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Background: Cucurbita maxima known as pumpkin belongs to the family Cucurbitaceae, widely used in traditional medicine. Methods: The present work evaluates the antioxidant activity of the different parts (leaves and fruit) of Cucurbita maxima. Antioxidant activity was assessed through the DPPH test and the β-carotene bleaching test. Result: The results showed that the ethanolic extract of fruit and leaves are rich in polyphenols, flavonoids and tannin with values, respectively (50.13±4.49 mg EAG/g dry extract), (0.75±3.64 mg EQ/g dry extract) and (477.05±6.67 mg EAT/g dry extract) for the fruit, (27.37±0.95 mg EAG/g dry extract), (1.83±0.28 mg EQ/g dry extract) and (481.69±5.77 mg EAT/g dry extract) for leaves. The ethanolic extract showed scavenger activity IC50 is 0.41±1.20 μg/ml fruit and 0.18±0.06 μg/ml leaf compared with 0.01±0.01 μg/ml BHT (Butylated hydroxytoluene). The results obtained in the β-carotene bleaching test of the ethanolic extracts of the leaves and fruit of Cucurbita maxima is of the order (70.13±13.84%) and (67.69±13.82%) respectively. [ABSTRACT FROM AUTHOR]

Objectives: The present study aimed to determine the phenolic compounds present in the water-soluble extracts of Thymus munbyanus subsp. ciliatus using high pressure liquid chromatography-time-of-flight mass spectrometry (MS). These phenolic compounds were further isolated and characterized for their antioxidant activities. Materials and Methods: The aerial parts of T. munbyanus subsp. ciliatus were air dried, powdered, and extracted using water:methanol three times. The concentrated hydromethanolic extract was further dissolved in H2O, filtered, and successively extracted using ethyl acetate, chloroform, and n-butanol. T. munbyanus extracts were further purified using column chromatography, and the purified extracts were subjected to in vitro antioxidant assays. Results: Two previously undescribed compounds, namely methyl 2,3,5,6-tetrahydroxybenzoate and 4-hydroxy-5-methoxy-2-oxo-2H-pyran- 3-carboxylic acid, and 14 known compounds, including 3 flavonoids; namely 3’,5,5’,7-tetrahydroxyflavanone, luteolin, and isorhamnetin-3-O-β- glucoside; a sterol glucoside named daucosterol; and 10 phenolic compounds, namely salicylic acid, ferulic acid, pluchoic acid, ethyl caffeate, methyl caffeate, protocatechuic acid, rosmarinic acid, p-coumaric acid, tyrosol, and protocatechuic aldehyde, were isolated from ethyl acetate and n-butanol extracts. The isolated compounds were characterized using 1D-2D-1H-13C nuclear magnetic resonance and MS methods. Conclusion: The compounds isolated from ethyl acetate and n-butanol extracts exhibited excellent antioxidant and 2,2-diphenyl-1-picrylhydrazyl scavenging activities. All these results highlighted the antioxidant potential of the isolated phenolic compounds and extracts, which could be further utilized for different pharmacological applications. [ABSTRACT FROM AUTHOR]

In this study, Polyphenol oxidases (PPO) from royal dates fruit was purified and characterized. These procedures led to 8-fold purification with 14.72% recovery. Three isoenzymes of royal dates PPO exhibited a molecular weight of 20.,45 and 64 kDa. The royal date PPOs had maximum activity at pH 4.6 and 8, 3.6–5.6 and 5.6 with pyrogallol, 4-methylcatechol and pyrocatechol substrates, respectively. The enzyme showed high stability in the temperature range of 30–60 °C.4-Methylcatechol was the most suitable substrate, due to the lowest Km and the biggest Vmax/Km values. The kinetic of thermal inactivation were performed in a temperature range of 60–75 °C. A biphasic model provided a good description of dates PPO thermal inactivation. Indole-3acetic acid markedly inhibited Royal dates PPO activity. Its Anti-browning effect on dates was investigated. IAA-treatment reduced weight loss, pericarp decay, browning index and membrane electrolyte leakage. Thus, a higher total anthocyanins contents and total phenolic contents was correlated with higher DPPH scavenging activity and lower MDH contents Such effect was accredited to maintain of membrane integrity and inhibition of oxidative enzymes by IAA. In conclusion, IAA could be used as a potent inhibitor of fruits enzymatic browning reaction. [ABSTRACT FROM AUTHOR]