Termitomenins A-E: Five new lignans from Terminalia chebula var. tomentella (Kurz) C. B. Clarke.

ABSTRACT

An elaborated phytochemical study on the fresh fruits of Terminalia chebula var. tomentella (Combretaceae) led to the isolation of five new lignans, including three tetrahydrofuran (1-3) and two furofuran (4 and 5) derivatives, namely termitomenins A-E (1-5), along with 10 known ones. All of them were obtained from the titled plant for the first time. Their structures were determined by extensive spectroscopic analysis, including 1D/2D NMR, MS, UV, IR, electronic circular dichroism (ECD), time-dependent density functional theory (TDDFT) calculation of ECD spectra, and single crystal X-ray diffraction in case of 3. Compounds 1-15 exhibited certain anti-inflammatory activities. Interestingly, compounds 6 (IC50 = 18.17 ± 0.57  µM) and 7 (IC50 = 13.66 ± 0.38 µM) which contain an aldehyde group displayed stronger NO inhibitory activity than the positive control L-NMMA (IC50 = 42.34 ± 0.66 µM).