Structurally diverse terpenoids and phenolic compounds from compound Ruteng, a Tibetan medicine

Compound Ruteng (CRT) is a Tibetan medicinal formulation commonly used to treat rheumatoid arthritis (RA). The main chemical components of CRT include terpenoids and phenolic compounds. This study aimed to isolate and characterize novel compounds from CRT, and to identify potential quality markers relevant to its anti-RA efficacy. A phytochemical investigation of CRT extract resulted in the discovery of 10 new terpenoids, including 8 tirucallane-type triterpenoids (compounds 1-8), 1 verticillane-type diterpenoid (compound 17), 1 prenylalloaromadendrane-type diterpenoid (compound 18), and 19 known compounds. Their structures were clarified using high resolution electrospray ionization mass spectroscopy, 1D and 2D NMR, and NMR calculations. Moreover, the electronic circular dichroism calculations were employed to determine the absolute configuration of compound 17. The discovery of the new compounds, together with the known anti-RA markers 3-keto-tirucall-8,24-dien-21-oic acid (9) and 3α-
O
-acetyl-11-keto-β-boswellic acid (13), provides a chemical foundation for developing terpenoids as quality markers from CRT. Thus, the findings have enriched the structural types of terpenoids, providing a material basis for ensuring the safety, efficacy, and stability of CRT.