[Polyphenolic compounds analysis and antioxidant activity in fruits of Prunus spinosa L.]

Prunus spinosa L. (blackthorn, sloe) is a com- mon species in the wild flora of Europe. Marmalade, syrup, and alcoholic beverages have been prepared from fruits. In folk medicine they'are used due to the astringent effect. However there are few studies on these indigenous fruits. According to the literature they contain tannins, anthocyanins, sugars, vitamin C etc.

Our objective is to determine the antioxidant activity as related to their phenolic composition. For this purpose we prepared extracts using methanol, methanol-water (1: 1) and water. The antioxidant activity was determined by DPPH method and by photochemiluminescens (PCL) method. The total polyphenols, total anthocyanins and flavonoids were determined by colorimetric methods. Individual polyphenols were identified by a RP-HPLC-UVIVIS method.

The antioxidant activity decreased in the extracts as follows: methanol > methanol-water > water (IC₅₀= 1.33 mg/ml for DPPH; 11.94 μmol AAEIml for PCL > IC₅₀ = 1.87 mg/ml for DPPH; 10.35 μmol AAElml for PCL > IC₅₀ = 15.29 mg/ml for DPPH, 1.89 μmol AAElml for PCL) which is cor- related with the total polyphenol content (369 mg/100g > 244 mg1100g > 101 mg1100g) and total anthocyanin content (37.11 mg/100 g > 16.33 mg/100g > 7.76 mg/100g). The fla- vonoid content is similar in the three extracts (between 35.82 - 37.32 mg1100 g). The HPLC analysis shows high chloro- genic and neochlorogenic acid levels, followed by glycosides of quercetin.

Our results demonstrated that blackthorn fruits are a rich source of phenolic compounds, with anti- oxidant activity, which are best extracted with methanol or methanol-water.