Neo-clerodane Diterpenoids Research Articles

Bioactive constituents from Clerodendrum trichotomum and their α-glucosidase inhibitory and PPAR-γ agonist activities

Three new neoclerodane diterpenoids (1–3), two new steroids (4–5), one new monoterpene (6), one new derivative of benzaldehyde (7) and one new iridoid glycoside (8), along with 19 known phenolic compounds, were isolated from Clerodendrum trichotomum. Their structures were established by a combination of detailed spectroscopic analyses (1D and 2D NMR) and high resolution electrospray ionization mass spectroscopy (HRESIMS). The isolated compounds were screened on α-glucosidase inhibitory and the peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist activities, and the results showed that three phenylethanoid glycosides, verbascoside (9), leucosceptoside a (10), and isoacteoside (13), and two flavonoids, apigenin (22) and luteolin (26) showed potent inhibitory effects against α-glucosidase, with IC50 values in the range from 15 to 700 μM. In addition, four flavonoids apigenin 7-O-β-D-glucuronide (19), apigenin (22), luteolin (26), and quercetin (27) exhibited significant PPAR-γ agonistic activities with EC50 values in the range 2.3–24.9 μM.

A chromosome level reference genome of Diviner’s sage (Salvia divinorum) provides insight into salvinorin A biosynthesis

BackgroundDiviner’s sage (Salvia divinorum; Lamiaceae) is the source of the powerful hallucinogen salvinorin A (SalA). This neoclerodane diterpenoid is an agonist of the human Κ-opioid receptor with potential medical applications in the treatment of chronic pain, addiction, and post-traumatic stress disorder. Only two steps of the approximately twelve step biosynthetic sequence leading to SalA have been resolved to date.ResultsTo facilitate pathway elucidation in this ethnomedicinal plant species, here we report a chromosome level genome assembly. A high-quality genome sequence was assembled with an N50 value of 41.4 Mb and a BUSCO completeness score of 98.4%. The diploid (2n = 22) genome of ~ 541 Mb is comparable in size and ploidy to most other members of this genus. Two diterpene biosynthetic gene clusters were identified and are highly enriched in previously unidentified cytochrome P450s as well as crotonolide G synthase, which forms the dihydrofuran ring early in the SalA pathway. Coding sequences for other enzyme classes with likely involvement in downstream steps of the SalA pathway (BAHD acyl transferases, alcohol dehydrogenases, and O-methyl transferases) were scattered throughout the genome with no clear indication of clustering. Differential gene expression analysis suggests that most of these genes are not inducible by methyl jasmonate treatment.ConclusionsThis genome sequence and associated gene annotation are among the highest resolution in Salvia, a genus well known for the medicinal properties of its members. Here we have identified the cohort of genes responsible for the remaining steps in the SalA pathway. This genome sequence and associated candidate genes will facilitate the elucidation of SalA biosynthesis and enable an exploration of its full clinical potential.

Plant metabolites modulate social networks and lifespan in a sawfly.

Social interactions influence disease spread, information flow and resource allocation across species, yet heterogeneity in social interaction frequency and its fitness consequences are still poorly understood. Additionally, the role of exogenous chemicals, such as non-nutritive plant metabolites that are utilised by several animal species, in shaping social networks remains unclear. Here, we investigated how non-nutritive plant metabolites impact social interactions and the lifespan of the turnip sawfly, Athalia rosae. Adult sawflies acquire neo-clerodane diterpenoids ('clerodanoids') from non-food plants and this can serve as a defence against predation and increase mating success. We found intraspecific variation in clerodanoids in natural populations and laboratory-reared individuals. Clerodanoids could also be acquired from conspecifics that had prior access to the plant metabolites, which led to increased agonistic social interactions. Network analysis indicated increased social interactions in sawfly groups where some or all individuals had prior access to clerodanoids, while groups with no prior access had fewer interactions. The frequency of social interactions was influenced by the clerodanoid status of the focal individual and that of other conspecifics. Finally, we observed a shorter lifespan in adults with prior clerodanoid access when grouped with individuals without prior access, suggesting that social interactions to obtain clerodanoids have fitness costs. Our findings highlight the role of intraspecific variation in the acquisition of non-nutritional plant metabolites in shaping social networks. This variation influences individual fitness and social interactions, thereby shaping the individualised social niche.

