Protease Inhibition and Antioxidant Actions of Some Aqueous Allium Extracts

Garlic and onion (Allium sp) have attracted particular attention of modern medicine because of its widespread health use around the world, and the cherished belief that it helps in maintaining good health warding off illnesses and providing more vigor. To date, many favorable experimental and clinical effects of garlic and onion preparations have been reported. These biological responses have been largely attributed to (i) reduction of risk factors for cardiovascular diseases and cancer, (ii) stimulation of immune function, (iii) enhanced detoxification of foreign compound, (iv) hepatoprotection, (v) antimicrobial effect, and (vi) antioxidant effect [1 – 7] . Beside these, recently was reported the sperm immobilization activity of the aqueous homogenate of garlic and onion extracts [8].

The aim of our work is to evaluate the inhibition effect of some Allium extracts on acrosin and trypsin, comparatively with antioxidant effect and cytotoxicity of extracts.

The methods used were acrosin proteolytic activity (APA) assay (with gelatin) and acrosin activity assay with N- α-benzoyl-DL-arginine-p-nitroanilide (BAPNA)-Triton X 100, and BAPNA assay for trypsin activity [9 – 11] . The antioxidant activity was tested spectrometrical with ABTS + [12] . Cytotoxicity of extracts was determined by MTT Cell Proliferation Assay [13] .

The experiment with 0.5 g/mL of crude extracts of different parts of Allium plants (bulb, green leaf, white stalk) showed the inhibition of acrosin and trypsin activities, mostly the red onion and garlic extracts. These results demonstrated that spermicidal effect of Allium extracts is determined also by their capacity of protease inhibition. The red onion extract shows the higher antioxidant capacity and a very low cytotoxicity.