Planta Med 2010; 76 - SL_21
DOI: 10.1055/s-0030-1264259

Potent immunostimulatory and antioxidant activities of three – (–) catechin-O-rhamnosides from Eastern Nigeria mistletoe

P Osadebe 1, A Kawamura 2, P Procksh 3, H Amal 3, D Abdessamad 3, J Nwodo 1, U Ajali 1, C Esimone 4, S Nworu 1, T Okoye 1, E Omeje 1
  • 1University of Nigeria, Nsukka, Department of Pharmaceutical and Medicinal Chemistry, Department of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmceutical Sciences, Nsukka, 410001 Enugu, Nigeria
  • 2City University of the New York, Department of Chemistry, Hunter College of CUNY, 10065 New York, United States
  • 3Heinrich-Hein University, Düsseldorf, Gebaude, Germany, Department of Pharmaceutical Biology, 40225 Düsseldorf, Germany
  • 4Nnamdi Azikiwe University, Awka, Anambra State, Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, PMB 6025, 420281 Awka, Nigeria

Mistletoes of Eastern Nigeria origin, Loranthus micranthus, harvested from our local Kola tree, Kola acuminata, was recently reported to be the most potent specie in terms of antidiabetic [1], immunostimulatory activities [2, 3]. Furthermore, an unpublished data showed that this mistletoe possesses pronounced in vitro antioxidant activities when compared to ascorbic acid. In bid to study the chemical composition of this specie of mistletoe, elaborate bioassay-guided fractionation and purification led to the isolation of three rhamnoside based glycosides namely; – (–) catechin-7-O-rhamnoside, – (–) catechin-3-O- rhamnoside and a 4′-methoxy derivative of the 7-O-rhamnoside. Characterization and unequivocal structural assignments of these compounds were achieved by a combination of UV/visible, IR, NMR, MS, COSY experiments including, HMBC and HQSC. These flavonoid glycosides exhibited very potent immunostimulatory activity on cell line (C57Bl/6 splenocytes) against Lipopolysaccharide and Concanavalin A standards. Their measured antioxidant potentials in terms of effective concentration at 50% reduction in diphenyl picrazyl hydrazyl radical activity (EC50) were remarkably high (< or=to 55. 42±0.99mg/ml) when compared to ascorbic acid (17.6±1.78mg/ml) We are herein reporting, for the first time, the presence and some biological activities of three catechin-based rhamnoside glycoside in mistletoe harvested from Eastern Nigeria

Acknowledgements: The authors specially acknowledge Mr. Alfred Ozioko of BDCP, Nsukka for collection and identification of the plant material.

References: 1. Osadebe PO, et al (2004)J Ethnopharmacology, 95: 133–138.

2. Osadebe PO, et al (2009)J Ethnopharmacology, 125:287–293.

3. Osadebe et al (2008), RPMP Vol 27: 473–485.