Chemical composition, antimicrobial and antioxidant activities of essential oils from the receptacle of sunflower (Helianthus annuus L.)

Sunflower ( Helianthus annuus L.) contains active ingredients, such as flavonoids, alkaloids and tannins. However, few studies have focused on essential oils from the receptacle of sunflower (SEOs). The chemical composition, antimicrobial and antioxidant activities of SEOs were assessed whether SEOs could be used as nature preservatives and medicines. The extraction rate of SEOs was 0.4% by using hydro-distillation and solvent with petroleum ether, which is much higher than that by only using hydro-distillation (0.2%) in the previous study. A total of 81 volatile constituents of SEOs were identified by gas chromatography-mass spectrometry (GC-MS). The main constituents of SEOs were α-pinene (31.17%), calamenene (5.66%), α-terpineol (4.71%), verbenone (3.15%), kaur-16-ene (2.52%) and terpinolene (1.47%). The antimicrobial activities of SEOs were assessed against three bacteria ( E. coli , P. aeruginosa , and S. aureus ) and two fungi ( S. cerevisiae and Candida albicans ). The MIC of SEOs against P. aeruginosa and S. aureus was 0.2 mg/mL. The MIC of SEOs against S. cerevisiae was 3.2 mg/mL. The MIC of SEOs against E. coli and Candida albicans was 6.4 mg/mL. The results showed that SEOs had high antibacterial and antifungal actions. The antioxidant activity was determined with three different analytical assays (DPPH, ABTS and iron reducing ability). The results of antioxidant activities showed that SEOs had high antioxidant activities. The results proved that SEOs could be used as natural preservatives and medicines, due to its excellent antimicrobial and antioxidant activities.