Lipoic acid ((R)-(+)-α-Lipoic acid) is an antioxidant, which is an essential cofactor of mitochondrial enzyme complexes. (R)-(+)-α-Lipoic acid is more effective than racemic Lipoic acid.
Lipoic acid ((R)-(+)-α-Lipoic acid) is the form biosynthesized in humans which is essential for aerobic metabolism. Lipoic acid ((R)-(+)-α-Lipoic acid) is the nutritionally and therapeutically preferred form due to its "vitamin-like" role in metabolism. Lipoic acid ((R)-(+)-α-Lipoic acid) and S-(-)-α-Lipoic acid) constitute the racemic mixture Lipoic acid. Only the Lipoic acid ((R)-(+)-α-Lipoic acid) exists in nature and is an essential cofactor of four mitochondrial enzyme complexes. Lipoic acid ((R)-(+)-α-Lipoic acid) has been suggested to be nutritionally and therapeutically preferred form as antioxidant[1].
References:
[1]. Nasole E, et al. Effects of alpha lipoic acid and its R+ enantiomer supplemented to hyperbaric oxygen therapy on interleukin-6, TNF-α and EGF production in chronic leg wound healing. J Enzyme Inhib Med Chem. 2014 Apr;29(2):297-302.