Abstract
Purpose: To investigate the probable antioxidant, antimicrobial and antipancreatic lipase effects of fermented Camellia japonica leaf extracts. Methods: Camellia japonica leaves fermented with Nuruk were extracted using methanol and ethanol. Total phenolic, flavonoid, carotenoid and L-ascorbic acid contents were determined by UV-visible spectrophotometry. The antioxidant activities of these extracts were determined by free radical scavenging, ferrous ion chelating and reducing power assays. Their antimicrobial properties against Gram-positive Staphylococcus epidermidis and Bacillus subtilis, and Gram-negative Klebsiella pneumonia and Escherichia coli bacteria were evaluated by disc diffusion method. Inhibition of pancreatic lipase was measured based on the hydrolytic reaction of p-nitrophenyl butyrate with pancreatic lipase. Results: The ethanol extracts of fermented Camellia japonica leaves exhibited higher phenolic (32274mg GAE/100 g) and flavonoid (20519 mg RE/100 g) contents with higher superoxide (IC 50 = 0.23 mg/mL), hydrogen peroxide (IC 50 = 0.28 mg/mL) radical scavenging and ferrous ion chelating (IC 50 = 0.21 mg/mL) activities than those of methanol. These ethanol extracts also showed higher antimicrobial activities against all bacterial strains tested with higher inhibitory effects on pancreatic lipase than methanol extracts. Conclusion: The results highlight the possible use of fermented Camellia japonica leaf extracts as a source of antioxidant, antibacterial and antiobesity agents. Ethanol is recommended as solvent for extracting antioxidants, antibacterial and antiobesity agents from this plant. Keywords: Antioxidant activity, Antimicrobial activity, Fermented Camellia japonica extracts, Pancreatic lipase inhibition
Highlights
Tea is a commonly consumed beverage worldwide due to its health benefits for human consumption
The objective of this study was to evaluate antioxidant, antimicrobial and antipancreatic lipase properties of methanol and ethanol extracts of Camellia japonica leaves fermented with Nuruk as well as their bioactive contents including total flavonoids, total carotenoids, and L-ascorbic acid
Contents of total phenols and flavonoids were significantly higher in ethanol extract (32274 and 20519 mg GAE/100 g, respectively) than those in methanol extract (27791 and 19273 mg GAE/100 g, respectively) (p < 0.05)
Summary
Tea is a commonly consumed beverage worldwide due to its health benefits for human consumption. Most commercially prepared tea is obtained from differential preparation of Camellia sinensis (L.) Kuntze (apical buds and terminal leaves) [1]. Fully-fermented tea is fermented by microorganisms such as Aspergillus, Penicillium, Rhizopus, and yeast that determine its taste, color and fragrance as well as functional components [2,3,4]. Monomeric catechins are oxidized by polyphenol oxidase leading to dimers and polymers such as theaflavin, thearubigin, and gallic acid [5]. These components are responsible for the dark coloration, lack of bitterness and health benefit of fermented teas
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