Five new insecticidal sesquiterpenoids from Celastrus angulatus

Molecular networking-guided isolation of melanogenesis inhibitory dihydro-β-agarofuran sesquiterpenoids from Celastrus orbiculatus

Seven previously undescribed dihydro-β-agarofurans (1-7) together with 28 known compounds were isolated from Celastrus orbiculatus fruits using LC-MS/MS-based molecular networking-guided purification. Their structures were elucidated through 1D and 2D-NMR, HRESIMS analysis, and ECD quantum chemical calculations. The inhibitory effects of all isolated compounds on α-MSH-induced melanin production in B16F0 melanoma cells were tested. Compounds 1, 11, 12, 19-21, 23, 29, 31, 34, and 35 showed significant inhibitory effects on melanin production with IC50 values ranging from 11.3 to 30.1 μM.

In-Depth Structural Simplification of Celangulin V: Design, Synthesis, and Biological Activity

Celangulin V is a novel botanical insecticide with significant bioactivity and a unique molecular target, but its complex polyol ester structure hinders its broader application in agriculture. To discover new analogues of celangulin V with a simpler structure and enhanced biological activities, we initiated a research project aimed at simplifying its structure and assessing insecticidal efficacy. In this study, a series of novel 1-tetralone derivatives were designed via a structure-based rational design approach and synthesized by a facile method. The biological activities of the target compounds were determined against Mythimna separata (M. separata), Plutella xylostella, and Rhopalosiphum padi. The results revealed that most of the synthesized compounds exhibited superior activities compared to celangulin V. Remarkably, the insecticidal activity of compound 6.16 demonstrated 102-fold greater stomach toxicity than celangulin V against M. separata. In addition, certain compounds showed significant contact toxicity against M. separata, a finding not reported previously in the structural optimization studies of celangulin V. Molecular docking analysis illustrated that the binding pocket of compound 6.16 with the H subunit of V-ATPase was the same as celangulin V. This study presents novel insights into the structural optimization of botanical pesticides.

The Chemical Ecology of Plant Natural Products

Plants are excellent chemists with an impressive capability of biosynthesizing a large variety of natural products (also known as secondary or specialized metabolites) to resist various biotic and abiotic stresses. In this chapter, 989 plant natural products and their ecological functions in plant-herbivore, plant-microorganism, and plant-plant interactions are reviewed. These compounds include terpenoids, phenols, alkaloids, and other structural types. Terpenoids usually provide direct or indirect defense functions for plants, while phenolic compounds play important roles in regulating the interactions between plants and other organisms. Alkaloids are frequently toxic to herbivores and microorganisms, and can therefore also provide defense functions. The information presented should provide the basis for in-depth research of these plant natural products and their natural functions, and also for their further development and utilization.

Sesquiterpene Polyesters from the Fruits of Euonymus sieboldianus

The MeOH extract from dried immature fruits of Euonymus sieboldianus (Celastraceae) plants yielded nineteen new β-dihydroagarofuran-type sesquiterpene polyesters. The structures of these compounds were established using NMR, MS spectroscopic analysis and chemical evidence.

Isolation and Identification of Phytocompounds from Maytenus dhofarensis and Their Biological Potentials

Maytenus dhofarensis Sebsebe (Celestraceae) is a naturally growing shrub in Oman. It is not a reputed medicinal plant in Oman, but it is regionally endemic and causes shivering attacks on goats that graze on it. The chemical investigation of the hexane and chloroform extracts of the fruits and stems of M. dhofarensis afforded dihydro-β-agarofuran-type sesquiterpene pyridine alkaloid (1), lupanyl myristoate (2) and lignanolactone (3). Compounds (1-3) are new isolates from M. dhofarensis. The structures of these compounds were assigned through comprehensive IR, NMR, and ESI-MS analyses, and the relative configurations of compounds 1 and 3 were deduced from density function theory (DFT) calculations and NMR experiments. Compound 1 was assayed against the kinase enzyme and showed no inhibition activity for p38 alpha and delta at a 10 µM test concentration. Compound 3 inhibited the 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH) by 69.5%, compared to 70.9% and 78.0% for gallic acid and butylated hydroxyanisole, respectively, which were used as positive controls.

Design, synthesis, and insecticidal activity evaluation of piperine derivatives

Structural optimization of natural products has become one of the most effective ways to develop novel pesticides. In this study, 30 novel pesticide derivatives containing a linear bisamide were synthesized. Then, their insecticidal activities against P. xylostella were evaluated. Results indicate that different bisamide substitutes show different larvicidal structure–activity relationships. At the same time, 2-trifluoroethyl is the most efficient substituent. The bioactivity results showed that most of the desired compounds exhibited better insecticidal activity against P. xylostella than piperine. Among them, compound D28 resulted in 90% mortality at 1 mg/ml concentration. This study provides a novel protocol for the discovery of new insecticides. The molecular docking results indicated that compound D28 could act on γ-aminobutyric acid receptors.

