Antifungal and Antioxidant Activity of Asteriscus graveolens subsp. odorus Essential Oil

Abstract

The essential oil of air-dried Asteriscus graveolens subsp. odorus, plant of southern Morocco, obtained by hydrodistillation were analysed by capillary gas chromatography-mass spectrometry (GC-MS). Twenty eight compound accounting 69.14% of the total oil was identified. The oxygenated sesquiterpenes 6-oxocyclonerolidol (30.72%) and epi-?-cadinol (14.50%) were the main constituents. The essential oil was tested for antifungal activity through mycelial growth inhibition tests in vitro against three agricultural pathogenic fungi: Penicillium digitatum, P. expansum and Botrytis cinerea. The essential oil at 125, 150, 200, 250, 500, 1000 and 2000 ppm was highly effective against mycelial growth of P. digitatum with 100% inhibition from the first day of incubation. Complete inhibition was also observed at 150, 200, 250, 500, 1000 and 2000 ppm concentrations of the essential oil from the first day of incubation for P. expansum. The doses 500, 1000 and 2000 ppm showed a percentage inhibition of 100% from day one for B. cinerea. Asteriscus graveolens subsp. odorus essential oil was also tested at different concentrations on Citrus fruits (Citrus reticulata Blanco cv. Nules) inoculated with P. digitatum (10⁵ conidia ml^-1, giving a fungistatic or fungicidal effect. In addition, the oil was subjected to screening for its possible antioxidant activity. For that, the in vitro assay based on the scavenging of the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was used. The Asteriscus graveolens subsp. odorus essential oil gave a value of CI₅₀ 0.2498 mg/ml. It inhibition percentage of free radical was slightly lower than that of BHT (the control compound) for all concentrations used. Our findings demonstrate that Asteriscus graveolens subsp. odorus essential oil possesses antioxidant and antifungal activities that might be a natural potential source of preservative and antifungal compounds used in food, in cosmetics and in pharmaceuticals products.

Keywords: Medicinal plant, antifungal activity, antioxidant activity, citrus fruits, natural product.