ent-Kaurane diterpenoids from Isodon henryi and their anti-inflammatory activities.

Phytochemical investigation of the 70% ethanol extract of Isodon henryi Kudô afforded fifteen ent-kaurane diterpenoids, including nine previously undescribed compounds, named isohenolides C-K (1-9). Compounds 1-6 featured an unusual 6,7;8,15-diseco-7,20-olide ent-kaurane diterpenoid scaffold, in which 1 also possessed an 11,15-lactone ring while 2-6 all contained a free α-methylene-γ-carboxylic acid. Compound 6 was also a rare 6,8-cyclo-7,20-olide ent-kauranoid. Their structures were elucidated primarily by HRESIMS, 1D and 2D NMR spectroscopy, electronic circular dichroism and X-ray diffraction (Cu Kα) methods. Additionally, most compounds were also screened for anti-inflammatory actions against lipopolysaccharide-induced RAW 264.7 cells, and compounds 9 and 13 exhibited stronger nitric oxide inhibition, with IC50 values of 15.99 ± 0.75 and 18.19 ± 0.42 µM, respectively.

Structurally diverse ent-clerodanoids from the aerial parts of Isodon scoparius.

Scoparodane C (1), a diterpenoid with a rare 3,4-seco-3-nor-2,11-epoxy-ent-clerodane scaffold, was obtained from the aerial parts of Isodon scoparius, along with isocopariusines A-E (2-6), five ent-clerodanoids featuring a 5/6-fused ring system, and isocopariusines F-H (7-9), three common ent-clerodanoids. The structures of these previously undescribed compounds were established by a combination of spectroscopic analysis, X-ray diffraction, chemical derivatization, and quantum chemical calculation. Remarkably, isocopariusine B (3) showed strong resistance reversal activity against fluconazole-resistant Candida albicans.

Isoxerophilusins A and B, Two Novel Polycyclic Asymmetric Diterpene Dimers from Isodon xerophilus: Structural Elucidation, Modification, and Inhibitory Activities against α-Glucosidase.

Isoxerophilusins A (1) and B (2), two unprecedented diterpene heterodimers biogenetically from ent-atisanes and abietanes, were isolated from the rhizomes of Isodon xerophilus. Their structures were determined by extensive spectroscopic analysis and single-crystal X-ray diffraction. Selective esterification of 1 generated 11 new derivatives. All derivatives showed excellent α-glucosidase inhibitory activity in comparison to acarbose. Compounds 12 and 13 demonstrated significant inhibition against α-glucosidase with IC50 values of 4.92 and 3.83 µM, respectively.

The water and oridonin sources in the ice ribbons of Isodon rubescens.

To study the source and content change of oridonin in the ice ribbons, the contents of oridonin in the ice ribbons and bleeding sap of Isodon rubescens at different times were determined with RP-HPLC. The paraffin sectioning and electron microscopy imaging were performed to study the transport channel of oridonin in the stem. The results showed that there were abundant xylem rays and perfect pit pairs in the secondary xylem of I. rubescens stems. The oridonin content in the ice ribbons of I. rubescens stems was lower than that in the stem of I. rubescens and even decreased over time. The contents of oridonin in the bleeding sap of I. rubescens stems was equal to that in second-day ice ribbons and was lower than that in first-day ice ribbons. The water in the ice ribbons of I. rubescens stems originated from water absorbed by the roots from soil. This water was transported from the roots of I. rubescens to the stem and then transferred through efficient lateral conducting tissues to the surface of the stem. The oridonin in the phloem and cortex of I. rubescens stems dissolves in water originating from the soil and freezes in the form of ice ribbons below 0 °C.

Abietane diterpenoids from Isodon amethystoides and their biological activities.

