Highly Oxidized Germacranolides from Elephantopus tomentosus and the Configurational Revision of Some Previously Reported Analogues

Natural products targeting RAS by multiple mechanisms and its therapeutic potential in cancer: An update since 2020

RAS proteins, as pivotal signal transduction molecules, are frequently mutated and hyperactivated in various human cancers, closely associated with tumor cell proliferation, survival, and metastasis. Despite extensive research on RAS targeted therapies, developing effective RAS inhibitors remains a significant challenge. Natural products, endowed with unique chemical structures and diverse biological activities through long-term natural selection, have emerged as a vital resource for discovering novel RAS-targeted therapeutic drugs. This review focuses on the latest advancements in targeting RAS with natural products and categorizes these natural products based on their mechanisms of action. Additionally, we discuss the challenges faced by these natural products during clinical translation, including issues related to pharmacokinetics. Strategies such as combination therapy, structural optimization, and drug delivery systems are anticipated to enhance efficacy and overcome these challenges. Natural products targeting RAS by multiple mechanisms.

Sesquiterpenoids from the whole plants of Elephantopus mollis with cytotoxicity activities

Five new sesquiterpenoids (1-5), elephantmollides A-E, along with four known compounds (6-9), were isolated from the whole plants of E. mollis. Their planar structures were elucidated using the spectroscopic methods, including HRESIMS, IR, UV, and NMR (1H, 13C, DEPT, HSQC, HMBC, 1H-1H COSY). The relative configurations of them were partially deduced by the NOESY experiment, and the absolute configurations were assigned by comparing the calculated electronic circular dichroism (ECD) results with the experimental data. In addition, cytotoxic activities of 1-9 against HepG2 cells ware tested, and compounds 1-9 exhibited cytotoxic activities with IC50 values ranging from 6.7 to 25.8 μM.

Anti-liver tumor ingredient exploration and validation of Elephantopus tomentosus Linn. by combining in silico and in vitro experiments

Elephantopus tomentosus (ET) Linn. was reported to be an anti-tumor plant. However, the chemical composition of ET and its anti-tumor compounds and potential mechanisms still unclear. In this paper, UPLC-Q-TOF-MS/MS was firstly used to identified the ingredients in ET and UPLC was used to determine the main compounds of ET. Network pharmacology was applied to predict the potential mechanisms of anti-liver cancer. Anti-tumor nuclear activate compounds and targets of ET were obtained and the anti-liver cancer effect was validated on HepG2. Finally, Molecule docking, RT-qPCR, and western blotting were used for verification of the relationship between nuclear activate compounds and nuclear targets and the potential anti-cancer mechanisms. The result showed that 42 compounds were identified in ET, which consisted of sesquiterpene lactones, flavonoids, and phenylpropanoid compounds. Scabertopin (ST), chlorogenic acid, Isochlorogenic acid B, Isochlorogenic acid A and Isochlorogenic acid C were identified as main compounds and were determined as 0.426%, 0.457%, 0.159%, 0.701%, and 0.103% respectively. 24 compounds showed high pharmacokinetics and good drug-likeness. 520 overlapping targets of the ET compounds and liver cancer were collected. The targets were used for KEGG and GO analysis. GO enrichment analysis suggested that the targets of 24 active compound closed related to promote apoptosis, inhibit proliferation, and regulate oxidative levels. KEGG enrichment analysis suggested that pathway in cancer was enriched most and p38 MAPK/p53 signaling pathway, which closely related to promoting apoptosis and inhibiting proliferation. Compounds-targets analysis based on the parameter of Betweenness, Closeness, Information, Eigenvector, Degree, and component content indicated that ST was the nucleus anti-tumor active compound of ET. HepG2 was first used to validated the anti-tumor effect of ST and the result showed that ST significantly inhibited HepG2 proliferation with a low IC50 less than 5 μM. Nucleus active compound targets, including TP53, CASP3, BCL2, EGFR, TNF-a, IL-1β, and IL-6 were enriched based on degree value of PPI analysis. Molecule docking suggested that ST showed a good combination to TGFBR1 with the combination energy less than - 5 kcal/mol. RT-qPCR result also suggested that ST significantly medicated the mRNA expression level of TP53, CASP3, BCL2, EGFR, TNF-a, IL-1β, and IL-6. Protein expression of p-p38/p38 and p-p53/p53 notable increased by ST treatment. In conclude, combining with UPLC-Q-TOF-MS/MS qualitative analysis, UPLC quantitative analysis, network pharmacology analysis, molecule docking, and in vitro experiments on HepG2, we suggest that ST is an anti-tumor ingredient of ET, which may target to TGFBR1 and promote apoptosis and inhibited proliferation of HepG2 by activating p38 MAPK/p53 signaling pathway. ST can be regarded as a quality marker of ET.

