Abstract

K. D. Tsai , B. R. Lin , D. S. Perng , J. C. Wei , Y. W. Yu and Jaw-Ming Cherng

Ocimum basilicum Linn. (OB) is an edible plant with high concentrations of caffeic (CA) and p-coumaric acid (pCA). In this study, the authors evaluated the immunomodulatory activities of aqueous extract of OB, CA and pCA on human peripheral blood mononuclear cells (PBMC) by lymphoproliferation test, and defined the responding cells by flow cytometry, secretion of various cytokines by ELISA, and expression of mRNA by quantitative Real Time-PCR (qPCR) methods. At concentrations tested (0.135, 0.27, and 0.54 µg/ml of OB extract, 2.5, 5, and 10 µg/ml of CA, 5, 10, and 20 µg/ml of pCA), OB, CA, and pCA were capable of dose-dependently stimulating DNA synthesis of human PBMC. In addition, OB extract suppressed cytokines produced by TH1 (IL-2, IFN-γ, and TNF-β), TH2 (IL-5, IL-10) as well as regulatory T (TGF-β) cells, and expression of ERK2 mRNA in PBMC. OB constituents CA and pCA also suppressed some of the cytokines. These data convincingly demonstrate that OB possesses direct immunomodulatory effect on basic functional properties of human immune cells, possibly mediated by the ERK2 MAP-kinase signal pathway. Thus, aqueous extract of OB can be considered as a powerful natural immunomodulatory spice influencing various types of immune-responses and may have potential health effects.