Chemical composition,antimicrobial potential against cariogenic bacteria and cytotoxic activity of Tunisian Nigella sativa essential oil and thymoquinone

We investigate in this work the chemical composition by GC–EIMS, the antibacterial and the cytotoxic activities of Tunisian Nigella sativa essential oil and its bioactive compound, thymoquinone, were tested against various clinical cariogenic bacteria (n = 30). Eighty-four compounds were identified in the essential oil. The major one was p-cymene (49.48%) whereas thymoquinone represented only 0.79%. The essential oil (2.43 mg/disc) containing only 3.35 μg of thymoquinone showed pronounced dose dependant antibacterial activity against Streptococcus mitis, Streptococcus mutans, Streptococcus constellatus and Gemella haemolysans (15.5 ± 0.707 mm). However, pure thymoquinone compound (150 μg/disk) was active against all the studied strains especially S. mutans and S. mitis (24.5 ± 0.71 and 22 ± 1.41 mm inhibition zones, respectively).     

An in vitro study on the dental caries preventing effect of oligomeric procyanidins in sorghum episperm

Procyanidins are abundant in sorghum episperm. In this study, the effects of procyanidins from Sorghum bicolor (L.) moench episperm (sorghum procyanidins, SPC) in preventing dental caries were investigated through analysis on SPCs’ effects on cariogenic bacteria and ability in scavenging superoxide anion free radicals. In addition, the SPC with activity in preventing dental caries were identified. The ESI-MS/MS analysis results revealed that the compositions of SPC purified by macroporous resin were dimmers, trimers, tetramers, pentamers and hexamers of procyanidins and catechin/epicatechin monomers. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of SPC on Streptococcus mutans (Ingbritt C) and Streptococcus sobrinus 6715 were 8 and 16 mg/ml, respectively. The SPC had a remarkable inhibition effect (P < 0.05) on acid production of S. sobrinus (Ingbritt C) and S. mutans 6715 compared with the control group, and a dose-dependent relationship was observed. By increasing the concentration of SPC in the experimental condition (200–600 mg/L), the scavenging ratio of superoxide anion radicals increased significantly, indicating that SPC could be used as a potential dental-caries-preventative medicine with its antibacterial and antioxidant ability.     

Angiotensin I-converting enzyme inhibitory properties of lentil protein hydrolysates: Determination of the kinetics of inhibition

ACE inhibitory activity was studied for different hydrolysates obtained from protein concentrates of two lentil varieties by in vitro gastrointestinal simulation, Alcalase/Flavourzyme, papain and bromelain. Protein/peptide profiles studied by electrophoresis and HPLC-SEC showed a rich composition of the hydrolysates in small peptides ranging in size from 0.244 to 1.06 kDa. ACE inhibitory activity was measured using the HPLC Hippuryl-His-Leu (HHL) substrate method. Significantly different (P < 0.05) IC₅₀ values ranging between 0.053 and 0.190 mg/ml were obtained for different hydrolysates. Furthermore, the inhibition mechanism investigated using Lineweaver–Burk plots revealed a non-competitive inhibition of ACE with inhibitor constants (K_i) between 0.16 and 0.46 mg/ml. These results demonstrate that hydrolysates of lentil proteins obtained by different enzymatic digestions may contain bioactive components.     

Effect of juice processing on cranberry antibacterial properties

The effects of the industrial juice process on the ability of neutralized cranberry samples and extracts (polar, apolar and anthocyanins) to inhibit the growth of Enterococcus faecium resistant to vancomycin (ERV), Escherichia coli O157:H7 EDL 933, E. coli ATCC 25922, Listeria monocytogenes HPB 2812, Pseudomonas aeruginosa ATCC 15442, Salmonella Typhimurium SL1344 and Staphylococcus aureus ATCC 29213 were investigated. The juice process appeared to have a general enhancing effect on the antibacterial properties of cranberry polar and anthocyanin extracts. The lowest minimum inhibitory concentrations (MICs) (1.80–7.0 μg phenol/well) were obtained when S. aureus, S. Typhimurium, and ERV were exposed to the juice concentrate. The growth of P. aeruginosa, L. monocytogenes, E. coli ATCC, and E. coli O157:H7 was not inhibited by the juice concentrate, but did show sensitivity (maximal tolerated concentrations of 0.007–0.4 μg phenol/well). The lowest MICs (22.6–90.5 μg phenol/well) for P. aeruginosa, S. aureus, S. Typhimurium, and ERV were observed when they were exposed to the cranberry anthocyanin extract obtained from cranberry pomace. The results also showed a negative effect of the juice process on the antibacterial properties of the cranberry apolar extracts: the one obtained from frozen cranberries was most efficient against P. aeruginosa, S. aureus, L. monocytogenes and S. Typhimirium (MIC of 45.50 μg phenol/well). The tested bacteria showed the greatest resistance toward the cranberry extracts obtained from the mash and the macerated and depectinized mash.     

