In the course of studies on polyphenol metabolism in wood, four new C-glycosidic ellagitannins named castacrenins D-G were isolated from the wood of the Japanese chestnut tree (Castanea crenata). Castacrenins D and F are related to vescalagin and have a gallic acid and an ellagic acid moiety, respectively. Castacrenins E and G are oxidative metabolites of castacrenins D and F, respectively, in which a pyrogallol ring of each C-glycosidic ellagitannin unit is replaced by a cyclopentenone ring.