Immunomodulatory Effect of Rhaphidophora korthalsii on Natural Killer Cell Cytotoxicity Swee Keong Yeap,1 Abdul Rahman Omar,1,2 Abdul Manaf Ali,3 Wan Yong Ho,4 Boon Kee Beh,5 and Noorjahan Banu Alitheen1,4
1Institute of Bioscience, Putra University, Malaysia, Serdang, 43400 Selangor, Malaysia 2Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine, Putra University, Malaysia, Serdang, 43400 Selangor, Malaysia 3Faculty of Agriculture and Biotechnology, Sultan Zainal Abidin University, Malaysia (UniSZA), Kota Campus, Jalan Sultan Mahmud, 20400 Kuala Terengganu, Malaysia 4Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Putra University, Malaysia, Serdang, 43400 Selangor, Malaysia 5Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Putra University, Malaysia, Serdang, 43400 Selangor, Malaysia
Abstract The in vivo immunomodulatory effect of ethanolic extracts from leaves of Rhaphidophora korthalsii was determined via immune cell proliferation, T/NK cell phenotyping, and splenocyte cytotoxicity of BALB/c mice after 5 consecutive days of i.p. administration at various concentrations. Splenocyte proliferation index, cytotoxicity, peripheral blood T/NK cell population, and plasma cytokine (IL-2 and IFN-𝛾) in mice were assessed on day 5 and day 15. High concentration of extract (350 μg/mice/day for 5 consecutive days) was able to stimulate immune cell proliferation, peripheral blood NK cell population, IL-2, and IFN-𝛾 cytokines, as well as splenocyte cytotoxicity against Yac-1 cell line. Unlike rIL-2 which degraded rapidly, the stimulatory effect from the extract managed to last until day 15. These results suggested the potential of this extract as an alternative immunostimulator, and they encourage further study on guided fractionation and purification to identify the active ingredients that contribute to this in vitro and in vivo immunomodulatory activity.
.....In this study, stimulation of the immune system by R. korthalsii methanol extract had significant effects on proliferation, NK cell population, and cytokine expression in the host, which further enhanced the cytolytic activity of the immune cells. Up till now, 5,6-dihydroxyindole (DHI) is the only compound successfully isolated from R. korthalsii. However, role of DHI on the immunomodulatory effect of R. korthalsii methanol extract and the other potential active secondary metabolites that play an important role in this immunostimulatory effect are still unknown. Thus, future study should focus on isolation and evaluation of active metabolites from the extract that contributes to the immunomodulatory effect against the NK cell.
Source : Evidence-Based Complementary and Alternative Medicine Volume 2012 (2012), Article ID 786487, 7 pages doi:10.1155/2012/786487 Link to Full Article