Dandan Duan

Acaricidal Activity of Ethyl Palmitate against Tetranychus cinnabarinus

Isolation and identification of bioactive compounds from medicinal plant of Inula flower is a potential approach for the development of new pesticides against the mite of Tetranychus cinnabarinus. Dry Inula Flower was used as the starting material to obtain active substances with acaricidal activity by organic solvent extraction and bioactivity assay verification. The main component of the active substances in fraction 33 was further identified by GC/MS and proven to be ethyl palmitate. In order to clarify the roles of ethyl palmitate playing against mites of Tetranychus cinnabarinus, the enzymatic activities were assayed regarding to four essential enzymes in the process of either nerve conduction or anti-oxidation reaction of the mites, including assays for Ca2+-ATPase, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). In addition, the substructures of the ethyl palmitate treated adult female mite of T. cinnabarinus were observed by transmission electron microscopy. In the bioassay, ethyl palmitae showed strong activities against the mites with the corrected mortality rates of more than 90% for samples at 2mg/ml concentration. The activity increases of antioxidant enzymes indicate a certain degree of stimulation of the anti-oxidant mechanisms to response for the ethyl palmitate treatment in vivo. The Ca2+-ATPase plays essential role in the maintenance of nerve cell excitability and conduction. Its enzymatic activity was subject to a certain degree of declination, which might cause the death of the mites due to suppression in nerve conduction. The toxicity effect of the mites by ethyl palmitate was further confirmed by TEM observation. The significant destruction of the skin structures and cellular substructures can directly affect the normal function of the cells, and ultimately lead to the death of the mites. Based on the strong acaricidal activity of ethyl palmitate has against the carmine spider mite, it is valuable to be further investigated for a new type of botanical pesticides development.

Acaricidal Activity of Stigmasterol from Inula Britannica against Tetranychus cinnabarinus

The activity of fraction 12 identified as stigmasterol by GC/MS from the petroleum ether extract of Inula britannica was evaluated against Tetranychus cinnabarinus in laboratory. The bioactivities and mechanism of stigmasterol against Tetranychus cinnabarinus was further investigated. Superoxide dismutase, peroxidase and catalase in T. cinnabarinus treated with stigmasterol were examined through biochemical methods. The ultrastructure of the treated mites was observed by using transmission electron microscope (TEM). The stigmasterol showed lethal effects on the mite adults, and corrected mortality was over 50% with the concentration of 2 mg/ml. Superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in treated mites were enhanced in activity. The results showed that stigmasterol can destroy the balance between oxidation and anti-oxidation. Glutathione-S-transferase (GSTs) activity was strongly induced after treatment. The results indicated that stigmasterol was perhaps attributing to over excitation and dead of treated mites. TEM observations revealed that the treated mites suffered from the ruptures of cuticle, muscular filament, nuclear membrane, mitochondria and endoplasmic reticulum. Thus, stigmasterol appears a strong acaricidal activity against Tetranychus cinnabarinus, can be exploited as new resources for developing potential botanical acaricides.

Acaricidal Activity of Lupeol from Inula britanica against Tetranychus cinnabarinus (Acari: Tetranychidae)

Extracts of Inula britanica were bioassayed to determine their acaricidal activities against Tetranychus cinnabarinus in the laboratory. The results showed lupeol from I. britanica is toxic to these mites, which showed high mite mortality. The present paper reports lupeol changed the balance of acetylcholinesterase (AChE), Na+-ATPase, POD, and catalase to damage the cuticle, muscular filament, nuclear membrane, mitochondria, and endoplasmic reticulum of treated mite, then ultimately killed T. cinnabarinus. This study is the first to report the acaricidal property of I. britanica and its potential as a botanical pest control agent.

The Effects of Lupeol from the Petroleum Ether Extract of Inula Britanica on the Biological and Enzyme Activity of Tetranychus Cinnabarinus

The acaricidal and relative enzyme activity in Tetranychus cinnabarinus treated with petroleum ether extract of Inula britanica were studied. Our results indicated that petroleum ether extract of Inula britanica had acaricidal activities against Tetranychus cinnabarinus, and its mortality to Tetranychus cinnabarinus had reached 92.05 % at the concentration of 2mg∙mL-1. After liquid chromatography and thin layer chromatography, there were 38 fractions gained in which fraction 7 had stronger toxicity than others, and its mortality to Tetranychus cinnabarinus was 92.05 %. Fraction 7 was identified as Lupeol by CG/MS, and the mortality of Lupeol to Tetranychus cinnabarinus was 66.46%. The activities of glutathione-S-transferase, Ca2+ - ATPase, SOD and protein content were assayed by colorimetric method after treatment with Lupeol. Our results showed that the activity of SOD was strongly induced whereas the activities of glutathione-S-transferase and Ca2+- ATPase were restrained, but there was little change in total protein content. These results suggested Lupeol from the petroleum ether extract of Inula britanica had acaricidal activities against Tetranychus cinnabarinus. These data provided useful information for the use of Inula britanica as a novel resource of botanical acaricide.