Isolation and structural identification of insecticidal compounds from Tripterygium wilfordii

Five compounds were identified from Tripterygium wilfordii, including two novel compounds and three previously known compounds. Two newly discovered compounds are celangulin CY (1α,2α,3β,4β,6β,8α,13-hepacetoxy-9β-benzoyloxy-β-dihydroagarofuran) and celangulin CQ (1α-nicotinoyloxy-2α,3β,6β-triacetoxy-9β-furancarbonyloxy-13-isobutanoyloxy-4β-hydroxy-β-dihydroagarofuran). Their structures were determined using nuclear magnetic resonance (NMR), mass spectrometry (MS), and high-pressure liquid chromatography (HPLC). The isolated compounds were tested for insecticidal activity against the third instar larvae of Spodoptera frugiperda. Both celangulin CY and celangulin CQ exhibited significantly higher oral toxicity in the larvae than that exhibited by the three known compounds.

First Report on Inhibitory Effect against Osteoclastogenesis of Dihydro-β-agarofuran-Type Sesquiterpenoids

Dihydro-β-agarofuran-type sesquiterpenoids are characteristic metabolites of Celastraceae plants, and the extracts of these plants have been developed into botanical pesticides. In the course of our efforts to find novel natural biologically active products, eight new dihydro-β-agarofuran-type sesquiterpenoids (1-8) were identified from the stems of Celastrus monospermus Roxb. Their structures were elucidated by extensive spectroscopic analysis, single crystal X-ray crystallography, and electronic circular dichroism (ECD) calculations. In consideration of the efficacy of certain Celastrus plants for the treatment of arthritis and arthralgia in folk medicine, the isolates were evaluated for their inhibitory activities against osteoclastogenesis. As a result, compounds 4, 6, and 7 were found to restrain osteoclastogenesis induced by receptor activator of nuclear factor-κB ligand (RANKL) with IC₅₀ values of 0.58, 1.2, and 6.1 μM, respectively. Furthermore, compound 4 was found to inhibit osteoclastogenesis-related gene (c-Fos, MMP-9, CTSK, TRAP) expression and block c-Fos protein expression and inhibited bone resorption of mature osteoclasts induced by M-CSF and RANKL in a dose dependent manner. This is the first report of dihydro-β-agarofuran-type sesquiterpenoid for their potential medical applications in bone metabolic diseases.

Nine new dihydro-β-agarofuran sesquiterpene polyesters from the leaves of Tripterygium wilfordii

Nine previously undescribed dihydro-β-agarofuran type sesquiterpene polyesters, tripteresters A–I (1–9) were isolated from the leaves of Tripterygium wilfordii.

Development of an Enantioselective Synthesis of (-)-Euonyminol

We detail the development of the first enantioselective synthetic route to euonyminol (1), the most heavily oxidized member of the dihydro-β-agarofuran sesquiterpenes and the nucleus of the macrocyclic alkaloids known as the cathedulins. Key steps in the synthetic sequence include a novel, formal oxyalkylation reaction of an allylic alcohol by [3 + 2] cycloaddition; a tandem lactonization-epoxide opening reaction to form the trans-C2-C3 vicinal diol residue; and a late-stage diastereoselective trimethylaluminum-mediated α-ketol rearrangement. We report an improved synthesis of the advanced unsaturated ketone intermediate 64 by means of a 6-endo-dig radical cyclization of the enyne 42. This strategy nearly doubled the yield through the intermediate steps in the synthesis and avoided a problematic inversion of stereochemistry required in the first-generation approach. Computational studies suggest that the mechanism of this transformation proceeds via a direct 6-endo-trig cyclization, although a competing 5-exo-trig cyclization, followed by a rearrangement, is also energetically viable. We also detail the challenges associated with manipulating the oxidation state of late-stage intermediates, which may inform efforts to access other derivatives such as 9-epi-euonyminol or 8-epi-euonyminol. Our successful synthetic strategy provides a foundation to synthesize the more complex cathedulins.

The P450 multigene family of Fontainea and insights into diterpenoid synthesis

BACKGROUND

Cytochrome P450s (P450s) are enzymes that play critical roles in the biosynthesis of physiologically important compounds across all organisms. Although they have been characterised in a large number of plant species, no information relating to these enzymes are available from the genus Fontainea (family Euphorbiaceae). Fontainea is significant as the genus includes species that produce medicinally significant epoxy-tigliane natural products, one of which has been approved as an anti-cancer therapeutic.

