Anti-inflammatory activity and phenolic profile of propolis from two locations in Region Metropolitana de Santiago, Chile

Abstract

Ethnopharmacological relevance: Propolis has long been used as a popular folk medicine due to its wide spectrum of alleged biological and pharmaceutical properties. In Chile, propolis is widely used by folklore medicine as an anti-inflammatory agent; however, this property has not been demonstrated by scientific methods.

Aim of the study: The objective of this study was to determine the anti-inflammatory activity in vivo and in vitro and to establish the phenolic profile of propolis collected in two localities in Region Metropolitana de Santiago (RM), Chile.

Materials and methods: Propolis was collected in the areas of Caleu and Buin, RM Chile. Following that, the samples were unwaxed to obtain the global ethanolic extracts of propolis (EEPs) and, from these, the serial extracts of dichloromethane (EEP-DCMs) and ethanol (EEP-EtOHs). The topic anti-inflammatory effect was evaluated through mice ear edema induced by arachidonic acid (AA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) at a dose of 3 mg/ear. Nitric oxide (NO) measurements were determined spectrophotometrically (Greiss reagent) by the accumulation of nitrite in the medium of macrophages RAW 264.7 stimulated with the lipopolysaccharide (LPS, 1 mu g/mL) for 20 h at different concentrations of the EEPs, EEP-DCMs and EEP-EtOHs (6.25-50.00 mu g/mL). The content of total phenols and flavonoids were determined through the methods of Folin-Ciocalteau and A1C1(3), respectively. The profile of phenolic compounds was determined by HPLC-UV-ESI-MS/MS.

Results: The EEP-EtOH (64%) and EEP (59%) of Buin were the most active in the inflammation induced by TPA and AA respectively, being the anti-inflammatory effect stronger than the same Caleu extracts. Regarding the release of NO, all the extracts from the Buin propolis inhibited significantly its release in a concentration-dependent manner, this inhibition was stronger than the extracts from Caleu propolis.

Conclusions: Our research shows for the first time a comparative study of the topical in vivo activity of two Chilean propolis. Both propolis showed in vivo topical anti-inflammatory activity against AA and TPA, the most active was Buin propolis and this difference is due in part to the variations in total phenols and flavonoids content and the phenolic profile. The phenols and flavonoids content of Buin propolis was higher than Caleu propolis. The extracts from Buin propolis result in a lower release of NO.