Antioxidant and antibacterial activity of safflower (Carthamus tinctorius L.) extract from four different cultivars

Antioxidant and antimicrobial activities were studied in safflower methanolic extracts of four different cultivars (IL111, Padide, Isfahan-28 and Mahali). The total phenolic and flavonoid content of the plant extracts ranged from 46.2 to 62.3 mg gallic acid equivalent/g dry extract and 7.5 to 9.6 mg catechin equivalent/g dry extract, respectively. The antioxidant capacity of methanolic extracts was assessed by reducing power assay, DPPH center dot (2,2-diphenyl-1-picrylhydrazyl) scavenging activity and beta-carotene bleaching methods. Results showed that cultivar 'IL111' had the highest phenolic and flavonoid content, as well as an antioxidant activity comparable to synthetic antioxidants. In addition, the antioxidant activity of the safflower extracts was evaluated in crude soybean oil by monitoring peroxide and thiobarbituric acid values, which showed a stabilisation effect on the soybean oil in the accelerated condition at 60 degrees C (oven test). Moreover, the analysis of phenolic compounds by HPLC showed that gallic acid was the predominant phenolic in safflower cultivar 'IL111'. The Isfahan-28 cultivar showed the best antimicrobial activity; the minimum inhibitory concentration against Staphylococcus aureus and Salmonella enterica serovar Typhi were 30 and 60 mg/ml, respectively.