BackgroundSynthetic antioxidants and antimicrobials are losing ground to their natural counterparts and therefore, the food industry has motivated to seek other natural alternatives. Apple pomace, a by-product in the processing of apples, is rich in polyphenols, and plant polyphenols have been used as food additives owing to their strong antioxidant and antimicrobial properties. The goal of this study was to screen the individual polyphenols with antioxidant and antimicrobial activities from the extracts (methanol, ethanol, acetone, ethyl acetate, and chloroform) of Golden Delicious pomace.ResultsFirst, the polyphenolic compounds (total phenol content, TPC; total flavonoids, TFD; total flavanols, TFL) and antioxidant activities (AAs) with four assays (ferric reducing antioxidant power, FRAP; 1,1-diphenyl-2-picryhydrazyl radical scavenging capacity assay, DRSC; hydroxyl radical averting capacity assay, HORAC; oxygen radical absorbance capacity assay, ORAC) were analyzed. The results showed a significant positive correlation (P < 0.05) between AAs and TFD. Ethyl acetate extract (EAE) exhibited the highest TFD with a concentration of 1.85 mg RE/g powder (expressed as rutin equivalents), and the highest AAs (expressed as butylated hydroxytoluene (BHT) equivalents) with 2.07 mg BHT/g powder for FRAP, 3.05 mg BHT/g powder for DRSC, 5.42 mg BHT/g powder for HORAC, and 8.89 mg BHT/g powder for ORAC. Composition and AA assays of individual polyphenols from the EAE were then performed. Phloridzin and phloretin accounted for 46.70 and 41.94 % of TFD, respectively. Phloretin displayed the highest AA, followed by phloridzin. Finally, the antimicrobial activities of the EAE, phloridzin, and phloretin were evaluated. EAE displayed good inhibitory activities against Staphylococcus aureus with a minimum inhibition concentration (MIC) of 1.25 mg/ml and against Escherichia coli with a MIC of 2.50 mg/ml. Phloridzin and phloretin showed better inhibitory activities than the EAE, which were MICs of 0.50 and 0.10 mg/ml, respectively, against S. aureus and MICs of 1.50 and 0.75 mg/ml, respectively, against E. coli.ConclusionsEthyl acetate was the best solvent of choice to extract natural products to obtain the maximum antioxidant and antibacterial benefits. Phloridzin and phloretin have the potential to be used as natural alternatives to synthetic antioxidants and antimicrobials.
Aspergillus oryzae, an industrially important fungus utilized for the traditional fermentative manufacturing, produces diverse metabolites and enzymes during fermentation. In our previous study, we have ever identified and characterized a basic helix-loop-helix (bHLH) transcription factor, SclR, and found that the transcription factor is importantly involved in the conidiation, sclerotial formation, and hyphal morphology in A. oryzae. In this study, we further analyzed the effect of SclR on metabolites production in A. oryzae. The control strain and ∆sclR strain were cultivated in dextrin-polypeptone-yeast extract (DPY) liquid medium at 30 °C for 3 days and metabolites were extracted from strains. Liquid chromatography-mass spectrometry (LC-MS) analysis result showed that a total of 1,855 precursor molecules were obtained in the positive ion mode and 2,475 precursor molecules were obtained in the negative ion mode. Comparative analysis of the metabolome indicated that 259 were differentially expressed metabolites. Among of them, 161 metabolites were increased by 1.5-fold, and 98 metabolites were decreased by 1.5-fold in an sclR gene deletion strain compared to the control. Further identification of differentially expressed metabolites revealed that the production level of some organic acids, amino acids, and sugar alcohols were markedly changed in ∆sclR strain relative to control strain. Especially, some organic acids were identified to be intermediates in the citric acid cycle, which is a key metabolic pathway that connects carbohydrate, fat, and protein metabolism. The result also implied that the SclR is potentially involved in energy metabolism.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.