Table 1. Comparison of the Physicochemical Properties of AXT from Different Sources.

source	isomers	3,3′-OH group modification	properties of dominant form	ref
Haematococcus pluvialis	3S, 3′S	70% monoesterified, 25% diesterified, 5% free form	high stability	(32, 33)
Paracoccus carotinifacience	3S, 3′S	100% free form	unstable, sensitive to oxidation, higher bioaccessibility	(34, 35)
Phaffia rhodozyma	3R, 3′R	100% free form
synthetic	1(3S, 3′S), 2(3R, 3′S), 2(3S, 3′R), 1(3R, 3′R)	free form