Valorisation of black mulberry and grape seeds: Chemical characterization and bioactive potential

Grape (Vitis vinifera L. var. Albarino) and mulberry (Morus nigra L.) seeds pomace were characterized in terms of tocopherols, organic acids, phenolic compounds and bioactive properties. Higher contents of tocopherols (28 +/- 1 mg/100 g fw) were obtained in mulberry, whilst grape seeds were richer in organic acids (79 +/- 4 mg/100 g fw). The phenolic analysis of hydroethanolic extracts characterised grape seeds by catechin oligomers (36.0 +/- 0.3 mg/g) and mulberry seeds by ellagic acid derivatives (3.14 +/- 0.02 mg/g). Both exhibited high antimicrobial activity against multiresistant Staphylococcus aureus MIC = 5 mg/mL) and no cytotoxicity against carcinogenic and non-tumour primary liver (PLP) cells. Mulberry seeds revealed the strongest inhibition (p < 0.05) against thiobarbituric reactive substances (IC50 = 23 +/- 2 mu g/mL) and oxidative haemolysis (IC50 at 60 min = 46.0 +/- 0.8 mu g/mL). Both seed by-products could be exploited for the developing of antioxidant-rich ingredients with health benefits for industrial application.

Automated summary

Mulberry seeds are rich in tocopherols while grape seeds are rich in organic acids; grape seeds are characterized by catechin oligomers as the main phenolic compound, while mulberry seeds are characterized by ellagic acid derivatives; Both exhibit high antimicrobial activity and inhibitory effects on oxidation.