Study On The Extraction And Insecticidal Activities Of Alkaloids From Radix Aconiti

Alkaloids are an important natural organic compounds containing nitrogen, and which are the earliest natural products researched by scientists. Radix Aconiti (Chuanwu) is a kind of traditional commonly used Chinese crude drug. The main chemical components of it are noxious diester aconite alkaloids. This paper studies on the extraction, insecticidal activity and action mode of alkaloids from Radix Aconiti. Meanwhile, the alkaloid content and proportion analysis in it were performed.Determination of aconitines in Radix Aconiti by HPLC. The HPLC system consisted of Microsorb-MV 100-5 C₁₈ (250×4.6mm×1/4 inch) as the stationary phase and CH₃OH-H₂O-CHCl₃-triethylamine (70:30:2:0.1, volume ratio) as the mobile phase, the detection wavelength was 230nm. The results provide the aconitines were on base line sepatated. Their average recoveries and RSD were: 96.06 %, 1.47 % (aconitine); 94.89 %, 1.82 % (hypaconitine); 95.78 %, 2.06 % (mesaconitine). The method was simple, rapid and precise.To study the extracting process of the effective components of Radix Aconiti, the orthogonal experimental design was used for the dominant selection and the content of aconitine with HPLC determination as quantitative estimation standard. The results indicate that the concentration and quantity of ethanol and time of extraction are the influence factors. The best process was set as follow: Radix Aconiti was marinated 3 times with 95% alcohol and 4d at a time, of which the quantity of alcohol was 8 times(V/V) of medicinal materials.The biological activity and action mode of aconite alkaloids against Spodoptera exigua (Hubner) by bioassay were performed in this paper. The results showed that the aconite alkaloids possess obviously biological activities, including stomach toxicity activity, anti-feedant activity and inhibition growth activity. The aconite alkaloids had neither fumigant nor contact poisoning to the insect. The LC₅₀ of total alkaloids in Radix Aconiti extracting solution against the 4th instars larvae of Spodoptera exigua Hubner is 630.80mg/L. The LC₅₀ of three diester aconite alkaloids against the insect were different, the hypacontine was basically corresponding with aconitine, was 121.51mg/L and 146.27mg/L respectively. But the mesaconitine has great different with them, the LC₅₀ of it was 495.09mg/L. There have different interactions between these three components under different mixed ratio, including antagonistic, additive or synergistic effects.