Constituents and Antioxidant Activity of Bleeding Sap from Various Xinjiang Grapes

Wine grape sap or bleeding sap of grapes (GBS) is commonly used in Xinjiang (China) for therapeutic aims. Do variations in composition related to region and variety affect its properties?

GBS samples originating in various parts of Xinjiang (Turpan, Hotan, Kashgar, and Atush) were tested for phenols and polyphenols, polysaccharides, saponin, proteins, individual amino acids, and minerals. Their antioxidant activity was measured using ascorbic acid as reference.

Polyphenol content varied from 2.6 to 6.6 mg/L, polysaccharides 18.3-816 mg/L, saponin 6.25-106 mg/L, and protein 3.0-22.4 mg/L. Mineral elements and amino acids ranged from 6.20 to 201.2 mg/L and 0.06-118.7 mg/L, respectively. ·OH scavenging ability varied from 70% to over 90%, higher than Vitamin C. Grapes from Turpan had lower antioxidant activity than other grapes even though the polyphenol content was generally higher.

Bleeding sap of Xinjiang grape is rich in amino acids, polysaccharides, polyphenols, and protein. The contents are different according to the origin, related possibly to species, climate, and environment. Antioxidant effects were not correlated with polyphenol content.

Antioxidant activity of plants or plant extracts is often associated with polyphenolsBleeding sap of grapes has strong antioxidant propertiesBleeding sap from different grape varieties from different parts of Xinjiang (China) had different polyphenol concentrationsThere was no correlation of polyphenol concentrations with antioxidant activity. Abbreviations used: GBS: Bleeding sap of grapes; PITC: phenyl isothiocyanate.