Antimicrobial Activities of Plant Extracts against Solanum tuberosum L. Phytopathogens.

The purpose of the study was to select an environmentally friendly plant biopesticide to protect seed potatoes against phytopathogens. The scope included the evaluation of the antimicrobial activities of 22 plant water extracts, 22 water-glycol extracts, and 3 subcritical carbon dioxide extracts using the agar diffusion method against 10 potato phytopathogens. For the most effective extracts, minimal inhibitory concentration (MIC), chemical composition analysis by gas chromatography-mass spectrometry and in situ assays on seed potatoes were performed. Garlic water extract was finally selected as the most effective in phytopathogen growth inhibition, both in vitro and in situ, with MIC values ranging between 6.3-25 mg/mL. 5-Hydroxymethylfurfural was determined to be the main component of this extract (33.24%). Garlic water extract was proposed as a potential biopesticide against potato phytopathogens.

Chemical and Biological Characteristics of Oxytropis pseudoglandulosa Plant of Mongolian Origin.

Oxytropis pseudoglandulosa is used in Mongolian traditional medicine due to its numerous reported health-promoting effects. To date, there are very few scientific reports that describe this species. In this article, its volatile oil composition, lipid extract composition, total phenolic and flavonoid content, antibacterial and allergenic properties are elucidated for the first time. Hexadecanoic acid, fokienol and tricosane were determined as the most notable components of the volatile oil, at 13.13, 11.46 and 5.55%, respectively. Methyl benzoate was shown to be the most abundant component of lipid extract at 40.69, followed by (E)-prop-2-enoic acid, 3-phenyl- and benzenepropanoic acid, at 18.55 and 9.97%. With a TPC of 6.620 mg GAE g-1 and TFC of 10.316 mg QE g-1, the plant extract of O. pseudoglandulosa indicated good antioxidant activity measured by IC50 at 18.761 µg mL-1. Of the 12 tested microorganisms, B. subtilis and S. cerevisiae were the shown to be most susceptible to the plant extract, with MIC at 2.081 and 0.260% (v/v), respectively. Bet v 1-a major birch pollen allergen found in plant-based foods-was determined to be at 192.02 ng g-1 with ELISA. Such a wide spectrum of biological activity indicated by O. pseudoglandulosa lends credence for its application in food industry. Its exerted antioxidant and antimicrobial effects could improve preservation of low-processed food dedicated for consumers afflicted with allergies. Hexadecanoic acid supplemented in foods with dietary plant extracts could add to the potential anti-inflammatory impact. The analysis of lipid makeup suggests O. pseudoglandulosa extract could also be considered as natural pesticide in organic farming.

Chemical and Biological Profile and Allergenicity of Thymus baicalensis Plant of Mongolian Origin.

Thymus baicalensis is a medicinal plant recognized as a traditional Mongolian therapeutic and health-promoting food supplement. The aim of the study was to check the suitability of the tested plant for supporting the treatment of certain diseases. The following study is the first one to showcase the versatile scope of characteristics of T. baicalensis, including its volatile oil composition, polyphenolic composition, lipid composition, phenolic and flavonoid contents, antioxidant activity, antimicrobial properties and ingestive allergenicity. Myrcene, at 26.15%, was shown to be the most abundant component of the volatile oil. Compounds known as inherent components of the Thymus genus: thymol and carvacrol made up only about 0.24% of the extracted oil. As much as 10.11 g kg-1 of polyphenol compounds were identified as derivatives of luteolin-7-O-glucuronide. The lipid extract was found to be rich in palmitic acid (31.05%), while unsaturated fatty acids were not reported. Spectrophotometric determination of the phenols and flavonoids indicated 7.541 mg of gallic acid g-1 and 4.345 mg of quercitin g-1, respectively. The free radical scavenging activity was determined by the 2,2-difenylo-1-pikrylohydrazyl method at IC50 = 206.97 µg mL-1. The extracts also had a strong inhibitory effect on M. flavus and P. fluorescenes bacteria, as well as S. cerevisiae yeasts. The Bet v 1 and profilin allergens in T. baicalensis were reported at 175.17 ng g-1 and 1.66 ng g-1, respectively.

Bis(4,6-dimethoxy-1,3,5-triazin-2-yl) ether as coupling reagent for peptide synthesis.

Bis(4,6-dimethoxy-1,3,5-triazin-2-yl) ether (4) was prepared by treatment of 2-hydroxy-4,6-dimethoxy-1,3,5-triazine with 2-chloro-4,6-dimethoxy-1,3,5-triazine in 61% yield. Ether 4, isoelectronic with pyrocarbonates, was found capable to activate carboxylic acids in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) to yield, under mild reaction conditions, superactive triazine esters. Versatility of this new coupling reagent was confirmed by condensation of lipophilic and sterically hindered carboxylic acids with amines in 71-98% yield, and by synthesis of peptides, including those containing Aib-Aib sequence, in solution with high yield and high enantiomeric purity.

4-(4,6-di[2,2,2-trifluoroethoxy]-1,3,5-triazin-2-yl)-4-methylomorpholinium tetrafluoroborate. Triazine-based coupling reagents designed for coupling sterically hindered substrates.

4-(4,6-Di[2,2,2-trifluoroethoxy]-1,3,5-triazin-2-yl)-4-methylomorpholinium tetrafluoroborate (DFET/NMM/BF(4)) was prepared and used as a reagent for coupling sterically hindered substrates. The formation of the appropriate triazine "superactive" ester in a reaction of DFET/NMM/BF(4) with carboxylic acids was confirmed. The efficiency of the reagent has been studied in the synthesis of Leu-enkephaline pentapeptide carried out on a Fmoc-RinkAmide-AM-PS resin, by systematically modifying the -Gly-Gly- fragment for N-methyl or α,α-disubstituted residues and compared with the efficiency of classic aminium salt 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU) under a variety of reaction conditions. In syntheses of Aib-Aib (Aib: α-aminoisobutyric acid), MeVal-MeVal, and MeLeu-MeLeu, the considerably superior performance of enkephaline analogues was obtained for DFET/NMM/BF(4) relative to TBTU, regardless of reaction conditions. Analysis of the couplings involving triazine reagent suggests that factors controlling efficiency of coupling sterically hindered substrates are the structure of the leaving group permitting formation of the cyclic intermediate or cyclic transition state and the absence of strongly solvating solvents. It has to be considered as highly probable that the absence of strongly solvating milieu favors cyclic intermediates or the cyclic transition state. Arrangement of both components into the cyclic intermediate or cyclic transition state by accumulation of the geminal (vicinal) substituents effect (known as the Thorpe-Ingold effect) would compensate retardation of the coupling process caused by steric hindrance.