RESULTS

A comparative species leaf metabolome analysis showed that Fontainea species possess a chemical profile different from various other plant species. The diversity and expression profiles of Fontainea P450s were investigated from leaf and root tissue. A total of 103 and 123 full-length P450 genes in Fontainea picrosperma and Fontainea venosa, respectively (and a further 127/125 partial-length) that were phylogenetically classified into clans, families and subfamilies. The majority of P450 identified are most active within root tissue (66.2% F. picrosperma, 65.0% F. venosa). Representatives within the CYP71D and CYP726A were identified in Fontainea that are excellent candidates for diterpenoid synthesis, of which CYP726A1, CYP726A2 and CYP71D1 appear to be exclusive to Fontainea species and were significantly more highly expressed in root tissue compared to leaf tissue.

CONCLUSION

This study presents a comprehensive overview of the P450 gene family in Fontainea that may provide important insights into the biosynthesis of the medicinally significant epoxy-tigliane diterpenes found within the genus.

Dihydro-β-agarofuran-Type Sesquiterpenoids from the Seeds of Celastrus virens and Their Multidrug Resistance Reversal Activity against the KB/VCR Cell Line

Twenty-nine dihydro-β-agarofuran-type sesquiterpenoids, including 17 new and 12 known compounds, were obtained from the seeds of Celastrus virens. The structures of the new isolates were characterized by spectroscopic methods and X-ray diffraction analysis. Among these, 20 sesquiterpenoids were evaluated for their multidrug resistance (MDR) reversal activity against the KB/VCR cell line. As a result, compounds 6 and 8 were found to exhibit MDR-reversal activity of more than 10-fold at a concentration of 2 μM, and the reversal fold (RF) ratios of compounds 19, 21, and 24 were >97.9 at a 20 μM nontoxic concentration level.

Neuroprotective Dihydro-β-agarofuran-Type Sesquiterpenes from the Seeds of Euonymus maackii

Twenty-one dihydro-β-agarofuran derivatives were purified from the seeds of Euonymus maackii, and eight compounds (1-8) were identified as new natural products. Their structures were deduced by extensive spectroscopic analysis, X-ray diffraction studies, and comparison of observed and reported NMR data. Compounds 10, 12, 17, and 18 significantly increased the cell viability of Aβ_25-35-treated SH-SY5Y cells with effects similar to that of epigallocatechin gallate (EGCG). In addition, the abundant compound 9 reduced the seizure-like locomotor activity of zebrafish at 10 μM compared with a pentylenetetrazol-treated group.

Two new sesquiterpene pyridine alkaloids from root barks of Celastrus angulatus

Two new sesquiterpene pyridine alkaloids, Chinese bittersweet alkaloid A (1) and Chinese bittersweet alkaloid B (2), together with five known compounds 3β- hydroxyolean-9(11),12-diene, β-sitosterol, 1β,2β,6α,15β-tetraacetoxy-8β,9α- dibenzoyloxy-β-dihydroagarofuran, angulatin A and angulatin J, were isolated from the root barks of Celastrus angulatus. The structures of 1 and 2 were elucidated as 1β,6α,8β,9β-tetraacetoxy-2β,4α-dihydroxy-15β-isobutanoyloxy-(3,12)-evoninoyloxy-β-dihydroagarofuran and 1β,2β,6α,8β,9β-pentaacetoxy-4α-hydroxy-15β- isobutanoyloxy- (3,12)- evoninoyloxy-β-dihydroagarofuran mainly by NMR spectroscopic means.

Tripterfordins A-O, Dihydro-β-agarofuran Sesquiterpenoids from the Leaves of Tripterygium wilfordii

Fifteen new dihydro-β-agarofuran-type sesquiterpenoids, tripterfordins A-O, were obtained from the aqueous EtOH extracts of the leaves of Tripterygium wilfordii. These constituted a class of highly oxygenated tricyclic sesquiterpenoid polyesters with a cinnamoyloxy group at C-1. The assignments of their structures were conducted via extensive analyses of the spectroscopic data and comparison of experimental and calculated ECD data. The absolute configurations of compounds 1, 4, 9, and 10 were established via single-crystal X-ray diffraction data. Additionally, compounds 1, 4, 9, 10, and 13 exhibited pronounced inhibitory effects on nitric oxide production in RAW 264.7 murine macrophages stimulated by lipopolysaccharide with IC₅₀ values ranging from 11.9 to 31.0 μM.

