African Journal of Immunology Research

African Journal of Immunology Research ISSN 9431-5833 Vol. 5 (7), pp. 375-385, July, 2018. © International Scholars Journals

Full Length Research Paper

Immunomodulatory effects of aqueous extract of Ocimum basilicum (Linn.) and some of its constituents on human immune cells

K. D. Tsai1,2, B. R. Lin3,4, D. S. Perng5, J. C. Wei6, Y. W. Yu6 and Jaw-Ming Cherng6*

1Department of Internal Medicine, China Medical University and Beigang Hospital, Yunlin 651, Taiwan, ROC.

2Institute of Molecular Biology, National Chung Cheng University, Chiayi 621, Taiwan, ROC.

3Department of Integrated Diagnostics and Therapeutics, National Taiwan University Hospital, Taipei 100, Taiwan, ROC.

4Department of Internal Medicine, National Taiwan University Hospital and National Taiwan University, College of Medicine, Taipei 100, Taiwan, ROC.

5Department of Internal Medicine, E-Da Hospital, I-Shou University, Kaohsiung County 824, Taiwan, ROC.

6Department of Internal Medicine, Chung Shan Medical University Hospital and Chung Shan Medical University, Taichung 402, Taiwan, ROC.

*Corresponding author: E-mail: happy.professor@yahoo.com. Tel: +886-4-24739595 ext. 34704. Fax: +886-4-24839376.

Accepted 25 April, 2017

Abstract

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.

Key words: Immunomodulation, Ocimum basilicum (Linn.), caffeic acid, immune cells, cytokines, p-coumaric acid.