Biocatalytic Stereoselective Synthesis of Chiral Precursors for Liposoluble ß1 Receptor Blocker Nebivolol.

Asymmetric reduction of 2-chloro-1-(6-fluorochroman-2-yl)ethan-1-one (NEB-7) into 2-chloro-1-(6-fluorochroman-2-yl)ethan-1-ol (NEB-8) is the crucial step for synthesis of liposoluble ß1 receptor blocker nebivolol. Four efficient and stereoselective alcohol dehydrogenases were identified, enabling the stereoselective synthesis of all enantiomers of NEB-8 at a substrate loading of 137 g·L-1 with ee values of >99% and high space-time yields. This study provides novel biocatalysts for the efficient synthesis of nebivolol precursors and uncovers the molecular basis for enantioselectivity manipulation by parametrization of Prelog's rule.

Directed reconstruction of a novel ancestral alcohol dehydrogenase featuring shifted pH-profile, enhanced thermostability and expanded substrate spectrum.

Ancestral enzymes are promising for industrial biotechnology due to high stability and catalytic promiscuity. An effective protocol was developed for the directed resurrection of ancestral enzymes. Employing genome mining with diaryl alcohol dehydrogenase KpADH as the probe, descendant enzymes D10 and D11 were firstly identified. Then through ancestral sequence reconstruction, A64 was resurrected with a specific activity of 4.3 U·mg-1. The optimum pH of A64 was 7.5, distinct from 5.5 of D10. The T15 50 and Tm values of A64 were 57.5 °C and 61.7 °C, significantly higher than those of the descendant counterpart. Substrate spectrum of A64 was quantitively characterized with a Shannon-Wiener index of 2.38, more expanded than D10, especially, towards bulky ketones in Group A and B. A64 also exhibited higher enantioselectivity. This study provides an effective protocol for constructing of ancestral enzymes and an efficient ancestral enzyme of industrial relevance for asymmetric synthesis of chiral alcohols.

Synthesis and preliminary biological evaluation of polyamine-aniline acridines as P-glycoprotein inhibitors.

We have synthesized a series of polyamine-based anilinoacridine derivatives. The preliminary biological evaluation indicated that the 9-anilinoacridine-polyamine derivatives had low or insignificant in vitro cytotoxicity against K562 cell line and K562/ADM, the drug-resistant cell line. However, the evaluation for P-gp modulation showed that they held potent P-gp inhibitory ability. Among them, the effect of compound 7c on P-gp was even greater than that of Verapamil, the known P-gp modulator. The results suggest that 9-anilinoacridine-polyamine derivatives can be employed as effective P-gp modulators.

Synthesis, structure-activity relationship and biological activity of acridine derivatives as potent MDR-reversing agents.

Multidrug resistance (MDR) mediated by P-glycoprotein is one of the best characterized transporter-mediated barriers to successful cancer chemotherapy. In an attempt to find MDR-reversing agents, a series of novel acridine derivatives were synthesized and evaluated for their in vitro antiproliferative activities against K562 and K562/ADM cells. Some of these compounds showed superior MDR-reversing activities than Amsacrine, the reference compound. Structure-activity relationships (SAR) of these compounds indicated that the N, N-diethylamine moiety had an affect on the in vitro antiproliferative activity. Interestingly, the compounds bearing N, N-diethylamine moiety showed higher growth-inhibitory activity against K562/ADM cells than K562 cells. The high duplex DNA binding affinity and inhibition of topoisomerase of these acridine compounds are maintained which were confirmed by fluorescent quenching and DNA topoisomerase II cleavage assay, respectively. Moreover, several compounds were examined for their ability to increase the accumulation of rhodamine 123 in K562 and K562/ADM cells, and the result suggested that they may be inhibitors for P-glycoprotein. Our study suggested that acridine framework is a potentially interesting scaffold for developing novel MDR-reversing agents.

The powerful applications of polyunsaturated fatty acids in improving the therapeutic efficacy of anticancer drugs.

Tumor-targeting delivery of drugs has received much attention in the field of drug development. Traditional antitumor agents are often nonspecific for tumor cells; therefore, tumor-targeting drug-delivery design is a promising approach to improve the therapeutic efficacy of chemotherapy. Polyunsaturated fatty acids (PUFAs), such as linoleic acid, α-linolenic acid, arachidonic acid and docosahexaenoic acid, are naturally occurring essential substances which play important roles in cell growth. Due to their lipophilic nature, PUFAs are readily incorporated into the lipid bilayer of cells, especially tumor cells. Therefore, PUFAs can be used as an applicable carrier to increase the therapeutic efficacy of anticancer drugs. In this review, several PUFA-drug conjugates with potent antitumor activities are summarized, and the bright prospects of PUFAs in drug development are also proposed. A general design strategy of PUFA-drug conjugates is provided, as well as a discussion of the recent progress in PUFA-drug conjugates and preclinical therapies. The tumor growth-related PUFAs are expected to play an important role in the development of more efficacious antitumor agents.