Total Phenolics, Antioxidant and Antimicrobial Activities of Dalmatian Laburnum (Petteria Ramentacea (Sieber) C. Presl) Methanol Extracts

Abstract

UDK 581.19:547.56]:582.736.3 The aim of this study was to determine the total concentrations of some phenolic compounds and antioxidant and antimicrobial activity of methanol extracts of different parts of Illyrian endemic Petteria ramentacea. Concentrations of phenolic compounds were determined with UV/VIS spectrophotometry. The antioxidant activity of plant extracts was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Antimicrobial activity of extracts was evaluated by measuring the inhibition's zone against six selected test bacteria and two fungi. The highest average total phenols concentrations were in seeds (10.78 mg GAE g-1 DW), root (10.51 mg GAE g-1 DW) and bark (10.40 mg GAE g-1 DW), and the lowest in inflorescences (2.99 mg GAE g-1 DW) and leaves (3.12 mg GAE g g-1 DW). The total flavonoids concentrations were determined only in leaves (8.25 mg CE g-1 DW) and in stem (5.66 mg CE g-1 DW). Both flavanols and proanthocyanidins (0.75 mg CE g-1 DW and 3.49 mg CE g-1 DW, respectively) were found only in leaves. Analysis of variance indicated presence of significant differences between total phenols and flavanols concentrations (p<0.05), and Duncan's test confirmed the presence of intraspecies variability according to their concentrations. The highest antioxidant activity (IC50) was observed for the seed's extract (6.86%) and the lowest for the bark’s (51.31%). All methanol extracts showed the most pronounced antibacterial activity against Staphylococcus epidermididis, and the lowest against S. aureus subsp. aureus. Antifungal activity against Candida albicans was moderate. Since Peteria ramentacea methanol extracts are potential natural antioxidant and antimicrobial preparations against selected microorganisms, it is necessary to continue with more detailed analysis.