Discovery of Novel Neo-Clerodane Derivatives as Potent Dual-Functional Antiosteoporosis Agents through Targeting Peroxisome Proliferator-Activated Receptor-γ.

A library of 31 natural neo-clerodanes isolated from Ajuga decumbens was assayed for antiosteoporosis. This results in 18 neo-clerodane osteoclastogenesis inhibitors, and compound 3 prevents bone loss in vivo. Further mechanistic studies demonstrated that these compounds inhibit osteoporosis by antagonizing peroxisome proliferator-activated receptor-γ (PPARγ). We designed and synthesized 17 compounds by chemically modifying the natural neo-clerodane 19 (highly potent and the major composition of A. decumbens extract) by means of structure-based drug design techniques. Among these neo-clerodane derivatives, compound 34 is the most potent osteoporosis inhibitor with a 46-fold improvement in inhibiting osteoclastogenesis (IC50 = 0.042 vs 1.92 μM), 11-fold increased activity in PPARγ antagonism (EC50 = 0.75 vs 8.35 μM), 66-fold enhancement in receptor affinity (KD = 0.27 vs 17.7 μM), and enhanced osteogenic promotion compared to 19. This underscores the potential of neo-clerodane diterpenoids as promising leads for osteoporosis treatment by targeting PPARγ.

Amarissinin F and its 16-epimer, two neo-clerodane diterpenoids from Salvia amarissima containing a 5-hydroxy-furan-2(5H)-one with MDR modulatory activity in cancer cells

Amarissinin F (1) and its 16-epimer (2) are two neo-clerodane diterpenoids isolated from the leaves and flowers of Salvia amarissima that occur as an unresolved epimeric mixture by chromatographic methods. The molecular structures of these compounds were deduced by the extensive analyses of their HRESIMS and their 1D/2D NMR data. Both compounds co-exist in the solid state as confirmed by single-crystal X-ray diffraction. In solution, both isolates appeared as the major compounds, which was corroborated by derivatization with Mosher reagents. However, the 1H and 13C NMR spectra demonstrated evidence for epimerization at C-20 and the possible interconversion of the 16-hydroxy-15,16-furanone to a 15-hydroxy-16,15-furanone, which was supported by a variable temperature 1H NMR analysis. The absolute configuration of compounds 1 and 2 was established by single-crystal X-ray diffraction and NMR. The cytotoxic effects of the isolated epimeric mixture (1 and 2) against a set of human cancer cells and the MDR modulatory activity in resistant MCF-7 breast cancer cells were explored.

Three neo-Clerodane Diterpenoids from Tinospora cordifolia Stems and Their Arginase Inhibitory Activities.

Three neo-clerodane diterpenoids, including two new tinocordifoliols A (1) and B (2) and one known tinopanoid R (3), were isolated from the ethyl acetate-soluble fraction of the 70% ethanol extract of Tinospora cordifolia stems. The structures were elucidated by various spectroscopic methods, including one dimensional (1D) and 2D-NMR, high resolution-electrospray ionization (HR-ESI)-MS, and electronic circular dichroism (ECD) data. The T. cordifolia extract and all isolated compounds 1-3 possessed arginase I inhibitory activities. Among them, 3 exhibited moderate competitive inhibition of human arginase I (IC50 = 61.9 µM). Furthermore, docking studies revealed that the presence of a β-substituted furan in 3 may play a key role in the arginase I inhibitory activities.

