Cycloartane-type triterpenoids from the leaves of Sandoricum koetjape and their efficacy on α-glucosidase inhibition activity

The preliminary α-glucosidase inhibitory activity of the methanol extract of the leaves of Sandoricum koetjape Merr. exhibited promising results. The leaves was extracted with methanol to obtain the methanol extract that was continuedly partitioned with hexane and ethyl acetate. Those fractions were further purified by various chromatographic techniques. The isolation of the potent fractions furnished two new cycloartane-type triterpenoids (1 and 2) along with ten known compounds (3–12). Their chemical structures were unambiguously established by interpretation of NMR (1 D & 2 D) and high-resolution electrospray ionization mass spectrometry (HRESIMS) data. Furthermore, the configurations of two new compounds were determined by using NOESY spectrum as well as comparing their NMR data to the reference. These compounds were evaluated against α-glucosidase. All tested compounds revealed potent activity with IC₅₀ value in the range of 2.17–49.2 µM compared to that of acarbose (IC₅₀ 100.6 µM). Compound 10 showed the lowest IC₅₀ value. This compound was reported as a mixed-type inhibitor. Compound 3 possessed the second strong activity with an IC₅₀ value of 14.0 μM and was further investigated on kinetic analysis which revealed as a mixed-type inhibitor with K_i and K_i′ values of 59.1 and 155.2 μM, respectively.

Graphical abstract