3.2. Total phenolic and flavonoid content of extracts
The active compounds of natural sources such as phenolic and flavonoids compounds have shown to have antioxidant activities due to their ability to donate the electrons and scavenge the free radicals. Many factors such as climate, soil and ecological conditions are involved in the amount of these plants secondary metabolites (Saboonchian et al., 2014). Average TPC of aqueous extracts of the exocarp (peel) of Senjed fruit were measured as 573.31 ± 3.57 mg GAE/100 g FW. Hassanzadeh & Hassanpour (2018) reported that TPC of peel and pulp methanolic extractof Elaeagnus angustifolia L. fruits from different locations of East and West Azerbaijan provinces of Iran was in the range of 444.74 – 669.86 and 423.91 – 561.00 (mg GAE/100 g FW), respectively. Cansev et al. (2011) reported that average TPC of aqueous, acetone and methanolic extracts of the mesocarp and exocarp in oleaster fruit was 778.11, 558.52, 390.44; and 361.24, 413.95, 524.40 (mg GAE/100 g FW), respectively. They concluded that extraction procedures using water showed much more antioxidant capacity and total phenolic content compared to methanol and acetone extraction procedures for tested samples (p<0.05 ).
TPC of oleaster fruits crust and crumb methanolic extracts grown in different locations of Turkey reported as in the range of 13.43-22.30 and 10.58-16.44 (mg GAE/g DM), respectively (Simsek & Sufer, 2021). TPC in seed, flesh and peel of different genotype of oleaster methanolic extracts ranged from 2.14 to 6.26 ± 0.04, 0.14 to 1.54, and 0.12 to 2.59 (mM QE/mg extract), respectively (Faramarz et al., 2015). A review of literature shows that the content of phenolic compounds in the exocarp (peel or crust) of Elaeagnus angustifolia L. fruit is higher than its mesocarp (flesh, pulp or crumb). The nature and polarity of solvent systems markedly influenced the phenolic contents of extracts. The results imply that the aqueous extract of Senjed peel could be effective in the antioxidant and free radical scavenging activity. The amount of the total phenolics of the aqueous extract of Phellodendron amurense was 70 μg mg-1 (Velmurugan et al., 2018).
TFC of the extracts obtained from the peel of Senjed fruit was 151.33 ± 2.67 mg CAE /100 g FW. Hassanzadeh & Hassanpour (2018) reported that TFC of Elaeagnus angustifolia L. fruits peel and pulp methanolic extract in five different locations of East and West Azerbaijan provinces of Iran was in the range of 73.69 – 226.5 and 94.27 – 209.42 mg CAE/100 g FW, respectively. TFC of the methanolic extracts obtained from the crust and crumb of oleaster fruit varied between 5.99 ± 0.45 and 16.24 ± 1.49 mg CE/g DM, and 3.10 ± 0.01 and 6.54 ± 2.68 mg CE/g DM, respectively (Simsek & Sufer, 2021). The TFC in methanolic extracts of seed, flesh and peel of different genotype of oleaster fruit ranged from 4.7 to 17.6, 0.62 to 1.90, 0.64 to 1.13 (mM QE/mg extract), respectively (Faramarz et al., 2015). TFC of the extracts obtained from the crust and crumb of oleaster fruit varied between 5.99 to 16.24, and 3.10 and 6.54 (mg CE/g DM), respectively (Simsek & Sufer, 2021).
After 24 days of storage, the trolox equivalent (TE) of soybean and cottonseed oils fortified with 400 mg/kg rosemary extract was significantly higher than the TE of oils fortified with 200 mg/kg of the synthetic antioxidants BHA and BHT (Yang et al., 2016).