Development of AKR1B10 inhibitors from Ajuga nipponensis based on diseases and targets

Ten compounds (1-10) including one new neoclerodane diterpenoid (1) and nine known compounds were isolated from the whole plants of Ajuga nipponensis. Their structures were established by performing detailed analysis of NMR, the structure of 1 was determined using HRESIMS, 1D and 2D NMR, UV, and IR. Compounds 1 and 4-10 were isolated from Ajuga nipponensis for the first time. And it was the first time to report compounds 9 and 10 as natural products. Based on network pharmacology methods, 45 key targets were selected, which were compounds mapping to diseases. And compounds 2, 3, 7, and a (ajugacumbin B) exhibited excellent AKR1B10 inhibitory activities, with IC50 values of 53.05±0.75, 87.22±0.85, 61.85±0.66, and 85.19±1.02nM respectively, with Epalrestat used as the positive control (82.09±1.62nM). Additionally, the interaction between active compounds and AKR1B10 had been discussed according to the molecular docking results. Ultimately, the analysis of GO and KEGG enrichment indicated that the key signaling pathway of the active compounds may be related to prostate cancer. Our study results demonstrate the hypoglycemic and anti-tumor properties of A. nipponensis for the first time, and provide a comprehensive understanding of its application in traditional medicine. Furthermore, this article establishes a reference for further research on the optimized experimental design of novel AKR1B10 inhibitors.

Discovery of neo-Clerodane Diterpenoids from Ajuga campylantha as Neuroprotective Agents against Ferroptosis and Neuroinflammation.

Twelve new neo-clerodane diterpenoids, eight undescribed methoxy/ethoxy acetal analogues, and one new nor-iridane monoterpenoid were isolated from Ajuga campylantha. Their structures were elucidated using a combination of spectroscopic data, quantum chemical calculations, and X-ray crystallography. This research reveals the distinctive structural features of A. campylantha diterpenes, including distinct C rings and 4,18-double bonds, distinguishing them from diterpenes of other plants in the Ajuga genus. Compound 2 represents the first example of a 19(5→6)-abeo-clerodane formed through a Wagner-Meerwein rearrangement. The isolated compounds were assessed for their neuroprotective effects against RSL3-induced ferroptosis in HT22 cells and LPS-induced neuroinflammation in BV-2 cells. Notably, compound 7 inhibits ferroptosis (EC50 = 10 μM) with a potentially new mechanism of action. The preliminary structure-activity relationship studies revealed that the furan-clerodane diterpenoids possess potential ferroptosis inhibitory activity, while the lactone-clerodanes do not. This study represents the first report of furan-containing clerodanes within the Ajuga genus, providing fresh insights into the phytochemistry and pharmacological potential of A. campylantha.

Structure and anti-inflammatory activity of neo-clerodane diterpenoids from Scutellaria barbata

Herein, 13 previously undescribed neo-clerodane diterpenoids (1–13) and 27 known analogs (14–40) were isolated from the aerial parts of Scutellaria barbata. Absolute configurations of undescribed compounds were assigned based on single-crystal X-ray diffraction analysis and comparison of experimental and circular dichroism. All isolates were evaluated for the inhibition of nitric oxide generation induced by lipopolysaccharide in RAW 264.7 macrophages. Compound 36 was found to be the most active with an IC50 value of 10.6 μM. Structure–activity relations of these neo-clerodane diterpenoids revealed that the α, β-unsaturated-γ-lactone moiety with an exocyclic conjugated double bond was necessary for maintaining and increasing its activity. Further mechanistic studies show that compound 36 suppressed nitric oxide synthase enzymes (iNOS) expression without affecting iNOS activity. Additionally, compound 36 suppresses NF-κB signaling by inhibiting IκBα phosphorylation.

Neo-Clerodane and tiliifolane-type diterpenoids, and other constituents from Salvia pennellii

Two undescribed neo-clerodanes (1 and 2) and a novel tiliifolane (3) diterpenoids, were isolated from the leaves and flowers of Salvia pennellii. Wirikutin (1) and 15-epi-wirikutin (2) were isolated as a C-15 epimeric mixture containing a 5-hydroxyfuran-2(5H)-one moiety in the side chain of the neo-clerodane framework. Wixarikolide (3) was isolated as a Δ3(20) derivative of tiliifodiolide. The structures of compounds 1/2 were deduced through the analyses of their MS spectrometric, and the 1D/2D NMR data. The structure of 3 was determined directly by single crystal X-ray diffraction. The PTP1B inhibitory activity of compounds 1/2 was assayed.

