Use of costic acid, a natural extract from Dittrichia viscosa, for the control of Varroa destructor, a parasite of the European honey bee

Methanolic Extracts of D. viscosa Specifically Affect the Cytoskeleton and Exert an Antiproliferative Effect on Human Colorectal Cancer Cell Lines, According to Their Proliferation Rate

Numerous studies have reported the pharmacological effects exhibited by Dittrichia viscosa, (D. viscosa) including antioxidant, cytotoxic, antiproliferative, and anticancer properties. In our research, our primary objective was to validate a prescreening methodology aimed at identifying the fraction that demonstrates the most potent antiproliferative and anticancer effects. Specifically, we investigated the impact of various extract fractions on the cytoskeleton using a screening method involving transgenic plants. Tumors are inherently heterogeneous, and the components of the cytoskeleton, particularly tubulin, are considered a strategic target for antitumor agents. To take heterogeneity into account, we used different lines of colorectal cancer, specifically one of the most common cancers regardless of gender. In patients with metastasis, the effectiveness of chemotherapy has been limited by severe side effects and by the development of resistance. Additional therapies and antiproliferative molecules are therefore needed. In our study, we used colon-like cell lines characterized by the expression of gastrointestinal differentiation markers (such as the HT-29 cell line) and undifferentiated cell lines showing the positive regulation of epithelial-mesenchymal transition and TGFβ signatures (such as the DLD-1, SW480, and SW620 cell lines). We showed that all three of the D. viscosa extract fractions have an antiproliferative effect but the pre-screening on transgenic plants anticipated that the methanolic fraction may be the most promising, targeting the cytoskeleton specifically and possibly resulting in fewer side effects. Here, we show that the preliminary use of screening in transgenic plants expressing subcellular markers can significantly reduce costs and focus the advanced characterization only on the most promising therapeutic molecules.

Syntheses of (+)-costic acid and structurally related eudesmane sesquiterpenoids and their biological evaluations as acaricidal agents against Varroa destructor

Synthesis of (+)-costic acid, isolated from Dittrichia viscosa (L.) W. Greuter as a natural acaricidal sesquiterpenoid, was achieved in 16 steps from (R)-carvone with an overall yield of 4.8%, involving the radical cyclization of selenoester to construct a decalone framework as the key step. Other structurally related natural products, (+)-costal, (+)-costol, and (+)-β-selinene, were also synthesized. The acaricidal activities of these four natural products and some synthetic intermediates were also evaluated against Varroa destructor. Among them, (+)-costal especially exhibited potent acaricidal activity.

In Vitro Anti-inflammatory Activity of Three Inula Species Essential Oils in Lipopolysaccharide-Stimulated RAW 264.7 Macrophages

In the face of the undesirable effects induced by anti-inflammatory drugs, there has been a return, nowadays, to the search for active ingredients based on plants. Herein, for the first time we study the anti-inflammatory activity of essential oils of three species of the genus Inula: Inula viscosa, Inula graveolens and Inula crithmoides in lipopolysaccharide (LPS)-activated macrophages. Essential oils have shown excellent preventive anti-inflammatory potential by causing inhibition of nitric oxide (NO) production in LPSactivated RAW264.7 macrophages with IC50s ranging between 15 and 35 µg  mL^− 1. On the other hand, the major acidic compounds, more precisely α- and β-costic acids, have been isolated from Inula viscosa and Inula graveolens essential oils and evaluated for their anti-inflammatory effect. These compounds appear to have a moderate preventive inhibitory effect on NO production relative to the significant effect generated by the neutral minority components present in the oils such as borneol, bornyl acetate, (E)-nerolidol, caryophyllene oxide, T-cadinol and eugenol. Therefore, we can deduce that the studied essential oils could be used as anti-inflammatory agents for the treatment of various inflammatory pathologies.

