| In this study,we extracted the raphides from the fresh and dried tubers of Arisaema erubescens by water extraction,and used Oncomelania hupensis as the treatment target to conduct the snail killing experiment.At the same time,the chemical composition of the raphides was identified and the physiological and pathological mechanisms of snail killing by raphides were analyzed.The results of the study were as follows.The intact raphides extracted from the fresh Arisaema erubescens tubers were superior to the dried product,and the quantity was 4.5 times higher than that extracted from the dried product.The lethality of the snail was 52.78% and 73.33% when the snail was treated with raphides in indoor water immersion method for 48 h and 72 h at a concentration of 100mg/L,respectively.It showed that raphides from a handful of Arisaema erubescens had good molluscicidal activity.The analysis of the chemical fraction of the raphides showed that it mainly consisted of calcium oxalate,protein and polysaccharide.The protein was analyzed qualitatively,and the protein isolated by water immersion was subjected to SDS-PAGE,and a clear protein band with a molecular weight of 12 k Da was obtained,which was identical to the lectin(AEL)protein purified from the fresh Arisaema erubescens tubers by ion exchange resin,both with a molecular weight of 12 k Da.The lectin protein was analyzed by LC-MC-MC and found to be a lectin protein containing four identical peptides.A comparison of the molluscicidal activity of Arisaema erubescens intact raphides,calcium oxalate and AEL was performed to analyze the principle of poisoning and killing.Experiments were conducted on nail snails by leaching method and mortality was counted.At a concentration of 100 mg/L,the snail-killing activity of the poisonous needle crystal solution after 72 h and 96 h treatment was in the order of intact raphides > calcium oxalate > AEL(P<0.05),and the molluscicidal activity of raphides from a handful of Arisaema erubescens was concentration and time dependent.Calcium oxalate and lectin protein had synergistic effects,producing toxic effects leading to the death of nail snails.The toxic physiological response of the raphides to the liver of the snail was measured by the activities of three key liver enzymes such as peroxidase(POD),superoxide dismutase(SOD),and catalase(CAT),and it was found that the activities of POD,SOD,and CAT were all significantly elevated(P<0.05)at low treatment concentrations and decreased either quickly or slowly at high treatment concentrations,while with the treatment time The activities of SOD,SOD,and CAT were all significantly elevated at low concentrations(P<0.05)and decreased at high concentrations,and also increased with treatment time.It is suggested that raphides from a handful of Arisaema erubescens caused oxidative damage by disrupting the function of antioxidant enzymes in the liver of the snail and exerted toxic effects leading to the death of the snail.Scanning electron microscopy and projection electron microscopy were used to observe the damage to the external tissues and internal cells of the snail,and the cephalopods and external tissues of the liver were damaged to different degrees with increasing drug concentration and time,and the effect of damage to liver cells was also significant.It was shown that raphides of Arisaema erubescens exerted toxic effects by destroying the liver and cephalopods of the nail snail,thus damaging its structure and function leading to its death.In conclusion,the raphides of Arisaema erubescens have good snail-killing effect,and its chemical composition,calcium oxalate needle crystals and lectin toxin have synergistic stimulation effect on the snail,and the toxic needle crystals mainly stimulate the snail liver to weaken its antioxidant capacity and lead to death.This paper provides scientific basis and theoretical support for other phytopharmaceuticals to kill snails through the study of the molluscicidal activity and its mechanism of Arisaema erubescens,and provides demonstration and reference for the research of snail-killing drugs by other raphides of the family Arisaema. |
