Immunomodulatory activity of a lupane triterpenoid ester isolated from the eastern Nigeria mistletoe,Loranthus micranthus(Linn)

摘要

Objective:To provide further evidence for the ethnomedicinal use of the Eastern Nigeria mistletoe,Loranthus micranthus (L. micranthus), as an immunostimulant.Methods: Solvent fractions from the crude extract of the mistletoe plant was obtained and screened by the cell mediated delayed type hypersensitivity reaction(DTHR) model in mice. Then the immunomodulatory potentials of a major lupane triterpenoid ester isolated from an active hexane fraction of the Eastern Nigeria mistletoe was investigated. Three lupeol-based triterpenoid esters:7β 15α-dihydroxyl-lup-20(29)-ene-3β-palmitate (Ⅰ), 7β, 15α-dihydroxyl-lup-20(29)-ene-3β-stearate(Ⅱ) and7β, 15α-dihydroxyl-lup-20(29)-ene-3β-decadecanoate(Ⅲ) were isolated from the plant leaves epiphyting on a local kola nut tree and were characterized. Compound 1 was subjected to cell proliferation studies usingC57Bl/6splenocytes at three dose levels (5, 25and100 μg/mL) in presence of controls. Furthermore, the effect of this compound on IL-8 receptor expression was evaluated at three doses (1, 5and10μg/mL) using the real time polymerase chain reaction assay.Results: This triterpenoid ester produced some enhancement of the splenocytes at the tested doses but at doses higher than5μg/mL caused inhibition of the IL-8 receptor expression.Conclusions:The present findings support the ethnomedicinal use of the Eastern Nigeria Mistletoe in the management of diseases affecting the immune system. The triterpenoid(s) have some immunomodulatory abilities on splenocytes andIL-8receptors and may partly account for the overall immunomodulatory activity of this plant.