Isolation and structure elucidation of three neo-clerodane diterpenes from Teucrium fruticans L. (LABIATAE)

Recently, the isolation from Teucrium fruticans of neo-clerodanes, namely 7beta-hydroxyfruticolone, 11-hydroxyfruticolone, deacetylfruticolone and 6-acetyl-10-hydroxyteucjaponin B, in addition to fruticolone, isofruticolone and 8beta-hydroxyfruticolone (three out of the four previously reported ones), and 6-acetylteucjaponin B (isolated from T. scordium and T. grisebachii) was reported. Minor compounds presumably of neo-clerodane nature were shown by HPLC analysis on a new extract. Three new compounds, difuranofruticol, deoxyfruticolone and 10-hydroxyteucjaponin B, and the known 7,8-didehydrofruticolone were unambiguously elucidated based on extensive NMR spectral studies (one- and two-dimensional experiments). The compounds were assayed for their antifeedant activity against Spodoptera littoralis and for their antifungal activity against Rhizoctonia solani. Compounds 9-11 showed low antifeedant activity and the feeding ratio of 12 was moderate-low. None of the tested compounds displayed significant activity against R. solani.     

Antifeedant activity of an anthraquinone aldehyde in Galium aparine L. against Spodoptera litura F

The insect antifeedant anthraquinone aldehyde nordamnacanthal (1,3-dihydroxy-anthraquinone-2-al) was identified in Galium aparine L., and isolated from the root powder of akane (Rubia akane), a member of the Rubiaceae. Structure-activity relationship (SAR) studies using a series of anthraquinone analogues suggested that the aldehyde group on the anthraquinone was more important than the quinone moiety for antifeedant activity against the common cutworm (Spodoptera litura). High levels of nordamnacanthal were found in the seed leaf stage and in callus tissue induced from seedlings of G. aparine, but its concentration decreased with plant development. Since these compounds are natural pigments for dying textiles, we also evaluated the antifeedant activity against the carpet beetle (Attagenus japonicus ), a textile pest was also evaluated. While nordamnacanthal had strong antifeedant activity against the common cutworm, it did not show any antifeedant activity against the carpet beetle. The most effective antifeedant against the carpet beetle was the major constituent in the extract of R. trictorum, lucidin-3-O-primeveroside, a food pigment.     

Antifeeding activity of limonoids from Khaya senegalensis (Meliaceae)

Abstract: Fifteen B,D-secolimonoids of mexicanolide, rearranged phragmalin, methyl angolensate and glycoside types have been isolated from ether and acetone extracts of the stem bark of Khaya senegalensis (Desr.). The antifeedant activity of the isolated compounds was assessed by conventional choice leaf disc method on the third-instar larvae of Spodoptera littoralis (Boisd.). Khayalactol, 1- O -acetylkhayanolide A, 2-hydroxyseneganolide, khayanolide A, khayanolide D and methyl angolensate displayed strong antifeedant activity at 1000  μ g/ml with antifeedant percentages of 83.8, 61.9, 60.1, 59.5, 57.1 and 55.7, respectively. 2-Hydroxyseneganolide and khayanolide D showed high activity at 500, 300 and 200  μ g/ml while 1- O -acetylkhayanolide A was the only compound that revealed antifeedant activity at a concentration as low as 100  μ g/ml. Antifeedant activity was dose-dependent in some of the isolated compounds. Correlation between antifeedant activity of the isolated compounds and chemical structure was discussed.     

Insect-antifeedant and antibacterial activity of diterpenoids from species of Plectranthus

Bio-assay guided fractionation of an acetone extract of leaf material from Plectranthus saccatus Benth. resulted in the isolation of a beyerane diterpenoid. This compound, characterised by spectroscopic methods as ent-3beta-(3-methyl-2-butenoyl)oxy-15-beyeren-19-oic acid, showed insect antifeedant activity against Spodoptera littoralis. Known quinonoid abietane diterpenoids obtained from new sources included a mixture of the (4R,19R) and (4R,19S) diastereoisomers of coleon A from P. aff. puberulentus J.K. Morton, coleon A lactone from P. puberulentus J.K. Morton, and coleon U and coleon U quinone from P. forsteri 'Marginatus' Benth. These compounds, and the crude acetone extracts from the leaf surfaces of 11 species of Plectranthus, were tested for antifeedant activity against S. littoralis, antibacterial activity against Bacillus subtilis and Pseudomonas syringae and antifungal activity against Cladosporium herbarum. The coleon A mixture showed potent antifeedant activity against S. littoralis, whereas coleon U showed the greatest antimicrobial activity.     