Seven undescribed abietane diterpenoids [abietamethinols A-G (1-7)] were isolated from the twigs and leaves of Isodon amethystoides. Their structures were elucidated on the basis of spectroscopic methods including 2D NMR, and they were further confirmed by X-ray crystallographic data. Lophanic acid was considered as the precursor of 1-7 in the biosynthesis pathway hypothesis. These compounds were evaluated for their cytotoxic, anti-bacterial and anti-AIV (avian influenza virus) activities. Compound 5 showed 42.9% inhibitory activity against the cancer cell line SMMC-7721 at the concentration of 40 µM, 3 and 4 could inhibit the bacterial growth of Streptococcus sobrinus by 55.3% and 63.2% at the concentrations of 148.6 and 141.9 µM, respectively, and 4 was demonstrated with antiviral activity against AIV with the inhibitory effect of 68.4% at 25 µM.

Diterpenoids from the Aerial Parts of Isodon serra with Selective Cytotoxic Activity.

Four new diterpenoids, isodosins A-D (1-4), together with nine known compounds (5-13) were isolated and identified from the aerial parts of Isodon serra (Maxim.) Hara. The structures of the new diterpenoids were elucidated based on the analysis of HR-ESI-MS data, 1D/2D-NMR-spectroscopic data, and electronic circular dichroism (ECD) calculations. Cytotoxicities of compounds 2, 3, 5, 6, and 9 against the HepG2 and H1975 cell lines were evaluated with the MTT assay. As a result, compounds 2, 3, and 6 revealed higher levels of cytotoxicity against HepG2 cells than against H1975 cells. Moreover, compund 6 demonstrated the most efficacy in inhibiting the proliferation of HepG2 cells, with an IC50 value of 41.13 ± 3.49 µM. This effect was achieved by inducing apoptosis in a dose-dependent manner. Furthermore, the relationships between the structures and activities of these compounds are briefly discussed.

Six new diterpenoids with anti-inflammatory and cytotoxic activity from Isodon serra.

Diterpenoids occupy an important slot of the natural products diversity space with wide ranges of bioactivities and complex structures, providing potential applications for the development of therapeutics. In this study, we reported four new abietane-type diterpenoids viroxocin B-E (1-4), a new totarane-type diterpenoid viroxocin F (5), and a new sempervirane-type diterpenoid viroxocin G (6) along with four known compounds (7-10), isolated and identified from a widely used Traditional Chinese Medicine, Isodon serra (I. serra). Their structures were established by spectroscopic data analysis, experimental and calculated electronic circular dichroism (ECD) data, as well as X-ray diffraction analysis. Compounds 2, 5, 7, 8 and 10 exhibited promising anti-inflammatory activities in lipopolysaccharide (LPS)-induced RAW 267.4 cells, and their inhibition rates on NO production were more than 60% at 10 µM. Compound 7 showed cytotoxicity against human renal cell carcinoma 769P at 20 µM, the inhibition rate was 52.66%.

[Analysis of chemical compositions in different parts of Isodon japonicus using UPLC-Q-TOF-MS technique combined with chemometrics].

In order to analyze the similarities and differences of chemical compositions between the roots and stems and leaves of Isodon japonicus(IJ), this study utilized UPLC-Q-TOF-MS technology to systematically characterize its chemical compositions, analyzed and identified the structure of its main compounds, and established a method for simultaneous determination of its content by refe-rence substance. A total of 34 major compounds in IJ, including 14 reference compounds, were identified or predicted online. Moreover, an UPLC-UV content determination method was developed for 11 compounds [danshensu, caffeic acid, vicenin-2,(1S,2S)-globoidnan B, rutin,(+)-rabdosiin,(-)-rabdosiin,(1S,2S)-rabdosiin, shimobashiric acid C, rosmarinic acid, and pedalitin]. The method exhibited excellent separation, stability, and repeatability, with a wide linear range(0.10-520.00 µg·mL~(-1)) and high linearity(R~2>0.999). The average recovery rates ranged from 94.72% to 104.2%. The principal component analysis(PCA) demonstrated a clear difference between the roots and stems and leaves of IJ, indicating good separation by cluster. Furthermore, the orthogonal partial least squares discriminant analysis(OPLS-DA) model was employed, and six main differentially identified compounds were identified: rosmarinic acid, shimobashiric acid C, epinodosin, pedalitin, rutin, and(1S,2S)-rabdosiin. In summary, this study established a strategy and method for distinguishing different parts of IJ, providing a valuable tool for quality control of IJ and a basis for the ratio-nal utilization and sustainable development of IJ.

