Chemical composition, N-nitrosamine inhibition and antioxidant and antimicrobial properties of essential oil from Coreopsis tinctoria flowering tops.

Coreopsis tinctoria flowering (CTF) tops from the Kunlun Mountains in Xinjing (north-western China) have been used for tea production for about a century. This study was to assess antioxidant, nitrite-scavenging and N-nitrosamine inhibitory and antimicrobial activities of the essential oil extracted from CTF tops. The essential oil was extracted through hydrodistillation and its chemical compositions were analysed by GC-MS. Seventy compounds of the oil were identified, representing 81.87% of total oil. The antioxidant capacities of the oil with IC50 values for scavenging DPPH and ABTS were 287.66 ± 12.60 and 1.251 ± 0.127 µg mL(- 1), respectively. The nitrite-scavenging and N-nitrosamine inhibitory activities (IC50) were 0.3912 ± 0.0127 and 0.6564 ± 0.036 µg mL(- 1), respectively. The oil has a certain antimicrobial capacity, but its capacity was weaker than that of penicillinG (24 µg mL(- 1)). The oil showed antioxidant and antimicrobial capacities and had a stronger nitrite-scavenging and N-nitrosamine inhibitory properties.