Objectives: This study was aimed to evaluate the chemical composition, antioxidant potential in vitro and in vivo, anti-inflammatory, and antinociceptive activity of turmeric oil.
Materials and methods: Chemical analysis of turmeric oil was done by gas chromatography/mass spectrometry. Antioxidant activities in vitro was done by six different methods and in vivo antioxidant activity was determined by measuring superoxide generation from macrophages treated with phorbol-12-myristate-13-acetate (PMA) as well as determining antioxidant level after feeding the oil orally for one month. Anti-inflammatory activity was studied in mice using carrageenan, dextran, and formalin. Antinociceptive activity was evaluated by using acetic acid-induced writhing movement in mice.
Results: The main constituent of essential oil of turmeric was found to be ar-turmerone (61.79%), curlone (12.48%), and ar-curcumene (6.11%). Turmeric oil was found to have in vitro antioxidant activity and IC(50) for scavenging superoxides, hydroxyl radicals, and lipid peroxidation were 135 μg/ml, 200 μg/ml, and 400 μg/ml, respectively. The ferric-reducing activity for 50 μg of turmeric essential oil was found to be 5 mM. Intraperitoneal administration of oil was found to inhibit PMA-induced superoxide radicals elicited by macrophages. Oral administration of turmeric oil for one month to mice significantly increased superoxide dismutase, glutathione, and glutathione reductase enzyme levels in blood and glutathione-S-transferase and superoxide dismutase enzymes in liver. Turmeric oil showed significant reduction in paw thickness in carrageenan, dextran-induced acute inflammation, and formalin-induced chronic inflammation. The drug produced significant antinociceptive activity (P < 0.001) at all doses studied.
Conclusions: These results demonstrated that turmeric oil has potential health benefits as it can scavenge the free radicals and produce significant anti-inflammatory and antinociceptive activities.
Keywords: Anti-inflammatory; Curcuma longa; antinociceptive; antioxidant; gas chromatography/mass spectrometry.