Transformation of saturated nitrogen-containing heterocyclic compounds by microorganisms

Synthesis of Azabicyclic Isosteres of Piperazine 2S-Carboxylic Acid

Methods have been developed for the stereocontrolled synthesis of bicyclic diaza [3.3.0] octane carboxylic acids as possible isosteres of piperazine 2S-carboxylic acid. In the first approach, l-pyroglutamic acid was functionalized adopting new as well as documented reaction sequences via Michael and aza-Michael reactions, leading to two of the four intended isosteres. An alternative shorter route relying on enolate chemistry starting with N-Pf 4-keto l-proline methyl ester led to two other isosteres. Calculated pKa values and density functional theory (DFT) calculations have provided some insights into the relative basicities of the nitrogen atoms in these diaza [3.3.0] octane carboxylic acids in relation to piperazine 2S-carboxylic acid.

Descriptive Bacterial and Fungal Characterization of Propolis Using Ultra-High-Throughput Marker Gene Sequencing

Bees harbor microorganisms that are important for host health, physiology, and survival. Propolis helps modulate the immune system and health of the colony, but little information is available about its microbial constituents. Total genomic DNA from samples of natural propolis from Apis mellifera production hives from four locations in Mexico were used to amplify a region of the 16S rRNA gene (bacteria) and the internal transcriber spacer (fungi), using PCR. The Illumina MiSeq platform was used to sequence PCR amplicons. Extensive variation in microbial composition was observed between the propolis samples. The most abundant bacterial group was Rhodopila spp. (median: 14%; range: 0.1%–27%), a group with one of the highest redox potential in the microbial world. Other high abundant groups include Corynebacterium spp. (median: 8.4%; 1.6%–19.5%) and Sphingomonas spp. (median: 5.9%; 0.03%–14.3%), a group that has been used for numerous biotechnological applications because of its biodegradative capabilities. Bacillus and Prevotella spp. alone comprised as much as 88% (53% and 35%, respectively) of all bacterial microbiota in one sample. Candida (2%–43%), Acremonium (0.03%–25.2%), and Aspergillus (0.1%–43%) were among the most abundant fungi. The results contribute to a better understanding of the factors associated with the health of Apis mellifera production hives.

Evolution in medicinal chemistry of sorafenib derivatives for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. Traditional chemotherapy drugs are hard to reach a satisfactory therapeutic effect since advanced HCC is highly chemo-resistant. Sorafenib is an oral multikinase inhibitor that can suppress tumor cell proliferation, angiogenesis and induce cancer cell apoptosis. However, the poor solubility, rapid metabolism and low bioavailability of sorafenib greatly restricted its further clinical application. During the past decade, numerous sorafenib derivatives have been designed and synthesized to overcome its disadvantages and improve its clinical performance. This article focuses on the therapeutic effects and mechanisms of various sorafenib derivatives with modifications on the N-methylpicolinamide group, urea group, central aromatic ring or others. More importantly, this review summarizes the current status of the structure-activity relationship (SAR) of reported sorafenib derivatives, which can provide some detailed information of future directions for further structural modifications of sorafenib to discovery new anti-tumor drugs with improved clinical performance.

Antifungal and Cytotoxic Assessment of Lapachol Derivatives Produced by Fungal Biotransformation

In the screening for biological active compounds, the biotransformation processes catalyzed by filamentous fungi are useful because they can provide information about the possible appearance of toxic metabolites after oral administration and also generate new leads. In this paper, biotransformation of lapachol (1) by three fungal strains, Mucor circinelloides NRRL3631, Botrytis cinerea UCA992 and Botrytis cinerea 2100, has been investigated for the first time. Lapachol (1) was biotransformed into avicequinone-A (2) by M. circinelloides, 3′-hydroxylapachol (3) by B. cinerea, and into dehydro-α-lapachone (4) by both fungi. All these compounds were evaluated for their cytotoxic activities. The metabolite 2 displayed non-selective cytotoxicity against tumor and normal cell lines, 3 did not show cytotoxicity against the same cells, while 4 showed higher cytotoxicity against cancer cell lines than lapachol (1). The transformation of 1 into harmless and reactive metabolites evidences the importance of the evaluation of drug metabolism in the drug discovery process. Antifungal potential of lapachol (1) and its metabolites 2 and 4 against B. cinerea has also been evaluated. Dehydro-α-lapachone (4) has been shown to be less toxic to fungal growth than lapachol (1), which indicates a detoxification mechanism of the phytopathogen.

Complete genome sequence of Rhodococcus erythropolis BG43 (DSM 46869), a degrader of Pseudomonas aeruginosa quorum sensing signal molecules

Rhodococcus erythropolis BG43 was isolated from soil and characterized as a degrader of the quorum sensing signal molecules 2-heptyl-3-hydroxy-4(1H)-quinolone (the Pseudomonas quinolone signal, PQS) and 2-heptyl-4(1H)-quinolone, produced by Pseudomonas aeruginosa. The complete genome of R. erythropolis BG43 consists of a circular chromosome and three plasmids, one of them circular and two linear ones. In total, 6158 protein-coding regions were identified. With this genome sequence, the genetic basis of its quorum-quenching ability and possible biotechnological applications can be explored further.