This study aimed to synthesize some new sulfone derivatives containing a 1,3,4-oxadiazole moiety and investigate their in vitro antibacterial activities against Xanthomonas oryzae pv. oryzae ( Xoo) and Xanthomonas axonopodis pv. citri ( Xac), the pathogens of rice bacterial leaf blight and citrus canker, respectively, by performing turbidimeter tests. Antibacterial bioassay results showed that compound 6d revealed excellent bioactivities against Xoo and Xac, with the 50% effective concentration (EC50) values of 0.17 and 1.98 μg/mL, respectively, compared with thiodiazole copper (121.82 and 77.04 μg/mL, respectively) and bismerthiazol (92.61 and 58.21 μg/mL, respectively). Meanwhile, greenhouse-condition trials indicated that, compared with thiodiazole copper and bismerthiazol, compound 6d more effectively reduced rice bacterial leaf blight.
The accurate prediction of undrained shear strength is of significant importance in areas such as slope stability, earthquake resistance, and pile foundation design. Therefore, enhancing the accuracy of undrained shear strength prediction is crucial. The research results indicate that employing the KMR model can improve the computational accuracy by 4.4% to 18.9%. Furthermore, compared to conventional empirical formulas, the KMR model evidently processes data more rapidly and can predict relevant parameters more accurately. This method provides a new research idea to some extent for addressing the issue of low prediction accuracy of traditional machine learning models for geotechnical parameters.
Yeast extract can impart thickness, complexity and long-lasting taste impression, coined kokumi taste, to blank chicken broth. In this research, the kokumi-active peptide in yeast extract was discovered by ultrafiltration, liquid chromatographic and quadrupole-time-of-flight-tandem mass spectrometric technologies. Furthermore, the sensory characters of these peptides were evaluated by a sensomics approach.A total of 10 kokumi peptides were identified from yeast extract. They were γ-Glu-Cys-Gly, γ-Glu-Leu, γ-Glu-Val, γ-Glu-Tyr, Leu-Lys, Leu-Gln, Leu-Ala, Leu-Glu, Leu-Thr and Ala-Leu. Apart from the well-known kokumi-active glutathione and γ-glutamyl dipeptides, five leucyl dipeptides were first proposed having kokumi activity. Among them, Ala-Leu was found to have the highest kokumi threshold concentration (1.5 mmol L(-1) ) in the blank chicken broth, while Leu-Glu was the lowest (0.3 mmol L(-1) ). A subsequent dose-response experiment indicated that the bitter-tasting leucyl dipeptides could impart kokumi taste to chicken broth at low concentrations (less than bitter threshold concentrations). Interestingly, the kokumi sensation began to decrease when such peptides exceeded the threshold concentration by approximately 16-fold in the blank chicken broth.Key kokumi-active fractions were purified from yeast extract. Among them, ten important kokumi peptides from yeast extract were identified.
In this study, sulfone derivatives containing 1,3,4-oxadiazole moieties indicated good antibacterial activities against rice bacterial leaf blight caused by the pathogen Xanthomonas oryzaepv. pv. oryzae (Xoo). In particular, 2-(methylsulfonyl)-5-(4-fluorobenzyl)-1,3,4-oxadiazole revealed the best antibacterial activity against Xoo, with a half-maximal effective concentration (EC50) of 9.89 μg/mL, which was better than those of the commercial agents of bismerthiazole (92.61 μg/mL) and thiodiazole copper (121.82 μg/mL). In vivo antibacterial activity tests under greenhouse conditions and field trials demonstrated that 2-(methylsulfonyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole was effective in reducing rice bacterial leaf blight. Meanwhile, 2-(methylsulfonyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole stimulate the increase in superoxide dismutase (SOD) and peroxidase (POD) activities in rice, causing marked enhancement of plant resistance against rice bacterial leaf blight. It could also improve the chlorophyll content and restrain the increase in the malondialdehyde (MDA) content in rice to considerably reduce the amount of damage caused by Xoo. Moreover, 2-(methylsulfonyl)-5-(4-fluorophenyl)-1,3,4-oxadiazole, at a concentration of 20 μg/mL, could inhibit the production of extracellular polysaccharide (EPS) with an inhibition ratio of 94.52%, and reduce the gene expression levels of gumB, gumG, gumM, and xanA, with inhibition ratios of 94.88%, 68.14%, 86.76%, and 79.21%, respectively.
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