Synthesis of ω‐Muricholic Acid by One‐Pot Enzymatic Mitsunobu Inversion using Hydroxysteroid Dehydrogenases

Abstract

The biocatalyzed conversion of hyocholic acid (3α,6α,7αtrihydroxy-5β-cholan-24-oic acid) into ω-muricholic acid (3α,6α,7β-trihydroxy-5β-cholan-24-oic acid) has been obtained exploiting a small library of 7α-and 7β-HSDHs (hydroxysteroid dehydrogenases). The process has been optimized and per-formed avoiding the isolation of the 7-oxo intermediate using the appropriate coupled enzymes for the in situ cofactor regeneration. Moreover, the biocatalyzed reduction of 6,7dioxolithocholic acid (3α-hydroxy-6,7-dioxo-5β-cholan-24-oic acid) was also investigated.

A ChemoEnzymatic Approach for the Preparation of “Linear‐Shaped” Diaryl Pyrazines as Potential Antiprotozoal Agents

“…At first, aiming at building a fully enzymatic entry to the target linear pyrazines, the biooxidation of compounds 1 a – 1 o was considered. Specifically, based on our previous works on similar substrates [39,40] and on synthetically relevant/bioactive bulky “challenging” ketones, [41–43] a library of promiscuous dehydrogenases (Table S1, SI), comprising alcohol dehydrogenase (ADH) and hydroxysteroid dehydrogenases (HSDH), was screened.…”

Stereoselective Biocatalyzed Reductions of Ginger Active Components Recovered from Industrial Wastes

“…Specifically, the biocatalysts library included ADHs which were previously studied in the stereoselective reduction of prochiral β‐diketones, for example the ADH from Rhodococcus ruber (Rr‐ADH), [34] Lactobacillus kefir (Lk‐ADH) [35] and L. brevis (Lb‐ADH), [36] or in the reduction of keto derivatives of fatty acids, such as the ADH from Micrococcus luteus (Ml‐ADH), [37] as well as Is2‐SDR, a wide‐substrate scope ADH recently discovered by us in an Icelandic hot spring metagenome, [38,39] and a collection of ADHs active on steroidal substrates, namely hydroxysteroid dehydrogenases (HSDHs), [40] recently investigated by us and showing interesting substrate promiscuity in the reduction of a panel of structurally different ketones [38,39,41] …”

“…showing interesting substrate promiscuity in the reduction of a panel of structurally different ketones. [38,39,41] The reduction reactions (1 mL final volume) were set up in the presence of a glucose/glucose dehydrogenase (GDH) system for the in situ regeneration of the NAD(P)H cofactor (Scheme 1).…”

Functional Characterization and Synthetic Application of Is2-SDR, a Novel Thermostable and Promiscuous Ketoreductase from a Hot Spring Metagenome

“…Accordingly, the enzymatic reduction of 31 was initially carried out in a 1:1 ( v/v ) mixture of tert -butyl methyl ether and PB buffer (pH 7.0, 50 mM) in the presence of Is2-SDR (1.0 U mL −1 ). Since BmGDH demonstrated a limited stability under these conditions, a formate dehydrogenase (FDH, 1.0 U mL −1 )/ammonium formate (0.1 M) system [ 24 ] was employed for NADP + (0.4 mM) regeneration and the reaction mixture was incubated at 25 °C and 180 rpm. To our surprise, no conversion was detected in TLC analysis even after 96 h. The same results were obtained using different biphasic systems (toluene, EtOAc, and petroleum ether as organic phase) regardless of the previously assessed Is2-SDR stability (see Figure 5 b, EMOB-based assay of Is2-SDR stability in biphasic systems).…”