Screening for antioxidant and antibacterial activities of phenolics from Golden Delicious apple pomace

Abstract

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.

Response Surface Modeling and Optimization of Polyphenols Extraction from Apple Pomace Based on Nonionic Emulsifiers

“…Due to the presence of phenolics apple pomace shows strong antioxidant and has been linked to the prevention of several diseases. It has been reported that phenolics rich extract of pomace exhibit anticarcinogenic activity by preventing colon cancer [10], anti-inflammatory [11], antimicrobial [12], antiviral [13], and hepatoprotective [14] activities.…”

Purification and characterization of a novel phloretin-2′-O-glycosyltransferase favoring phloridzin biosynthesis

“…However, Md P2′GT exhibits a lower k cat /K m toward isoliquiritigenin than kaempferol, although isoliquiritigenin has similar structure to phloretin with a flexible open-chain three-carbon linker. This discrepancy might be related to the presence of a C7-C8 double bond, lacking OH group on 6′ position of the A ring, and the absence of isoliquiritigenin in apples 41 42 . Luteolin lacks one OH group at the C3 position of the C ring but has one extra OH group at the C3′ position of the B ring compared to kaempferol ( Fig.…”

“…We speculate the presence of a C7-C8 double bond on the flexible open-chain three-carbon linker might create a steric hindrance on the 2′-OH and made the 4-OH amenable to be glycosylated based on the similar finding in previous studies 9 10 39 40 . Besides, isoquercitrin and hyperoside, which are native or accumulated as their aglycones in apples 41 42 , could be synthesized by Md P′2GT but couldn’t by the reported P2′GTs. Reported P2′GTs such as UGTA15, UGT71K1, UGT71K2, and DicGT4 can accept quercetin as substrate, but the sugar donor must be UDPG, and the formed glycosides were quercetin-3- O -glucoside (quercitrin) and 7- O -glucoside not isoquercitrin 14 20 .…”

ВИВЧЕННЯ КОМПОНЕНТНОГО СКЛАДУ ТА ПРОТИКОРОЗІЙНОЇ ЕФЕКТИВНОСТІ ПРОДУКТІВ ПЕРЕРОБКИ АБРИКОСА (Prunus armeniaca L.)

“…Проте наукова інформація про компонентний склад різних рослин, особливо тих, які менш широко використовуються в медицині або харчовій промисловості, усе ще залишається дефіцитною. Тому цікавим і корисним завданням є пошук нових джерел для виділення природних активних сполук та отримання різних продуктів [3][4][5][6][7]. Деякі типи рослинної сировини промислового значення -це відходи обробки плодових та ягідних культур.…”

“…Є багато успішних наукових праць про використання різних екстрактів рослинних матеріалів, у тому числі вичавків абрикоса, в різних сферах «зеленої» хімічної технології. Основними з них є косметична і харчова промисловість, а також виробництво наночастинок, розробка екологічно чистих інгібіторів корозії [4][5][6], створення альтернативи синтетичним антиоксидантам та консервантам [13][14][15].…”