Phytotoxic and Nematicidal Components of Lavandula luisieri

Natural Occurring Terpene Cyclic Anhydrides: Biosynthetic Origin and Biological Activities

Cyclic acid anhydride is a not very widespread structure in nature, but with a determining role in natural products possessing this functionality in their skeleton. To the best of our knowledge, no revision of terpenes containing cyclic anhydrides has been previously reported. The result was that more than 100 terpenic cyclic anhydrides and related compounds were found to be in need of being reported. This review has been systematically organized by terpene skeletons, from the smallest to largest, describing their sources and bioactivities. In addition, different biosynthetic pathways for their final oxidations, namely, routes A, B and C, leading to the formation of these heterocyclic natural products, have been proposed. We have also included the most plausible precursors of these natural products, which mostly happened to be present in the same natural source. Some molecules derived from terpene cyclic anhydrides, such as their natural imide derivatives, have also been described due to their significant biological activity. In this sense, special attention has been paid to cantharidin because of its historical relevance and its broad bioactivity. A plausible biosynthesis of cantharidin has been proposed for the first time. Finally, cyclic anhydride structures that were firstly assigned as anhydrides and later corrected have been also described.

Composition Characterization of Cinnamomum osmophloeum Kanehira Hydrosol and Its Enhanced Effects on Erectile Function

Cinnamomum osmophloeum Kanehira (CO) is an endemic species of Taiwan. This study elucidated the composition of CO hydrosol, revealing trans-cinnamaldehyde (65.03%), trans-cinnamyl acetate (7.57%), and coumarin (4.31%) as the main volatile compounds. Seven compounds were identified in the water fraction of hydrosol, including a novel compound, 2-(2-hydroxyphenyl)oxetan-3-ol. This marks the first investigation into high-polarity compounds in hydrosol, extending beyond the volatile components. Notably, two compounds, trans-phenyloxetan-3-ol and cis-phenyloxetan-3-ol, demonstrated significant inhibition activity against phosphodiesterase type five (PDE5), with IC50 values of 4.37 µM and 3.40 µM, respectively, indicating their potential as novel PDE5 inhibitors. Furthermore, CO hydrosol was evaluated against enzymes associated with erectile dysfunction, namely acetylcholinesterase (AChE), angiotensin-I converting enzyme (ACE), and arginase type 2 (ARG2). These findings underscore the potential of CO hydrosol to modulate erectile function through diverse physiological pathways, hinting at its prospects for future development in a beverage or additive with enhanced effects on erectile function.

Lavandula stoechas L. subsp. stoechas, a New Herbal Source for Ursolic Acid: Quantitative Analysis, Purification and Bioactivity Studies

In this study, methanol, ethanol, methanol-dichloromethane (1 : 1, v/v), acetone, ethyl acetate, diethyl ether, and chloroform extracts of lavender (Lavandula stoechas L. subsp. stoechas) were prepared by maceration, and the ursolic acid contents in the extracts were determined quantitatively by HPLC analyses. The present results show that the methanol-dichloromethane (1 : 1, v/v) solvent system is the most efficient solvent system for the extraction of ursolic acid from the plant sample with the highest yield (2.22 g/100 g plant sample). In the present study, a new practical method for the isolation of ursolic acid from polar extracts was also demonstrated for the first time. The inhibition effects of the extracts and ursolic acid were also revealed on α-glycosidase, acetylcholinesterase, butyrylcholinesterase, and human carbonic anhydrase I and II enzymes by determining IC50 values for the first time. The extracts and ursolic acid acted as potent antidiabetic agents by strongly inhibiting the α-glycosidase activity, whereas they were found to be very weak neuroprotective agents. In view of the present results, L. stoechas and its major metabolite, ursolic acid, can be recommended as a herbal source to control postprandial blood sugar levels and prevent diabetes by delaying the digestion of starch in food.

Natural nematicidal metabolites and advances in their biocontrol capacity on plant parasitic nematodes

Covering: 2010 to 2021Natural nematicidal metabolites are important sources of nematode control. This review covers the isolation and structural determination of nematicidal metabolites from 2010 to 2021. We summarise chemical structures, bioactivity, metabolic regulation and biosynthesis of potential nematocides, and structure-activity relationship and application potentiality of natural metabolites in plant parasitic nematodes' biocontrol. In doing so, we aim to provide a comprehensive overview of the potential roles that natural metabolites can play in anti-nematode strategies.

