Phenolic and polyphenolic profiles of defatted camelina, chia and sophia seeds and their invitro antioxidant and biological activities

Phenolic compounds in oilseeds occur in the free, esterified and insoluble-bound forms. The phenolics in seeds act as natural antioxidants by preventing deteriorative oxidative processes in foods as well as oxidative stress and various disorders in the human body once consumed. The free, esterified and insoluble-bound phenolics were extracted from defatted camelina (Camelina sativa), chia (Salvia hispanica) and sophia (Descurainia sophia) seeds meals. All samples were evaluated for their total phenolic content (TPC), total flavonoid content (TFC), and total proanthocyanidin (PC) content as well as antioxidant activity of their various phenolic fractions. The TPC in camelina, chia and sophia defatted meal was 11.69 ± 0.44, 14.22 ± 0.44 and 22.40 ± 0.87 mg GAE per gram sample, respectively. The corresponding values for TFC were 6.81 ± 0.68, 8.45 ± 0.80 and 8.59 ± 0.13 mg CE per gram defatted meal, respectively. Meanwhile, the PC in camelina, chia and sophia meals was 3.73 ± 0.03, 0.08 ± 0.02 and 2.23 ± 0.06 mg CE per gram sample, respectively. Several in vitro free radical scavenging assays, namely 2, 2- diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, trolox equivalent antioxidant capacity (TEAC), hydroxyl radical scavenging capacity (HRSC), reducing power (RP), β-carotene/ linoleate model system and metal chelation activity were investigated for all fractions. In addition, inhibition activity against lipase, α-glucosidase, low density lipoprotein (LDL) oxidation and DNA strand scission induced by peroxyl and hydroxyl radicals for all fractions was examined in biological systems. High performance liquid chromatography (HPLC) and HPLC-tandem mass spectrometry (HPLC-MSⁿ) led to positive identification of 36 phenolic compounds belonging to simple phenols, phenolic acids and their derivatives, flavonoids and procyanidins in the three phenolic fractions of camelina, chia and sophia. Esterified fraction was the predominant form of phenolics compared to the free and insoluble bound forms of phenolics in both defatted camelina and sophia seeds whereas the free phenolic fraction was the predominant form in defatted chia seed meal. Thus, camelina, chia and sophia seeds may serve as viable functional food ingredients with protective antioxidant potential but further research is required to confirm their cardiovascular diseases (CVD) preventive effects