Cycloartanes from leaves of Combretum quadrangulare growing in Vietnam

Abstract

Two new cycloartanes, combretic acid C (1) and combretanone I (3), were isolated from the leaves of Combretum quadrangulare Kurz, together with the previously-reported combretic acids A-B (2 and 5) and combretanone A (4). An extensive set of spectroscopic methods were used to elucidate the structures of these compounds. Cytotoxicity against the K562 cancer cell line was evaluated.Compound 1 showed strong activity, with an IC50 value of 9.7 µM. The other compounds showed moderate activity. Alpha-glucosidase inhibition was also evaluated. The isolated compounds showed moderate inhibition, with IC50 values in the range 102.2-194.7 µM.

α‐Glucosidase Inhibitory Cycloartanes from the Vietnamese Combretum quadrangulare

“…These spectroscopic features were highly similar to those of cycloartane having an acetyl group at C-7 that were found in combretic acids and combretanones isolated in the same biosource. [8,9] Careful observation of the 1 H and 13 C-NMR spectra of 1 indicated that there are some signals of the side chains that appeared as a pair of signals, from CH-23 to CH 2 -27. This finding proposed that 1 was a mixture of two epimers 1a and 1b (Figure S1).…”

“…[1] Although diverse skeletons were reported in this plant, cycloartane-type triterpenoid is a major class with over 35 compounds isolated. [2][3][4][5][6][7][8][9] These compounds showed a range of biological activities. In 2021, Nguyen et al isolated combretanones G and H that exhibited potent anthelmintic.…”

“…[9] Combretic acids and combretanones are potential anticancer compounds against several cell lines. [8][9] The Vietnamese native plant had much attention of phytochemists. [1,[8][9][10] Dao and co-workers indicated that the extracts of the plant growing in Vietnam showed potent α-glucosidase inhibition.…”

“…[8][9] The Vietnamese native plant had much attention of phytochemists. [1,[8][9][10] Dao and co-workers indicated that the extracts of the plant growing in Vietnam showed potent α-glucosidase inhibition. The previous reports focused on the bioactive fractions (so-called P9 and EA2) to find the bioactive compounds.…”

“…The previous reports focused on the bioactive fractions (so-called P9 and EA2) to find the bioactive compounds. [1,9] Unfortunately, isolated compounds showed moderate or weak activity against α-glucosidase. In this article, the remaining bioactive fractions of C. quadrangulare growing in Vietnam were chemically investigated.…”