MS/MS-based molecular networking discovery of sesquiterpenes from Carpesium abrotanoides L. with their cytotoxic and acetylcholinesterase inhibitory activity

Employing an MS/MS-based molecular networking-guided strategy, three new eudesmane-type sesquiterpenes (1-3) and one undescribed pseudoguaianolide sesquiterpene (8), along with four known eudesmane-type sesquiterpene lactones (4-7) were extracted and purified from the herbs of Carpesium abrotanoides L. Structural elucidation encompassed comprehensive spectroscopic analysis, NMR calculations, DP4+ analysis, and ECD calculations. The cytotoxicity activity of all isolates was evaluated against two human hepatoma carcinoma cells (HepG2 and Hep3B) in vitro. It was demonstrated that compounds 2 and 4 showed moderate cytotoxic against HepG2 and Hep3B cells. Furthermore, all compounds were evaluated for their acetylcholinesterase (AChE) inhibitory activity. Particularly noteworthy is that, in comparison to the positive control, compound 1 demonstrated significant AChE inhibition with an inhibition rate of 77.86%. In addition, the inhibitory mechanism of compound 1 were investigated by in silico docking analyze and molecular dynamic simulation.

Collective Synthesis of Highly Oxygenated (Furano)germacranolides Derived from Elephantopus mollis and Elephantopus tomentosus

Germacranolides, secondary metabolites produced by plants, have garnered academic and industrial interest due to their diverse and complex topology as well as a wide array of pharmacological activities. Molephantin, a highly oxygenated germacranolide isolated from medicinal plants, Elephantopus mollis and Elephantopus tomentosus, has exhibited antitumor, inflammatory, and leishmanicidal activities. Its chemical structure is based on a highly strained ten-membered macrocyclic backbone with an (E,Z)-dienone moiety, which is fused with an α-methylene-γ-butyrolactone and adorned with four successive stereogenic centers. Herein, we report the first synthesis of molephantin in 12 steps starting from readily available building blocks. The synthesis features the highly diastereoselective intermolecular Barbier allylation of the β,γ-unsaturated aldehyde with optically active 3-bromomethyl-5H-furan-2-one intermediate and ensuing Nozaki-Hiyama-Kishi (NHK) macrocyclization for the construction of the highly oxygenated ten-membered macrocyclic framework. This synthetic route enabled access to another germacranolide congener, tomenphantopin F. Furthermore, cycloisomerization of molephantin into 2-deethoxy-2β-hydroxyphantomolin could be facilitated by irradiation with ultraviolet A light (λmax=370 nm), which opened a versatile and concise access to the related furanogermacranolides such as EM-2, phantomolin, 2-O-demethyltomenphantopin C, and tomenphantopin C.

The specialized sesquiterpenoids produced by the genus Elephantopus L.: Chemistry, biological activities and structure-activity relationship exploration

The genus Elephantopus L. is a valuable resource rich in sesquiterpenoids with structural diversity and various bioactivities, showing great potential for applications in medicinal field and biological industry. Up to now, over 129 sesquiterpenoids have been isolated and identified from this plant genus, including 114 germacrane-type, 7 guaianolide-type, 5 eudesmane-type, 1 elemanolide-type, and 2 bis-sesquiterpenoids. These sesquiterpenoids were reported to show a diverse range of pharmacological properties, including cytotoxic, anti-tumor, anti-inflammatory, antimicrobial, and antiprotozoal. Consequently, some of them were identified as active scaffolds in the design and development of drugs. Considering that there is currently no overview available that covers the sesquiterpenoids and their biological activities in the Elephantopus genus, this article aims to comprehensively review the chemical structures, biosynthetic pathways, pharmacological properties, and structure-activity relationship of sesquiterpenoids found in the Elephantopus genus, which will establish a theoretical framework that can guide further research and exploration of sesquiterpenoids from Elephantopus plants as promising therapeutic agents.