Chemical constituents of Ajuga forrestii and their anti-ferroptosis activity

Six new neoclerodane diterpenoids (1–6), along with ten known compounds (7–16), were isolated from Ajuga forrestii. Their structures were elucidated by HRESIMS, 1D and 2D NMR, ECD calculation, and single-crystal X-ray diffraction analysis. The structure of a known neoclerodane diterpene ajudecunoid C (6) was revised based on the reported NMR empirical rules. All the isolates were evaluated for their inhibitory effect on RSL3-induced ferroptosis in HT22 mouse hippocampal neuronal cells. Among them, compounds 8, 9, and 12 significantly inhibited RSL3-induced ferroptosis with EC50 values of 0.45 μM, 0.076 μM, and 0.14 μM.

New neo-Clerodane Diterpenoids Isolated from Ajuga decumbens Thunb., Planted at Pingtan Island of Fujian Province with the Potent Anticancer Activity.

The aim of this study is to find the anticancer lead compounds or drug candidates from Chinese Traditional Plant Medicine of Ajuga decumbens Thunb. Ajuga decumbens Thunb. has been used in clinical for a long time in China and was selected in "Chinses Pharmacopoeia" (part I in 1977) for its wide spectrum biological activities: such as anticancer, antioxidant, antifeedant, antibacterial, anti-inflammatory, antihyperlipidemic, anti-cholinesterase and cytotoxicity activities. However, there are relatively fewer studies of Ajuga decumbens Thunb. that have been carried out till now. For some years, our research group focused on the discovery of new anticancer agents, so we studied the chemical compositions of Ajuga decumbens Thunb., planted in Pingtan island of Fujian Province, to discover new anticancer lead compounds or candidates from this Chinese Traditional Plant Medicine. The dichloromethane (DCM) extract was obtained in this work, and then this extract was used for silica gel column chromatography to obtain different polar fractions. Several similar fractions were combined according to TLC or HPLC analysis. The combined fractions were isolated by preparative TLC or preparative HPLC to obtain the pure compounds and HPLC was used to detect the purity. All isolated compounds were determined by NMR (1HNMR, 13CNMR, DEPT, HMBC, HSQC, 1H-1H COSY and NOESY), HRESIMS and single crystal X-ray diffraction methods. The in vitro anticancer activity was evaluated using CCK8 method. Seven compounds [three new compounds 1-3; and four known compounds (Ajugacumbins A, Ajugacumbin B, Ajugamarin A2 and Ajugamarin A1)] were isolated from Ajuga decumbens Thunb. in this work, and their structures were confirmed. The biological evaluation showed that 3 and Ajugamarin A1 exhibited potent in vitro anticancer activity both against A549 cell lines with IC50s=71.4 μM and 76.7 μM; and against Hela cell lines with IC50s=71.6 mM and 5.39×10-7 μM, respectively. Compounds (3 and Ajugamarin A1) can be regarded as the lead compounds for the development of anticancer agents.

Fatimanols Y and Z: two neo-clerodane diterpenoids from Teucrium yemense.

Teucrium yemense (Defl.), a medicinal plant, grows in Yemen and Saudi Arabia and is also referred to as Reehal Fatima. The plant has a long history of use in these regions for the treatment of diabetes, rheumatism, and renal conditions. Phytochemical investigation of the aerial parts of T. yemense yielded two previously undescribed neo-clerodane diterpenoids, namely fatimanols Y and Z (1 and 2) along with the known teulepicephin (3), 8-acetylharpagide (4) and teucardosid (5). Structure elucidation was accomplished from their 1D and 2D NMR, ECD, and MS characteristics as well as by comparing them to related reported compounds. The new molecules expand understanding of secondary metabolites of this genus. Compounds 1-5 did not show antimicrobial activity against various bacterial and fungal strains.

