Structure Revision of Anti-Inflammatory Indole Alkaloids with a 1,2-Benzisoxazole Ring

Ju Ryeong Lee; Kyoung Jin Park; Song Lim Ham; Jonghwan Kim; Chung Sub Kim

doi:10.1021/acsomega.3c00408

Structure Revision of Anti-Inflammatory Indole Alkaloids with a 1,2-Benzisoxazole Ring

ACS Omega. 2023 Apr 6;8(15):13967-13970. doi: 10.1021/acsomega.3c00408. eCollection 2023 Apr 18.

Authors

Ju Ryeong Lee¹, Kyoung Jin Park², Song Lim Ham¹, Jonghwan Kim¹, Chung Sub Kim^{1

2

3}

Affiliations

¹ Department of Biopharmaceutical Convergence, Sungkyunkwan University, Suwon 16419, Republic of Korea.
² School of Pharmacy, Sungkyunkwan Univ ersity, Suwon 16419, Republic of Korea.
³ Department of Biohealth Regulatory Science, Sungkyunkwan University, Suwon 16419, Republic of Korea.

Abstract

(R)- and (S)-2-(benzo[d]isoxazol-3-yl)-2-ethylindolin-3-one [(±)-1] were previously isolated from NIRAM, a natural blue dye from Polygonum tinctorium, and their structures were initially proposed to possess a 1,2-benzisoxazole ring. In this study, the structures of (±)-1 were revised to have an indole-anthranilic acid fused tetracyclic ring rather than the 1,2-benzisoxazole ring by reanalysis of one-dimensional (1D) and two-dimensional (2D) NMR followed by density functional theory (DFT) chemical shift calculation, DP4+ technique, and ECD simulation.