酶解猪血浆蛋白粉制备ACE抑制肽的工艺优化

选用胃蛋白酶、胰蛋白酶、碱性蛋白酶和中性蛋白酶水解猪血浆蛋白粉,通过单因素和正交试验考察其水解产物对ACE的抑制活性,并优选酶解工艺条件。结果显示:胃蛋白酶适宜水解血浆蛋白粉,制备ACE抑制肽;影响胃蛋白酶水解的4个因素主次顺序为底物质量浓度>酶解时间>pH值>酶与底物质量比(m酶:m底物),其中底物质量浓度和酶解时间的影响显著(P<0.05),pH值和m酶:m底物的影响不显著(P>0.05);适宜胃蛋白酶水解的条件为pH2.3、水解时间1.5h、底物质量浓度1g/100mL、m酶:m底物1:6。     

Inhibitory mechanisms of promising antimicrobials from plant byproducts: A review

Plant byproducts and waste present enormous environmental challenges and an opportunity for valorization and industrial application. Due to consumer demands for natural compounds, the evident paucity of novel antimicrobial agents against foodborne pathogens, and the urgent need to improve the arsenal against infectious diseases and antimicrobial resistance (AMR), plant byproduct compounds have attracted significant research interest. Emerging research highlighted their promising antimicrobial activity, yet the inhibitory mechanisms remain largely unexplored. Therefore, this review summarizes the overall research on the antimicrobial activity and inhibitory mechanisms of plant byproduct compounds. A total of 315 natural antimicrobials from plant byproducts, totaling 1338 minimum inhibitory concentrations (MIC) (in μg/mL) against a broad spectrum of bacteria, were identified, and a particular emphasis was given to compounds with high or good antimicrobial activity (typically <100 μg/mL MIC). Moreover, the antimicrobial mechanisms, particularly against bacterial pathogens, were discussed in-depth, summarizing the latest research on using natural compounds to combat pathogenic microorganisms and AMR. Furthermore, safety concerns, relevant legislation, consumer perspective, and current gaps in the valorization of plant byproducts–derived compounds were comprehensively discussed. This comprehensive review covering up-to-date information on antimicrobial activity and mechanisms represents a powerful tool for screening and selecting the most promising plant byproduct compounds and sources for developing novel antimicrobial agents.     

An application in Gouda cheese manufacture for a strain of Lactobacillus helveticus ND01

Gouda cheese was manufactured with Lactococcus lactis ssp. lactis IMAU60010, L. lactis ssp. cremoris IMAU40136 and L. helveticus ND01 isolated from the naturally fermented milk in China. Starter cultures added with L. helveticus ND01 produced Gouda cheese with dramatically more proteolysis than control cheeses. Compared with control cheese, experimental cheese with L. helveticus ND01 adjunct revealed dramatic increase in both Angiotensin I‐converting enzyme (ACE)‐inhibitory activity and γ‐aminobutyric acid content. The ACE‐inhibitory activity of Gouda cheeses with the addition of 1 × 10⁵ CFU/mL L. helveticus ND01 increases from 53.7 to 83.1% at 6 weeks of ripening.     

山核桃壳棕色素的生物活性及其红外光谱分析

用体积分数95%乙醇提取山核桃壳棕色素,经AB-8大孔树脂纯化后,对其生物活性及红外光谱进行研究。结果表明:质量浓度为3.0g/L时,山核桃壳棕色素的总抗氧化能力相当于126.65mmol/Lα-生育酚;棕色素还原能力的EC50值(吸光度为0.5时的质量浓度)为0.286g/L;质量浓度为1.0g/L时,棕色素对.OH的清除率达到60.84%。抑菌实验表明:山核桃壳棕色素对酿酒酵母(Saccharomyces cerevisiae)、金黄色葡萄球菌(Staphylococcusaureus)、枯草芽孢杆菌(Bacillus subtilis)、大肠杆菌(Escherichia coli)、黑曲霉(Aspergillus niger)均有抑制作用,最低抑菌浓度分别为0.125、0.25、0.25、1.0、0.5g/L。红外光谱分析结果表明:该棕色素含有苯环和酚羟基结构。