New protostane triterpenoids and their bioactivities from the fruits of Schinus terebinthifolius.

Abstract

Two new protostane triterpenoids, schifoliusterpenes A and B (1 and 2), were isolated from the fruits of Schinus terebinthifolius. Their structures were elucidated by NMR, HRESIMS, DP4 probability analysis, and comparison with previously reported data. These new compounds were evaluated for α-glucosidase and acetylcholinesterase (AChE) inhibition, nitric oxide (NO) suppression, and antioxidant, antimicrobial, and cytotoxic activities. Compound 1 was identified as an effective AChE inhibitor (IC₅₀ 31.3 μM), and 2 exhibited a significant effect in decreasing NO production (IC₅₀ 26.4 μM). Moderate cytotoxicity of 1 was recorded against KB, HepG2, A549, and MCF7 cancer cell lines, with IC₅₀ values ranging from 65.3 to 71.6 μM, while 2 exhibited a selective effect against KB (IC₅₀ 92.5 μM). Significant susceptibility to gram-positive bacteria rather than gram-negative bacteria and fungi was observed for both compounds, particularly against Bacillus subtilis (IC₅₀ 5.4-5.5 μM, MIC 8.8-35.0 μM) and Staphylococcus aureus (IC₅₀ 77.9-93.8 μM). In contrast, compounds 1 and 2 demonstrated weak activity in both α-glucosidase inhibitory and antioxidant assays. Further molecular docking simulation on 1 and 2 proposed the determinant role of the C-26 carboxyl and C-3 ketone groups in their structures for the positive bioactivities, providing stable binding interactions with the target proteins via effective hydrogen-bond formation.