This study investigated the antioxidant activity of crude lignan extracts and purified lignans (sesamin, sesamolin, and sesamol) in sunflower and flaxseed oils. Lignan extracts were prepared from roasted sesame seed oil (LRSO) and unroasted sesame seed oil (LUSO). Additionally, the individual lignans were purified from both oils. The crude extracts and purified lignans were added at concentrations of 0.01, 0.02 and 0.03% to the oils and stored at 25 and 65°C over time and peroxide values and thiobarbituric acid values were measured. Each oil showed an increase in oxidation over time, with the samples stored at 65°C exhibiting accelerated oxidation. In general, LRSO showed higher antioxidant activity than LUSO and the antioxidant activity was similar to the antioxidant activity of butylated hydroxytoluene (0.02% BHT) in both oils when used at concentrations of 0.02 and 0.03%. Sesamol showed the highest antioxidant activity of each of the purified lignans followed by sesamin and sesamolin respectively. Crude and purified sesame lignans may have potential applications as natural antioxidants in food systems

This study was conducted to investigate certain characteristics of the purified Phenylalanine ammonia lyase (PAL). The results revealed that the molecular weight was 180 kDa by gel filtration and Native-PAGE. The optimal pH and temperature for enzyme activity were 7 and 40 °C respectively. The enzyme activity was stable against pH values range of 6-8. The enzyme retained 79% of its total activity after incubation for one hour at 50 °C and retained 7% (lost 93%) of its activity at 70 °C. The entire activity was completely lost when the enzyme was incubated for 1 hour at temperatures over 70 °C. Carbohydrate content of the purified enzyme was estimated to be 24.61%. Km, Kcat and Vmax were estimated with phenylalanine as substrate, the values were 0.021 mM, 20.67 sec-1 and 4.13 mM/min respectively.

In the present study, Phenylalanine ammonia lyase (PAL) activity was detected in different parts of grape plant (leaves, pulp, whole seeds and defatted seeds) extracts. The results revealed that the whole seed possess highest PAL activity (69.44 U), followed by defatted seed (44.22 U), whereas extracts of leaves and pulp gave the lowest activity values (22.77 and 5.11 U, respectively). The optimum conditions for crude PAL extraction achieved using 50mM potassium phosphate buffer (pH 7) at mixing ratios of (1:7) for 1 h. extraction time. PAL was shown to precipitate out at the saturation range between 20-90%. For further purification, gel filtration chromatography using Sephadex G-200 column (1.5×70) and ion exchange chromatography using DEAE- Cellulose (DE 52) column (3.2× 10) were applied. The specific activity, number of folds and yield of purified PAL was 1157 U/mg, 19.94 and 15.32 % respectively.