Efficacy Of The Extracts From The Ragweed Against Pomacea Canaliculata And The Active Components

Molluscicidal activities and active compounds of the extracts from the aerial part of Ambrosia artemisiifolia L. were studied. This research evaluated the efficacy of the extracts against Pomacea canaliculata (GAS) and determined the influence on the rice yield. The active compounds were isolated from the methanol extracts of A. artemisiifolia by bioassay-guided with normal and reversed phase column chromatography, Sephadex LH-20 gel column chromatography, thin-layer chromatography, recrystallization and high performance liquid chromatography (HPLC), and elucidated mainly by nuclear magnetic resonance (NMR) and mass spectrometry (MS) methods. This research is aimed at providing the basis for exploring and utilizing A. artemisiifolia as the molluscicide against GAS and expected to find the new type of molluscicidal active lead compounds. The results were as following:1. The methanol extracts of A. artemisiifolia exhibited moderate molluscicidal toxicity against GAS, after 72 hours of exposure, with the value of LC50 being 194.0 mg/L. Sublethal effects of the extracts on GAS were investigated with the decrease in weight, length, width and fecundity of snails. This demonstrated that the ragweed extracts caused various disturbances in the growth and reproduction of GAS and showed chronic toxicity.2. The ragweed powders exhibited good molluscicidal toxicity against GAS in the field. More than 90% of the snails were killed and no egg masses were found when the dosage of the ragweed powders reached 15 kg/667m2. The ragweed powder in all experiments significantly inhibited the spawning of GAS. When the GAS exposed by 5 and 10 kg powder/667m2, the inhibition rates were 88.4% and 95.9%, respectively. The decreased fecundity and reproductive performance of the GAS, exposed to the powder, result in a decline of snail populations, and that is very important for the control of the snails in field.3. The powders of ragweed showed no harmful effects, and even somehow promoting effects on the yield of rice. Obviously, it is a potential non-chemical method to use ragweed to manage GAS in rice production, which is valuable done further investigations.4. Twenty one compounds including four new sesquiterpenes (1-4), eight known sesquiterpenoids (5-12), four known flavonoids (18-21), and other five known compounds (13-17) had been isolated and identified from the methanol extracts of A. artemisiifolia, they were:3?-acetoxy-4a-hydroxy-1,7,10,11?H-pseudoguaia-12,8a-olide (1),1?,7?,9?,10?, 13aH-guaia-4(5)-en-12,6?-olide 9-O-?-D-glucoside (2),4?-hydroxy-la,5a,7a,9aH-guaia-10 (14),11(13)-dien-12-acid 9-O-?-D-glucoside (3), 1?,6a-dihydroxyeudesman-4(15)-ene-1-O-?-D-apiofuranosyl (1"-6')-O-?-D-glucopyranoside (4), 1?,6a-dihydroxyeudesman-4(15)-ene-1-O-?-D-glucopyranoside (5),7-epi-eudesm-4(15)-ene-la,6a-diol 1-O-?-D-glucopy-ranoside (6), pumilaside A (7), ilicic acid (8), 1?-hydroxyendesma-4,11(13)-dien-12-oic acid (9), icarisid VI (10), psilostachyin B (11), psilostachyin (12),4-benzyl-2-oxazolidinone (13),4-({6-O-[(4-hydroxy-3,5-dimethoxyphenyl)carbonyl]-?-glucopyranosyl} oxy)-3,5-di-methoxybenzoic acid (14),?-amyrin acetate (15), eugenyl-O-?-apiofuranosyl-(1"-6')-O-?-glucopyranoside (16), p-anisic acid (17), axillarin (18), isoquercitrin (19), tamarixetin-3-O-?-D-glucoside (20), isorhamnetin-3-O-rutinoside (21). Sesquiterpenoids were the major components to the ragweed, including six eudesmane sesquiterpenoids (4-9), five sesquiterpene lactones (1-3?11-12), and one megastigmane sesquiterpenoid (10).5. Psilostachyin (12) and psilostachyin B (11) demonstrated the mainly molluscicidal activity against GAS, after 24 hours of exposure, with the LC50 values of 15.9 and 27.0 mg/L, respectively.