Multi-omics analysis of small RNA, transcriptome, and degradome to identify putative miRNAs linked to MeJA regulated and oridonin biosynthesis in Isodon rubescens.

Isodon rubescens has garnered much attention due to its anti-tumor or anti-cancer properties. However, little is known about the molecular mechanism of oridonin biosynthesis leveraging the regulatory network between small RNAs and mRNAs. In this study, the regulatory networks of miRNAs and targets were examined by combining mRNA, miRNA, and degradome. A total of 348 miRNAs, including 287 known miRNAs and 61 novel miRNAs, were identified. Among them, 51 miRNAs were significantly expressed, and 36 miRNAs responded to MeJA. A total of 3066 target genes were associated with 228 miRNAs via degradome sequencing. Multi-omics analysis demonstrated that 27 miRNA-mRNA pairs were speculated to be involved in MeJA regulation, and 36 miRNA-mRNA pairs were hypothesized to be involved in the genotype-dependence of I. rubescens. Furthermore, 151 and 7 miRNA-mRNA modules were likely engaged in oridonin biosynthesis as identified by psRNATarget and degradome sequencing, respectively. Some miRNA-mRNA modules were confirmed via RT-qPCR. Moreover, miRNAs targeting plant hormone signal transduction pathway genes were identified, such as miR156, miR167, miR393, and PC-3p-19822_242. Collectively, our results demonstrate for the first time that miRNAs are identified in I. rubescens, and laid a solid foundation for further research on the molecular mechanism of oridonin biosynthesis mediated by miRNA.

Dimeric ent-kauranoids isolated from Isodon japonica var. Glaucocalyx and their anti-inflammatory activities.

The phytochemical investigation of the aerial parts of Isodon japonica var. glaucocalyx afforded four undescribed (glaucocalyxin O-R, 1-4) and six known ent-kauranoids (5-10). Their structures were established using NMR and MS measurements. Compounds 1 and 2 are dimeric ent-kaurane-type diterpenoids. Moreover, the plausible biogenetic pathways for compounds 1 and 2 were proposed as Michael addition between two monomers. Eight compounds were assayed for their anti-inflammatory activity by evaluating NO production in LPS-induced RAW 267.4 cells, and compounds 7, 8 and 9 exhibited relatively remarkable anti-inflammatory activities at 10 µM.

The intramolecular SN2 reaction tautomeric ent-Kauranoids isolated from the aerial parts of Isodon amethystoides.

As our ongoing searching for the bioactive natural terpenoids, nine ent-kauranoids (1-9), including three previously undescribed ones (1, 2, and 9), were isolated from the aerial parts of Isodon amethystoides. Their structures were elucidated on the basis of spectroscopic data analysis, including NMR, MS, and ECD. Compounds 1 and 2 were a pair of tautomeric compounds, which was confirmed by the HPLC analysis and low temperature NMR testing. The underlying mechanism of the tautomer was proposed as an intramolecular SN2 reaction, which was explained by quantum chemical calculation. The HOMO-LUMO gap and the free energy revealed the spontaneous of the tautomeric of the 1 and 2. Additionally, the similar phenomena were also found in the two groups of known compounds 3 and 4 and 6 and 7, respectively. Apart from the tautomer, compounds 3 and 4 can be hydrolyzed into 5 through ester hydrolysis in CDCl3, while compounds 6, 7 can be hydrolyzed into 8 through ester hydrolysis. These phenomena were also confirmed through HPLC analysis and low temperature nuclear magnetic resonance tests and the mechanism was studied using quantum chemical calculation.

Guidongnins I-J: Two New 6,7-seco-7,20-Olide-ent-kaurene Diterpenes with Unusual Structures from Isodon rubescens.

