Polyphenolic profile and antioxidant properties of Momordica charantia L. 'Enaja' cultivar grown in Romania.

This is the first study describing phenolics of Momordica charantia L. 'Enaja' cultivar (bitter melon) produced in Romania. Total polyphenol content, total tannin content, total flavonoid content, and antioxidant activity of bitter melon stems and leaves, young fruits, and ripe fruits grown in Romania were analysed, along with fruits imported from India. The UPLC-DAD analysis led to the identification of (+)-catechin, (-)-epicatechin, luteolin-3',7-di-O-glucoside, luteolin-7-O-glucoside and vanillic acid. (-)-Epicatechin (859 µg/g) and (+)-catechin (1677 µg/g) were the most abundant compounds in stems and leaves, while in the ripe fruits, luteolin-7-O-glucoside (310 µg/g) was the main phenolic. Stems and leaves were the most active for capturing free DPPH radicals (IC50 = 216.9 ± 11.91 µg/ml); the scavenging activity strongly correlated with the flavonoid content (r = 0.8806, r2 = 0.7754). Momordica charantia fruits from Romania, both young and ripe, are a source of polyphenols as valuable as those imported from India.

Extractability of polyphenols from black currant, red currant and gooseberry and their antioxidant activity.

In this study, we analyzed extracts of Ribes (black currant, red currant and gooseberry) fruits obtained with methanol, methanol 50% and water. For each extract total polyphenol content, total flavonoid content and total anthocyanin content was assessed. The antioxidant activity of extracts was evaluated by 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging capacity and by the photo-chemiluminescence (PCL) method. Identification and quantification of individual phenolic compounds was performed by means of high performance liquid chromatograph coupled with diode array detector (HPLC-DAD) analyses. From each fruit, best extraction of polyphenols was obtained with methanol 50%. In case of red currants and gooseberry there was no significant difference in flavonoids and anthocyanins extraction rate by the different extraction solvents. For black currants the methanol and methanol 50% extract presented the highest antioxidant activity. For red currants extracts with methanol 50% showed stronger antioxidant activity (IC50 = 5.71 mg/ml for DPPH, IC50 = 1.17 mg/ml for ABTS) than those with methanol or water. In case of gooseberry by the DPPH test the water extract proved to be the most active (IC50 = 5.9 mg/ml). In the PCL test black currants methanol 50% extract was over 6 times more powerful as the ones from red currants. In case of gooseberries, water extract presented the highest antioxidant activity (41.84 µmol AAE/g). In black currant cyanidin-3-glucoside was the major compound. Quercetin 3-O-glucoside was identified in each sample. From cinnamic acid derivatives neochlorogenic acid was present in black currants in the highest amount (356.33 µg/g).