Microbial fermentation of cabbage by a bacterial strain of Pectobacterium atrosepticum for the production of bioactive material against Candida species

Microbial Biotransformation to Obtain New Antifungals

Antifungal drugs belong to few chemical groups and such low diversity limits the therapeutic choices. The urgent need of innovative options has pushed researchers to search new bioactive molecules. Literature regarding the last 15 years reveals that different research groups have used different approaches to achieve such goal. However, the discovery of molecules with different mechanisms of action still demands considerable time and efforts. This review was conceived to present how Pharmaceutical Biotechnology might contribute to the discovery of molecules with antifungal properties by microbial biotransformation procedures. Authors present some aspects of (1) microbial biotransformation of herbal medicines and food; (2) possibility of major and minor molecular amendments in existing molecules by biocatalysis; (3) methodological improvements in processes involving whole cells and immobilized enzymes; (4) potential of endophytic fungi to produce antimicrobials by bioconversions; and (5) in silico research driving to the improvement of molecules. All these issues belong to a new conception of transformation procedures, so-called "green chemistry," which aims the highest possible efficiency with reduced production of waste and the smallest environmental impact.

Ultrasound-Assisted Extraction and Biological Activities of Extracts of Brassica oleracea var. capitata

In this work, the antioxidant and antimicrobial activities of Brassica oleracea var. capitata extracts obtained through ultrasound-assisted extraction are evaluated. The extracts obtained using the best extraction conditions were subjected to different hydrolysis conditions before their use in the biological tests. The crude and hydrolysed extracts were characterized using gas chromatography coupled with a mass detector. The use of ultrasound at 30 °C with 60% (by volume) solvent enabled obtaining a richer extract. All extracts had antioxidant activities against DPPH (13.0-80.0%), superoxide (35.2-63.2%) and peroxyl (89.3-99.5%) radicals, but the use of hydrolysed extracts considerably improved the antioxidant activities. Antimicrobial activities only of the hydrolysed extracts of Brassica oleracea var. capitata were detected. It was confirmed that antioxidant activity of vegetable extracts can be considerably increased when hydrolysis is applied as a pretreatment to their extraction.

Chemical composition, antibacterial activity, and mechanism of action of the essential oil from Amomum kravanh

Amomum kravanh is widely cultivated and used as a culinary spice. In this work, the chemical composition of the essential oil obtained by hydrodistillation of A. kravanh fruits was analyzed by gas chromatography-mass spectrometry, and 34 components were identified. 1,8-Cineole (68.42%) was found to be the major component, followed by α-pinene (5.71%), α-terpinene (2.63%), and β-pinene (2.41%). The results of antibacterial tests showed that the sensitivities to the essential oil of different foodborne pathogens tested were different based on the Oxford cup method, MIC, and MBC assays, and the essential oil exhibited the best antibacterial activity against Bacillus subtilis, a gram-positive bacterium, and Escherichia coli, a gram-negative bacterium. Growth in the presence of Amomum kravanh at the MIC, as measured by monitoring optical density over time, demonstrated that the essential oil was bacteriostatic after 12 h to both B. subtilis and E. coli. Observations of cell membrane permeability, cell constituent release assay, and transmission electron microscopy indicated that this essential oil may disrupt the cell wall and cell membrane permeability, leading to leakage of intracellular constituents in both B. subtilis and E. coli.

Supercritical CO2 extraction, chemical characterisation and antioxidant potential of Brassica oleracea var capitata against HO·, O2(·-) and ROO·

In this work were extracted bioactive compounds from Brassica oleracea var capitata using supercritical CO2 and evaluated the antioxidant potential of the extracts. Five extractions were accomplished to investigate the influence of pressure (10-25 MPa) and temperature (20-60 °C) in the extraction yield, chemical composition and antioxidant potential towards peroxyl, superoxide and hydroxyl radicals. The highest extraction yield was obtained at 60 °C and 25 MPa, which was 0.47 wt% (run 2). In the characterisation of the extracts obtained was possible the identification of sulforaphane and iberin nitrile that present known biological properties. The extracts of all runs presented antioxidant activities towards the three radicals, but the highest activities for all radicals were using the extracts obtained in the run 2. The use of supercritical CO2 extraction to obtain bioactive compounds of B. oleracea var capitata showed to be a promising alternative to conventional extraction methods, since allowed the extraction of compounds with scientific and industrial interest.