Traditional uses, secondary metabolites, and pharmacology of Celastrus species - a review

ETHNOPHARMACOLOGICAL RELEVANCE

Plants of genus Celastrus (Celastraceae) have been widely used in traditional Chinese medicine (TCM) and Indian medicine to treat cognitive dysfunction, epilepsy, insomnia, rheumatism, gout, and dyspepsia for thousands of years.

AIM OF STUDY

We critically summarized the current evidence on the botanic characterization and distribution, ethnopharmacology, secondary metabolites, pharmacological activities, qualitative and quantitative analysis, and toxicology of Celastrus species to provide perspectives for developing more attractive pharmaceuticals of plant origin.

MATERIALS AND METHODS

The relevant information on Celastrus species was gathered from worldwide accepted scientific databases via electronic search (Web of Science, SciFinder, PubMed, Elsevier, SpringerLink, Wiley Online, China Knowledge Resource Integrated, and Google Scholar). Information was also obtained from the literature and books as well as PhD and MSc dissertations. Plant names were validated by "The Plant List" (www.theplantlist.org).

RESULTS

Comprehensive analysis of the above mentioned databases and other sources confirmed that ethnomedical uses of plants of Celastrus genus had been recorded in China, India, and other countries in Southern Asia. The phytochemical investigation revealed the presence of β-dihydroagarofuranoids, diterpenoids, triterpenoids, tetraterpenes, phenylpropanoids, alkaloids, flavonoids, lignans, and others. The crude extracts and isolated constituents have exhibited a wide range of in vitro and in vivo pharmacological effects, including antitumor, cytotoxic, insecticidal, antimicrobial, anti-rheumatoid arthritis (RA), anti-inflammatory, anti-ageing and antioxidative, and neuroprotective activities.

CONCLUSION

Plants of genus Celastrus have been confirmed to show a strong potential for therapeutic and health-maintaining effects, in light of their long traditional use and the phytochemical and pharmacological studies summarized here. Currently, pharmacological studies of this genus mainly focus on Celastrus paniculatus Willd. and Celastrus orbiculatus Thunb. Therefore, more pharmacological investigations should be implemented to support traditional uses of other medicinal plants of the genus Celastrus. Moreover, studies on the toxicity, bioavailability, and pharmacokinetics, in addition to clinical trials, are indispensable for assessing the safety and efficacy of the secondary metabolites or extracts obtained from plants belonging to this genus.

A New Antitumour Sesquiterpene from the Euonymus Nanoides

A new (1) and a known (2) β-dihydroagarofuran sesquiterpene polyol ester were isolated from Euonymus nanoides and they showed antitumor activities in vitro.

De novo leaf and root transcriptome analysis to explore biosynthetic pathway of Celangulin V in Celastrus angulatus maxim

Background

Celastrus angulatus Maxim is a kind of crucial and traditional insecticidal plant widely distributed in the mountains of southwest China. Celangulin V is the efficient insecticidal sesquiterpenoid of C. angulatus and widely used in pest control in China, but the low yield and discontinuous supply impeded its further popularization and application. Fortunately, the development of synthetic biology provided an opportunity for sustainable supply of Celangulin V, for which understanding its biosynthetic pathway is indispensable.

Results

In this study, six cDNA libraries were prepared from leaf and root of C. angulatus before global transcriptome analyses using the BGISEQ-500 platform. A total of 104,950 unigenes were finally obtained with an average length of 1200 bp in six transcriptome databases of C. angulatus, in which 51,817 unigenes classified into 25 KOG classifications, 39,866 unigenes categorized into 55 GO functional groups, and 48,810 unigenes assigned to 135 KEGG pathways, 145 of which were putative biosynthetic genes of sesquiterpenoid and triterpenoid. 16 unigenes were speculated to be related to Celangulin V biosynthesis. De novo assembled sequences were verified by Quantitative Real-Time PCR (qRT-PCR) analysis.

Conclusions

This study is the first report on transcriptome analysis of C. angulatus, and 16 unigenes probably involved in the biosynthesis of Celangulin V were finally collected. The transcriptome data will make great contributions to research for this specific insecticidal plant and the further gene mining for biosynthesis of Celangulin V and other sesquiterpene polyol esters.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5397-z) contains supplementary material, which is available to authorized users.

Celamonols A–D, four triterpenoid and catechin conjugates with immunosuppressive activities from the stems of Celastrus monospermus

Celamonols A–D (1–4), four dimers between a friedelane-type triterpenoid and a catechin, were isolated from the stems of Celastrus monospermus.

