Antimicrobial Metabolites Produced by Penicillium mallochii CCH01 Isolated From the Gut of Ectropis oblique, Cultivated in the Presence of a Histone Deacetylase Inhibitor

Abstract

Three chemical epigenetic modifiers [5-azacytidine, nicotinamide, and suberoylanilide hydroxamic acid (SAHA)] were applied to induce the metabolites of Penicillium mallochii CCH01, a fungus isolated from the gut of Ectropis oblique. Metabolite profiles of P. mallochii CCH01 were obviously changed by SAHA treatment. Four metabolites (1–4), including two new natural sclerotioramine derivatives, isochromophilone XIV (1) and isochromophilone XV (2), and two known compounds, sclerotioramine (3) and (+)-sclerotiorin (4), were isolated and purified from P. mallochii CCH01 treated with SAHA. Their structures were determined by spectroscopic analyzes. Anti-phytopathogenic activities of the isolated compounds 1–4 were investigated under laboratory conditions, and compound 4 showed broad and important inhibition activities against Curvularia lunata (IC50 = 2.1 μg/mL), Curvularia clavata (IC50 = 21.0 μg/mL), Fusarium oxysporum f. sp. Mornordica (IC50 = 40.4 μg/mL), and Botryosphaeria dothidea (IC50 = 27.8 μg/mL), which were comparable to those of referenced cycloheximide, with IC50 values of 0.3, 5.0, 12.4, and 15.3 μg/mL, respectively. Ingredients 2 and 3 showed selective and potent activities against Colletotrichum graminicola with IC50 values of 29.9 and 9.7 μg/mL, respectively. Furthermore, the antibacterial bioassays showed that compounds 3 and 4 exhibited strong inhibition activities against Bacillus subtilis, with disc diameters of zone of inhibition (ZOI) of 9.1 mm for both compounds, which were a bit weaker than that of referenced gentamycin with a ZOI of 10.8 mm. Additionally, the new metabolite 1 showed a promising activity against Candida albicans (ZOI = 10.5 mm), comparable to that of positive amphotericin B with a ZOI of 23.2 mm. The present results suggest that chemical epigenetic modifier induction was a promising approach to obtaining antimicrobial metabolites encoded by silent biosynthetic genes of P. mallochii.

Proposed “Biosynthesis” of Primarolides A and B from a Common 2-Formylbenzophenone Precursor

“…Regarding the pronounced nucleophilicity of hydroxamic acids [10] one can expect suberoylanilid hydroxamic acid (SAHA, 3), present as an additive, to assist as a nucleophilic catalyst in the formation of lactone rac-1. In accordance to other recent reports on the isolation of aniline-derived natural products from fungi cultured in the presence of SAHA (3) [11][12][13] one can also assume that aniline is readily formed from SAHA (3) under the action of fungal amidohydrolases. Thus, the reaction of 16 with aniline would directly give rise to racemic primarolide B (rac-2) according to the above-mentioned reaction path.…”

Metabolomic Analysis of The Chemical Diversity of South Africa Leaf Litter Fungal Species Using an Epigenetic Culture-Based Approach

“…Several studies have reported the use of epigenetic modifiers for inducing metabolomic changes during fungal fermentations through the activation of biosynthetic pathways that are silent under standard culture conditions [ 1 , 5 , 6 , 7 , 11 , 12 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. Specifically, SAHA is the most used histone deacetylase inhibitor due to its capacity to modulate the fungal SM profiles and to induce the production of new metabolites in specific fungal strains [ 24 , 25 , 26 , 27 ]. However, the ability of SAHA to enhance the chemical diversity on a wide diverse fungal population set has never been analytically supported.…”

“…Small molecule epigenetic modifiers can modulate the microbial metabolism through the activation of cryptic biosynthetic pathways. Several reports have revealed the ability of epigenetic modifiers to alter the expression of silent or under-expressed BGCs, resulting in the modulation of the metabolomic profile and enhancement of the production of metabolites that were not synthetized under normal growth conditions [ 1 , 5 , 6 , 7 , 11 , 12 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]: Treatment of Alternaria alternata and Penicillium expansum with the histone deacetylase inhibitor trichostatin A resulted in a statistically significant increase in numerous unidentified metabolites for both species [ 21 ]. The addition of 5-azacytidine to cultures of Cladosporium cladosporioides stimulated the production of several oxylipins, and, when the culture was supplemented with suberoylanilide hydroxamic acid, it led to the isolation of two new perylenequinones (cladochromes F and G), four known cladochromes A, B, D, E and calphostin B [ 5 ].…”

“…The following metabolites were only produced when the strains were cultured with SAHA: Nygerone A produced by Aspergillus niger in semi-solid culture with vermiculite [ 24 ]; the anti-infective cytosporones by the marine fungus Leucostoma persoonia [ 25 ]; (10′S)-verruculide B, vermistatin and dihydrovermistatin induced in the endophytic fungus Phoma sp. nov. LG0217 [ 26 ]; two new natural sclerotioramine derivatives, isochromophilone XIV and XV, and two known compounds, sclerotioramine and (+)-sclerotiorin induced in the insect-associated fungi Penicillium mallochii CCH01 [ 27 ].…”

Community Composition, Antifungal Activity and Chemical Analyses of Ant-Derived Actinobacteria

“…Our chemical investigation of four antderived Streptomyces strains led to the discovery of eight known compounds and two new polyketide compounds (Liu et al, 2016(Liu et al, , 2017Cao et al, 2017;Ye et al, 2017;Jiang et al, 2018). Among the ten compounds, amphotericin, and kanchanamycin are known as excellent antifungal agents (Fiedler et al, 1996;Hamill, 2013;Zhang et al, 2019). In this report, we investigated the secondary metabolites from ant-derived Streptomyces strain 1H-XA2 with broad-spectrum antifungal activity, which resulted in the discovery of furamycins I and II (2 and 3), as well as a novel polyene amide compound (1).…”