Kombucha is a healthy traditional beverage which is made by fermenting products with a symbiotic culture of acetic acid bacteria and yeasts. In present study, leaves of kitchen mint (Mentha cordifolia Opiz. Ex Fresen) and leaves of oolong tea (Camellia sinensis) were fermented in kombucha formula. After fermentation, titratable acidity contents and ethanol of kitchen mint, oolong tea, and mixtures of oolong tea and kitchen mint kombucha samples gradually increased with a period of fermentation time. At day 14 of fermentation, phenolic compounds and flavonoids were increased in all kombucha samples. The numbers of acetic acid bacteria and yeast in kombucha had gradually raised during 7-14 days of fermentation. DPPH and ABTS scavenging activities of these kombucha increased over a period of fermentation time and shown the highest antioxidant capacity on day 14 of fermentation. In addition, all kombucha samples exhibited the antioxidant effects by attenuating H 2 O 2-induced ROS production, increasing mRNA expression of catalase, glutathione reductase (GRe), and Mn-SOD, and inducing GRe enzymatic activity in HEK-293 cells. Kombucha beverage can be used as the healthy beverages for attenuation of oxidative stress in many diseases. K E Y W O R D S antioxidant activity, antioxidant enzyme, glutathione reductase, kitchen mint, kombucha, oolong tea How to cite this article: Tanticharakunsiri W, Mangmool S, Wongsariya K, Ochaikul D. Characteristics and upregulation of antioxidant enzymes of kitchen mint and oolong tea kombucha beverages.
Context: Citrus hystrix de Candolle (Rutaceae), an edible plant regularly used as a food ingredient, possesses antibacterial activity, but there is no current data on the activity against bacteria causing periodontal diseases. Objective: C. hystrix essential oil from leaves and peel were investigated for antibiofilm formation and mode of action against bacteria causing periodontal diseases. Materials and methods: In vitro antibacterial and antibiofilm formation activities were determined by broth microdilution and time kill assay. Mode of action of essential oil was observed by SEM and the active component was identified by bioautography and GC/MS. Results and discussion: C. hystrix leaves oil exhibited antibacterial activity at the MICs of 1.06 mg/mL for P. gingivalis and S. mutans and 2.12 mg/mL for S. sanguinis. Leaf oil at 4.25 mg/ mL showed antibiofilm formation activity with 99% inhibition. The lethal effects on P. gingivalis were observed within 2 and 4 h after treated with 4 Â MIC and 2 Â MIC, respectively. S. sanguinis and S. mutans were completely killed within 4 and 8 h after exposed to 4 Â MIC and 2 Â MIC of oil. MICs of tested strains showed 4 times reduction suggesting synergistic interaction of oil and chlorhexidine. Bacterial outer membrane was disrupted after treatment with leaves oil. Additionally, citronellal was identified as the major active compound of C. hystrix oil. Conclusions: C. hystrix leaf oil could be used as a natural active compound or in combination with chlorhexidine in mouthwash preparations to prevent the growth of bacteria associated with periodontal diseases and biofilm formation.
Chitosan-grafted thymol (CST) coated on gold nanoparticles has been synthesized and characterized for the design of antimicrobial materials. CST was synthesized via adapting the Mannich reaction, and it acted as the capping agent for the synthesis of gold nanoparticles (AuNPs). The grafting of thymol onto the side chain of chitosan has provided a degree of substitution value (%DS NMR ) of 10.0%, calculated by nuclear magnetic resonance spectroscopy. UV–visible spectrometry and elemental analysis were used to confirm the successful synthesis of CST through adapting the Mannich reaction. The appropriate concentration of CST for AuNP synthesis was found to be 0.020%w/v. A red-wine colloidal AuNP solution of 2.41–3.30 nM particle size exhibits a strong surface plasmon resonance at 502 nm, which shows negative charges at pH = 9 of −36.37 mV. This result evidenced that the AuNPs showed electrostatic repulsion and CST played a role as a capping agent to provide a good dispersion and stability state. CST coated on the AuNP surface was successfully utilized for the control of cariogenic bacteria in the oral cavity. The results obtained from this study show that the tuning of the capping agent used in the synthesis step strongly influences the latter antimicrobial activity of the nanoparticles against Streptococcus mutans ATCC 25175 and Streptococcus sobrinus ATCC 33402 activity, with an inhibition zone of 15.90 and 14.25 mm, respectively. The average minimum inhibitory concentration values against S. mutans ATCC 25175 and S. sobrinus ATCC 33402 were found to be 25 and 100 mg/L, respectively, whereas the minimum bactericidal concentration values were 100 and 200 mg/L, respectively.
Histamine fish poisoning becomes highly concern not only in public health but also economic aspect. Histamine is produced from histidine in fish muscles by bacterial decarboxylase enzyme. Several techniques have been developed to determine the level of histamine in fish and their products but the effective method for detecting histamine producing bacteria is still required. This study was attempted to detect histamine producing bacteria by newly developed PCR condition. Histamine producing bacteria were isolated from scombroid fish and determined the ability to produce histamine of isolated bacteria by biochemical and TLC assays. PCR method was developed to target the histidine decarboxylase gene (hdc). The result showed that fifteen histamine producing bacterial isolates and three standard strains produced an amplicon at the expected size of 571 bp after amplified by PCR using Hdc_2F/2R primers. Fifteen isolates of histamine producing bacteria were classified as M. morganii, E. aerogenes, and A. baumannii. The lowest detection levels of M. morganii and E. aerogenes were 10(2) and 10(5) Cfu/mL in culture media and 10(3) and 10(6) Cfu/mL in fish homogenates, respectively. The limit of detection by this method was clearly shown to be sensitive because the primers could detect the presence of M. morganii and E. aerogenes before the histamine level reached the regulation level at 50 ppm. Therefore, this PCR method exhibited the potential efficiency for detecting the hdc gene from histamine producing bacteria and could be used to prevent the proliferation of histamine producing bacteria in fish and fish products.
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