Two New β-Dihydroagarofuran Sesquiterpenes from Celastrus orbiculatus Thunb and Their Anti-Proliferative Activity

Two new β-dihydroagarofuran-type sesquiterpenes (1-2) were isolated and identified from the fruit of Celastrus orbiculatus Thunb, together with seventeen known compounds (3-19). The structures of the isolated new compounds were elucidated based on extensive spectroscopic analyses. The cytotoxic activities of the 19 sesquiterpenes on three cell lines, human acute promyelocytic leukemia HL-60, human leukemic K562, and human colon cancer HCT-116 cells, were evaluated in vitro. Compound 4 exhibited potent cytotoxic activity against HL-60, K562, and HCT116 cell lines with IC50 values of 3.61 μΜ, 17.13 μΜ and 10.15 μΜ, respectively, and the other compounds displayed moderate activity.

Synthesis and insecticidal activity of β-dihydroagarofuran ether analogues

BACKGROUND

1β, 2β, 4α, 6α, 8β, 9α, 12-hepthydroxyl-β-dihydroagarofuran is the main skeleton of β-dihydroagarofuran sesquiterpenoids, which exhibit excellent insecticidal activity. To study further the structure-activity relationship of β-dihydroagarofuran sesquiterpenoids towards finding novel botanical pesticides, two series of new structurally modified ether analogues were designed and synthesised, and their insecticidal activities were evaluated.

RESULTS

Twenty-two ether derivatives were synthesised using 1β, 2β, 4α, 6α, 8β, 9α, 12-hepthydroxyl-β-dihydroagarofuran as starting material. Bioassay results indicated that most of the derivatives, particularly compounds 5.1.2, 5.1.3, 5.1.7, 5.2.3, 5.2.6 and 5.2.7, exhibited significant insecticidal activity against the third-instar larvae of the oriental armyworm Mythimna separata. Most importantly, compound 5.2.7 showed the lowest LD50 value of 29.2 µg g(-1) among these synthesised compounds, which provides some important hints for further design, synthesis and structural modification of β-dihydroagarofuran sesquiterpenoids towards developing novel botanical insecticides.

CONCLUSION

The structure-activity relationship illustrated that the moiety at the 1-position affected the insecticidal activity significantly, and that specifically the derivatives with two or three carbon atoms at the 1-position showed promising insecticidal activity, with mortality over 60%, while those with o-F-Bn and p-F-Bn at the 6-position showed similar activity.

Exploration of Novel Botanical Insecticide Leads: Synthesis and Insecticidal Activity of β-Dihydroagarofuran Derivatives

The discovery of novel leads and new mechanisms of action is of vital significance to the development of pesticides. To explore lead compounds for botanical insecticides, 77 β-dihydroagarofuran derivatives were designed and synthesized. Their structures were mainly confirmed by (1)H NMR, (13)C NMR, DEPT-135°, IR, MS, and HRMS. Their insecticidal activity was evaluated against the third-instar larvae of Mythimna separata Walker, and the results indicated that, of these derivatives, eight exhibited more promising insecticidal activity than the positive control, celangulin-V. Particularly, compounds 5.7, 6.6, and 6.7 showed LD50 values of 37.9, 85.1, and 21.1 μg/g, respectively, which were much lower than that of celangulin-V (327.6 μg/g). These results illustrated that β-dihydroagarofuran ketal derivatives can be promising lead compounds for developing novel mechanism-based and highly effective botanical insecticides. Moreover, some newly discovered structure-activity relationships are discussed, which may provide some important guidance for insecticide development.

New eudesmane-type sesquiterpenoids from the root bark of Pseudolarix kaempferi

The phytochemical investigation of the root bark of Pseudolarix kaempferi yielded eight eudesmane-type sesquiterpenoids, including three new ones, 1α-hydroxyl-4(14)-en-β-dihydroagarafuran (1), 1α, 2α-diacetoxy-8β-isobutanoyloxy-9α-benzoyl oxy-15-β-(β-furancarbonyloxy)-4β, 6β-dihydroxy-β-dihydroagarofuran (7), and 1α-acetoxy-2 α-furancarbonyloxy-8β-isobutanoyloxy-9α-benzoyloxy-15β-(β-acetoxy)-4β, 6β-dihydroxy-β-dihydroagarofuran (8). Herein the new compounds 7 and 8 were reported as a mixture. The molecular structures of the isolated compounds were elucidated on the basis of extensive spectroscopic analysis, including UV, IR, NMR, and MS, and comparison with the literature data.