Effects of Stigmasterol to Activities of Several Enzymes of Tetranychus cinnabarinus

The acaricidal activity of stigmasterol was carried out on the Tetranychus cinnabarinus, using the slide dip technique. Here the female adult mites were treated by the Stigmasterol extracted from Inula japonica. Bioassay-guided purification of the 12th fraction had higher activity against the T. cinnabarinus, Gas chromatography-mass spectrometry (GC/MS) demonstrated that the chemical composition of the active fraction 12th sample was mainly composed of Stigmasterol. That had not been reported before. And the acaricidal mechanism of Stigmasterol to T. cinnabarinus is unknown. Our results showed that the nervous symptoms of the T. cinnabarinus in response to the Stigmasterol. The protein content, the acetylcholine esterase (AChE) activity, the Calcium enzyme ATP (Ca2+-ATPase) activity and Sodium enzyme ATP (Na+-ATPase) activity of the mites treated with Stigmasterol were assayed. The results showed that the protein content and the activity of AchE in the T. cinnabarinus treated with the Stigmasterol were increased. The activity of Ca2+-ATPase and Na+-ATPase were induced by the Stigmasterol. The effects of the T. cinnabarinus indicated that the central nervous system was the main target of Stigmasterol. The long time over excitation caused the treated mites to die.

Identification of Acarcidal Compounds in Inula japonica Extracts against Tetranychus cinnabarinus

In this study, we aimed to identify acaricidal compounds in Inula japonica against Tetranychus cinnabarinus. Here, I. japonica petroleum-ether extracts were found toxic to T. cinnabarinus with a LC50 value of 1.18 mg/ml. Silica gel column chromatography was used to further separate acaricidal components from I. japonica petroleum-ether extracts. Contact toxicity data showed that 17 out of 38 fractions groups had mite mortality rates above 50%, 9 fraction groups above 60 %, and fractions groups G5, G7 and G15 even above 80 % at a concentration of 2 mg/ml. The major vital compounds in the bioactive fraction groups were identified by GC/MS, and four compounds, namely β-Sitosterol (1), Stigmasterol (2), Lupeol (3), and α-Amyrin (4) were determined to have acaricidal activity to Tetranychus cinnabarinus.

Effects of Inula britannica Extracts on Biological Activities against Tetranychus cinnabarinus and Several Enzyme Systems in Tetranychus cinnabarinus

Acaricidal activities of the extracts from Inula britannica (I. britannica) against Tetranychus cinnabarinus (T. cinnabarinus) and several enzyme systems in T. cinnabarinus treated with I. Britannica extracts were evaluated under laboratory conditions. It was found that crude extracts from I. britannica with petroleum ether exhibited high acaricidal activities against T. cinnabarinus, and the corrected mortality after treatment for 24 h was 92.05 % at the concentration of 2 mg ml-1. After a liquid-liquid partition from petroleum ether crude extracts with methanol, the resulting petroleum ether extracts were separated into 38 fractions by column chromatography, and further tests for their acaricidal activities were conducted. Fraction 33, the most major component of the resulting extracts, was found to possess the strongest acaricidal activity against T. cinnabarinus in all 38 fractions, and its corrected mortality against T. cinnabarinus was 90.12 % after 24 h. Moreover, GC-MS analysis results determined that chemical composition of fraction 33 was ethyl palmitate. Laboratory bioassay results indicated that the corrected mortality of ethyl palmitate against T. cinnabarinus after treatment for 24 h was 90.61 %, and the mean lethal concentration (LC50) was 1.255 ± 0.167 mg ml-1. In order to determine the mechanism of the toxic effect of ethyl palmitate on T. cinnabarinus, several kinds of important enzyme systems including glutathione S-transferase (GSTs), acetylcholinesterase (AChE) and Na+-adenosine triphosphatase (Na+-ATPase) as well as total protein content in T. cinnabarinus were tested by the colorimetric method. The experimental results showed that after treatment with ethyl palmitate, total protein content in T. cinnabarinus obviously increased, and the activities of GSTs and AChE in T. cinnabarinus were strongly induced, while the activities of Na+-ATPase in T. cinnabarinus were restrained. Been restrained of Na+-ATPase could cause the transmit block of nerve, and eventually result in the death of the mite. These results indicated that Inula britannica extracts possessed significantly high acaricidal activity.