Chemical Constituents from the Root Woods of Ochna integerrima (Lour.) Merr. and Their Biological Activities

Abstract

Ochna integerrima (Louri) Merr. is one of the two species of the genus Ochna (family Ochnaceae) found in Thailand. Its barks and roots are used in traditional Thai medicine to treat digestive disorders, the leaves have historically been utilized to treat a range of conditions such as asthma, dysentery, epilepsy, gastric disorders, menstrual disorders, lumbago, ulcers, and snakebites. Phytochemical investigation of the crude methanol extract of the root woods of O. integerrima furnished an unreported isoflavone glycoside, gerontoisoflavone A-4'-O-β-D-xylopyranoside (35), together with the previously described iriskumaonin methyl ether (11), irisolone methyl ether (12), a flavone glycoside, vitexin (13), a chromone derivative, lophilone A (20), isoprunetin (26), gerontoisoflavone A (27), and iriskumaonin (36). The structure of 35 was elucidated by 1D and 2D NMR spectral analysis as well as HRMS data. All the compounds except compound 20 were evaluated for antimalarial activity against a chloroquine- and pyrimethamine-resistant strain of Plasmodium falciparum (multidrug-resistant strain K1), antibacterial activity against methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), and Bacillus cereus, and their 2,2-diphenyl-1-picrylhydrazil radical (DPPH●) scavenging activity. Compounds 27 exhibited strongest scavenging activity, with SC50 of 137.7 μM, while 36 and 26 displayed weak scavenging activity, with SC50 values of 4 and 5 times higher than that of 27. None of the tested compounds showed antimalarial activity against P. falciparum (K1) at a concentration of 5 μg/mL and compound 36 showed antibacterial activity against the S. aureus MSSA with a MIC and MBC values of 0.25 and >0.25 mg/mL, respectively.

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