Identification of Resveratrol as Bioactive Compound of Propolis from Western Romania and Characterization of Phenolic Profile and Antioxidant Activity of Ethanolic Extracts

Abstract

The present study aimed to assess the phenolic content of eight ethanolic propolis samples (P1–P8) harvested from different regions of Western Romania and their antioxidant activity. The mean value of total phenolic content was 214 ± 48 mg gallic acid equivalents (GAE)/g propolis. All extracts contained kaempferol (514.02 ± 114.80 μg/mL), quercetin (124.64 ± 95.86 μg/mL), rosmarinic acid (58.03 ± 20.08 μg/mL), and resveratrol (48.59 ± 59.52 μg/mL) assessed by LC-MS. The antioxidant activity was evaluated using 2 methods: (i) DPPH (2,2-diphenyl-1-picrylhydrazyl) assay using ascorbic acid as standard antioxidant and (ii) FOX (Ferrous iron xylenol orange OXidation) assay using catalase as hydrogen peroxide (H2O2) scavenger. The DPPH radical scavenging activity was determined for all samples applied in 6 concentrations (10, 5, 3, 1.5, 0.5 and 0.3 mg/mL). IC50 varied from 0.0700 to 0.9320 mg/mL (IC50 of ascorbic acid = 0.0757 mg/mL). The % of H2O2 inhibition in FOX assay was assessed for P1, P2, P3, P4 and P8 applied in 2 concentrations (5 and 0.5 mg/mL). A significant H2O2% inhibition was obtained for these samples for the lowest concentration. We firstly report the presence of resveratrol as bioactive compound in Western Romanian propolis. The principal component analysis revealed clustering of the propolis samples according to the polyphenolic profile similarity.

Extracts of Poplar Buds (Populus balsamifera L., Populus nigra L.) and Lithuanian Propolis: Comparison of Their Composition and Biological Activities

“…On the basis of the total amount of active compounds and the test results of their antibacterial and antioxidant activity, the extracts can be grouped as N1, N3 and N2. Bioactive compounds from plants are classified according to functional, pharmacological and toxicological effects [ 27 ]. The results of our research show that poplar buds are a source of active compounds in propolis, which have antioxidant and antimicrobial actions.…”

“…The most often used solvent in the production of propolis extracts is 70% ethanol, because it is very effective in separation of active compounds from the raw material [ 26 ]. Phenolic compounds often dissolve easier in organic solvents than in water [ 27 ]. Therefore, with the aim to investigate and compare the quality of the poplar bud extracts with the propolis extracts, we chose 70% ethanol for their production.…”

Mongolian crude propolis content analysis and antioxidant activity

“…The ethanolic of western Romanian propolis samples also showed a high antioxidant effect at 5 mg/ml from 79.57-92.5% on DPPH assay. The high antioxidant activity is possibly due to phenolic compounds found in propolis samples [13].…”

Anti-tumor activity of resveratrol against gastric cancer: a review of recent advances with an emphasis on molecular pathways

“…However, exposing to the UV is associated with formation of cis-isomer [34][35][36]. Accumulating data demonstrates that Res has a variety of pharmacological and health-promoting impacts such as antioxidant [37], anti-inflammatory [38], antidiabetic [39], anti-tumor [40], hepatoprotective [41], and cardioprotective [42].…”