Serine

The standards of Glutamic acid (1), Lysine (2), Histidine (3), Arginine (4), Threonine (5), Aspartic acid (6), Serine (7), Alanine (8), Proline (9), Valine (10), Cytidine (11), Uracil (12), Guanine (13), 2′-deoxyCytidine (15), IsoLeucine (16), Uridine (17), Leucine (18), Tyrosine (19), Adenosine (20), Inosine (21), Guanosine (22), PhenylAlanine (23), 2′-deoxyGuanosine (24), and Thymidine (25) were purchased from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). Ophiopojaponin C (26), Ophiopogonin D (27), Ophiopogonin D′ (28), Methylophiopogonone A (29), Methylophiopogonanone A (30), and Methylophiopogonanone B (31) were purchased from Nanjing Liangwei biotechnology Co., Ltd. (Nanjing, China). Methionine (14) was obtained from Chengdu Chroma Biotechnology Co., Ltd. (Chengdu, China). Ruscogenin (32) was offered by Shanghai nature standard Bio-Technology Co., Ltd. (Shanghai, China). The purities of all compounds were greater than 98%, checked by HPLC analysis. The structures of the 32 standards were shown in Figure S1. Formic acid, acetonitrile and methanol of HPLC grade (Merck, Darmstadt, Germany). Ultrapure water was prepared using a Milli-Q water purification system (Millipore, Bedford, MA, USA). All the other chemicals and solvents were of analytical grade.

Methanol and acetonitrile of HPLC grade were purchased from Merck (Damstadt, Germany); ultrapure water was prepared using a Milli-Q purifying system (Millipore, Bedford, MA, USA); standard compounds of chlorogenic acid, cryptochlorogenic acid, neochlorogenic acid, isochlorogenic acid A, isochlorogenic acid B, ferulic acid, caffeic acid, loganin, proline, alanine, serine, leucine, lysine, histidine, arginine, cytidine, uridine, adenosine, and phenylalanine were obtained from Shanghai Yuanye Biotechnology Co. Ltd (Shanghai, China); 1,3‐O‐dicaffeoylquinic acid, isochlorogenic acid C, protocatechuic acid were purchased from Chengdu Prefa Technology Development Co. Ltd (Sichuan, China); quinic acid, rutin, hyperoside, astragalin, isoquercitrin were acquired by the Control of Pharmaceutical and Biological Products (Beijing, China); diosmetin, apigenin, kaempferol, kaempferol‐3‐O-rutinoside, sweroside were purchased from Chengdu Chroma Biotechnology Co. Ltd (Sichuan, China); 4,5‐O-dicaffeoylquinic acid methyl ester, luteolin, luteoloside, rhoifolin, lonicerin, secologanic acid, loganin acid, morroniside were provided by Liangwei Chemical Reagent Co. Ltd (Nanjing, China); secoxyloganin were taken from Nanjing Jingzhu Biotechnology Co. Ltd (Nanjing, China). The purity of all standard compounds was more than 98%.

Dehulled quinoa cultivar ‘Jili 3’ was grown and harvested at Zhangjiakou Yuerwan Quinoa Planting Cooperative, which is located in Zhangjiakou City (115°36′ E, 415°27′ N), Hebei Province, China. The seeds were preserved in the dark at −20 °C under vacuum until germination. GABA, with a purity ≥ 99%, and 2,2-diphenyl1-picrylhydrazyl (DPPH) were purchased from Sigma-Aldrich (Shanghai, China). Threonine (99%), valine (99%), methionine (98%), isoleucine (98%), leucine (98%), phenylalanine (98%), lysine (98%), histidine (98%), arginine (98%), aspartate (98%), serine (98%), glutamate (98%), glycine (98%), alanine (98%), cysteine (98%), tyrosine (99%), proline (98%), gallic acid (99%), rutin (95%), saponin (98%), 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) (98%), sodium cholate (65%), sodium taurocholate (98%), sodium deoxycholate (98%), and sodium glycocholate (97%), as well as α-amylase (100,000 U/g), α-glucosidase (50,000 U/g), and pancreatic lipase (30,000 U/g), were obtained from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). Acetonitrile (chromatographically pure) was purchased from Macklin Biochemical Co. Ltd. (Shanghai, China). All other chemicals were analytical reagent grade.