Study On Formulating Of Celangulin Microemulsions

The Chinese bittersweet (Celasutrus angulatus Max.) is a potential insecticidal plant. The extracts of the root bark have been formulated to emulsifier concentration(EC), a formulation comprising 0.2% celangulin V(about 20% extract), 10% emulsifier and 70% dimethylbenzene. With respect to the use of organic solvents, these are generally disadvantageous from an environmental and cost viewpoint. To solve this problem, the microemulsion (ME) of celangulin, a new formulation that reduce the content of organic solvents, has been developed.According to the theories of composite membrane and R-ratio, the defined concentrations of DBS-Ca in the system were 2%,5%, 10%, then different non-ionic surfactants were added respectively. Scanning at the temperature range of 0-60t, the eligible system should be transparent or semitransparent at certain point. After this system was adjusted by co-solvent or co-surfactant, the optimal system was selected finally.The microemulsion of celangulin was obtained by providing an inert matrix composition comprising a defined mixture of a nonionic surfactant(DBS-Ca) and an anionic surfactant(emulsifier A), mixing with the extract to form a microemulsion concentrate, and diluting with water. Preferably, the aqueous microemulsion includes methanol herein as a co-solvent in the microemulsion system.The quality control of botanical insecticide is a key role in the development of formulation. A PTLC-HPLC analytical method for celangulin V has been established. Compared with the results of a parallel bioassay, the content of celangulin V could represent the actual efficacy.According to the related universal standard of pesticide, the quality indexes for 0.15% celangulin(ME) were established. It comprises appearance, content of celangulin V, PH value, cold stability, heat stability, and dilute stability and temperature range of transparence. The technic indexes of 0.15%celangulin(ME) are as follows:(1) The composition should appear as a single phase without anyparticulate or colloidal material or a second phase being present when viewed by the naked eye.(2)The dispersion should remain clear and free of precipitation or flotage at the temperature range of-5'---600C.(3)The freeze-thaw test indicates that the frozen formulation could recover independently at the room temperture.(4)After heat storage at the temperature of 54 ± 2 0C, the decomposition rate of celangulin V should be lower than 8%.The results of field trials showed that Plutella xylostella (L.) could be effectively controlled by spray a 1000 fold dilution of 0.15% celangulin.As a competitive new product, the patent has been applied.