Cardenolides in the defensive fluid of adult large milkweed bugs have differential potency on vertebrate and invertebrate predator Na/K-ATPases.

Aposematic animals rely on diverse secondary metabolites for defence. Various hypotheses, such as competition, life history and multifunctionality, have been posited to explain defence variability and diversity. We investigate the compound selectivity hypothesis using large milkweed bugs, , to determine if distinct cardenolides vary in toxicity to different predators.

Regiodivergent biosynthesis of bridged bicyclononanes.

Medicinal compounds from plants include bicyclo[3.3.1]nonane derivatives, the majority of which are polycyclic polyprenylated acylphloroglucinols (PPAPs).

A Mechanism to Transform Complex Salicinoids with Caffeoylquinic Acids in Lepidopteran Specialist Herbivores (Notodontidae).

Larvae of the Salicaceae-adapted Notodontidae have developed a unique mechanism to metabolize the chemical defenses of their Salicaceae host plants. Salicinoids and salicortinoids are enzymatically transformed into salicyloyl, benzoyl and mixed salicyloyl-benzoyl quinates. The source of quinates and benzoates was previously unknown.

Diarylheptanoid Derivatives (Musellins A-F) and Dimeric Phenylphenalenones from Seed Coats of , the Chinese Dwarf Banana.

Phenylphenalenones (PPs) are phytoalexins protecting banana plants (Musaceae) against various pathogens. However, how plants synthesize PPs is still poorly understood. In this work, we investigated the major secondary metabolites of developing seed coats of to determine if this species might be a good model system to study the biosynthesis of PPs.

Reductive Conversion Leads to Detoxification of Salicortin-like Chemical Defenses (Salicortinoids) in Lepidopteran Specialist Herbivores (Notodontidae).

Lepidopteran specialist herbivores of the Notodontidae family have adapted to thrive on poplar and willow species (Salicaceae). Previous research showed that Cerura vinula, a member of the Notodontidae family occurring throughout Europe and Asia, uses a unique mechanism to transform salicortinoids, the host plant's defense compounds, into quinic acid-salicylate conjugates. However, how the production of this conjugates relates to the detoxification of salicortinoids and how this transformation proceeds mechanistically have remained unknown.

New Structures, Spectrometric Quantification, and Inhibitory Properties of Cardenolides from Seeds.

Cardiac glycosides are a large class of secondary metabolites found in plants. In the genus , cardenolides in milkweed plants have an established role in plant-herbivore and predator-prey interactions, based on their ability to inhibit the membrane-bound Na/K-ATPase enzyme. Milkweed seeds are eaten by specialist lygaeid bugs, which are the most cardenolide-tolerant insects known.

Precursor-Directed Synthesis of Apoptosis-Initiating N-Hydroxyalkyl Phenylbenzoisoquinolindione Alkaloids.

A precursor-directed approach to access N-hydroxyalkyl phenylbenzoisoquinolindiones (PBIQs) has been developed. Incubation of plant material of Xiphidium caeruleum with hydroxylamines of various chain lengths (C , C , C , C , C and C ) resulted in 11 new 5-hydroxy- and 5-methoxy PBIQs with different N-hydroxyalkyl side chain lengths. The antiproliferative effect and the cytotoxicity against HUVEC, K-562, and HeLa cell lines of 26 previously reported PBIQs and the 11 newly synthesized N-hydroxyalkyl PBIQs was determined for the first time.

Recycling Upstream Redox Enzymes Expands the Regioselectivity of Cycloaddition in Pseudo-Aspidosperma Alkaloid Biosynthesis.

Nature uses cycloaddition reactions to generate complex natural product scaffolds. Dehydrosecodine is a highly reactive biosynthetic intermediate that undergoes cycloaddition to generate several alkaloid scaffolds that are the precursors to pharmacologically important compounds such as vinblastine and ibogaine. Here we report how dehydrosecodine can be subjected to redox chemistry, which in turn allows cycloaddition reactions with alternative regioselectivity.

The downside of metabolic diversity: Postingestive rearrangements by specialized insects.

Deploying toxins in complex mixtures is thought to be advantageous and is observed during antagonistic interactions in nature. Toxin mixtures are widely utilized in medicine and pest control, as they are thought to slow the evolution of detoxification counterresponses in the targeted organisms. Here we show that caterpillars rearrange key constituents of two distinct plant defense pathways to postingestively disable the defensive properties of both pathways.

Natural history-guided omics reveals plant defensive chemistry against leafhopper pests.

Although much is known about plant traits that function in nonhost resistance against pathogens, little is known about nonhost resistance against herbivores, despite its agricultural importance. leafhoppers, serious agricultural pests, identify host plants by eavesdropping on unknown outputs of jasmonate (JA)-mediated signaling. Forward- and reverse-genetics lines of a native tobacco plant were screened in native habitats with native herbivores using high-throughput genomic, transcriptomic, and metabolomic tools to reveal an -elicited JA-JAZi module.

Chromane Derivatives from Underground Parts of and Their In Vitro Antimicrobial, Cytotoxicity and Antiproliferative Evaluation.

Phytochemical investigation of the ethanol extract of underground parts of Pall. afforded five new compounds; an unusual macrolide termed moniristenulide (), 5-methoxy-6,7-methylenedioxy-4--2'-cycloflavan (), 5,7,2',3'-tetrahydroxyflavanone (), 5-hydroxy-6,7-dimethoxyisoflavone-2'---d-glucopyranoside (), 5,2',3'-dihydroxy-6,7-dimethoxyisoflavone (), along with seven known compounds (-, -). The structures of all purified compounds were established by analysis of 1D and 2D NMR spectroscopy and HR-ESI-MS.

