Efficient preparation of the chiral intermediate of luliconazole with Lactobacillus kefir alcohol dehydrogenase through rational rearrangement of the substrate binding pocket

Structure-Guided Engineering of Carbonyl Reductase LbCR to Simultaneously Enhance Catalytic Activity and Thermostability toward Bulky Ketones

(S)-2-Chloro-1-(2,4-dichlorophenyl)ethanol ((S)-TCPE) is an important building block for the synthesis of antifungal drug luliconazole. Herein, a carbonyl reductase (CR) from Levilactobacillus brevis (LbCR) was identified for synthesis of (S)-TCPE. Through comprehensive Ala scanning and site-saturated mutagenesis (SSM) targeting the residues surrounding the substrate-binding pocket, the "best" variant LbCRM4 (N96V/E145A/A202L/M206A) was developed, which displays a 26.0-fold increase in catalytic activity, 83.5-fold enhancement in half-life (t1/2) at 40 °C (101.4 h), excellent enantioselectivity (>99.9% e.e.), and broad substrate scope. Compared to the wild-type (WT) LbCR, catalytic efficiency (kcat/KM) of LbCRM4 was increased by 28.0 folds. Furthermore, a high concentration of TCAP (400 g/L) can be transformed (99.9% conversion) within 7 h by using LbCRM4 and an isopropanol/alcohol dehydrogenase/NADPH cofactor regeneration system, giving (S)-TCPE in >99.9% e.e., which is the highest recorded space-time yield (STY, 1288.9 g/L/day) to date. Molecular dynamics (MD) simulations and dynamic cross-correlation matrix analysis elucidated the substantial catalytic performance improvement of LbCRM4. Together, the development of LbCRM4 not only overcomes the trade-offs between catalytic activity and thermostability but also affords an efficient biocatalytic approach for the synthesis of (S)-TCPE featuring a record STY, laying a solid foundation for industrial manufacturing of luliconazole and other active pharmaceutical intermediates.

Theoretical Analysis of Selectivity Differences in Ketoreductases toward Aldehyde and Ketone Carbonyl Groups

Lactobacillus kefir alcohol dehydrogenase (LkADH) and ketoreductase from Chryseobacterium sp. CA49 (ChKRED12) exhibit different chemoselectivity and stereoselectivity toward a substrate with both keto and aldehyde carbonyl groups. LkADH selectively reduces the keto carbonyl group while retaining the aldehyde carbonyl group, producing optically pure R-alcohols. In contrast, ChKRED12 selectively reduces the aldehyde group and exhibits low reactivity toward ketone carbonyls. This study investigated the structural basis for these differences and the role of specific residues in the active site. Molecular dynamics (MD) simulations and quantum chemical calculations were used to investigate the interactions between the substrate and the enzymes and the essential cause of this phenomenon. The present study has revealed that LkADH and ChKRED12 exhibit significant differences in the structure of their respective active pockets, which is a crucial determinant of their distinct chemoselectivity toward the same substrate. Moreover, residues N89, N113, and E144 within LkADH as well as Q151 and D190 within ChKRED12 have been identified as key contributors to substrate stabilization within the active pocket through electrostatic interactions and van der Waals forces, followed by hydride transfer utilizing the coenzyme NADPH. Furthermore, the enantioselectivity mechanism of LkADH has been elucidated using quantum chemical methods. Overall, these findings not only provide fundamental insights into the underlying reasons for the observed differences in selectivity but also offer a detailed mechanistic understanding of the catalytic reaction.

Microbial alcohol dehydrogenases: recent developments and applications in asymmetric synthesis

Alcohol dehydrogenases are a well-known group of enzymes in the class of oxidoreductases that use electron transfer cofactors such as NAD(P)+/NAD(P)H for oxidation or reduction reactions of alcohols or carbonyl compounds respectively. These enzymes are utilized mainly as purified enzymes and offer some advantages in terms of green chemistry. They are environmentally friendly and a sustainable alternative to traditional chemical synthesis of bulk and fine chemicals. Industry has implemented several whole-cell biocatalytic processes to synthesize pharmaceutically active ingredients by exploring the high selectivity of enzymes. Unlike the whole cell system where cofactor regeneration is well conserved within the cellular environment, purified enzymes require additional cofactors or a cofactor recycling system in the reaction, even though cleaner reactions can be carried out with fewer downstream work-up problems. The challenge of producing purified enzymes in large quantities has been solved in large part by the use of recombinant enzymes. Most importantly, recombinant enzymes find applications in many cascade biotransformations to produce several important chiral precursors. Inevitably, several dehydrogenases were engineered as mere recombinant enzymes could not meet the industrial requirements for substrate and stereoselectivity. In recent years, a significant number of engineered alcohol dehydrogenases have been employed in asymmetric synthesis in industry. In a parallel development, several enzymatic and non-enzymatic methods have been established for regenerating expensive cofactors (NAD+/NADP+) to make the overall enzymatic process more efficient and economically viable. In this review article, recent developments and applications of microbial alcohol dehydrogenases are summarized by emphasizing notable examples.

Multipotentiality of Luliconazole against Various Fungal Strains: Novel Topical Formulations and Patent Review

BACKGROUND

Luliconazole is a broad-spectrum antifungal agent with impactful fungicidal and fungistatic activity. It has shown exceptional potency against miscellaneous fungal strains like Candida, Aspergillus, Malassezia, Fusarium species and various dermatophytes.

OBJECTIVE

Luliconazole belongs to class Ⅱ of the Biopharmaceutical Classification System with low aqueous solubility. Although it is available conventionally as 1% w/v topical cream, it has limitations of lower skin permeation and shorter skin retention. Therefore, nanoformulations based on various polymers and nanostructure carriers can be employed to overcome the impediments regarding topical delivery and efficacy of luliconazole.

METHODS

In this review, we have tried to provide insight into the literature gathered from authentic web resources and research articles regarding recent research conducted on the subject of formulation development, patents, and future research requisites of luliconazole.

RESULTS

Nanoformulations can play a fundamental role in improving topical delivery by escalating dermal localization and skin penetration. Fabricating luliconazole into nanoformulations can overcome the drawbacks and can efficiently enhance its antimycotic activity.

CONCLUSION

It has been concluded that luliconazole has exceptional potential in the treatment of various fungal infections, and therefore, it should be exploited to its maximum for its innovative application in the field of mycology.