Neo-clerodane diterpenes from Teucrium fruticans

In addition to three out of the four previously reported neo-clerodanes already found in Teucrium fruticans (fruticolone, isofruticolone and 8 beta-hydroxyfruticolone), and 6-acetylteucjaponin B (isolated from T. scordium and T. grisebachii), four new neo-clerodanes, namely 7 beta-hydroxyfruticolone, 11-hydroxyfruticolone, deacetylfruticolone and 6-acetyl-10-hydroxyteucjaponin B were also isolated. The structures were unambiguously elucidated based on extensive NMR spectral studies (one- and two-dimensional experiments). Semi-prep-HPLC proved to be a convenient purification procedure, occasionally being followed by TLC. The new compounds were assayed against Spodoptera littoralis and two of them were shown to have potent antifeedant activity.     

Semisynthetic derivatives of ent-kauranes and their antifeedant activity

Chemical modification of functional groups on linearol yielded several ent-kaurane derivatives. These compounds were tested for their antifeedant activity against larvae of Spodoptera littoralis. Although linearol did not influence the feeding behaviour of larvae, some of its derivatives showed significant antifeedant activity.     

Phytochemicals and Insect Control: An Antifeedant Approach

Plants based pest control agents have long been touted as alternatives to synthetic chemicals for integrated pest management. Such phytochemicals reputedly pose little threat to the environment or to human health. Bioactivity of plant-based compounds is well documented in literature and is a subject of increasing importance. An antifeedant approach for insect control has been extensively studied, at least at laboratory level, though only a handful of plant-based compounds are currently used in agriculture. The known active plant-based antifeedants belong to groups like chromenes, polyacetylenes, saponins, quassinoids, cucurbitacins, cyclopropanoid acids, phenolics, alkaloids, various types of terpenes and their derivatives etc., and each insect species may process these allomones in a thoroughly idiosyncratic way, so that the same compound may have very different fates and consequences in different species of insects, thus pointing to different mechanisms involved in antifeedant action. It can also be visualized that insect feeding deterrents may be perceived either by stimulation of specialized deterrent receptors or by distortion of the normal function of neurons, which perceive phagostimulating compounds. Some plant antifeedants influence the feeding activity through a combination of these two principal modes of action. Only a few highly active antifeedants have been looked into from a commercial point of view, which makes it impossible to systemize or to predict any molecular motifs in feeding inhibition. Structure activity relationship studies also do not point to any generalization. “Mix and Match” systems may help in developing a cocktail of feeding inhibitors that can be used in developing a customized formulation against a specific category of pests. Application of such products will be broad and will not be limited to targeted pests and to plant parts. Decreased deterrence resulting from habituation has been suggested that could pose different implications for pest management than does decreased deterrence resulting from increased tolerance to toxic substances. Genetically modified plants, which could produce the active antifeedant substances in amounts high enough to protect the plants from further herbivorous damage, could be a possibility in the future.     

Antifeedant activity and toxicity of two alkaloids from Adhatoda vasica Nees leaves against diamondback moth Plutella xylostella (Linn.) (Lepidoptera: Plutellidae) larvae

Two natural alkaloids viz., Vasicine acetate and 2-Acetyl benzylamine, isolated from Adhatoda vasica leaves, showed antifeedant, larvicidal and moult inhibiting properties against diamondback moth Plutella xylostella in laboratory experiments. Maximum antifeedant activity of 98.5% was recorded at 1000 ppm concentration of Vasicine acetate treatment, whereas as 2-Acetyl benzyl amine recorded only 71.4% antifeedant activity at 1000 ppm concentration. Azadirachtin treatment presented 82% antifeedant activity at the highest concentration (1000 ppm). Both the active compounds of A. vasica showed lethal toxicity on larvae and pupae. The highest larvicidal and pupicidal activities were recorded in 2-Acetyl benzylamine treatment at 125 ppm concentration. The two A. vasica compounds also affected the normal growth and development and moulting process of P. xylostella. Final moulting of larvae into pupae was disrupted by the treatments, which resulted in larval–pupal intermediates and abnormal pupae. Treatments also produced small-size pupae and malformed adults with poorly developed wings.     