Two undescribed ent-kaurene diterpenes, named guidongnins I (1) and J (2), were isolated from the medicinal plant Isodon rubescens. Compound 1 was determined to contain an unprecedented 23 carbons in the skeleton by bearing an extra isopropyl group at C-17 out of the diterpenoid parent structure, and compound 2 was the first example of 6,7-seco-7,20-olide-ent-kaurenes with two fused-tetrahydrofuran rings formed between C-6 and C-19/C-20 through oxygen bridges. Their structures, including their absolute configurations, were determined using the analyses of the spectroscopic and X-ray diffraction data. Guidongnins I (1) and J (2) were assessed for their anti-cancer activities against the growth of various cancer cell lines, and 2 displayed cytotoxic potency against HepG2 at IC50 27.14 ± 3.43 µM.

Network Pharmacology and Molecular Docking Reveal the Mechanism of Isodon ternifolius (D. Don) Kudo Against Liver Fibrosis.

Aim: Many studies have demonstrated the hepatoprotective or anti-fibrotic effects of Isodon ternifolius, but its pharmacological basis and mechanism remain unclear. In this study, we used in vitro models to validate the predicted results and revealed the potential mechanism of action and active ingredients through network pharmacology methods and molecular docking. Methods: The chemical components of Isodon ternifolius were identified by literatures. Potential targets of Isodon ternifolius were predicted by Swiss Target Prediction. The disease targets were collected through the databases of Gene Card. Common targets of Isodon ternifolius and liver fibrosis were obtained by online tool Venny 2.1. PPI protein interaction network was obtained using String database, and target protein interaction network was drawn using Cytoscape software. Signaling pathway enrichment analysis was performed on drug-disease targets with of DAVID database. Results: Twenty-one potential active ingredients and 298 potential targets were predicted by Swiss Target Prediction platform. Ninety pathways related to liver fibrosis were obtained by KEGG enrichment. The TLR4, MAPK and PI3K-Akt signaling pathways are mostly associated with liver fibrosis. Molecular docking techniques were used to validate the core target proteins TNF, Akt1, MAPK1, EGFR and TLR4 binding to the ingredients of Isodon ternifolius, which showed that a multitude of ingredients of Isodon ternifolius were able to bind to the above target proteins, especially 2α-hydroxy oleanolic acid and (-)-Lambertic acid. Our experimental validation results showed that Isodon ternifolius inhibited the activation of PI3K-Akt and ERK1/2 signaling pathways. Conclusion: Through a network pharmacology approach and in vitro cell assay, we predicted and validated the active compounds of Isodon ternifolius and its potential targets for LF treatment. The results suggest that the mechanism of Isodon ternifolius treating LF by inhibiting angiogenesis may be related to the ERK1/2 and PI3K/Akt signaling pathways.

[Effect of Isodon ternifolius-medicated serum on hepatic stellate cells based on TLR4/NF-κB/NLRP3 signaling pathway].

