. 2022 May 31;11(6):1103. doi: 10.3390/antiox11061103

Table 3.

Identification and quantification of the main compounds of the two extracts, the EtOH-UAE and the BP. Peaks were tentatively identified after comparison of the UV-vis maxima obtained by the HPLC-DAD and UHPLC-DAD-MS analysis, the ions observed in the mass spectra after UHPLC-DAD-MS, and their elution order to the literature. The retention times of the HPLC-DAD analysis used for quantification are presented. The concentrations (mean ± standard deviation, n = 3) are presented as mg astaxanthin equivalents per g dry original microalgal biomass.

Peak Number	Tentative Identification	Rt (min)	MW	UV-Vis Maxima (nm)	Positive Ionization (m/z)	EtOH-UAE	BP
1	violaxanthin derivative [8]	6.67	618.9	417, 441, 470	619.5 [M+H]⁺ 601.5 [M−18+H]⁺ 583.5 [M−18−18+H]⁺	0.94 ± 0.06	0.53 ± 0.04
2	luteoxanthin derivative	7.84	618.9	400, 423, 450	619.5 [M+H]⁺ 601.5 [M−18+H]⁺ 583.5 [M−18-−18+H]⁺	nq	nq
3	neoxanthin derivative [54]	8.64	618.9	412, 435, 465	619.5 [M+H]⁺ 601.4 [M−18+H]⁺ 583.5 [M−18−18+H]⁺	nq	nq
4	violaxanthin [8,54,55]	9.12	600.9	417, 441, 470	601.5 [M+H]⁺ 584.5 [Μ−18+H]⁺ 583.4 [Μ−18]⁺	10.41 ± 0.94	2.34 ± 0.23
5	luteoxanthin derivative [7]	10.32	616.9	400, 423, 450	601.6 [Μ−15]⁺ 583.6 [M−18−15]⁺ 617.5 [Μ+H]⁺	1.35 ± 0.07	0.55 ± 0.04
6	luteoxanthin derivative [7]	10.54	616.9	400, 423, 450	601.6 [Μ−15]⁺ 583.6 [M−18−15]⁺ 617.5 [Μ+H]⁺	1.39 ± 0.08	0.60 ± 0.03
7	auroxanthin derivative + canthaxanthin [7,56]	11.64	614.9 (M₁) & 564.9 (M₂)	381, 402, 427 (sh472)	615.4 [M₁+H]⁺ 599.6 [M₁−15]⁺ 584.6 [M₁−15−15]⁺ 565.3 [M₂+H]⁺	0.52 ± 0.02	nq
8	cis-hydroxylated carotenoid [54]	12.36	600.9	315, 330, 417, 440, 464	601.5 [M+H]⁺ 584.5 [M−18+H]⁺	0.84 ± 0.06	0.30 ± 0.02
9	auroxanthin [7,57]	12.92	600.9	381, 402, 427	601.6 [M+H]⁺ 583.6 [M−18]+	0.49 ± 0.03	0.18 ± 0.01
10	antheraxanthin [7,8,54,57]	15.12	584.9	420, 444, 472	585.5 [M+H]⁺	5.50 ± 0.49	0.59 ± 0.06
11	Luteoxanthin [7,57]	18.20	600.9	400, 424, 452	601.5 [M+H]⁺ 584.5 [M−18+H]⁺]⁺	nq	nq
12	antheraxanthin derivative [8] (propionyl ester?)	19.15	640.9	420, 445, 472	641.5 [M+H]⁺ 623.6 [M−18+H]⁺	1.54 ± 0.11	0.26 ± 0.02
13	cis-carotenoid [54] (9-cis-violaxanthin isomer)	19.85		330, 418, 438, 466		nq	nq
14	chlorophyll-a [7,8]	28.85	893.5	432		-	-
15	pheophytin a [58]	41.21	871.2	408	593.3 [M−C₂₀H₃₈]⁺	-	-
16	β-carotene [7,8,54,55]	41.85	536.9	450, 480	537.5	1.52 ± 0.14	0.18 ± 0.01

The previous references that helped in the identification are provided in the second column, and, in the parentheses, a suggestion for the nature of the identified compound is given. nq: not quantified.