螺旋粉虱产卵蜡泌物对香蕉网蝽的拒食活性

螺旋粉虱产卵分泌物所圈定的叶片范围可阻碍一些植食性昆虫如香蕉网蝽的取食。本文采用叶碟法测定了螺旋粉虱产卵分泌物中的芳香酯类、酚类和烷烃类物质对香蕉网蝽5龄若虫的拒食活性。结果表明:在10mg·mL-1质量浓度下,邻苯二甲酸二丁酯表现出较强的拒食活性,其次为3,5-二(1,1-二甲基乙基)-4-羟基苯丙酸甲酯、邻苯二甲酸正辛酯和正十六烷,4,4’-亚甲基双(2,6-二叔丁基苯酚)则没有拒食活性;浓度梯度试验显示,邻苯二甲酸二丁酯对香蕉网蝽若虫的拒食活性随浓度增大而增强,拒食中浓度为0.929mg·mL-1;表明螺旋粉虱产卵分泌物中的芳香酯对一些植食性昆虫有很强的拒食活性,同时为植食性昆虫种间竞争关系提供了理论依据。     

湘西黑藤藤中对小菜蛾幼虫有拒食活性化合物的分离与鉴定

为探明湘西黑藤Derric cavalerei 藤中对小菜蛾Plutella幼虫有拒食活性的化合物及其拒食活性,通过活性跟踪、利用柱色谱、借助核磁共振和质谱分离,鉴定了其拒食成分,并使用叶碟法测定各化合物的拒食活性.结果包括:首次从该植物藤中得到4个化合物,即isolonchcarpin,magnificol,oval...     

Bioactivity of two major constituents isolated from the essential oil of Artemisia judaica L

The essential oil of Artemisia judaica L., grown on Sinai Peninsula of Egypt, was extracted via hydrodistillation. Chromatographic separation on repeated silica gel columns led to isolate two compounds namely piperitone and trans-ethyl cinnamate. Insecticidal, antifeedant and antifungal properties of the isolated compounds were examined. Both compounds showed pronounced insecticidal and antifeedant activity against the third instar larvae of Spodoptera littoralis (Boisd). trans-Ethyl cinnamate (LD₅₀ = 0.37 μg/larva) was more toxic than piperitone (LD₅₀ = 0.68 μg/larva). The two isolated compounds revealed antifeedant activity in a concentration dependent manner, with complete feeding inhibition at a concentration of 1000 μg/ml. When tested for antifungal activity against four plant pathogenic fungi, the isolated compounds exhibited a moderate to high activity.     

Bioactive triterpene derivatives from latex of two Euphorbia species

We have investigated the antifeedant and toxic effects of 23 semisynthetic terpenoid derivatives obtained through chemical modifications of the major components of Euphorbia resinifera (alpha-euphol and alpha-euphorbol) and E. officinarum (obtusifoliol and 31-norlanostenol) latex on several insect species (Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi), their selective cytotoxicity on insect Sf9 and mammalian CHO cells and their phytotoxic effects on Lactuca sativa. The conversions focused mainly on positions 3,7,11, and 24 with several oxidizing agents. A total of 18 compounds affected S. littoralis growth (IGR). Our results support the importance of the C-3 substituent, suggest the involvement of the C-7 substituent and indicate that the C-3 hydroxyl is not essential for the IGR effect. Overall, Sf9 cells were more sensitive to the active compounds than CHO cells. All of these compounds had non selective moderate phytotoxic effects on radicle elongation of L. sativa.     

Piperine analogs in a hydrophobic fraction from Piper ribersoides (Piperaceae) and its insect antifeedant activity

Piper ribersoides Wall. (Piperaceae), which is called “Khua Sa khan” in the local language, is mainly grown in Laos. This plant is used as a food in Laos, but no report on its metabolites exists. Crushed stems were immersed in methanol. The ethyl acetate fraction showed potential insect antifeedant activity for Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), and some of the active compounds were piperine analogs. Piperine and its geometrical isomer independently showed potent antifeedant activities, and piperine was presumably the main active compound in the methanol extract. Interestingly, we discovered that the antifeedant activity was reduced when they were mixed (50:50).     

