Influence of Different Extraction Methods on Antioxidant and Antibacterial Activities of Nonnea lutea

Background and No reports are found on biological activities of Nonea lutea (boraginaceae). The aim of this study was to investigate the antioxidant and antibacterial activities of this plant.
The aerial parts were extracted by three different methods, i.e. meceration (MA), ultrasonic assisted (US), and soxhlet assisted (SO) extractions with methanol. Antioxidative capacity was assessed by utilizing four DPPH and nitric oxide (NO) free radicals scavenging, reducing power and iron chelating activity. The total phenolic and flavonoid contents were also determined. Antibacterial activities were evaluated by disc diffusion method against four bacteria.
The highest amount of total phenolic and flavonoid contents were found in SO and US extracts, respectively. In DPPH radical scavenging activity, SO extract (IC50 = 99.14 ± 0.3 µg ml-1) had a higher activity which was significantly different from that of other extracts (P0.05). The extracts showed weak iron chelating and nitric oxide radical scavenging activities indicating no significant differences (P> 0.05). Findings showed that all extracts had the highest activity against B. subtilis and the least activity against S. aureus. SO extract showed the highest activity against B. subtilis, US extract showed the highest activity against E coli and P. aeruginosa, and MA extract showed the highest activity against S. aureus.
The results indicated that extraction methods significantly affect antioxidant and antibacterial capacities and total phenolic and flavonoid contents. For this plant, SO extraction method was found to be more efficient.