Antimicrobial Furancarboxylic Acids from a Penicillium sp.

Abstract

Ten novel (1, 2, 3a, 3b, 4a, 4b, 5a, 5b, 6a, and 6b) furancarboxylic acids including four pairs of epimers (3a, 3b; 4a, 4b; 5a, 5b; 6a, 6b), together with seven known analogues (7a, 7b, 8a, 8b, 9a, 9b, and 10), were isolated from the fermentation of the soil-derived fungus Penicillium sp. sb62. Their structures were established on the basis of spectroscopic data analysis, and the absolute configurations were determined by time-dependent density functional theory electronic circular dichroism calculations, comparison of the specific optical rotation values, and modified Mosher's method. Compounds 1−4 represent the first class of natural furancarboxylic acids featuring a thiophene moiety. Compounds 1−7 showed antimicrobial inhibitory activities against Escherichia coli, Staphylococcus aureus, and Candida albicans with MIC values ranging from 0.9 to 7.0 μg/mL, from 1.7 to 3.5 μg/mL, and from 3.3 to 7.0 μg/mL, respectively.

Thiophenes—Naturally Occurring Plant Metabolites: Biological Activities and In Silico Evaluation of Their Potential as Cathepsin D Inhibitors

“…They possessed antimicrobial capacities versus E. coli, S. aureus, and C. albicans with MICs 0.9-7.0, 1.7-3.5, and 3.3-7.0 µg/mL, respectively, in the broth microdilution assay. It was observed that the absence of methoxy or a hydroxy substituent on the side chain enhanced the activity similar to 89 and 90, and the configurations of the methoxy or hydroxy groups on the side chain had a little effect as in 91, 92, 93, and 94 [16].…”

“…The relative configuration was determined by NOESY and ROESY (rotating frame Overhauser effect spectroscopy), as well as by [α] D measurement [34]. The exciton coupled circular dichroism (ECCD) analysis and electronic circular dichroism (ECD) calculations were utilized to assess the absolute configuration by comparing the theoretical and experimental CD spectra [16,17,37,49]. Additionally, the determination of the absolute configuration was carried out using Mosher's method and analyzing chemical shift differences between (S)-and (R)-MTPA [16].…”

“…The exciton coupled circular dichroism (ECCD) analysis and electronic circular dichroism (ECD) calculations were utilized to assess the absolute configuration by comparing the theoretical and experimental CD spectra [16,17,37,49]. Additionally, the determination of the absolute configuration was carried out using Mosher's method and analyzing chemical shift differences between (S)-and (R)-MTPA [16]. The X-ray structure crystallographic analysis of the crystalline derivatives is another tool utilized for the absolute configuration determination [49].…”

“…Indeed, many of the reported derivatives possess an alkyl chain with an acetylenic unit that may contain chiral centers due to introducing a hydroxy group [8]. These metabolites have remarkable biological and pharmacological effectiveness, including antiviral, antimicrobial, antileishmanial, anti-inflammatory, larvicidal, antioxi-dant, insecticidal, HIV-1 (human immunodeficiency virus-1) protease inhibitory, cytotoxic, nematicidal, and phototoxic effects [8,[15][16][17][18][19][20] (Figure 2). In our previous review, 96 natural thiophene derivatives were listed from various plant species belonging to the Asteraceae family till 2015, with a particular focus on their biosynthesis, bioactivities, and physical and spectral data [8].…”

Asperosin A, a [4 + 2] Diels–Alder cycloaddition polyketide dimer from Aspergillus rugulosa with immunosuppressive activity

“…5 The isolation, chemical synthesis, structural revision, and biosynthesis of these compounds have always attracted chemists and biochemists. [6][7][8][9][10][11][12] For example, gregatin A, was isolated in 1975 and its structural determination was finally achieved in 2012 after two rounds of revisions. 9,12,13 Moreover, the biosynthesis of gregatin A involves the fusing of two different polyketide chains, which are synthesized by a single polyketide synthase.…”