Two rare sulphate ellagic acid derivatives were isolated from the rhizome of Geum rivale L. in three simple steps. Their structures were identified by comprehensive NMR studies (1H NMR, 13C NMR, 1H-1H COSY, HMBC, HSQC) as 3,3′-dimethoxy-4-sulphoxyellagic acid potassium salt (1) and 3,3′,4′-trimethoxy-4-sulphoxyellagic acid potassium salt (2). Subsequently, a new precise (RSD < 2.6%), accurate (...
