Targeted isolation of previously undescribed fortunefuroic acid-type triterpenoids from Keteleeria pubescens using 1H NMR/LC-PDA-MS and assessment of ACL Inhibition.

Keteleeria is a small genus of conifer in the family Pinaceae (the extant pine family). Fortunefuroic acids (FFAs) have recently been documented as characteristic specialized metabolites of this genus. FFAs constitute a unique class of triterpenoids characterized by the presence of a furoic acid moiety in the side chain. Using 1H NMR and LC-PDA-MS guided isolation and dereplication approaches, four previously undescribed (1-4, fortunefuroic acids Q-T, resp.) and one known (fortunefuroic acid H, 5) FFA-type analogues were isolated from the renewable leaves and twigs of Keteleeria pubescens W. C. Cheng & L. K. Fu, a rare conifer endemic to China. Compounds 1-3 were identified as cycloart-16,23,25(27)-trien-26-oic acid derivatives, whereas compound 4 was characterized as 3-oxo-lanost-16,23,25(27)-trien-26-oic acid. Their chemical structures were elucidated using a combination of spectroscopic techniques and comparative analysis of experimental and calculated electronic circular dichroism data. Compounds 3 and 4 exhibited inhibitory activity against ATP-citrate lyase (ACL), a promising drug target for hyperlipidemia and related metabolic disorders, with IC50 values of 16.6 and 17.2 μM, respectively. Molecular docking studies were performed to elucidate the binding interactions of these compounds within the ACL enzyme active site. The isolated FFAs further support their chemotaxonomical significance within the genus Keteleeria. Collectively, these findings expand the structural diversity of naturally occurring triterpenoids and highlight their potential as lead compounds for the development of therapeutics targeting ACL-associated diseases, while also providing insights into the sustainable utilization and scientific conservation of endangered plant species.