Phytochemical investigation of Teucrium pruinosum and biological potential assessment of the isolated diterpenoids

Twenty-three compounds of diverse classes including iridoid glycosides (1–3), phenylethanoids (4 and 14), neo-clerodane diterpenoids (5–9), abietene diterpenoids (10–12), sesquiterpenoids (13), steroids (15), and flavonoids (16–23) were isolated from the whole plant Teucrium pruinosum. Their structures were determined by analysis of spectoscopic data. The diterpenoids (5–12) were tested for antimicrobial, antiplasmodial, and anti-inflammatory activities. 7-O-acetylhorminone (10) showed significant activity against chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum with IC50 values of 7.1 and 12.0 μM, respectively, and anti-inflammatory activity via iNOS inhibition with an IC50 value of 0.55 ± 0.07 μM. This is the first report regarding the chemical constituents and biological activities of T. pruinosum. The chemotaxonomic significance of the isolated compounds is discussed.

Iridoids Isolation from a Phytochemical Study of the Medicinal Plant Teucrium parviflorum Collected in Iraqi Kurdistan.

Herbal medicines are still widely practiced in Kurdistan Region-Iraq, especially by people living in villages on mountainous regions. Among plants belonging to the genus Teucrium (family Lamiaceae), which are commonly employed in the Kurdish traditional medicine, we have analyzed, for the first time, the methanol and aqueous methanol extracts of T. parviflorum aerial parts. The plant is mainly used by Kurds to treat jaundice, liver disorders and stomachache. We aimed to determine the phytochemical profile of the extracts and the structures of the main components, so to provide a scientific rationale for the ancient use of the plant in the ethno-pharmacological field. TLC analysis of the two extracts on silica gel and reversed phase TLC plates, using different visualization systems, indicated similar contents and the presence of phenolics, flavonoids, terpenoids and sugars. The chlorophyll-free extracts exhibited weak/no antimicrobial activities against a panel of bacteria (MICs = 800–1600 µg/mL) and fungal strains (MICs ≥ 5 mg/mL). At the concentration of 600 µg/mL, the methanol extract showed moderate antiproliferative effects against A549 and MCF-7 cancer cell lines in the MTS assay. Moreover, both extracts exhibited a significant dose-dependent free radical scavenging action against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (EC50 = 62.11 and 44.25 μg/mL, respectively). In a phytochemical study, a high phenolic content (77.08 and 81.47 mg GAE/g dry extract, respectively) was found in both extracts by the Folin–Ciocalteu assay. Medium pressure liquid chromatographic (MPLC) separation of the methanol extract on a reversed phase cartridge eluted with a gradient of MeOH in H2O, afforded two bioactive iridoid glucosides, harpagide (1) and 8-O-acetylharpagide (2). The structures of 1 and 2 were established by spectral data, chemical reactions, and comparison with the literature. Interestingly, significant amounts of hepatotoxic furano neo-clerodane diterpenoids, commonly occurring in Teucrium species, were not detected in the extract. The wide range of biological activities reported in the literature for compounds 1 and 2 and the significant antiradical effects of the extracts give scientific support to the traditional use in Iraqi Kurdistan of T. parviflorum aerial parts for the preparation of herbal remedies.

Teuchamaedol A, a new neo-clerodane diterpenoid from the aerial parts of Teucrium chamaedrys

A new neo-clerodane diterpenoid, teuchamaedol A (1) was isolated from the EtOAc-soluble materials of the aerial parts of Teucrium chamaedrys. The structure of 1 was elucidated on the basis of spectral data. The absolute configuration of 1 was determined by modified Mosher’s method. Teuchamaedol A (1) is the first neo-clerodane diterpenoid possessing a tetrahydrofuran moiety without additional oxygen function.

