Antifungal activity of essential oil and its constituents from Calocedrus macrolepis var. formosana Florin leaf against plant pathogenic fungi

Resistance to conventional fungicides causes the poor disease control of agriculture. Natural products from plants have great potential as novel fungicide sources for controlling pathogenic fungi. In this study antipathogenic activity of the leaf essential oil and its constituents from Calocedrus macrolepis var. formosana Florin were evaluated in vitro against six plant pathogenic fungi. Chemical analysis of leaf oil by GC/MS allowed identification of α-pinene (44.2%), limonene (21.6%), β-myrcene (8.9%), β-caryophyllene (8.2%), caryophyllene oxide (2.4%), α-cadinol (1.6%), β-pinene (1.2%), and T-muurolol (1.1%) as main components. Sesquiterpenoid components of the oil were more effective than monoterpenoid components of the oil. In particular, T-muurolol and α-cadinol strongly inhibited the growth of Rhizoctonia solani and Fusarium oxysporum, with the IC50 values < 50 μg ml−1. These compounds also efficiently inhibited the mycelial growths of Colletotrichum gloeosporioides, P. funerea, Ganoderma australe and F. solani. These results showed that T-muurolol and α-cadinol possess antifungal activities against a broad spectrum of tested plant pathogenic fungi and could be used as potential antifungal agents for the control of fungal diseases in plants.