Antioxidant and relaxant activity of fractions of crude methanol extract and essential oil of Artemisia macrocephala jacquem

BACKGROUND: The current work is an attempt to know about additional chemical profile of Artemisia macrocephala. Antioxidant activity is performed as the plant is reported to contain flavonoids, which have antioxidant activity in general. Relaxant activity of fractions of crude methanol extract is performed to know in which fraction(s) the relaxant constituents concentrate as we have already reported that its crude methanol has relaxant activity. Antispasmodic activity of essential oil is also performed as the plant is rich with essential oil. METHODS: Phytochemical profile of the plant is performed. Free radical scavenging activity was performed using 2, 2-diphenyl-1-picrylhydrazyl (DPPH). Relaxation activity tests of fractions and essential oil of Artemisia macrocephala were performed on sections of rabbits’ jejunum. Calcium chloride curves were constructed to investigate the mode of action of plant extracts and its essential oil. RESULTS: We detected carbohydrates, flavonoids and saponins in A. macrocephala. At concentration 0.005 mg/ml, free radical scavenging activity of ethyl acetate fraction was 121.5 ± 2.02% of ascorbic acid. n- hexane fraction relaxed spontaneous activity with EC(50) 0.74 ± 0.04 mg/ml. Essential oil relaxed spontaneous activity with EC(50) 0.8 ± 0.034 mg/ml. Chloroform and ethylacetate fractions relaxed both spontaneous and KCl-induced contractions suggesting its possible mode through calcium channels. Constructing calcium chloride curves, the test fractions showed a right shift in the EC(50). Essential oil at concentration 0.1 mg/ml produced right shift with EC(50) (log [Ca(++)]M) -2.08 ± 0.08 vs. control with EC(50) -2.47 ± 0.07. The curve resembled the curves of verapamil, which caused a right shift at 0.1 μM, with EC(50) -1.7 ±0.07 vs. control EC(50) (log [Ca(++)]M) -2.45 ± 0.06. CONCLUSIONS: Crude methanol and its fractions (ethyl acetate, chloroform and butanol) are rich sources of antioxidant constituents. The relaxing constituents following calcium channel blocking mechanisms are more concentrated in n-hexane, chloroform and ethyl acetate fractions that warrant isolation.