Microbial transformation of mestanolone byMacrophomina phaseolinaandCunninghamella blakesleeanaand anticancer activities of the transformed products

Endogenous production of 2-phenylethanol by Cunninghamella echinulata inhibits biofilm growth of the fungus

The filamentous fungus Cunninghamella echinulata is a model of mammalian xenobiotic metabolism. Under certain conditions it grows as a biofilm, which is a natural form of immobilisation and enables the fungus to catalyse repeated biotransformations. Putative signalling molecules produced by other Cunninghamella spp., such as 3-hydroxytyrosol and tyrosol, do not affect the biofilm growth of C. echinulata, suggesting that it employs a different molecule to regulate biofilm growth. In this paper we report that 2-phenylethanol is produced in higher concentrations in planktonic cultures of C. echinulata than when the fungus is grown as a biofilm. We demonstrate that exogenously added 2-phenylethanol inhibits biofilm growth of C. echinulata but has no effect on planktonic growth. Furthermore, we show that addition of 2-phenylethanol to established C. echinulata biofilm causes detachment. Therefore, we conclude that this molecule is produced by the fungus to regulate biofilm growth.

Structural transformation of methasterone with Cunninghamella blakesleeana and Macrophomina phaseolina

An anabolic-androgenic synthetic steroidal drug, methasterone (1) was transformed by two fungi, Cunninghamella blakesleeana and Macrophimina phaseclina. A total of six transformed products, 6β,7β,17β-trihydroxy-2α,17α-dimethyl-5α-androstane-3-one (2), 6β,7α,17β-trihydroxy-2α,17α-dimethyl-5α-androstane-3-one (3), 6α,17β-dihydroxy-2α,17α-dimethyl-5α-androstane-3,7-dione (4), 3β,6β,17β-trihydroxy-2α,17α-dimethyl-5α-androstane-7-one (5), 7α,17β-dihydroxy-2α,17α-dimethyl-5α-androstane-3-one (6), and 6β,9α,17β-trihydroxy-2α,17α-dimethyl-5α-androstane-3-one (7) were synthesized. Among those, compounds 2-5, and 7 were identified as new transformed products. MS, NMR, and other spectroscopic techniques were performed for the characterization of all compounds. Substrate 1 (IC50 = 23.9 ± 0.2 μg mL-1) showed a remarkable anti-inflammatory activity against nitric oxide (NO) production, in comparison to standard LNMMA (IC50 = 24.2 ± 0.8 μg mL-1). Whereas, its metabolites 2, and 7 showed moderate inhibition with IC50 values of 38.1 ± 0.5 μg mL-1, and 40.2 ± 3.3 μg mL-1, respectively. Moreover, substrate 1 was found to be cytotoxic for the human normal cell line (BJ) with an IC50 of 8.01 ± 0.52 μg mL-1, while metabolites 2-7 were identified as non-cytotoxic. Compounds 1-7 showed no cytotoxicity against MCF-7 (breast cancer), NCI-H460 (lung cancer), and HeLa (cervical cancer) cell lines.

Effects of Microbial Transformation on the Biological Activities of Prenylated Chalcones from Angelica keiskei

Microbial transformation is an alternative method for structural modification. The current study aimed at application of microbial transformation for discovering new derivatives and investigating the structure-activity relationship of isobavachalcone (1), 4-hydroxyderricin (2), and xanthoangelol (3) isolated from the herb Angelica keiskei. In the initial screening process, 1-3 were incubated with microbes using a two-stage fermentation method and analyzed through TLC monitoring. The screening results showed that Rhizopus oryzae and Mucor hiemalis were able to transform 1 and 2, respectively. Additionally, M. hiemalis and Mortierella ramanniana var. angulispora were able to transform 3. Following scale-up fermentation, four new (4, 5, 7, and 10) and five known (6, 8, 9, 11, and 12) metabolites were produced. Cytotoxicity of all the compounds (1-12) was investigated using three human cancer cell lines including A375P, HT-29, and MCF-7 by MTT method. Meanwhile, the tyrosinase inhibitory activity of 1-12 was evaluated using l-tyrosine as a substrate. Overall, 1 and 3 displayed the highest cytotoxicity, and 5 and 7 exhibited the most potent tyrosinase inhibitory activity with relatively low cytotoxicity. This allowed us to postulate that the introduction of 4'-O-glucopyranosyl group led to the reduction in cytotoxicity and improvement in tyrosinase inhibitory activity.

