-Isolation and structrural elucidation of chemical constituents of Siegesbeckia orientalis.
-Evaluation of xanthine oxidase inhibitory activity of the isolated compounds.

- From methanolic extract of Siegesbeckia orientalis, 16 compounds (SO1-SO16) were isolated. Their structures were detemined and classified into three groups: sesquiterpenes, diterpenes, and derivatives of benzoate ester. Among them, 9 new compounds were obtained.
- Derivatives of benzoate ester exhibited potential xanthine oxidase inhibitory activity. Two compounds SO9 and SO10 exhibited the best inhibitory activity with their IC50 values of 0.76 ± 0.17 and 0.98 ± 0.26 µM, respectively.
- Compounds SO9 and SO10 comparative inhibited xanthine oxidase enzyme with their Ki values of 0.13 and 0.16 µM, respectively.
- Molecular docking results indicated that 12 among 16 isolated compounds were good binding with xanthine oxidase enzyme (binding energy in range of − 8.92 to − 13.04 Kcal/mol) which are better than that of positive control, allopurinol (binding energy of − 6.37 Kcal/mol)

- Nine new compounds were ontained
- This is the first report on the xanthine oxidase inhibitory activity of all the isolated compounds.

- Scientific papers in referred journals (list):
[1]. Dan Thi Thuy Hang, Do Thi Trang, Duong Thi Dung, Duong Thi Hai Yen, Nguyen Huy Hoang, Ngo Anh Bang, Nguyen Thi Cuc, Nguyen Xuan Nhiem, Phan Thi Thanh Huong, Bui Huu Tai, Phan Van Kiem, Guaianolide sesquiterpenes and benzoate esters from the aerial parts of Siegesbeckia orientalis L. and their xanthine oxidase inhibitory activity, Phytochemistry, 190, 112889 (2021).
[2]. Do Thi Trang, Phan Thi Thanh Huong, Nguyen Thi Cuc, Duong Thi Dung, Bui Thi Thu Trang, Nguyen Xuan Nhiem, Bui Huu Tai, and Phan Van Kiem, Four new acyclic diterpenes from Siegesbeckia orientalis, Natural Product Communications, 16, 1934578X211056140 (2021).
- Technological products (deposited in the Institute of Marine Biochemistry):
+ Report on the isolation of 16 compounds from Siegesbeckia orientalis and isolated compounds
+ Report on the structural determination of 16 compounds with their spectral data
+ Report on in vitro xanthine oxidase inhibitory activity of isolated compounds, enzyme kinetic analysis for inhibition type of compounds SO9 and SO10, molecular docking results of compounds SO1-SO12 on xanthine oxidase enzyme.

- Natural products on treatment of gout should be deverloped from S. orientalis.
- 5 compounds (SO8-SO12) exhibited potent xanthine oxidase inhibitory activity with IC50  values equal or smaller than positive control allopurinol which should be further studied their activity to confirm and use as lead compounds.