Mediterranean Lavenders from Section Stoechas: An Undervalued Source of Secondary Metabolites with Pharmacological Potential

Globally, climate change and wildfires are disrupting natural ecosystems, thus setting several endemic species at risk. The genus Lavandula is widely present in the Mediterranean region and its species, namely, those included in the section Stoechas, are valuable resources of active compounds with several biological assets. Since ancient times lavenders have been used in traditional medicine and for domestic purposes. These species are melliferous, decorative, and essential oil-producing plants with a high economic interest in the pharmaceutical, flavor, fragrance, and food industries. The essential oils of Lavandula section Stoechas are characterized by high amounts of 1,8-cineole, camphor, fenchone, and specifically for L. stoechas subsp. luisieri one of the major compounds is trans-α-necrodyl acetate. On the other hand, the diversity of non-volatile components like phenolic compounds, such as phenolic acids and flavonoids, make these species an important source of phytochemicals with pharmacological interest. Rosmarinic, caffeic, and salvianolic B acids are the major phenolic acids, and luteolin and eriodictyol-O-glucuronide are the main reported flavonoids. However, the concentration of these secondary metabolites is strongly affected by the plant’s phenological phase and varies in Lavandula sp. from different areas of origin. Indeed, lavender extracts have shown promising antioxidant, antimicrobial, anti-inflammatory, and anticancer properties as well as several other beneficial actions with potential for commercial applications. Despite several studies on the bioactive potential of lavenders from the section Stoechas, a systematized and updated review of their chemical profile is lacking. Therefore, we carried out the present review that gathers relevant information on the different types of secondary metabolites found in these species as well as their bioactive potential.

Anti-Trypanosomatidae Activity of Essential Oils and Their Main Components from Selected Medicinal Plants

Kinetoplastida is a group of flagellated protozoa characterized by the presence of a kinetoplast, a structure which is part of a large mitochondria and contains DNA. Parasites of this group include genera such as Leishmania, that cause disease in humans and animals, and Phytomonas, that are capable of infecting plants. Due to the lack of treatments, the low efficacy, or the high toxicity of the employed therapeutic agents there is a need to seek potential alternative treatments. In the present work, the antiparasitic activity on Leishmania infantum and Phytomonas davidi of 23 essential oils (EOs) from plants of the Lamiaceae and Asteraceae families, extracted by hydrodistillation (HD) at laboratory scale and steam distillation (SD) in a pilot plant, were evaluated. The chemical compositions of the EOs were determined by gas chromatography-mass spectrometry. Additionally, the cytotoxic activity on mammalian cells of the major components from the most active EOs was evaluated, and their anti-Phytomonas and anti-Leishmania effects analyzed. L. infantum was more sensitive to the EOs than P. davidi. The EOs with the best anti-kinetoplastid activity were S. montana, T. vulgaris, M. suaveolens, and L. luisieri. Steam distillation increased the linalyl acetate, β-caryophyllene, and trans-α-necrodyl acetate contents of the EOs, and decreased the amount of borneol and 1,8 cineol. The major active components of the EOs were tested, with thymol being the strongest anti-Phytomonas compound followed by carvacrol. Our study identified potential treatments against kinetoplastids.

Direct and Indirect Effects of Essential Oils for Sustainable Crop Protection

Plant essential oils (EOs) are gaining interest as biopesticides for crop protection. EOs have been recognized as important ingredients of plant protection products including insecticidal, acaricidal, fungicidal, and nematicidal agents. Considering the growing importance of EOs as active ingredients, the domestication and cultivation of Medicinal and Aromatic Plants (MAPs) to produce chemically stable EOs contributes to species conservation, provides the sustainability of production, and decreases the variations in the active ingredients. In addition to these direct effects on plant pests and diseases, EOs can induce plant defenses (priming effects) resulting in better protection. This aspect is of relevance considering that the EU framework aims to achieve the sustainable use of new plant protection products (PPPs), and since 2020, the use of contaminant PPPs has been prohibited. In this paper, we review the most updated information on the direct plant protection effects of EOs, focusing on their modes of action against insects, fungi, and nematodes, as well as the information available on EOs with plant defense priming effects.

