A Potent Antioxidant Sesquiterpene, Abelsaginol, from Abelmoschus sagittifolius: Experimental and Theoretical Insights

Thuc Dinh Ngoc; Mai Vu Thi Ha; Thanh Nguyen Le; Hue Vu Thi; Thi Van Anh Nguyen; Adam Mechler; Nguyen Thi Hoa; Quan V Vo

doi:10.1021/acsomega.2c02974

A Potent Antioxidant Sesquiterpene, Abelsaginol, from Abelmoschus sagittifolius: Experimental and Theoretical Insights

ACS Omega. 2022 Jul 1;7(27):24004-24011. doi: 10.1021/acsomega.2c02974. eCollection 2022 Jul 12.

Authors

Thuc Dinh Ngoc¹, Mai Vu Thi Ha¹, Thanh Nguyen Le², Hue Vu Thi², Thi Van Anh Nguyen³, Adam Mechler⁴, Nguyen Thi Hoa⁵, Quan V Vo⁵

Affiliations

¹ Department of Science and Technology Management, Hong Duc University, Thanh Hóa, Thanh Hóa 40000, Vietnam.
² Institute of Marine Biochemistry (IMBC), Graduate University of Science and Technology (GUST), Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi 10000, Vietnam.
³ University of Science and Technology of Hanoi (USTH), Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi 10000, Vietnam.
⁴ Department of Biochemistry and Chemistry, La Trobe University, Melbourne, Victoria 3086, Australia.
⁵ The University of Danang - University of Technology and Education, Danang 550000, Vietnam.

Abstract

The sesquiterpenoid compound abelsaginol (AS) was successfully isolated from Abelmoschus sagittifolius for the first time. The compound was identified using NMR and MS data. The antioxidant activity of AS was also evaluated both theoretically and experimentally. AS was found to be a weak HOO^• radical scavenger in organic solvents such as pentyl ethanoate and dimethyl sulfoxide (k _overall = ∼ 10² M^-1 s^-1), in a good agreement with the results of the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assay. However, AS exhibited good HOO^• antiradical activity in water at pH 7.40 (k _overall = 9.00 × 10⁶ M^-1 s^-1) through the single-electron transfer mechanism of the anion state. Further calculations also demonstrated that AS could exert good to moderate activity against CH₃O^•, CH₃OO^•, CCl₃OO^•, NO₂, and SO₄ ^•- radicals, with k _f values from 4.00 × 10³ to 1.52 × 10⁷ M^-1 s^-1. However, AS exerted much lower activity against HO^•, CCl₃O^•, NO, O₂ ^•-, and N₃ ^• radicals under the studied conditions. In general, the activity of AS in water at pH 7.40 is higher than that of Trolox or butylated hydroxytoluene, which are common reference antioxidants. Thus, in an aqueous physiological milieu, AS is a promising natural antioxidant.