Six isomers of diphenylheptane dimers from Zingiber officinale peel exert renal protection activities through anti-fibrosis and anti-inflammatory effects

Abstract

As the symbolic compounds in Zingiberaceae, most of diphenylheptane are exist in plants in the form of aglycones, and relatively rare dimers and glycosides of them have been found. A particular phytochemical investigation of Zingiber officinale peel led to the finding of six novel diphenylheptane dimers, including five aglycone isomers (1–5) and one new glycoside (6). Various spectroscopic and computational methods combined with acid hydrolysis were applied in their structurally elucidation. Biological evaluations of anti-inflammatory and anti-renal fibrosis activities of these compounds were carried out in vitro. Compounds 1–5 displayed effective anti-inflammatory activity in LPS induced RAW264.7 cells, especially that 2, 3 and 5 reduced the production of iNOS at a low concentration of 0.625 μM. Compound 3 could significantly inhibit the expression of fibronectin, collagen I and α-SMA in TGF-β1 induced NRK-52e cells at 5 μM. The stereoscopic configurations of the diphenylheptane isomers can markedly influence the biological activities, and compound 3 is a potential molecule for kidney protection via inhibiting inflammation.