Oxygenated Cyclopentenones via the Pauson-Khand Reaction of Silyl Enol Ether Substrates

We report here the application of silyl enol ether moieties as efficient alkene coupling partners within cobalt-mediated intramolecular Pauson–Khand reactions. This cyclization strategy delivers synthetically valuable oxygenated cyclopentenone products in yields of ≤93% from both ketone- and aldehyde-derived silyl enol ethers, incorporates both terminal and internal alkyne partners, and delivers a variety of decorated systems, including more complex tricyclic structures. Facile removal of the silyl protecting group reveals oxygenated sites for potential further elaboration.

Antiparasitic Effects of Potentially Toxic Beetles (Tenebrionidae and Meloidae) from Steppe Zones

Arthropods and specifically beetles can synthesize and/or sequester metabolites from dietary sources. In beetle families such as Tenebrionidae and Meloidae, a few studies have reported species with toxic defensive substances and antiparasitic properties that are consumed by birds. Here we have studied the antiparasitic activity of extracts from beetle species present in the habitat of the Great Bustard (Otis tarda) against four pathogen models (Aspergillus niger, Meloidogyne javanica, Hyalomma lusitanicum, and Trichomonas gallinae). The insect species extracted were Tentyria peiroleri, Scaurus uncinus, Blaps lethifera (Tenebrionidae), and Mylabris quadripunctata (Meloidae). M. quadripunctata exhibited potent activity against M. javanica and T. gallinae, while T. peiroleri exhibited moderate antiprotozoal activity. The chemical composition of the insect extracts was studied by gas chromatography coupled with mass spectrometry (GC-MS) analysis. The most abundant compounds in the four beetle extracts were hydrocarbons and fatty acids such as palmitic acid, myristic acid and methyl linoleate, which are characteristic of insect cuticles. The presence of cantharidin (CTD) in the M. quadripunctata meloid and ethyl oleate (EO) in T. peiroleri accounted for the bioactivity of their extracts.

Sesquiterpene Lactones from Artemisia absinthium. Biotransformation and Rearrangement of the Insect Antifeedant 3α-hydroxypelenolide

Three new compounds, the sesquiterpenes absilactone and hansonlactone and the acetophenone derivative ajenjol, have been isolated from a cultivated variety of Artemisia absinthium. In addition, the major lactone isolated, 3α-hydroxypelenolide, was biotransformed by the fungus Mucor plumbeus affording the corresponding 1β, 10α-epoxide. A cadinane derivative was formed by an acid rearrangement produced in the culture medium, but not by the enzymatic system of the fungus. Furthermore, 3α-hydroxypelenolide showed strong antifeedant effects against Leptinotarsa decemlineata and cytotoxic activity to Sf9 insect cells, while the biotransformed compounds showed antifeedant postingestive effects against Spodoptera littoralis.

Chemical Nematicides: Recent Research Progress and Outlook

Plant-parasitic nematodes have caused huge economic losses to agriculture worldwide and seriously threaten the sustainable development of modern agriculture. Chemical nematicides are still the most effective means to manage nematodes. However, the long-term use of organophosphorus and carbamate nematicides has led to a lack of field control efficacy and increased nematode resistance. To meet the huge market demand and slow the growth of resistance, new nematicides are needed to enter the market. The rational design and synthesis of new chemical scaffolds to screen for new nematicides is still a difficult task. We reviewed the latest research progress of nematicidal compounds in the past decade, discussed the structure-activity relationship and mechanism of action, and recommended some nematicidal active fragments. It is hoped that this review can update the recent progress on nematicide discoveries and provide new ideas for the design and mechanism of action studies of nematicides.

