Aspergetherins A‐D, New Chlorinated Biphenyls with anti‐MRSA Activity from the Marine Sponge Symbiotic Fungus Aspergillus terreus 164018

Abstract

Aspergetherins A-D (1 -4), four new chlorinated biphenyls, were isolated from the rice fermentation of a marine sponge symbiotic fungus Aspergillus terreus 164018, along with seven known biphenyl derivatives (5 -11). The structures of four new compounds were determined by a comprehensive analysis of the spectroscopic data, including HR-ESI-MS and 2D NMR data. All 11 isolates were evaluated for their anti-bacterial activity against two strains of methicillin-resistant Staphylococcus aureus (MRSA). Among them, compounds 1, 3, 8 and 10 showed anti-MRSA activity with MIC values of 1.0 -128 μg/mL. Preliminary structure-activity relationship analysis unveiled that both chlorinated substitution and esterification of 2-carboxylic acid could impact the antibacterial activity of biphenyls.

Naturally Occurring Asterric Acid Analogs: Chemistry and Biology

“…Therefore, a primary structure− activity relationship was presented: both chlorinated substitution and esterification of carboxylic group could impact the antibacterial activity of asterric acid analogs. 86 With regard to pathogenic fungi, analog 9 and neoplaether (52) were verified to show inhibitory activities (MIC values = 8 and 6.2 μg/mL, respectively) against Candida albicans. 18,44 Likewise, asterric acid (1), methyl asterrate (3), methyl 3chloroasterric acid (19), and methyl 3,5-dichloroasterric acid (20) could inhibit the spore germination rates of Curvularia lunata (17.3%−67.6% at 500 mg/L).…”

“…aureus (MRSA), methyl dichloroasterrate ( 17 ) and methyl chloroasterrate ( 18 ) showed anti-MRSA activity with MIC values of 1.0–64.0 μg/mL, while the MIC values of methyl asterrate ( 3 ) and geodin hydrate ( 12 ) were both greater than 128.0 μg/mL. Therefore, a primary structure–activity relationship was presented: both chlorinated substitution and esterification of carboxylic group could impact the antibacterial activity of asterric acid analogs …”

Marine Aspergillus: A Treasure Trove of Antimicrobial Compounds

“…The antibacterial activity of these compounds against MRSA was evaluated, with MIC values ranging from 1.0 to 128 μg/mL. Notably, compound 61 had obvious inhibitory effects on two different MRSA strains, with MIC values of 1 and 16 μg/mL [ 69 ].…”

“…Nine antimicrobial compounds were isolated from marine fungus A. fumigatus H22. These compounds included 12,13-dihydroxyfumitremorgin C (66), fumitremorgin B (67), 13oxofumitremorgin B (68), fumagillin (69), helvolic acid ( 70…”