Investigating the antioxidant potential of Turkish herbs and spices

Herbs and spices have been used for many purposes including medicine, flavourings, and preservatives, etc. Constituents of herbs and spices can function as natural antioxidants and thus improve human nutrition and health. The main objective of this study was to evaluate the total phenolic and flavonoid contents of 35 different Turkish herbs and spices and to determine their antioxidant activity. Total phenolics, flavonoids, and total antioxidant capacities were analysed by four different methods: 2,2’-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and cupric ion reducing antioxidant capacity (CUPRAC) assay. The correlation coefficients (R2) between spectrophotometric assays were calculated. Wide variation in total phenolics (TP; 0.36-104 mg GAE/g), flavonoids (TF; 0.44-53.7 mg CE/g) and antioxidant capacity (TAC; 0.88-1007 mg trolox equivalent/g) was observed. Clove (Eugenia caryophyllata), yarrow (Achillea millefolium) and rosemary (Rosmarinus officinalis) showed the highest TP, TF and TAC values, respectively, whereas mahaleb (Prunus mahaleb) showed the lowest TP and TAC. The relationships between TP, TF and TAC generally indicated a weak correlation, ranging from R2=0.163 (between ABTS and CUPRAC) to R2=0.760 (between FRAP and CUPRAC). This study provides direct comparative data on TP, TF and TAC of the 35 commonly consumed herbs and spices in Turkey.