Antifungal Activity of Osthole on Microsporum canis through Interfering with Biosynthesis of Fungal Cell Wall

Osthole extracted from Cnidii Fructus, a herb used in traditional Chinese medicine, was reported to possess multiple activities such as antibacterial, antiinflammatory, antitumor and insecticidal. However, its antifungal activity against Microsproum canis has not been investigated yet. The present study aimed to investigate the antifungal effect of osthole against Microsproum canis. The minimum inhibitory concentration and a growth inhibitory curve of osthole on Microsporum canis were according to the program of M38-A2 of Clinical and Laboratory Standards Institute. HPLC analysis, aniline blue test and spectrophotometry were used to determine contents of ergosterol, 1,3-β-D-glucan and chitin from Microsporum canis, respectively. The results indicated that minimum inhibitory concentration of osthole against Microsporum canis was 1.95 µg/ml. HPLC analysis demonstrated that there was no significant change in the content of ergosterol between the osthole and control group. Compared with the control group, the content of 1,3-β-D-glucan and chitin in the cell wall of Microsporum canis was decreased. Taken together, this research showed that osthole could notably inhibit the growth of Microsporum canis and the antifungal activity was related to inhibiting the biosynthesis of 1,3-β-D-glucan and chitin in the cell wall of Microsporum canis, making osthole a potential future antifungal agent.