In vitro antioxidant and anti-inflammatory activities of extracts from Potentilla recta and its main ellagitannin, agrimoniin.

ETHNOPHARMACOLOGICAL RELEVANCE

Potentilla recta is one of the numerous cinquefoil species growing in Poland. It is used in traditional medicine e.g. in the treatment of skin inflammation.

AIM OF THE STUDY

The purpose of the present study is to evaluate antioxidant and anti-inflammatory activities of extracts and subfractions of the P. recta herb (obtained by using solvents of different polarity) in in vitro systems as well as to examine their chemical composition.

MATERIALS AND METHODS

Antioxidant activities of the extracts, subfractions and agrimoniin were evaluated using DPPH and three other radicals (O2(-), H2O2, and HClO) generated in cell-free systems. Anti-hyaluronidase activity was measured by using the turbidimetric method. Inhibition of lipoxidase activity was measured spectrophotometrically, using linoleic acid as a substrate. The composition of the most active subfraction was determined using the HPLC-DAD-MS(n) method.

RESULTS

All tested samples showed scavenging activity against all the examined reactive species in a concentration-dependent manner. The highest scavenging activity against DPPH, H2O2 and HClO was observed in the ethyl acetate subfraction (PRE3) (SC50 ± SEM [μg/mL]: 25.39 ± 2.49, 1.79 ± 0.25 and 8.52 ± 1.16 respectively). It was only in the xanthine/xanthine oxidase system that the antioxidation potential of the diethyl ether subfraction (PRE2) (SC50 ± SEM [μg/mL]: 6.59 ± 1.33) was higher than that of the subfraction PRE3 (SC50 ± SEM [μg/mL]: 8.57 ± 1.37). Also, in the studies of lipoxidase and hyaluronidase inhibition activity the strongest effect was observed for PRE3, with IC50 [μg/mL] = 86.31 ± 5.46, and 12.99 ± 1.31, respectively. The chromatographic method (HPTLC-DPPH) revealed that the principal substance responsible for the activity, is a tannin like compound. Isolated agrimoniin showed significant reactive oxygen species scavenging activity and significant enzyme inhibition activity (including xanthine oxidase inhibition activity). Agrimoniin exerted the strongest scavenging activity against H2O2 (SC50 ± SEM [μM]: 0.20 ± 0.01). This compound also significantly inhibited the enzymatic activity of lipoxidase (IC50 [μM] = 36.47 ± 1.29), and, particularly, of hyaluronidase (IC50 [μM] = 2.65 ± 0.40).

CONCLUSIONS

The strong scavenging activity against H2O2, and the inhibition of the enzymatic activity of lipoxidase, and particularly, hyaluronidase observed for the tested subfractions and agrimoniin, partly explain the beneficial effects of P. recta in treatment of skin inflammation.