Traditional uses, phytochemistry, and toxic potential of Teucrium polium L.: A comprehensive review

The aim of this study was to present information about the traditional use and phytochemistry of T. polium, to discuss contradictory views about chemotaxonomy and its toxic effect on liver and kidneys, and to make suggestions about controversial areas and gaps in the literature. Literature data showed that T. polium has toxic effect on kidney tissue. Moreover, in some of the studies on the liver and in all clinical reports, T. polium has also been proven to have toxic effect on the liver. The components responsible for toxicity are thought to be neo-clerodane diterpenoids. However, it has been reported that flavonoids and some polyphenols in the plant also show antioxidant and anti-inflammatory effects. It has been concluded that more attention should be paid to the use of this plant. More clinical studies are needed to better understand the effects of T. polium on the liver. The effects of the plant on blood serum parameters and histological changes on the liver tissue should be documented in more detail. It was also concluded that that regular consumption of T. polium should be avoided for long periods of time.

Identification of the Metabolites of Scutebarbatine A in Rat Plasma, Bile, Urine, and feces by Using Ultra-high-performance Liquid Chromatography Coupled with Q Exactive Hybrid Quadrupole-orbitrap High-resolution Mass Spectrometry.

Scutebarbatine A is a new neo-Clerodane Diterpenoid Alkaloids from Scutellaria barbata, which has many pharmacological effects, such as anti-tumor, antibacterial, and anti-inflammatory. However, there are no studies on the metabolism of Scutebarbatine A. The objective of this study is to explore the metabolism of Scutebarbatine A in the body, the bile, plasma, urine, and feces samples of rats after administration were investigated. The biological samples were investigated using ultra-high-performance liquid chromatography coupled with Q Exactive hybrid quadrupole-orbitrap high-resolution mass spectrometry (UPLC-Q-Orbitrap-HRMS). A total of 20 metabolites were identified: 16 phase I metabolites and 4 phase II metabolites. The main metabolic pathways were hydrolysis, oxidation, hydrogenation, dehydration, and combination with sulfate. This study further elucidates the metabolism of Scutebarbatine A in rats and provides a reference for the study of its pharmacodynamic material basis and pharmacological mechanism.

Comparative analysis of five Salvia species using LC-DAD-QToF

Several Salvia species, commonly known as sage plants, are an integral part of various culinary and folklore preparations for the perceived wide range of effects from organoleptic to psychological. As a result, many of these species are an integral part of botanical drug applications, highlighting the need for accurate identification and quality control for consumer’s safety. Five closely related Salvia species (S. officinalis, S. miltiorrhiza, S. divinorum, S. mellifera, and S. apiana) within a same botanical family were analyzed and differentiated using LC-QToF. Accurate mass measurement (<5 ppm) of protonated and deprotonated molecules together with resulting fragments and product ions allowed unequivocal or tentative identification of more than 180 compounds either by comparison with reference standards or literature data. The leaf part were identified based on various phenolic acids, flavonoids as well as di- and tri-terpenoids. Polyphenolics, viz., salvianolic A/B and rosmarinic acids in S. officinalis, lipophilic diterpenoids, viz., tanshinones in S. miltiorrhiza, abietatriene diterpenes and triterpenoids (ursane-/olean-type) in S. mellifera, and S. apiana were identified as characteristic, significant components. In comparison, salvinorins and divinorins representing a class of neoclerodane diterpenoids were detected only in S. divinorum. The presented methodology can successfully be applied to qualitatively assess sage-based ingredients in various finished products and formulations.

Neo-Clerodane Diterpenoids from the Aerial Parts of Scutellaria barbata with Anti-Inflammatory Activity.

The bioactivity-guided isolation on the Scutellaria barbata extract resulted in the purification of four undescribed neo-clerodane diterpenoids, scuttenlines A-D (1-4), alone with 20 known diterpenoids (5-24). The chemical structures of them were elaborated by extensive spectroscopic means, including 1D, 2D-NMR and HR-MS. The anti-inflammatory potential ability of 1-24 was screened in lipopolysaccharide-stimulated mouse RAW 264.7 cells. Scuttenline C (IC50 =1.9 μM) and 18 (IC50 =3.7 μM) exhibited potent activity to inhibit NO production.