Stoechanones A and B, Phytotoxic Copaane Sesquiterpenoids Isolated from Lavandula stoechas with Potential Herbicidal Activity against Amaranthus retroflexus

From the organic extract of Lavandula stoechas, a Mediterranean native plant species, two new phytotoxic copaane sesquiterpenoids were isolated and named stoechanones A and B (1 and 2). They were obtained together with the methyl esters of caffeic and p-coumaric acids and the flavonoid apigenin (3-5, respectively). The structures of stoechanones A and B were determined by spectroscopic (essentially 1D and 2D ¹H and ¹³C NMR and HRESIMS) and chemical methods, and they were characterized as 9,10-dihydroxy-8-isopropyl-1,5-dimethyltricyclo[4.4.0.0^2.7]dec-4-en-3-one and its 9-O-acetyl derivative. Their relative configurations were assigned by NOESY experiments, and the absolute configurations by comparison of the experimental and DFT-computed ECD spectra. When assayed through Petri dish bioassays, both stoechanones A and B showed phytotoxic effects against seed germination and seedling growth of Amaranthus retroflexus, strongly inhibiting seed germination percentage and radicle and hypocotyl lengths of seedlings. Owing to the herbicidal activity toward A. retroflexus, these two new tricyclic sesquiterpenoids could be proposed and developed as natural bioherbicides in order to increase the control of this problematic weed in the future.

Reconsidering Hydrosols as Main Products of Aromatic Plants Manufactory: The Lavandin (Lavandula intermedia) Case Study in Tuscany

: The present work evaluates for the first time two Lavandin (Lavandula × intermedia Emeric ex Loisel.) aromatic waters obtained from different plant organs, the flowers and the stems. Both extracts were analysed by GC-MS, which indicates semi-quantitative differences between the major metabolites including linalool, 1,8-cineole, camphor, linalyl acetate and 4-terpineol. ¹H-NMR and LC-MS investigation confirmed the presence of these compounds. Moreover, behavioural tests with the food insect pest Tribolium confusum (Coleoptera Tenebrionidae) showed a good repellency for both hydrosols extracts with RD₅₀ values of 3.6 and 3.3 µL cm^-2 for the flowers and stems, respectively; at the higher concentrations, however, the hydrosol extract from the flowers is expected to be more effective than the one from the stems. The effect of the flowers and stems aromatic water of Lavandin on seed germination of Raphanus sativus was also evaluated. Results showed that seed germination was completely inhibited by flowers hydrolate, having a possible application as natural herbicide. The overall experience with these Lavandin extracts indicates the potential of improved hydrolates to become the main distillation products, rather than by-products, of the aromatic plants manufacturing; this stimulates further discussions about the potential positive impacts that such a shift could have in the context of ecopharmacognosy.

Supercritical Carbon Dioxide Antisolvent Fractionation for the Sustainable Concentration of Lavandula luisieri (Rozeira) Riv.- Mart Antimicrobial and Antioxidant Compounds and Comparison with Its Conventional Extracts

Lavandula stoechas subsp. luisieri is a Spanish subspecies from the Lamiaceae family. Its essential oil has been traditionally used for several medical applications though little is known about other extracts. Similar to many other studies aiming to obtain traditional plant extracts to be used in different applications, this work evaluated the antioxidant and antimicrobial activities of Lavandula luisieri extracts and the correlation with their composition. Traditional hydrodistillation and ethanolic maceration were used to obtain the essential oil and the maceration extract, respectively. A green and sustainable methodology was applied to the maceration extract that was under a Supercritical Antisolvent Fractionation process to obtain a fine solid enriched in rosmarinic acid and the terpenes oleanolic and ursolic acids. Antimicrobial activities of all extracts and pure identified compounds (rosmarinic and ursolic acids) were evaluated against five bacterial strains; Listeria monocytogenes, Enterococcus faecium, Staphylococcus aureus, Salmonella Typhimurium and Escherichia coli and were compared with the pure compounds identified, rosmarinic and ursolic acids. All strains were sensitive against L. luisieri essential oil. The solid product obtained from the supercritical process was concentrated in the identified actives compared to the maceration extract, which resulted in higher antimicrobial and DPPH scavenging activities. The supercritical sustainable process provided L. luisieri compounds, with retention of their antimicrobial and antioxidant activities, in a powder exemptof organic solvents with potential application in the clinical, food or cosmetic fields.

