Performance Of Camphor Leaf Extractives And Its Complex Formation On Fungal And Mold Resistance Of Wood

Mould growth not only reduces the application value of wood but also negatively influences human health. Camphor leaves extractive is rich in natural antimicrobial substances such as linalool, and it is environmentally friendly and safe without toxic side-effect. Single-factor experiments method and response surface method were used to optimize the extraction techniques of camphor leaves, and a HS-SPME coupled with GC-MS method was applied for the compounds analysis in the extraction which is under the optimal parameters. The minimum inhibitory concentration(MIC) of the extractive for Penicillium citrinum, Trichoderma viride and Aspergillus niger was determined by oxford plate assay system. In order to search the optimum concentration of the extractive for inhibition of mould growth, the antifungal performance of camphor leaves extractive in different concentration was determined. The extractive respectively was compounded with cinnamaldehyde and iodopropargyl carbamate (IPBC), and the antifungal performance of different concentration mixed reagents about three moulds was measured in order to search the optimum concentration of the mixed reagents. In the potato dextrose medium, the variation of three moulds growth cycle and shape in different reagents was analyzed via ultraviolet and visible spectrophotometer and microscope. The wood samples were treated with camphor leaf extractives and its complex formation via impregnation method, brushing method and impregnation-brushing method. Then the preventing efficiency of the samples on three moulds and mixed mould was measured, and the influence of various treatments for preventing efficiency was analyzed. The main research results and conclusions are as follows:(1) The optimal extraction parameters of extraction rate of camphor leaves were ethanol concentration of 45%, liquid -material ratio of 16：1 (ml· g-1), extraction temperature of 58 ℃ and extraction time of 78min. Under the optimal parameters, the average extraction rate of camphor leaves was 19.33%. The camphor leaves ethanol-water extraction, under the optimal parameters, contain plenty of Alfin compounds which included high economical compounds such as Methyl isoeugenol, Linalool, Nerolidol and Methyl eugenol.(2) The sensitivity of three moulds for the extractive is different. The sensitivity of Penicillium citrinum is highest, the minimum inhibitory concentration(MIC) is 0.25%. The sensitivity of Aspergillus niger is medium, the MIC is 0.50%. The sensitivity of Trichoderma viride is lowest, and the MIC is 1.00%. The optimum concentration of the extractive for inhibition of mould growth is 12.50%.(3) It is could significantly improve the antifungal performance of camphor leaves extractive that cinnamaldehyde or iodopropargyl carbamate (IPBC) blended in the extractive. The optimum concentration of cinnamaldehyde and IPBC respectively is 0.40% and 0.60%. The antifungal performance of complex formation is result of the synergistic effect of two reagents.(4) In the potato dextrose medium, the variation of three moulds growth cycle and shape in different reagents camphor leaf extractive and its complex formation. Two complex formations made moulds stay at lag phase and molds hyphae not grow. The extractives only made the lag phase of moulds lengthen and molds hyphae become smaller and thinner.(5) It is reasonable that the complex formation with the extractives and cinnamaldehyde employs impregnation method to treat wood samples, and the preventing efficiency of the samples reached 75.00% on mixed mould. The average infection value of samples only was 1.0, which means the infected area on specimen less than 1/4. It is reasonable that the complex formation with the extractives and IPBC employs impregnation-brushing method to treat wood samples, and the preventing efficiency of the samples reached 87.50% on mixed mould, the average infection value samples is 0.5. The preventing efficiency of the samples treated with camphor leaf extractive weren’t exceeding 55.00% on three moulds and mixed mould.