Terpenoid lactones with the p-menthane system as feeding deterrents to the lesser mealworm, Alphitobius diaperinus

The application of antifeedants, often in combination with other methods within integrated pest management (IPM) strategies, has proven to be a good way to control insect pests. Little is known about compounds that have antifeedant activity against the lesser mealworm, Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae). The antifeedant properties of optically pure isomers of pulegone and isopulegol and some enantiomeric pairs of bicyclic terpenoid lactones with the p -menthane system, derived from these isomeric starting compounds, were studied in choice and no-choice tests with the lesser mealworm. The original monoterpenes and γ-spirolactones were weak feeding deterrents to larvae and adults of A. diaperinus . The δ-hydroxy-γ-spirolactones showed significant activity against adults, but substituting the hydroxy group with a ketone group considerably reduced the deterrent activity of the resulting δ-keto-γ-spirolactones. The bicyclic γ-hydroxy-δ-lactones with condensed rings and with the (1 S ,6 R ,8 R )-(+) and (1 R ,6 S ,8 S )-(–) configuration of the chiral centres, and δ-hydroxy-γ-lactone (1 S ,4 S ,6 S )-(+) were very strong antifeedants to both larvae and adults. The hydroxy groups and the configuration of the chiral centres of the molecules were very important features for determining the antifeedant activity of the lactones tested. Generally, the compounds studied were better antifeedants to adults than to larvae.     

Polyoxygenated cyclohexane derivatives and other constituents from Kaempferia rotunda L

Methanol extracts of Kaempferia rotunda L. rhizomes yielded seven compounds including six polyoxygenated cyclohexane derivatives identified as (-)-6-acetylzeylenol (1), four acylated derivatives of 1-benzoyloxymethyl-1,6-epoxycyclohexan-2,3,4,5-tetrol (3-6), a Diels-Alder adduct of 3-benzoyl-1-benzoyloxymethylcyclohexa-4,6-dien-2,3-diol (7), and a triacylated derivative of salicin (9). The cyclohexane diepoxide, crotepoxide (8), was also obtained. Spectroscopic methods were used for structure determination. The methanol extract of the rhizomes of K. rotunda and (-)-2-acetyl-4-benzoyl-1-benzoyloxymethyl-1,6-epoxycyclohexan-2,3,4,5-tetrol (2-acetylrotepoxide B; 6), had antifeedant activity against larvae of Spodoptera littoralis. (-)-Zeylenol (2) also showed antifeedant activity, whereas (-)-6-acetylzeylenol (1) was inactive.     

多种植物提取物对桃蚜和萝卜蚜的拒食活性研究

采用改进的蜜露色斑法 ,测试 34种植物乙醇提取物 (0 0 1g干重·mL-1,0 0 1gDW·mL-1)和几种天然源药剂对桃蚜Myzuspersicae(Sulzer)和萝卜蚜Lipaphiserysimi(Kaltenbach)取食的影响。结果表明 ,白蝴蝶Syngonium podophyllumSchott.、苍耳XanthiumsibiricumPrtr.etWidd、白花非洲山毛豆Tephrosiavo gelliHook .的提取物对两种蚜虫的活性均较高 ,2 4h对桃蚜的拒食率分别达 0 6 82、0 6 2 9和 0 80 6 ,对萝卜蚜的拒食率分别为 0 4 0 5、0 370和 0 383,与对照之间差异极显著 ;油茶Camelliaoleifera和花椒Zanthoxylumschinifolium的提取物拒食作用亦较强 ,2 4h对桃蚜的拒食率分别为 0 5 5 2和 0 5 14 ,对萝卜蚜的拒食率分别为 0 5 70和 0 5 18。三种药剂 (0 3%印楝素乳油、鱼藤酮精、机油乳剂 )在所测试的浓度对两种蚜虫的拒食率均达 0 719以上 ,拒食效果显著。     

萜类化合物对小菜蛾幼虫的拒食活性

采用叶碟浸液法测试从松节油合成的26个不同结构萜类化合物样品对小菜蛾Plutella xylostella(L.)4龄幼虫的拒食活性。结果显示,编号为2,4,8,13,27,31的6个化合物,即诺卜醇、诺卜丙基醚、内型异莰烷基甲醇丙酸酯、4-(1-甲基乙烯基)-1-环己烯-1-乙醇丙酸酯、羟基香茅醛丙酸酯、羟基香茅醛1,2-丙二醇缩醛具有较高的拒食活性。处理有效成分为0.01g/mL时,这6个化合物24h拒食率为70%～100%。其中2,4,8号3个化合物拒食活性最高,处理有效成分为0.01g/mL和0.001g/mL时,24h拒食率分别为98.33%,99.80%,100.00%和85.60%,83.90%,66.97%;并且持效性较好,72h拒食率分别为92.67%,89.97%,98.73%和63.20%,63.30%,45.93%。     

