(2R,3R)-Butane-2,3-diol (levo-2,3-Butanediol) is found in cocoa and cocoa products. (2R,3R)-2,3-Butanediol is isolated from cocoa butter and roots of Ruta graveolens (rue).2,3-Butanediol is one of the constitutional isomers of butanediol. The 2R,3R stereoisomer of 2,3-butanediol is produced by a variety of microorganisms, in a process known as butanediol fermentation. It is found in cocoa butter and in the roots of Ruta graveolens.

活体研究显示，D-Asp通过下丘脑-垂体-性腺轴间接促进精子生成。成年大鼠口服和/或腹膜内给予D-Asp后，可见血清孕酮和LH水平上升，以及睾丸/血清睾酮水平增加，而17β-雌二醇(E2)水平则无变化。