Chemical Composition and Biological Activities of Artemisia pedemontana subsp. assoana Essential Oils and Hydrolate

Given the importance of the genus Artemisia as a source of valuable natural products, the rare plant Artemisia pedemontana subspecies assoana, endemic to the Iberian Peninsula, has been experimentally cultivated in the greenhouse and aeroponically, to produce biomass for essential oil (EO) extraction. The chemical composition of the EOs was analyzed, and their plant protection (insects: Spodoptera littoralis, Rhopalosiphum padi, and Myzus persicae; plants: Lactuca sativa and Lolium perenne; fungi: Aspergillus niger; and nematode: Meloidogyne javanica) and antiparasitic (Trypanosoma cruzi, Phytomonas davidi, and antiplasmodial by the ferriprotoporphyrin biocrystallization inhibition test) properties were studied, in addition to the hydrolate by-product. The EOs showed a 1,8-cineole and camphor profile, with quantitative and qualitative chemical differences between the cultivation methods. These oils had moderate insect antifeedant, antifungal, and phytotoxic effects; were trypanocidel; and exhibited moderate phytomonacidal effects, while the hydrolate showed a strong nematicidal activity. Both EOs were similarly antifeedant; the EO from the greenhouse plants (flowering stage) was more biocidal (antifungal, nematicidal, and phytotoxic) than the EO from the aeroponic plants (growing stage), which was more antiparasitic. The major components of the oils (1,8-cineole and camphor), or their 1:1 combination, did not explain any of these effects. We can conclude that these EOs have potential applications as insect antifeedants, and as antifungal or antiparasitic agents, depending on the cultivation method, and that the hydrolate byproduct is a potent nematicidal.

Ecotoxicity of a new biopesticide produced by Lavandula luisieri on non-target soil organisms from different trophic levels

Plant-based biopesticides have become an eco-friendly alternative to synthetic pesticides by reducing the undesired environmental impacts and side-effects on human health. However, their effects on the environment and especially on non-target organisms have been little studied. This study analyses the ecotoxicological effects of the extract of Lavandula luisieri on soil non-target organisms from different trophic levels: the earthworm Eisenia fetida, the plant Allium cepa and a natural-soil microbial community whose taxonomy was analysed through 16S rRNA gene sequencing. The extract tested is the hydrolate -product from a semi industrial steam distillation process- of a Spanish pre-domesticated variety of L. luisieri. This hydrolate has been recently shown to have bionematicide activity against the root-knot nematode Meloidogyne javanica. A previous study showed that the main components of the hydrolate are camphor and 2,3,4,4-Tetramethyl-5-methylidenecyclopent-2-en-1-one. Hydrolate caused acute toxicity (LC₅₀ 2.2% v/v) on A. cepa, while only a slight toxicity on E. fetida (LC₅₀ > 0.4 mL/g). All the concentrations tested (from 1 to 100% v/v) caused a significant decrease in bacterial growth (LC₅₀ 9.8% v/v after 120 h of exposure). The physiological diversity of the community was also significantly altered, except in the case of the lowest concentration of hydrolate (1% v/v). The ability of soil microbial communities to use a variety of carbon sources increased for all substrates at the highest concentrations. These results show that both the plants and bacterial communities of the soil can be affected by the application of biopesticides based on these hydrolates, which highlights the need for a more detailed risk assessment during the development of plant-based products.

Ecotoxicity of a novel biopesticide from Artemisia absinthium on non-target aquatic organisms

Biopesticides are increasingly being used to replace synthetic pesticides for pest control. This change raises concern for its environmental impacts, especially on non-target organisms. In this study, the ecotoxicological effects of a potential nematicide from Spanish populations of Artemisia absinthium (var. Candial) were evaluated on freshwater and aquatic non-target organisms. The study focused on the aqueous extract (hydrolate), the principal component of which ((-) -(Z) -2,6-dimethylocta-5,7-diene-2,3-diol) is responsible for its nematicidal effect. Until now, the hydrolate has been considered a byproduct of the process used to obtain essential oils, and there are no studies on its ecotoxicity from any plant with biopesticide properties. Our results indicated that A. absinthium hydrolate caused acute toxicity for non-target organisms at dilutions as low as 0.2%. The sensitivity of the organisms, from the most to the least sensitive, was: Daphnia magna (LC₅₀ = 0,236%) > Vibrio fisheri (LC₅₀ = 1,85%) > Chlamydomonas reinhardtii (LC₅₀ = 16,49). Moreover, the A. absinthium organic extract was highly toxic to D. magna (LC₅₀ = 0,093 mg/L). A. absinthium hydrolate toxicity was also tested on a natural river microbial community. Bacterial growth was not affected; the physiology of the community was only slightly modified, namely through an increased ability to degrade different substrates, mainly carbohydrates. This study provides for the first time an exhaustive assessment of the environmental exposure of a plant-derived biopesticide and shows that these products may cause a broad range of toxicity on non-target aquatic organisms.

