Lipoxygenase Inhibitory Activity of Some Extracts Prepared from Flaxseed (Linum usitatissimumv L.)

Background: Lignans are biologically important phenolic compounds that exist in different levels of various plants; yet, flaxseed is one of the richest sources of such compounds. Lipoxygenase enzymes are associated with many inflammatory-related diseases such as arthritis, allergic asthma, psoriasis, cardiovascular disease, kidney disease, skin diseases, and neuropsychiatric disorders, as in Alzheimer's disease. Not only are these enzymes involved in many types of cancers, but they are also very crucial to find new LOX inhibitors to treat human diseases such as cancer or cardiovascular disease. Screening for lipoxygenase inhibitory activities of flaxseeds lignans extracts in various methods is reported in this work. Methods: Extracts of samples of flaxseeds (Linum usitatissmum) were prepared using the following methods: a- extraction with continuous stirring with 80% ethanol, b- extraction with a mixture of equal volumes of diethyl ether and ethyl acetate after direct acid hydrolysis, c- Extraction with 50% ethanol followed by alkaline hydrolysis. Total flavonoids, total phenolic of these extracts were compared. The scavenging potential of free radicals was determined using the DPPH method. The inhibitory potential against the lipoxygenase enzyme was determined by using the soybean lipoxygenase enzyme. Results: The highest phenolic content was in the extract prepared with ethanol 80% with continuous stirring, with phenolic content of (126.848 mg GAE /g). While the highest flavonoid was content in the extract prepared with a mixture of equal volumes of diethyl ether and ethyl acetate after direct acid hydrolysis, with flavonoid content reached (7.8 mg QE / g). Moreover, the scavenging potential of free radicals expressed in terms of IC50 (μg/ml) showed extraction with a mixture of equal volumes of diethyl ether and ethyl acetate after direct acid hydrolysis exhibited higher antioxidant capacity (IC50=22.257±0.095 μg/ml) followed by 80% ethanol extract. The median inhibitory concentration (IC50) was calculated according to the LOX enzyme inhibitory method. The IC50 value of a mixture of equal volumes of diethyl ether and ethyl acetate after direct acid hydrolysis extract of flaxseeds is 73.689±0.585 μg/ml. Conclusion: The mixture of equal volumes of diethyl ether and ethyl acetate extract after direct acid hydrolysis gives stronger scavenging potential of free radicals and lipoxygenase inhibitory effects than the other extracts in this study. Therefore, according to the results we got in our study, flaxseed extracts can be a potential source of novel therapeutics to treat many diseases related to the LOX enzyme.