Guanosine

Ultrapure water was prepared using a Milli-Q purifying system (Millipore, Bedford, MA, USA). Methanol and acetonitrile of HPLC grade were purchased from Merck (Damstadt, Germany). Standard compounds of histidine (1), arginine (3), cysteine (4), asparagine (5), serine (6), lysine (7), glutamine (8), proline (9), cytidine (10), hypoxanthine (11), deoxycytidine (12), uridine (13), tyrosine (14), guanine (15), guanosine(16), inosine(17), deoxyguanosine (19), isoleucine (20), leucine (21), thymidine (23), phenylalanine (24), tryptophan (27), epicatechin (33), rutin (34), hyperoside (35), and quercitrin (37) were purchased from Shanghai Yuanye Biotechnology (Shanghai, China); glutamic acid (2), gallic acid (22) and apigenin (43) were obtained from Chinese National Institute of Control of Pharmaceutical and Biological Products (Beijing, China); fumaric acid (18), gallocatechin (25), epigallocatechin (28), cryptochlorogenic acid (31), kaempferol 3-O-rutinoside (39) and amentoflavone (42) were acquired from Chengdu Chroma Biotechnology (Chengdu, China); neochlorogenic acid (26), chlorogenic acid (29), catechin (30), caffeic acid (32), isoquercitrin (36), avicularin (38), trifolin (40), and astragalin (41) were bought from Baoji Chenguang Biotechnology Co., LTD. (Baoji, China) with the purity greater than 98% and their structures were presented in Figure S4.

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.

The reference compounds of glycine (1), alanine (2), serine (3), proline (4), valine (5), threonine (6), leucine (7), isoleucine (8), aspartic acid (9), glutamic acid (10), lysine (11), methionine (12), histidine (13), phenylalanine (14), arginine (15), tyrosine (16), uracil (17), adenine (18), hypoxanthine (19), guanine (20), dideoxycytidine (21), thymidine (22), cytidine (23), uridine (24), dideoxyguanosine (25), adenosine (26), inosine (27), and guanosine (28) were purchased from Shanghai Yuanye-Biotechnology Co., Ltd. (Shanghai, China). Heterophyllin A (29) and heterophyllin B (30) were kindly provided by Professor Ninghua Tan (Kunming Institute of Botany, Chinese Academy of Science, Kunming, China). The structures of the 30 reference compounds are shown in Figure 2. The purity of all compounds by HPLC analysis was greater than 98%. Formic acid of MS grade and acetonitrile were purchased from Merck (Darmstajt, Germany). Ultrapure water was prepared using a Milli-Q water purification system (Millipore, Bedford, MA, USA).