## 2 Materials and Methods  
### Plant Material and Chemicals  
Samples of _Mertensia serrulata_ (herb) were collected during the flowering period in Republic of Buryatia, Kurumkansky District. The samples were collected in subalpine meadow in 5 locations, 10 samples from each (31.VII.2022, 54\({}^{\circ}\)18\({}^{\circ}\)9.4837\({}^{\prime\prime}\) N, 110\({}^{\circ}\)10\({}^{\prime}\)20.1782\({}^{\prime\prime}\) E, 1216 m a.s.l.; voucher No BKD/MSe0722/33-83). Samples of _M. stylosa_ (herb) were collected during the flowering period in Irkutsk Oblast, Slyudyansky District. The samples were collected on the bank of the Slyudyanka river in 5 locations, 10 samples from each (11.VII.2022, 51\({}^{\circ}\)37\({}^{\prime}\)43.0338\({}^{\prime\prime}\) N, 103\({}^{\circ}\)40\({}^{\prime}\)28.5175\({}^{\prime\prime}\) E, 596 m a.s.l.; voucher No ISDMst-0722/42-92). The species were authenticated by Prof. [PERSON] (IGEB SB RAS, Ulan-Ude, Russia).  
Figure 1: _Mertensia_ species in their natural habitat: (**a**)—_M. stylosa_ ([PERSON].) DC.; (**b**)—_M. serrulata_ ([PERSON].) DC.  
Plant material was dried in the ventilated heat oven at 35 \({}^{\circ}\)C within 7-12 days and stored at 4-6 \({}^{\circ}\)C before analysis.  
The reference compounds were purchased from BioCrick Co., Ltd. (Chengdu Tianfu, Sichuan, China): 7-acetyllycopsamine (Cat. No. BCN2000, \(\geq\)98%), 7-O-acetyllycopsamine \(N\)-oxide (Cat. No. BCN8935, \(\geq\)98%), 4-O-coumaroylquinic acid (Cat. No. BCX0010, \(\geq\)98%), 5-O-coumaroylquinic acid (Cat. No. BCX0028, \(\geq\)98%), 3-O-feruloylquinic acid (Cat. No. BCN3353, \(\geq\)98%), 4-O-feruloylquinic acid (Cat. No. BCN3352, \(\geq\)98%), 5-O-feruloylquinic acid (Cat. No. BCN3788, \(\geq\)98%); Sigma-Aldrich (St. Louis, MO, USA): acetonitrile for HPLC (Cat. No. 34851, \(\geq\)99.9%), 2,2'-azino-bis(3-ethylbenzothiazazoline-6-sulfonic acid) diammonium salt (Cat. No. A1888, \(\geq\) 98%), 3-O-caffeoylquinic acid (Cat. No. PHL89175, \(\geq\)95%), 4-O-caffeoylquinic acid (Cat. No. 65969, \(\geq\)98%), 5-O-caffeoylquinic acid ((eochlorogenic acid; Cat. No. 94419, \(\geq\)98%), \(N\),N-dimethyl-\(p\)-phenylenediamine (Cat. No. 193992, \(\geq\) 97%), 2,2-diphenyl-1-picrylhydrazyl (Cat. No. D9132), 3,5-di-O-caffeoylquinic acid (Cat. No. SMB00131, \(\geq\)95%), 3,4-di-O-caffeoylquinic acid (Cat. No. SMB00224, \(\geq\)90%), 4,5-di-O-caffeoylquinic acid (Cat. No. SMB00221, \(\geq\)85%), caftaric acid (Cat. No. PHL89170, \(\geq\)95%), 3-O-coumaroylquinic acid (Cat. No. FC71593, \(\geq\)95%), kaempfer-3-O-trutinoside (nicotiformis; Cat. No. 90422, \(\geq\)98%), kaempfer-3-O-glucose (astragalim; Cat. No. 68437, \(\geq\)90%), lithium perchlorate (Cat. No. 205281, \(\geq\)95%), lycopsamine (Cat. No. PHL89726, \(\geq\)95%), lycopsamine \(N\)-oxide (Cat. No. PHL83447, \(\geq\)90%), methanol (Cat. No. 322415, \(\geq\)98.%), perchloric acid (Cat. No. 244252, \(\geq\)70%), rosmarinic acid (Cat. No. PHL89266, \(\geq\)95%), quercetin-3-O-glucose (isoquercitrin; Cat. No. 16654, \(\geq\)98%), quercetin-3-O-rutinoside (rutin; Cat. No. CFN99642, \(\geq\)98%), trolox (Cat. No. 238813, \(\geq\)97%). 2-O-Caffeoylartronic acid, 2-O-, 3-O-, 4-O-caffeoylthreronic acids, as well as 2-O-, 3-O-caffeoylglyceric acid were previously isolated from _Nonea rossica_ and _Tournefortia sibirica_[17].