Natural β-Dihydroagarofuran-Type Sesquiterpenoids as Cognition-Enhancing and Neuroprotective Agents from Medicinal Plants of the Genus Celastrus

Alzheimer's disease (AD) is an irreversible, multifaceted, and progressive neurodegenerative disorder. Over the past 30 years, the search for anti-AD drugs has been primarily based on the cholinergic deficiency hypothesis and/or the β-amyloid (Aβ) cascade hypothesis. In this study, we report the identification of 16 new and 38 known β-dihydroagarofuran-type sesquiterpenoids from Celastrus flagellaris and Celastrus angulatus. The β-dihydroagarofuran-type sesquiterpenoids 58, 59, 61, and 63 significantly attenuated scopolamine-induced prolonged escape latency and increased number of errors compared with the control group. At 10 μM, 21 of the 62 tested β-dihydroagarofuran-type sesquiterpenoids rescued Aβ25-35-induced SH-SY5Y cells from viability reduction, which increased the cell viability from 64.6% for the model to more than 74.0%. The majority of the β-dihydroagarofuran-type sesquiterpenoids with ester groups exhibited stronger activity than those with free hydroxy groups or without substituents at the same positions. These results identified a new chemical skeleton as drug lead for the investigation of novel therapeutic agents against AD.

Restoration of Chemosensitivity in P-Glycoprotein-Dependent Multidrug-Resistant Cells by Dihydro-β-agarofuran Sesquiterpenes from Celastrus vulcanicola

Multidrug resistance (MDR) caused by the overexpression of ABC drug transporters is a major obstacle in clinical cancer chemotherapy and underlines the urgent need for the development of new, potent, and safe reversal agents. Toward this goal, reported herein are the structure elucidation and biological activity of nine new (1-9) and four known (10-13) dihydro-β-agarofuran sesquiterpenes, isolated from the leaves of Celastrus vulcanicola, as reversers of MDR mediated by human P-glycoprotein expression. The structures of these compounds were elucidated by extensive NMR spectroscopic and mass spectrometric analysis, and their absolute configurations were determined by circular dichroism studies, chemical correlations (1a, 8a, and 8b), and biogenetic means. Four compounds from this series were discovered as potent chemosensitizers for MDR1-G185 NIH-3T3 murine cells (3, 4, 6, and 7), showing higher efficacies than the classical P-glycoprotein inhibitor verapamil, a first-generation chemosensitizer, when reversing resistance to daunomycin and vinblastine at the lowest concentration tested of 1 μM.

Denhaminols A-H, dihydro-β-agarofurans from the endemic Australian rainforest plant Denhamia celastroides

Eight new dihydro-β-agarofurans, denhaminols A-H (1-8), were isolated from the leaves of the Australian rainforest tree Denhamia celastroides. The chemical structures of 1-8 were elucidated following analysis of 1D/2D NMR and MS data. The absolute configuration of denhaminol A (1) was determined by single-crystal X-ray crystallography. All compounds were evaluated for cytotoxic activity against the human prostate cancer cell line LNCaP, using live-cell imaging and metabolic assays. Denhaminols A (1) and G (7) were also tested for their effects on the lipid content of LNCaP cells. This is the first report of secondary metabolites from D. celastroides.

β-Agarofurans and Sesquiterpene Pyridine Alkaloids from Maytenus spinosa

Nine new β-dihydroagarofurans (1-9) and four new sesquiterpene pyridine alkaloids (10-13) were isolated from the leaves of Maytenus spinosa. Their structures were determined mainly by 1D- and 2D-NMR spectroscopic studies. The absolute configuration of compound 6 was established using CD spectroscopy. Several derivatives (14-20) were prepared from the sesquiterpene 13. Most of the sesquiterpenoids were tested for anti-HIV activity, but only compound 1 was found to be active.

Wightianines A-E, dihydro-β-agarofuran sesquiterpenes from Parnassia wightiana, and their antifungal and insecticidal activities

Five new sesquiterpene polyol esters with a dihydro-β-agarofuran skeleton, designated as wightianines A-E (1-5), besides two known compounds, were isolated from the methanolic extract of the whole plant of the traditional herbal medicine Parnassia wightiana Wall. The structures of the isolated compounds were elucidated on the basis of spectroscopic analyses, including two-dimensional nuclear magnetic resonance techniques (correlation spectroscopy, heteronuclear multiple-quantum coherence, nuclear Overhauser effect spectrometry, and heteronuclear multiple-bond correlation) and electronic circular dichroism studies. The antifungal and insecticidal activities of five compounds were evaluated against several plant pathogenic fungi and armyworm larvae (Mythimna separata Walker). Among the test metabolites, compounds 2 and 7 both exhibited potent antifungal activity against the phytopathogenic fungus Cytospora sp. with minimum inhibitory concentration values of 0.78 μg/mL, which are equal to the two positive controls, hymexazol and carbendazim. However, no insecticidal activity of the test compounds was observed in the present study. Compounds 2 and 7 could be promising leads for developing new fungicides against agriculturally important fungus Cytospora sp.

