Chemical constituents and antioxidant activity of essential oil and organic extract from the peel and kernel parts of Citrus japonica Thunb. (kumquat) from Iran

The constituents of essential oils and organic extracts from peel and kernels of Citrus japonica were analysed by GC and GC/MS. The content of essential oil in peel and kernel was 1.1 and 0.8% based on dry weight. The essential oil of C. japonica peel and kernel was characterised by a higher amount of limonene (51.0 and 47.1%) and germacrene D (12.1 and 6.3%), and the hexane extracts of its peel and kernel were characterised by a higher amount of dodecanol-1(12.9 and 20.8%) and linolenic acid (13.1 and 16.3%), respectively. The antioxidant activities of oils were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The results indicate that both oils from different parts of C. japonica possess considerable antioxidant activity. The fruit peel and kernel essential oil could thus be useful in the industries, chiefly in the food and pharmaceutical industries.