A highly oxidized germacranolide from elephantopus tomentosus inhibits the growth of hepatocellular carcinoma cells by targeting EGFR in vitro and in vivo

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide, with high mortality and poor prognosis. WBDC-1 is a novel highly oxidized germacranolide from the Elephantopus tomentosus in our previous work, which has excellent anti-HCC activity, but the detailed mechanism is still unclear. In this study, we found that WBDC-1 was able to inhibit the proliferation and colony formation of Hep3B and HepG2 cells, as well as the cell migration ability and EMT. In addition, WBDC-1 showed no obvious toxicity to normal liver epithelial cells L-02. The potential targets of WBDC-1 were predicted by network pharmacology, and the following verified experiments showed that WBDC-1 exerted anti-HCC effect by targeting EGFR. Mechanismly, subsequent biological analysis showed that WBDC-1 can inhibit EGFR and its downstream RAS/RAF/MEK/ERK and PI3K/AKT signaling pathways. Overexpression of EGFR reversed the anticancer properties of WBDC-1. Consistent with in vitro experiments, WBDC-1 was able to inhibit tumor growth and was non-toxic in xenograft tumor models. In summary, this study revealed a potential tumor suppressive mechanism of WBDC-1 and provided a novel strategy for HCC treatment. It also laid a foundation for further research on the anti-tumor effect of highly oxidized germacranolides.

New caffeoyl derivatives with potent DPPH radical scavenging activity from Elephantopus tomentosus

Eight new caffeoyl derivatives, elephantomentosides A-H (1 - 8), together with ten known ones (9 - 18), were isolated from the whole plant of Elephantopos tomentosus L. Their structures were elucidated using detailed spectroscopic analysis. Structurally, compounds 1 - 8 are composed of β-D-glucopyranose, and almost all of the substituent positions are at the C-1' and C-4' of glucopyranose. The anti-inflammatory and antioxidant activities of all isolated compounds were evaluated in vitro. Compounds 9-10, 13-15, and 17-18 exhibited significant DPPH scavenging capacity with IC50 values in the range of 10.01-25.07 μM, in comparison with Vc (IC50, 17.98 μM).

Stereochemical insights into structurally diverse lignanamides from the herbs of Solanum lyratum Thunb

A chemical investigation of Solanum lyratum Thunb. (Solanaceae) afforded six pairs of enantiomeric lignanamides consisting of twelve undescribed compounds, along with two undescribed racemic mixtures, and the separations of the enantiomers were accomplished by chiral-phase HPLC. The structures of these undescribed compounds were elucidated by the analysis of spectroscopic data, NMR and electronic circular dichroism calculations. All isolated compounds were assessed for neuroprotective activities in H2O2-induced human neuroblastoma SH-SY5Y cells, and acetylcholinesterase (AChE) inhibitory activities. Among tested isolates, some enantiomeric lignanamides exhibited conspicuous neuroprotective effects and AChE inhibitory effect.

Four Pairs of Neuroprotective Aryldihydronaphthalene-Type Lignanamide Enantiomers from the Herbs of Solanum lyratum

Four pairs of aryldihydronaphthalene-type lignanamide enantiomers were isolated from Solanum lyratum (Solanaceae). The enantiomeric separation was accomplished by chiral-phase HPLC, and five undescribed compounds were elucidated. Analysis by various spectroscopy and ECD calculations, the structures of undescribed compounds were illuminated. The neuroprotective effects of all compounds were evaluated using H2 O2 -induced human neuroblastoma SH-SY5Y cells and AchE inhibition activity. Among them, compound 4 a exhibited remarkable neuroprotective effects at high concentrations of 25 and 50 μmol/L comparable to Trolox. Compound 1 a showed the highest AchE inhibition with the IC50 value of 3.06±2.40 μmol/L. Molecular docking of the three active compounds was performed and the linkage between the compounds and the active site of AchE was elucidated.

HSQC-based small molecule accurate recognition technology discovery of diverse cytotoxic sesquiterpenoids from Elephantopus tomentosus L. and structural revision of molephantins A and B

Elephantopus tomentosus L. is a perennial herb taxonomically belonging to the family Asteraceae, which has been used as a folk medicine for the treatment of hepatobiliary diseases. Sesquiterpenoids from this plant have broad biological activities, including anti-tumor, anti-inflammatory, and antibacterial effects. In this study, fifteen structurally diverse sesquiterpenoids comprised 11 germacrane-type and 4 eudesmane-type sesquiterpenoids were prioritized to isolated from Elephantopus tomentosus L. based on the HSQC-based Small Molecule Accurate Recognition Technology (SMART) strategy. Among them, ten sesquiterpenoids were previously unreported, and their structures were elucidated by spectroscopic data, computational methods, single-crystal X-ray diffraction crystallographic data or electronic circular dichroism calculations. In addition, the structures of two known sesquiterpenoids, molephantin A and B, which were reported to possess E-geometry for the Δ¹⁽¹⁰⁾ double bond, were revised by reanalyzing their spectroscopic and X-ray crystallographic data. Some sesquiterpenoids exhibited significant cytotoxic activities against Hep3B and HepG2 cell lines.