Antiplasmodial sesquiterpenes from the seeds of Salacia longipes var. camerunensis

Phytochemical investigation of the seeds of Salacia longipes var. camerunensis led to the isolation of four sesquiterpenoid derivatives, salaterpene A (1) (1α,2β,8β-triacetoxy-6β,9β-dibenzoyloxy-4β-hydroxy-dihydro-β-agarofuran), salaterpene B (2) (1α,2β,8β-triacetoxy-9β-benzoyloxy-6β-cinnamoyloxy-4β-hydroxy-dihydro-β-agarofuran), salaterpene C (3) (1α,2β-diacetoxy-6β,9β-dibenzoyloxy-4β-hydroxy-dihydro-β-agarofuran) and salaterpene D (4) (2β-acetoxy-1α,6β-dibenzoyloxy-4β-hydroxy-9β-nicotinoyloxy-dihydro-β-agarofuran) together with two known compounds (5 and 6). The structures of the compounds were established by means of NMR spectroscopy. Compounds 1-4 and 6 were tested in vitro for their antiplasmodial activity against Plasmodium falciparum chloroquine-resistant strain W2. All the tested compounds exhibited a moderate potency with IC50 below 2.7 μM.

Cytotoxic constituents from Celastrus paniculatus induce apoptosis and autophagy in breast cancer cells

Celastrus paniculatus is a traditional medicinal plant with diverse pharmacological activities. To identify its bioactive constituents, three new β-dihydroagarofuranoid sesquiterpenes were isolated from the whole plant, of which the major constituent is (1α,2α,8β,9β)-1,8-bis(acetyloxy)-2,9-bis(benzoyloxy)-14-hydroxy-β-dihydroagarofuran. It was assessed for its antiproliferative activity, and it suppressed the viability of MCF-7 breast cancer cells with an IC50 of 17±1μM. This growth inhibition was, in part, attributable to apoptosis. Moreover, this drug treatment led to LC3B-II accumulation, indicative of autophagy. Western blot analysis established its ability to target a broad range of signaling effectors related to survival and cell cycle progression, including Akt, NF-κB, p53, and MAP kinases. In addition, flow cytometry analysis indicates increased reactive oxygen species production in response to this compound. Taken together, these findings suggest a pleiotropic mode of mechanism that underlies the antiproliferative activity of this compound in MCF-7 breast cancer cells.

Simultaneous identification of multiple celangulins from the root bark of Celastrus angulatus using high-performance liquid chromatography-diode array detector-electrospray ionisation-tandem mass spectrometry

INTRODUCTION

Celangulins are a small family of β-dihydroagarofuran sesquiterpenoids endowed with diverse polyoxygenated polyol esters and various biological properties. Since our research focuses on celangulins, the development of rapid and sensitive online analytical methods to analyse and characterise them is of great significance.

OBJECTIVE

To develop an HPLC-DAD-ESI-MS/MS method capable of simple and rapid analysis of celangulins in crude extract of root bark of C. angulatus extracts.

METHODOLOGY

High-performance liquid chromatography coupled with a diode array detector and electrospray ionisation tandem mass spectrometry was established for the efficient and rapid identification of the celangulins. Chromatographic separations of celangulins were performed on a Hypersil Gold C(18) reverse-phase column by gradient elution with acetonitrile-water as mobile phase at a flow-rate 0.2 mL/min.

RESULTS

ESI/MS/MS analysis of sodium adduct ion ([M + Na](+) ) of each celangulin shows that all the celangulins produced very similar fragmentation profiles, and that the characteristic fragments at m/z 245, m/z 229 and m/z 231 were defined as the diagnostic ions for celangulins. Simultaneously, 46 components in the extracts of this plant were separated, and 36 of them were characterised as celangulins by online ESI/MS/MS and by comparing their retention times, UV and MS spectra with those of authentic compounds.

CONCLUSION

HPLC-DAD-ESI-MS/MS was demonstrated to be a powerful tool for the characterisation of minor celangulins in complex samples.

Plant use in the medicinal practices known as "strict diets" in Chazuta valley (Peruvian Amazon)

AIM OF THE STUDY

Strict diets are traditional medicinal practices where plant remedies are consumed with nearly fasting and with some sort of social seclusion. The aim of this work was to describe these practices of Chazuta and the use of plants within, as well as to analyse the possible functions of the last.

MATERIAL AND METHODS

The information was obtained through interviews to the 6.3% of the district rural adult population (140 individuals, 75% of which was considered Quechua).

