Identification and characterization of some bioactive components in selected local wheat (Triticum spp.) varieties

This study was carried out to determine some bioactive compounds and their antioxidant properties in whole wheat grains of selected on-farm conserved Turkish wheat genotypes (including 4 monococcum, 3 dicoccum, 4 durum, and 7 aestivum varieties). The chemical composition of whole wheat grains has been extensively studied, yet the literature on the bioactive compounds of Turkish local wheat genotypes is limited. For this purpose, 18 different wheat varieties including 4 different genotypes were supplied from TAGEM, Ankara. The total phenolics (including soluble-free, soluble-conjugated, and insoluble-bound phenolics), individual phenolic acid composition, total flavonoids, fatty acid composition, phytosterol profile, and steryl ferulate contents were determined in all whole wheat samples by UV/Vis Spectrophotometer, GC-FID, GC-MS, and HPLC-DAD. Overall, a comprehensive analysis of all results was performed using statistical tools such as Heatmap. Sünter was selected as a representative wheat for advanced purification (TLC, PTLC, and MPLC) and characterization due to its high phenolic content in local wheat varieties. Metabolites such as phenolic acids, fatty acids, sterol/stanols, steryl ferulates, α-tocopherol, phospholipids, sugars, sugar alcohols, organic acids etc., were identified in different whole and isolated extracts of Sünter wheat with GC-MS, GC-FID, and HPLC-DAD, whereas characterization of purified compounds was achieved with the help of 1H and 13C NMR. The results indicated that the dicoccum genotypes had the highest soluble-free and soluble-conjugated phenolics, whereas aestivum was rich in insoluble-bound, total phenolic, and flavonoid contents. The antioxidant capacity of monococcum and dicoccum wheat was slightly higher compared to the durum and aestivum genotypes. The major fatty acids in wheat lipids were identified as linoleic, oleic, and palmitic acids. Phytosterol/stanols included campesterol, campestanol, stigmasterol, β-sitosterol, β-sitostanol, and Δ5-avenasterol, whereas campesteryl, campestanyl & sitosteryl, and sitostanyl ferulate were identified as steryl ferulates. The monococcum wheat varieties were considered healthier for human consumption due to the presence of low amounts of saturated fatty acids. Also, monococcum varieties were found rich in terms of total phytosterol and steryl ferulate contents as compared to other genotypes. The analyses lead to the conclusion that local wheat genotypes, particularly dicoccum and aestivum, serve as valuable sources of both phenolic and antioxidant compounds. The local wheat varieties, such as Sünter, Zerun, AK-702, Köse 220/33, Spelt S. başak Siyez-4, and Karakılçık, contained higher amounts of beneficial bioactive compounds, e.g., phenolics, flavonoids, ferulic acid, unsaturated fatty acids, phytosterols, and steryl ferulates, making them a better choice over the commercial ones. This study offered a quick approach to obtain the important information regarding bioactive compounds in local wheat varieties. Furthermore, it could also provide valuable insights into the selection of on-farm conserved wheat genotypes for future wheat breeding programs. This study is expected to make important contributions to the limited literature on the bioactive composition of local Turkish wheat genotypes.