Varroa destructor from the Laboratory to the Field: Control, Biocontrol and IPM Perspectives-A Review

Varroa destructor is a real challenger for beekeepers and scientists: fragile out of the hive, tenacious inside a bee colony. From all the research done on the topic, we have learned that a better understanding of this organism in its relationship with the bee but also for itself is necessary. Its biology relies mostly on semiochemicals for reproduction, nutrition, or orientation. Many treatments have been developed over the years based on hard or soft acaricides or even on biocontrol techniques. To date, no real sustainable solution exists to reduce the pressure of the mite without creating resistances or harming honeybees. Consequently, the development of alternative disruptive tools against the parasitic life cycle remains open. It requires the combination of both laboratory and field results through a holistic approach based on health biomarkers. Here, we advocate for a more integrative vision of V. destructor research, where in vitro and field studies are more systematically compared and compiled. Therefore, after a brief state-of-the-art about the mite's life cycle, we discuss what has been done and what can be done from the laboratory to the field against V. destructor through an integrative approach.

Enantioselective synthesis of a costic acid analogue with acaricidal activity against the bee parasite Varroa destructor

One major disease of the pupae and the adult bee is the so-called Varroosis that is owing to the bee parasite Varroa destructor. It is an ectoparasite of bees, causing significant losses in the bee population needed for honey production as well as for pollination in agriculture. Costic acid is a sesquiterpene-carboxylic acid present in the plant Dittrichia viscosa. Recent studies by our group have shown that costic acid acts as acaricide against V. destructor. Oxalic acid is also an acaricide commonly used against varroa mites. In spite of its structural simplicity-it is the simplest bicarboxlic acid-it is equipotent to costic acid which consists of a trans-decalin system with three chiral centres. The basic goal of this project was to design and synthesize a hybrid entity, incorporating aspects of both oxalic acid and costic acid that would be more active than the parent compounds. This approach introduces a useful strategy for the preparation of congeners of bioactive compounds and proposes a structural framework for a new series of acaricidal agents.

Potential Applications of Guayulins to Improve Feasibility of Guayule Cultivation

Guayule (Parthenium argentatum Gray) is an interesting alternative and renewable source of rubber/latex which has been used in the past. Guayule rubber and latex products are not available in the market largely because the raw material cost is higher than the current sources produced in South-East Asia and other tropical countries (Hevea brasiliensis). Guayule contains many other compounds whose joint exploitation could make guayule cultivation profitable, especially in semi-desert areas where cultivation of other crops is difficult or impossible. Guayulins A–D, sesquiterpene esters, appear to have some commercial promise. Despite being accumulated in relatively high concentrations (its majority representative, guayulin A, can account for up to 13.7% of the resin content of this plant, which itself ranges from 6%–12%), guayulins have received little direct attention from scientists. This review presents the current knowledge about the activity of these compounds and, based on known activities of similar compounds from other species, potential uses as fungicides, miticides and insecticides are suggested.

α-Costic acid, a plant sesquiterpene with acaricidal activity against Varroa destructor parasitizing the honey bee

The organic extract of the aerial parts of Dittrichia viscosa, a perennial native plant of the Mediterranean basin, showed a significant acaricidal activity against Varroa destructor, the parasite mite of Apis mellifera, commonly called honey bee. Among the metabolites isolated from the organic extract of this Asteraceae, α-costic acid showed to be one of the compounds responsible for the toxic activity exhibited by the crude plant extract on this parasite mite species. In addition to the toxic effect a clear acaricidal response has been recorded when the parasitic mite was exposed to 1 mg/mL concentration of α-costic acid while no effects have been showed on honey bees using the same compound at the same concentration. This finding suggests a potential use of α-costic acid to control Varroa mites. The possibility to reliably achieve absolute configuration of α-costic acid by DFT computational analysis of chiroptical spectra has been also demonstrated.^†.