neo-Clerodane Diterpenoids from Salvia polystachya Stimulate the Expression of Extracellular Matrix Components in Human Dermal Fibroblasts

Eleven neo-clerodane diterpenoids (1-11) including the new analogues 1, 2, and 10, and 3',5,6,7-tetrahydroxy-4'-methoxyflavone (12) were isolated from the aerial parts of Salvia polystachya. Polystachyne G (1) and 15-epi-polystachyne G (2) were isolated as an epimeric mixture, containing a 5-hydroxyfuran-2(5H)-one unit in the side chain at C-12 of the neo-clerodane framework. Polystachyne H (10) contains a 1(10),2-diene moiety and a tertiary C-4 hydroxy group. The structures of these compounds were established by analysis of their NMR spectroscopic and MS spectrometric data. The absolute configurations of compounds 3, 4, and 10 were determined through single-crystal X-ray diffraction analysis. The antibacterial, antifungal, and phytotoxic activities of the diterpenoids were determined. In addition, the stimulatory effect of the expression of extracellular matrix components of nine of the isolates (1-8 and 11) was assayed. Compounds 1-4, 8, and 11 increased the expression of the genes codifying for type I, type III, and type V collagens and for elastin.

Bioactive constituents from transformed root cultures of Nepeta teydea

A phytochemical study of an extract from transformed root cultures of Nepeta teydea, induced by Agrobacterium rhizogenes, led to the isolation of the following new compounds: the sesquiterpene (-)-cinalbicol, the diterpene teydeadione (6,11,14-trihydroxy-12-methoxy-abieta-5,8,11,13,15-penten-7-one), a degraded C23-triterpene (teydealdehyde) and three fatty acid esters of lanosta-7,24-dien-3β-ol. The propyl ester of rosmarinic acid was also isolated for the first time from a natural source. In addition, two dehydroabietane diterpenes, eight triterpenes and eighteen known phenolic compounds were obtained. The antifeedant, cytotoxic and phytotoxic activities of the isolated compounds have also been investigated.

Protective Effect of RA on Myocardial Infarction-Induced Cardiac Fibrosis via AT1R/p38 MAPK Pathway Signaling and Modulation of the ACE2/ACE Ratio

Rosmarinic acid (α-o-caffeoyl-3,4-dihydroxyphenyllactic acid, RA) is a major active constituent of Rosmarinus officinalis Linn. (rosemary) having significant anti-inflammatory, anti-apoptotic, and antioxidant effects. However, the cardioprotection of RA is still not understood. The present study was designed, for the first time, to investigate the cardioprotection of RA on myocardial infarction (MI)-induced cardiac fibrosis and to clarify the possible mechanisms. MI was induced in adult rats by left anterior descending coronary artery ligation, and animals were then administered RA (50, 100, or 200 mg/kg) by gavage. Compared with the model group, RA treatment ameliorated changes in the left ventricular systolic pressure (LVSP), +dp/dtmax, and -dp/dtmax after 4 weeks. This was associated with attenuation of infarct size, collagen volume fraction (CVF), expression of collagen I, collagen III, alpha smooth muscle actin (α-SMA), and hydroxyproline (Hyp) concentrations. RA treatment was also associated with decreased angiotensin-converting enzyme (ACE) expression and increased ACE2 expression, as well as decreased expression of angiotensin type 1 receptor (AT1R) and phospho-p38 mitogen-activated protein kinase (p38 MAPK). Thus, RA can protect against cardiac dysfunction and fibrosis following MI, likely due to decreasing ACE expression and increasing ACE2 expression via the AT1R/p38 MAPK pathway.