Metal-Free, Redox-Neutral, Site-Selective Access to Heteroarylamine via Direct Radical-Radical Cross-Coupling Powered by Visible Light Photocatalysis

Transition-metal-catalyzed C-N bond-forming reactions have emerged as fundamental and powerful tools to construct arylamines, a common structure found in drug agents, natural products, and fine chemicals. Reported herein is an alternative access to heteroarylamine via radical-radical cross-coupling pathway, powered by visible light catalysis without any aid of external oxidant and reductant. Only by visible light irradiation of a photocatalyst, such as a metal-free photocatalyst, does the cascade single-electron transfer event for amines and heteroaryl nitriles occur, demonstrated by steady-state and transient spectroscopic studies, resulting in an amine radical cation and aryl radical anion in situ for C-N bond formation. The metal-free and redox economic nature, high efficiency, and site-selectivity of C-N cross-coupling of a range of available amines, hydroxylamines, and hydrazines with heteroaryl nitriles make this protocol promising in both academic and industrial settings.

Whole-cell fungal-mediated structural transformation of anabolic drug metenolone acetate into potent anti-inflammatory metabolites

Seven new derivatives, 6α-hydroxy-1-methyl-3-oxo-5α-androst-1-en-17-yl acetate (2), 6α,17β-dihydroxy-1-methyl-3-oxo-5α-androst-1-en (3), 7β-hydroxy-1-methyl-3-oxo-5α-androst-1-en-17-yl acetate (4), 15β,20-dihydroxy-1-methyl-3-oxo-5α-androst-1-en-17-yl acetate (5), 15β-hydroxy-1-methyl-3-oxo-5α-androst-1-en-17-yl acetate (6), 12β,17β-dihydroxy-1-methyl-3-oxoandrosta-1,4-dien (11), and 7β,15β,17β-trihydroxy-1-methyl-3-oxo-5α-androst-1-en (14), along with six known metabolites, 17β-hydroxy-1-methyl-3-oxoandrosta-1,4-dien (7), 17β-hydroxy-1-methyl-3-oxo-5α-androst-1-en (8), 17β-hydroxy-1-methyl-3-oxo-5β-androst-1-en (9), 1-methyl-5β-androst-1-en-3,17-dione (10), 1-methyl-3-oxoandrosta-1,4-dien-3,17-dione (12), and 17β-hydroxy-1α-methyl-5α-androstan-3-one (13) of metenolone acetate (1), were synthesized through whole-cell biocatalysis with Rhizopus stolonifer, Aspergillus alliaceous, Fusarium lini, and Cunninghamella elegans. Atamestane (12), an aromatase inhibitor, was synthesized for the first time via F. lini-mediated transformation of 1 as the major product. Hydroxylation, dehydrogenation, and reduction were occurred during biocatalysis. Study indicated that F. lini was able to catalyze dehydrogenation reactions selectively. Structures of compounds 1-14 were determined through NMR, HRFAB-MS, and IR spectroscopic data. Compounds 1-14 were identified as non-cytotoxic against BJ human fibroblast cell line (ATCC CRL-2522). Metabolite 5 (81.0 ± 2.5%) showed a potent activity against TNF-α production, as compared to the substrate 1 (62.5 ± 4.4%). Metabolites 2 (73.4 ± 0.6%), 8 (69.7 ± 1.4%), 10 (73.2 ± 0.3%), 11 (60.1 ± 3.3%), and 12 (71.0 ± 7.2%), also showed a good inhibition of TNF-α production. Compounds 3 (IC50 = 4.4 ± 0.01 µg/mL), and 5 (IC50 = 10.2 ± 0.01 µg/mL) showed a significant activity against T-cell proliferation. Identification of selective inhibitors of TNF-α production, and T-cell proliferation is a step forward towards the development of anti-inflammatory drugs.