Biological activity of Dittrichia viscosa (L.) Greuter extracts against adult Sitophilus granarius (L.) (Coleoptera, Curculionidae) and identification of active compounds

Dittrichia viscosa (L.) Greuter, a perennial weed of the Mediterranean area, was reported to be source of active substances. Here, by means of both ingestion and contact assays, the biological activity of three different extracts (n-hexane, methanol, and distilled water) of D. viscosa aerial part has been evaluated against Sitophilus granarius (L.) adults, an important pest of stored grains. Ingestion assays showed negligible mortality and food deterrence for all the extracts, whereas only a slight reduction of some nutritional parameters (relative growth rate, relative consumption rate, food efficiency conversion) was recorded for water extract. High contact toxicity was found only for the n-hexane extract (24 h median lethal dose LD50 = 53.20 μg/adult). This extract was further subfractioned by silica gel column chromatography and then by thin layer chromatography. Further contact toxicity bioassays highlighted two active subfractions which were analyzed by GC-MS. This revealed the occurrence, in both subfractions, of two major peaks that were identified as α- and γ- costic acid isomers. Moreover, D. viscosa active subfractions, did not cause acetylcholinesterase (AChE) inhibition; therefore, in the light of progressive limitation of compounds acting by this mechanism of action, D. viscosa represents a promising eco-sustainable source of natural products for pest control.

Chemical characterization and acaricidal activity of Drimia maritima (L) bulbs and Dittrichia viscosa leaves against Dermanyssus gallinae

The emergence of resistance to chemical acaricides in Dermanyssus gallinae, together with their toxicity and high costs, has prompted investigations into the use of plant extracts as alternatives to chemical acaricidal treatments. Drimia maritima bulbs and Dittrichia viscosa (D. viscosa) leaf extracts were here characterized by HPLC-PDA-ESI-MS/MS, and their toxicity against D. gallinae was evaluated using contact methods. Twenty-nine compounds were identified in D. maritima extracts, with glucoscilliphaeoside derivatives (i.e., quercetin, kaempferol and bufadienolides) as the major components. Twenty-four phenolic compounds, mainly caffeic acid derivatives, were detected in D. viscosa extracts. D. maritima extracts displayed a significantly higher (p < 0.05) acaricidal activity than D. viscosa extracts, with 100% of D. gallinae mortality at a concentration of 100 mg/mL following 24 h exposure. The mortality rate of D. gallinae induced by D. viscosa extracts ranged from 25 to 45% following 48 h exposure at a concentration of 200 mg/mL. The acetonic extract of D. viscosa and D. maritima displayed the highest efficacy against D. gallinae. This study provides evidence of the diversity of bioactive compounds present in D. maritima bulbs and D. viscosa leaf extracts, which are both efficacious against D. gallinae. The higher efficacy of D. maritima bulb extracts might be linked to the presence of bufadienolides in its extracts.

A nutraceutical extract from Inula viscosa leaves: UHPLC-HR-MS/MS based polyphenol profile, and antioxidant and cytotoxic activities

Nowadays, advanced extraction techniques and highly sensitive metabolic profiling methods are effectively employed to get new information on plant chemical constituents. Among them wild medicinal plants or their parts, with large and ancient use in folk medicine, are investigated for their potential functional use and cultivation. In this context, Inula viscosa leaves engaged our attention. A simple experimental design, based on Soxhlet extraction and chromatographic fractionation, allowed us to obtain the investigated polyphenol fraction (IvE). UHPLC-HRMS analyses revealed shikimoyl depsides of caffeic acid and unusual dihydrobenzofuran lignans as main secondary metabolites. These compounds, together with cinchonain-type phenols, and hydroxycinnamoyl flavonol glycosides, are reported for the first time in inula. Overall, forty-three secondary metabolites were identified. The extract exerted a remarkable antiradical activity towards DPPH^• and ABTS^+•. Furthermore, it was able to inhibit cell viability and mitochondrial redox activity of neuroblastoma, hepatoblastoma and colon carcinoma cells, whereas it did not affect cell density of HaCaT cells immortalized human keratinocytes. As detected by the oxidant-sensing probe 2′,7′-dichlorodihydrofluorescein diacetate, the inhibitory responses seemed to be related to IvE-induced increase of intracellular reactive oxygen species (ROS). The obtained results highlighted that inula leaves, nowadays even undervalued and unexplored, could be considered a renewable source of nutraceutical compounds.