The present study aimed to investigate the inhibitory effect and mechanism of Isodon terricolous-medicated serum on lipopolysaccharide(LPS)-induced hepatic stellate cell(HSC) activation. LPS-induced HSCs were divided into a blank control group, an LPS model group, a colchicine-medicated serum group, an LPS + blank serum group, an I. terricolous-medicated serum group, a Toll-like receptor 4(TLR4) blocker group, and a TLR4 blocker + I. terricolous-medicated serum group. HSC proliferation was detected by methyl thiazolyl tetrazolium(MTT) assay. Enzyme-linked immunosorbent assay(ELISA) was used to measure type Ⅰ collagen(COL Ⅰ), COL Ⅲ, transforming growth factor-ß1(TGF-ß1), intercellular adhesion molecule-1(ICAM-1), α-smooth muscle actin(α-SMA), vascular cell adhesion molecule-1(VCAM-1), cysteinyl aspartate-specific proteinase-1(caspase-1), and monocyte chemotactic protein-1(MCP-1). Real-time PCR(RT-PCR) was used to detect mRNA expression of TLR4, IκBα, and NOD-like receptor thermal protein domain associated protein 3(NLRP3), nuclear factor-κB(NF-κB) p65, gasdermin D(GSDMD), and apoptosis-associated speck-like protein containing a CARD(ASC) in HSCs. Western blot(WB) was used to detect the protein levels of TLR4, p-IκBα, NF-κB p65, NLRP3, ASC, and GSDMD in HSCs. The results showed that I. terricolous-medicated serum could inhibit the proliferation activity of HSCs and inhibit the secretion of COL Ⅰ, COL Ⅲ, α-SMA, TGF-ß1, caspase-1, MCP-1, VCAM-1, and ICAM-1 in HSCs. Compared with the LPS model group, the I. terricolous-medicated serum group, the colchicine-medicated serum group, and the TLR4 blocker group showed down-regulated expression of p-IκBα, NLRP3, NF-κB p65, GSDMD, and ASC, and up-regulated expression of IκBα. Compared with the TLR4 blocker group, the TLR4 blocker + I. terricolous-medicated serum group showed decreased expression of TLR4, p-IκBα, NLRP3, NF-κB p65, GSDMD, and ASC, and increased expression of IκBα. In conclusion, I. terricolous-medicated serum down-regulates HSC activation by inhibiting the TLR4/NF-κB/NLRP3 signaling pathway.

Antiproliferative Activities of Diterpenes from Leaves of Isodon trichocarpus against Cancer Stem Cells.

Two new diterpenes named trichoterpene I (1) and trichoterpene II (2) were isolated from the extract from the leaves of Isodon trichocarpus together with 19 known diterpenes. Their chemical structures were elucidated on the basis of chemical and physicochemical properties. Among them, oridonin (3), effusanin A (4), and lasiokaurin (9) with the α,ß-unsaturated carbonyl moiety showed antiproliferative activities against breast cancer MDA-MB-231 and human astrocytoma U-251 MG cells [i.e., non-cancer stem cells (non-CSCs)] and their cancer stem cells (CSCs) isolated by sphere formation. In particular, compound 4 (IC50 = 0.51 µM) showed a higher antiproliferative activity against MDA-MB-231 CSCs than against MDA-MB-231 non-CSCs. The antiproliferative activity toward CSCs of compound 4 was equal to adriamycin (positive control, IC50 = 0.60 µM).

Di- and Triterpenoids from the Rhizomes of Isodon amethystoides and Their Anti-inflammatory Activities.

Amethystoidesic acid (1), a triterpenoid with an unprecedented 5/6/6/6 tetracyclic skeleton, and six undescribed diterpenoids, amethystoidins A-F (2-7), were isolated from the rhizomes of Isodon amethystoides along with 31 known di- and triterpenoids (8-38). Their structures were fully elucidated via extensive spectroscopic analysis including 1D and 2D NMR, high-resolution electrospray ionization mass spectrometry (HRESIMS), and electronic circular dichroism (ECD) calculations. Compound 1 is the first example of a triterpenoid possessing a rare ring system (5/6/6/6) derived from a contracted A-ring and the 18,19-seco-E-ring of ursolic acid. Compounds 6, 16, 21, 22, 24, and 27 significantly inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW264.7 cells, which could be partly mediated by the downregulation of LPS-induced inducible nitric oxide synthase (iNOS) protein expression.

Cyclobutane-Containing Meroditerpenoids, (+)-Isoscopariusins B and C: Structure Elucidation and Biomimetic Synthesis.

(+)-Isoscopariusins B (1) and C (2), two meroditerpenoids containing a 6/6/4 tricyclic carbon skeleton and seven continuous stereocenters, were identified from Isodon scoparius. The structures were determined by nuclear magnetic resonance analysis and concise biomimetic syntheses from readily available alkene 5 in seven and six steps, respectively. An intermolecular [2+2] photocycloaddition with cooperative catalysis of a Lewis acid and an Ir photocatalyst was used to construct a cyclobutane core with four stereogenic centers.

Cytotoxic C-20 non-oxygenated ent-kaurane diterpenoids from Isodon wardii.