RESULTS

In total, 122 strict diets were recorded and 106 different plant species were reported to be used. Strict diets present a characteristic structure and plant use. The main effects reported in strict diets were antinflammatory, antiinfective, brain function alteration and depuration.

CONCLUSIONS

Strict diets are well structured traditional medicinal practices, also with a symbolic significance in the life cycle of chazutian men. Plants used in strict diets can contribute to the main effects through antinflammation, antiinfective actions, psychoactivity and depurative related activities. The correlation between literature evidence of activity of most used plants and effects reported for the correspondent diet (i.e. in which the plant was used) are 36% for antinflammatory activity, 29% for antimicrobial activity, 18% for psychoactivity and 5% for depurative related activities. The percentages go to 77%, 64%, 73% and 32%, respectively, when literature evidences on related taxa are also considered.

Two new sesquiterpene polyol esters from the root barks of Celastrus angulatus

Angulatin F (1) and angulatin I (2), two new sesquiterpene polyol esters, were isolated from the root barks of Celastrus angulatus, together with six known compounds 1β,2β-diacetoxy-4α,6α-dihydroxy-8α-isobutanoyloxy-9β-benzoyloxy-15-(α-methyl) butanoyloxy-β-dihydroagrofuran (3), angulatin A (4), angulatin B (5), celangulatin E (6), 1β,2β,15-triacetoxy-4α,6α-dihydroxy-8α-isobutanoyloxy-9β-benzoyloxy-β-dihydroagrofuran (7), and celangulin I (8). The structures of 1 and 2 were elucidated as 1β,2β,6α,15-tetraacetoxy-4α-hydroxy-8β,9α-difuroyloxy-β-dihydroagrofuran and 1β,2β,6α,8β,15-pentaacetoxy-4α-hydroxy-9β-furoyloxy-β-dihydroagrofuran by spectroscopic means.

Isolation, biological evaluation and 3D-QSAR studies of insecticidal/narcotic sesquiterpene polyol esters

For the first time, a set of (43) natural sesquiterpene polyol esters isolated from the root bark of Celastrus angulatus Maxim and Euonymus japonicus Thunb were subjected to 3D-QSAR comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) studies, with the aim of proposing novel sesquiterpene-based compounds with optimal narcotic or insecticidal activities. The established 3D-QSAR models exhibit reasonable statistical quality and prediction capabilities, with internal cross-validated Q (2) values of ∼ 0.5 and external predicted R (2) values of >0.9, respectively. The relative contributions of the steric/electrostatic fields of the 3D-QSAR models show that the electronic effect governs the narcotic activities of the molecules, but the hybrid effect of the electrostatic and hydrophobic interactions is more influential in the insecticidal activities of the compounds. These findings may have valuable implications for the development of novel natural insecticides.

Three New Insecticidal Sesquiterpene Polyol Esters from Celastrus angulatus

Three new insecticidal sesquiterpene polyol esters with dihydro-β-agarofuran skeletons, Kupiteng esters A (1), B (2) and C (3), were isolated from the methanol extracts of the root bark of Celastrus angulatus and their structures elucidated by analyses of MS and NMR spectral data. The insecticidal activities of these compounds against the 4th instar larvae of Mythimna separata were evaluated. The KD50 values of compounds 1-3, were 260.2, 445.5 and 1260.0 μg-g−1, respectively.

Three Novel Sesquiterpene Esters from Celastrus Angulatus

Three new sesquiterpene polyol esters with a β-dihydroagarofuran skeleton, NW12 (1), NW27 (2), and NW31 (4), together with a known compound, NW30 (3), were isolated from the root bark of Celastrus angulatus. Their chemical structures were elucidated by analyses of MS and NMR spectral data. Preliminary insecticidal and antitumor activities of these compounds were evaluated. Compounds 1-4 showed moderate stomach toxicity against Mythimna separata, and their KD50 values were 673.6, 1121.3, 1720.0 and 548.6 μg/g, respectively. Only 1 and 3 exhibited slight antitumor activity against human breast cancer cell line (Bcap-37), and their IC50 values were all above 50 μM.

A new insecticidal sesquiterpene ester from Celastrus angulatus

A new sesquiterpene polyol ester with a β-dihydroagarofuran skeleton, NW37 (1), and three known compounds NW13 (2), NW16 (3) and NW35 (4) were isolated by bioassay-guided fractionation from the highly polar MeOH extracts of the root bark of Celastrus angulatus. Their chemical structures were elucidated mainly by analyses of MS and NMR spectral data. The insecticidal activity of compound 1 against 4^th instar Mythimna separata larvae with a KD₅₀ value of 252.3 μg·g^-1 was demonstrated.