Study On The Bioactivity And Mechanism Of The Alkaloids From Aconitum Carmichaeli Debx

To search new bioactive compositions from natural products is one of effective ways to develop novel pesticides. Aconitum carmichaeli Debx is an important Chinese herbs plant and the whole plant is strong toxic. In recent years,some preliminary studies on the bioactivity of the extracts from Aconitum carmichaeli Debx have been done. However these studies are not systematic and in-depth, results are scattered. To develope the total alkaloids into a new botanical pesticide, and widely use it in agriculture and forestry, there are still many problems to resolve. For this purpose, the author systematically made studies on the bioactivity and mechanism on insect pests of the alkaloids from Aconitum carmichaeli Debx. The major findings and conclusions are as follows.1. Insecticidal principal components of the alkaloids are aconitine, mesaconitine and hypoconitine, secondary component is aldohypaconitine.2. The alkaloids on the tested insects have strong contact, stomach toxicity and paralytic and antifeeding effects, certain role in killing the eggs, and impact on larval survival, but no fumigation effect.3. Laboratory and field tests show that the alkaloids have typical neurological symptoms on the Pieris rapae L. we preliminary concluded that the target of the alkaloids meight be in insect nervous system.4. After treatment, the alkaloids can cause a series of lesions in the midgut tissues of Parocneria orienta Chao, resulting in disorders of partial cell, shedding of longitudinal muscle and microvilli, ablation of some cell membrane and cytoplasm of the intestinal wall, which are one of the causes of death. Midgut digestive enzyme is not the target of the alkaloids.5. Acetylcholinesterase is the major target of the alkaloids, while Na+, K+-ATP enzymes also were inhibited, which can lead to the inhibition of Na+ lon transportation, cause the release of all kinds of neurotransmitters(acetylcholine) and glutamates, and breed the rapid response of organism.Therefore the tested insect showed neurological symptoms of poisoning in a very short period of time.6. The alkaloids interfered with normal physiological metabolism by inhibiting carboxyl esterase activity, which played a synergistic effect on the inhibition of acetylcholine esterase activity. The alkaloids induced the glutathione-s-transferases activity of tested insect, enhanced the metabolism and played the role of detoxification, which is an emergency response on the non-preferable material.