and (3R, 3’R) enantiomers account for ~25% each in synthetic ASTX [4]. In addition, as ASTX has a polyene chain consisting of multiple double-bonds, geometrical cis- or trans- isomers of ASTX also exist. Trans-ASTX esters predominantly present in nature, whereas cis-ASTX esters are thermodynamically less stable but still detectable [14]. ASTX in H. pluvialis is composed of 3:1 ratio of trans-ASTX to cis-ASTX [15]. Studies have shown ASTX isomers may have different bioavailability in humans [16-18]. This aspect is described in detail below