Twenty new ent-kaurane diterpenoids, wardiisins A-T (1-20), along with two previously undescribed artefactual compounds (21 and 22) and twelve known analogues (23-34), were isolated from the aerial part of Isodon wardii. Their structures were elucidated by comprehensive analysis of spectroscopic data and single-crystal X-ray diffraction, and most of them were found to bear unusual C-12 oxygenation. Compounds 4, 7, 8, 19, 20, 21 exhibited remarkable cytotoxicity against the cancer cell lines HL-60, SMMC-7721, A-549, MDA-MB-231, and SW480, with IC50 values ranging from 0.3 to 5.2 µM. Moreover, 7 was found to induce G2/M cell cycle arrest and promote apoptosis in SW480 cell lines.

Identification and functional characterization of three cytochrome P450 genes for the abietane diterpenoid biosynthesis in Isodon lophanthoides.

MAIN CONCLUSION: We identify two ferruginol synthases and a 11-hydroxyferruginol synthase from a traditional Chinese medicinal herb Isodon lophanthoides and propose their involvement in two independent abietane diterpenoids biosynthetic pathways. Isodon lophanthoides is a traditional Chinese medicinal herb rich in highly oxidized abietane-type diterpenoids. These compounds exhibit a wide range of pharmaceutical activities, yet the biosynthesis is barely known. Here, we describe the screening and functional characterization of P450s that oxidize the abietane skeleton abietatriene. We mainly focused on CYP76 family and identified 12 CYP76AHs by mining the RNA-seq data of I. lophanthoides. Among the 12 CYP76AHs, 6 exhibited similar transcriptional expression features as upstream diterpene synthases, including root or leaf-preferential expression pattern and highly MeJA inducibility. These six P450s were considered as first-tier candidates and functionally characterized in yeast and plant cells. In yeast assays showed that both CYP76AH42 and CYP76AH43 were ferruginol synthases hydroxylating the C12 position of abietatriene, whereas CYP76AH46 was characterized as a 11-hydroxyferruginol synthase which catalyzes two successive oxidations at C12 and C11 of abietatriene. Heterologous expression of three CYP76AHs in Nicotiana benthamiana resulted in the formation of ferruginol. qPCR analysis showed CYP76AH42 and CYP76AH43 were mainly expressed in the root, which was consistent with the distribution of ferruginol in the root periderms. CYP76AH46 was primarily expressed in the leaves where barely ferruginol or 11-hydroxyferruginol was detected. In addition to distinct organ-specific expression pattern, three CYP76AHs exhibited different genomic structures (w or w/o introns), low protein sequence identities (51-63%) and were placed in separate subclades in the phylogenetic tree. These results suggest that the identified CYP76AHs may be involved in at least two independent abietane biosynthetic pathways in the aerial and underground parts of I. lophanthoides.

5-epi-ent-Kaurane diterpenoids from the aerial parts of Isodon eriocalyx and their anti-atherosclerotic potential.

The phytochemical investigation of the EtOAc extract from the aerial parts of Isodon eriocalyx afforded seventeen diterpenoids, including eight undescribed compounds. Eriocalyxins H-L have unique structural characteristics featuring a 5-epi-ent-kaurane diterpenoid scaffold with eriocalyxins H-K also possess an unusual 6,11-epoxyspiro-lactone ring while eriocalyxin L, a 1,7:3,20-diepoxy-ent kaurene, features an 1,7-oxygen linkage. The structures of these compounds were elucidated by spectroscopic data interpretation, and the absolute configurations of eriocalyxins H, I, L, and M were confirmed by single-crystal X-ray diffraction. The isolates were screened for their inhibitory activities against VCAM-1 and ICAM-1 at 5 µM. While eriocalyxin O, coetsoidin A and laxiflorin P were found to significantly inhibit both VCAM-1 and ICAM-1, 8 (17),13-ent-labdadien-15 â†’ 16-lactone-19-oic acid displayed evidently inhibitory effect against ICAM-1.