plant in India, has long been used to treat variety of ailments including swellings, gout, arthritic and rheumatic disorders, nervine and skin diseases, and also acts as immunorestorative.

Aim Of The Study: The present study was aimed to explore in vitro and in vivo immunomodulatory activities of the iridoids fraction i.e. n-butanol fraction of methanol extract from Barleria prionitis aerial parts (IFBp).

Materials And Methods: IFBp was studied for in vitro [nitroblue tetrazolium (NBT) test and neutrophils candidacidal assay] and in vivo immunomodulatory activity on cellular and humoral immune responses to the antigenic challenge by sheep red blood cells (SRBCs) and by neutrophil adhesion test, phagocytic activity and cyclophosphamide-induced myelosuppression. The study comprised the preliminary phytochemical screening, HPTLC standardization and maximum tolerable dose determination of IFBp.

Results: IFBp (50, 100 and 200μg/ml) significantly (P≤0.01) increased the intracellular killing activity of stimulated neutrophils assayed by in vitro NBT reduction test and neutrophils candidacidal assay. Pretreatment of IFBp (100 and 200mg/kg; p.o.) evoked a significant increase in percent neutrophils and neutrophils adhesion to nylon fibres. Oral administration of IFBp augmented the humoral immune response to SRBCs, evidenced by increase in antibody titres and dose dependently potentiated the delayed-type hypersensitivity reaction induced by SRBCs in mice. IFBp potentiated significantly (P≤0.01) the macrophage phagocytic activity and ameliorated the red blood cells, total white blood cells and platelets count and haemoglobin concentration, and also restored the myelosuppressive effects induced by cyclophosphamide. The content (% w/w; mean±SD, n=3) of main iridoids i.e. shanzhiside methyl ester and barlerin was found to be 21.55±2.40 and 10.03±1.69 in IFBp of BP, respectively.

Conclusion: The present investigation reveals that IFBp is a potent immunostimulant, stimulating both the specific and non-specific immune mechanisms.