A new alkaloid, sinensine (1), had been isolated from the fruiting bodies of Ganoderma sinense Zhao, Xu et Zhang. Its structure was elucidated on the basis of 1D and 2D spectral analysis. This alkaloid exhibited activity in protecting the injury induced by hydrogen peroxide oxidation on HUVEC, with EC(50) value 6.2 mu mol/L. (C) 2009 RuoYun Chen. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.