Chemistry and pharmacology of Rhaponticum carthamoides: A review

Rhaponticum carthamoides (Willd.) Iljin is a perennial herb, commonly known as a maral root or Russian leuzea, which has been used for centuries in eastern parts of Russia for its marked medicinal properties. This review based on 117 literary sources, with many of them being originally published in non-English languages (mainly in Russian), discusses the current knowledge of traditional uses, chemistry, biological effects and toxicity of this species. Several different classes of compounds were previously isolated from various parts of R. carthamoides of which the main groups are steroids, particularly ecdysteroids, and phenolics (flavonoids and phenolic acids) accompanied with polyacetylenes, sesquiterpene lactones, triterpenoid glycosides and terpenes (essential oil). A comprehensive account of the chemical constituents is given in this review (figures of 120 structures are shown). Various types of preparations, extracts and individual compounds derived from this species have been found to possess a broad spectrum of pharmacological effects on several organs such as the brain, blood, cardiovascular and nervous systems as well as on different biochemical processes and physiological functions including proteosynthesis, work capacity, reproduction, and sexual function. Moreover, the extracts and preparations from the plant, which are hopefully safe, exhibited various additional biological effects e.g. antioxidant, immunomodulatory, anticancerogenic, antimicrobial, antiparasitic and insect antifeedant or repellent activities. The results of data analysis on the chemical, pharmacological and toxicological characteristics of R. carthamoides support the view that this species has beneficial therapeutic properties and indicate its potential as an effective adaptogenic herbal remedy. Finally, some suggestions for further research on chemical and pharmacological properties are given in this review.     

Constituents of glandular trichomes of Tithonia diversifolia: relationships to herbivory and antifeedant activity

The herbivory activity of the bordered patch larvae (Chlosyne lacinia, Lepidoptera) on leaves of a Brazilian population of Tithonia diversifolia and the antifeedant potential of its leaf rinse extract were investigated. The caterpillars fed only on the adaxial face, where the density of glandular trichomes is very low, and avoided the abaxial face, which contains high levels of trichomes. Deterrent activity against the larvae was observed in leaf discs treated with leaf rinse extract at concentrations of 1-5% of fresh leaf weight. High-performance liquid chromatography (HPLC) analysis indicated that sesquiterpene lactones are the main constituents of the glandular trichomes. Dichloromethane rinse extracts of the leaves and inflorescences were chemically investigated, and 16 compounds were isolated and identified: 14 sesquiterpene lactones, a flavonoid and a diterpenoid. In this study, five sesquiterpene lactones are described for the first time in the genus, including two lactones, one of which has an unusual seco-guaianolide skeleton. Our findings indicate that the caterpillars avoid the sesquiterpene-lactone-rich glandular trichomes, and provide evidence for the antifeedant activity of the dichloromethane leaf rinse extract. In addition, a study of the seasonal variation of the main constituents from the leaf surface throughout a year demonstrated that a very low qualitative but a very high quantitative variation occurs. The highest level of the main metabolite tagitinin C was observed between September and October and the lowest was from March to June, the later corresponding to the period of highest infestation by the larvae.     

Cordyceps: a traditional Chinese medicine and another fungal therapeutic biofactory?

Traditional Chinese medicines (TCM) are growing in popularity. However, are they effective? Cordyceps is not studied as systematically for bioactivity as another TCM, Ganoderma. Cordyceps is fascinating per se, especially because of the pathogenic lifestyle on Lepidopteron insects. The combination of the fungus and dead insect has been used as a TCM for centuries. However, the natural fungus has been harvested to the extent that it is an endangered species. The effectiveness has been attributed to the Chinese philosophical concept of Yin and Yang and can this be compatible with scientific philosophy? A vast literature exists, some of which is scientific, although others are popular myth, and even hype. Cordyceps sinensis is the most explored species followed by Cordyceps militaris. However, taxonomic concepts were confused until a recent revision, with undefined material being used that cannot be verified. Holomorphism is relevant and contamination might account for some of the activity. The role of the insect has been ignored. Some of the analytical methodologies are poor. Data on the "old" compound cordycepin are still being published: ergosterol and related compounds are reported despite being universal to fungi. There is too much work on crude extracts rather than pure compounds with water and methanol solvents being over-represented in this respect (although methanol is an effective solvent). Excessive speculation exists as to the curative properties. However, there are some excellent pharmacological data and relating to apoptosis. For example, some preparations are active against cancers or diabetes which should be fully investigated. Polysaccharides and secondary metabolites are of particular interest. The use of genuine anamorphic forms in bioreactors is encouraged.