In Vitro Liver Metabolism of Six Flavonoid C-Glycosides.

Several medical plants belonging to the genera , , and accumulate flavonoid C-glycosides, which likely contribute to their efficacy. Information regarding their phase I and II metabolism in the liver are lacking. Thus, in vitro liver metabolism of orientin, isoorientin, schaftoside, isoschaftoside, vitexin, and isovitexin, all of which accumulated in L.

Biosynthesis and antifungal activity of fungus-induced O-methylated flavonoids in maize.

Fungal infection of grasses, including rice (Oryza sativa), sorghum (Sorghum bicolor), and barley (Hordeum vulgare), induces the formation and accumulation of flavonoid phytoalexins. In maize (Zea mays), however, investigators have emphasized benzoxazinoid and terpenoid phytoalexins, and comparatively little is known about flavonoid induction in response to pathogens. Here, we examined fungus-elicited flavonoid metabolism in maize and identified key biosynthetic enzymes involved in the formation of O-methylflavonoids.

A beta-glucosidase of an insect herbivore determines both toxicity and deterrence of a dandelion defense metabolite.

Gut enzymes can metabolize plant defense compounds and thereby affect the growth and fitness of insect herbivores. Whether these enzymes also influence feeding preference is largely unknown. We studied the metabolization of taraxinic acid β-D-glucopyranosyl ester (TA-G), a sesquiterpene lactone of the common dandelion () that deters its major root herbivore, the common cockchafer larva ().

New Guaianolide Sesquiterpene Lactones and Other Constituents from Pyrethrum pulchrum.

is a rare Mongolian plant species that has been traditionally used as an ingredient in various remedies. Bioactivity-guided fractionation performed on the methanol extract of its aerial parts led to the isolation of 2 previously undescribed guaianolide-type sesquiterpene lactones, namely 1,10-epoxy-8-hydroxyguaia-3,11(13)-dien-6,12-olide (1: ) and 1,8,10-trihydroxyguaia-3,11(13)-dien-6,12-olide (2: ), along with the isolation or chromatographic identification of 11 compounds, arglabin (3: ), 3-hydroxycostunolide (4: ), isocostic acid (5: ), ()-9-(2-thienyl)-6-nonen-8-yn-3-ol (6: ), ()-9-(2-thienyl)-6-nonen-8-yn-3-ol (7: ), , , , -tetra-p-coumaroyl spermine (8: ), chlorogenic acid (9: ), 3,5-di--caffeoylquinic acid (10: ), 3,5-di--caffeoylquinic acid methyl ester (11: ), 3,4-di--caffeoylquinic acid (12: ), and tryptophan (13: ). Their structures were assigned based on spectroscopic and spectrometric data.

Activation and detoxification of cassava cyanogenic glucosides by the whitefly Bemisia tabaci.

Two-component plant defenses such as cyanogenic glucosides are produced by many plant species, but phloem-feeding herbivores have long been thought not to activate these defenses due to their mode of feeding, which causes only minimal tissue damage. Here, however, we report that cyanogenic glycoside defenses from cassava (Manihot esculenta), a major staple crop in Africa, are activated during feeding by a pest insect, the whitefly Bemisia tabaci, and the resulting hydrogen cyanide is detoxified by conversion to beta-cyanoalanine. Additionally, B.

An Integrated-Omics/Chemistry Approach Unravels Enzymatic and Spontaneous Steps to Form Flavoalkaloidal Nudicaulin Pigments in Flowers of L.

Flower colour is an important trait for plants to attract pollinators and ensure their reproductive success. Among yellow flower pigments, the nudicaulins in L. (Iceland poppy) are unique due to their rarity and unparalleled flavoalkaloid structure.

Early and Late Steps of Quinine Biosynthesis.

The enzymatic basis for quinine biosynthesis was investigated. Transcriptomic data from the producing plant led to the discovery of three enzymes involved in the early and late steps of the pathway. A medium-chain alcohol dehydrogenase (CpDCS) and an esterase (CpDCE) yielded the biosynthetic intermediate dihydrocorynantheal from strictosidine aglycone .

Plumbagin, a Potent Naphthoquinone from Plants with Growth Inhibiting and Larvicidal Activities.

Some plant species are less susceptible to herbivore infestation than others. The reason for this is often unknown in detail but is very likely due to an efficient composition of secondary plant metabolites. Strikingly, carnivorous plants of the genus show extremely less herbivory both in the field and in green house.

Controlled hydroxylations of diterpenoids allow for plant chemical defense without autotoxicity.

Many plant specialized metabolites function in herbivore defense, and abrogating particular steps in their biosynthetic pathways frequently causes autotoxicity. However, the molecular mechanisms underlying their defense and autotoxicity remain unclear. Here, we show that silencing two cytochrome P450s involved in diterpene biosynthesis in the wild tobacco causes severe autotoxicity symptoms that result from the inhibition of sphingolipid biosynthesis by noncontrolled hydroxylated diterpene derivatives.

11-Keto-α-Boswellic Acid, a Novel Triterpenoid from spp. with Chemotaxonomic Potential and Antitumor Activity against Triple-Negative Breast Cancer Cells.

Boswellic acids, and particularly 11-keto-boswellic acids, triterpenoids derived from the genus (), are known for their anti-inflammatory and potential antitumor efficacy. Although boswellic acids generally occur as α-isomers (oleanane type) and β-isomers (ursane type), 11-keto-boswellic acid (KBA) was found only as the β-isomer, β-KBA. Here, the existence and natural occurrence of the respective α-isomer, 11-keto-α-boswellic acid (α-KBA), is demonstrated for the first time.