Garcixanthone E and Garcimangophenone C: New Metabolites from Garcinia mangostana and Their Cytotoxic and Alpha Amylase Inhibitory Potential

Garcinia mangostana (Clusiaceae) is a rich pool of metabolites with diversified bioactivities. A new xanthone, garcixanthone E (1), and a new benzophenone, rhamnoside, as well as garcimangophenone C (9) together with garcinone E (2), α-mangostin (3), γ-mangostin (4), garcinone C (5), garcixanthone C (6), gartanin (7), and 2,4,6,3',5'-pentahydroxybenzophenone (8) were purified from G. mangostana EtOAc extract. Their structural verification was accomplished utilizing assorted spectral tools and relating to the literature. The in vitro cytotoxic potential versus MCF-7, A549, and HCT-116 cell lines demonstrated the moderate potential of 1 (IC₅₀s 8.5, 5.4, and 5.7 µM, respectively) in comparison to doxorubicin (IC₅₀s 0.18, 0.6 and 0.2 µM, respectively) using a sulforhodamine B (SRB) assay. Additionally, 1 and 9 had AAI (α-amylase inhibition) with IC₅₀s 17.8 and 12.9 µM, respectively, compared to acarbose (IC₅₀ 6.7 µM). Further, their AAI mechanisms were inspected utilizing molecular-docking evaluation by employing the crystal structure of the human α-amylase (PDB-ID: 5EOF). Compound 9 possessed a reasonable docking score of -7.746 kcal/mol compared with the native ligand 7JR which had a docking score of -9.932 kcal/mol. These results could further provide new insight into the potential usage of G. mangostana as a functional food for regulating postprandial hyperglycemia via suppressing AA.