Chemical Constituents from the Broth Extract of Cultivated Fomitopsis meliae and the Leaves of Gyrinops vidalii (P. H. Ho)

Abstract

PART I: Chemical Constituents from the Broth Extract of Cultivated Fomitopsis meliae

This study aimed to identify antibacterial compounds from the broth extract of Fomitopsis meliae (Mahasarakham University Culture Collection; MSUCC009). From small-scale fermentation, the broth extract of F. meliae showed antibacterial activity. Therefore, the fermentation of this fungal strain was scaled up and the broth extract was chemically investigated. Purification of the broth extract led to the isolation of two 5-hydroxymethylfuran metabolites, 5-hydroxymethyl-2-furoic acid methyl ester (94) and 5-hydroxymethyl-2-furancarboxylic acid (HMFCA; 95), together with a pyrimidine base, uracil (96). This is the first isolation report of 5-hydroxymethylfuran derivatives from the genus Fomitopsis. The structures of isolated compounds (94–96) were elucidated based on nuclear magnetic resonance (NMR) and mass spectrometry (MS) spectroscopic methods, and comparison with previous reports. Compound 95 exhibited antibacterial activity against methicillin-susceptible Staphylococcus aureus (MSSA) with MIC and MBC values of > 0.25 mg/mL. Compounds 94 and 95, were also tested against human lung adenocarcinoma (A549) cell lines. These two compounds were inactive in this cytotoxicity assay.

PART II: Chemical Constituents from the Leaves of Gyrinops vidalii (P. H. Ho)

Plants in the genus Gyrinops are widely distributed in Southeast Asia; however, Gyrinops vidalii is the only species found specifically in Thailand and Laos. In our present study, the ethyl acetate (EtOAc) extract from the leaves of G. vidalii collected from northeastern Thailand exhibited antioxidant activity toward 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, with an SC₅₀ value of 47.23 ± 3.84 µg/mL. This EtOAc extract was chemically investigated for the first time, leading to the isolation of a C-glycosylxanthone, mangiferin (18), two benzophenoneglycosides, aquilarinenside E (40) and iriflophenone 2-O-α-L-rhamnoside (41), a terpenoid, blumenol A or vomifoliol (42), a flavonoid, 5,7,4'-trimethoxyflavone (43), and a phenolic compound, 4-methoxybenzoic acid (44), together with three unknown compounds, A–C. The structures of 18, 40–44, were identified based on NMR and mass spectroscopic data, and confirmed by comparison with the previous reported data in literatures. Iriflophenone (40a) was obtained from acid hydrolysis of compound 40. The structures of A–C are currently under elucidation.

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