Determination of the effect of lawsone on catalase activity

Catalase is one of the antioxidant enzymes that converts hydrogen peroxide into water and molecular oxygen and protects cells from oxidative damage. Studies have shown that inhibition of this enzyme can help to treat Alzheimer s and cancer. On the other hand, catalase-positive pathogens produce catalase to inactivate peroxide radicals and survive in the host s environment .Henna is used as an herbal medicine and decreases growth of tumors, inflammation and relieve pain. Lawsone is one of the hennas derivatives which is responsible for the red-orange color of the henna powder. Lawsone is used for treatment of dermatitis and acts against microbes and bacteria such as staphylococcus aureus. Due to antimicrobial and antioxidant properties of lawsone, it is used by the pharmaceutical industries. In this study, activity of catalase in the presence and absence of lawsone studied by uv-visible spectroscopy and binding parameters estimated using molecular docking. Results showed that lawsone inhibits the activity of bovin liver catalase after two minutes of preincubation. The inhibition was non-competitive and decreasing of Vmax was observed as a result of lawsone concentration rise while Km was constant. Also the result of molecular docking demonstrated that hydrophobic interactions and one hydrogen bond play the main role in the binding of lawsone to catalase and the optimum binding energy obtained -5.54 kcal.mol-1 which indicate that it has a good interaction with catalase. Therefore, binding of lawsone to catalase enzyme changes its catalytic activity that may play an important role in the antimicrobial activity of henna extract.

Keywords:

Catalase activity , Lawsone , Non-competitive inhibition