Flavonoids in Juglans regia L. Leaves and Evaluation of In Vitro Antioxidant Activity via Intracellular and Chemical Methods

Table 1

The retention time, fragment ions, tentative identification, and quantification results of flavonoids and phenolic acids in Juglans regia L. Leaves.

Peak	𝑅𝑡 (min)	[M–H]^−; (𝑚/𝑧)	MS^2  (𝑚/𝑧)	Compound	Content; (μg/g)^e	Reference
1	8.7	353	191, 179, 135	5-O-Caffeoylquinic acid (neochlorogenic acid)	29.72±1.85	Std.
2	9.0	289	202.2, 123.0	Epicatechin^a	8.86±1.87	Std.
3	9.5	337	191, 163, 118.9	3-p-Coumaroylquinic acid	6.72±0.13^b	Ref. [10, 11]
4	11.1	507	327.3	Syringetin-O-hexoside^a	5.99±0.47^c	Ref. [12]
5	11.2	339	158.6	Unknown^a	38.63±3.00^c
6	12.0	479	316	Myricetin-3-O-glucoside^a	21.73±1.69^c	Ref. [12, 13]
7	13.1	449	316	Myricetin-3-O-pentoside^a	8.88±0.69^c	Ref. [13, 14]
8	13.2	177	131.3, 115.2, 92.3	Esculetin^a	9.79±0.76^c	Ref. [15, 16]
9	13.3	435	285, 150.8	Taxifolin-pentoside^a	18.23±1.42^c	Ref. [17, 18]
10	13.5	477	300.9, 150.8	Quercetin-3-O-glucuronide^a	4.30±0.23^c	Std.
11	13.8	463	300.0, 270.8	Quercetin-3-O-galactoside (hyperoside)	48.61±0.11	Std.
12	14.3	433	300, 270.9	Quercetin-3-O-pentoside derivative	16.31±0.24^d	Ref. [1, 5, 11]
13	14.7	433	299.7, 271.1	Quercetin-3-O-xyloside	70.04±2.77^d	Ref. [1, 11, 19, 20]
14	14.9	433	301.0, 299.9, 270.8	Quercetin-3-O-arabinoside	73.91±0.32	Std.
15	15.3	447	300.1, 284.2, 254.9	Quercetin-3-O-rhamnoside (huercitrin)	453.11±11.65	Std.
16	16.2	417	285.0, 254.7, 226.9	Kaempferol-O-pentoside^a	48.46±3.78^c	Ref. [21, 22]
17	16.8	417	284.7, 254.7	Kaempferol-O-pentoside derivative	49.04±1.82^c	Ref. [11, 21, 22]
18	17.4	431	285.2	Kaempferol-O-rhamnoside^a	28.96±1.26^c	Ref. [23, 24]

aCompounds identified for the first time in J. regia leaves; bexpressed in equivalents of 5-O-caffeoylquinic acid; cexpressed in equivalents of quercetin-3-O-rhamnoside; dexpressed in equivalents of quercetin-3-O-arabinoside; emean ± RSD; Ref.: literature where the compound has been characterized by MS analysis; Std.: standard.