Cucurbitane-type triterpenes from the tubers of Hemsleya penxianensis and their bioactive activity

Recent progress on triterpenoid derivatives and their anticancer potential

Cancer poses a significant global public health challenge, with commonly used adjuvant or neoadjuvant chemotherapy often leading to adverse side effects and drug resistance. Therefore, advancing cancer treatment necessitates the ongoing development of novel anticancer agents with diverse structures and mechanisms of action. Natural products remain crucial in the process of drug discovery, serving as a primary source for pharmaceutical leads and therapeutic advancements. Triterpenoids are particularly compelling due to their complex structures and wide array of biological activities. Recent research has demonstrated that naturally occurring triterpenes and their derivatives have the potential to serve as promising candidates for new drug development. This review aims to comprehensively explore the anticancer properties of triterpenoids and their synthetic analogs, with a focus on recent advancements. Various aspects, such as synthesis, phytochemistry, and molecular simulation for structure-activity relationship analyses, are summarized. It is anticipated that triterpenoid derivatives will emerge as notable anticancer agents following further investigation into their mechanisms of action and in vivo studies.

Cucurbitane triterpenes from Hemsleya chinensis tubers and their anti-inflammatory activities

Six new cucurbitane-type triterpenes, hemchinins A-F (1-6), together with thirteen known ones (7-19) were isolated from ethyl acetate extraction of Hemsleya chinensis tubers. Compounds 1-2 were a group of cucurbitane triterpenes possessing an infrequent pentacyclic framework. Their structures were established by comprehensive UV, IR, HRMS, 1D/2D NMR, and ECD analyses. Bioassay results showed that most isolated compounds exhibited anti-inflammatory actions, in which compounds 13 and 15 exhibited stronger activities at 6.25 μM, with NO inhibition rates of 49.00 ± 0.05% and 48.40 ± 0.10%, respectively.

Cucurbitane triterpenoid entities derived from Hemsleya penxianensis triggered glioma cell apoptosis via ER stress and MAPK signalling cross-talk

In the present study, six new cucurbitane type compounds, including three triterpenoids hemsleyacins P-R (6-7, 13) and three cucurbitane-type triterpenoid glycosides hemsleyaosides L-N (15-17), along with seventeen known cucurbitacin analogues were separated from the root tuber of Hemsleya penxianensis and elucidated based on NMR and HRESIMS. Then, 23 analogues of three types, namely, polyhydroxy-type (I) (1-7), monohydroxy-type (II) (8-13), and glycosides-type (III) (14-23), were assessed for their antitumor activity and structure-activity relationship analysis (SAR). We determined temozolomide (TMZ)-resistant GBM cell was the most sensitive to the tested compounds, and found hemsleyaoside N (HDN) displayed the best antineoplastic potency. Furthermore, we confirmed the anti-glioma activity of HDN in patient-derived recurrent GBM strains, GBM organoid (GBO) and orthotopic nude mouse models. Investigations exploring the mechanism made clear that HDN induced synchronous activation of UPR and MAPK signaling, which triggered deadly ER stress and apoptosis. Taken together, the potent antitumor activity of HDN warrants further comprehensive evaluation as a novel anti-glioma agent.

Inhibitory Effects of Cucurbitane-Type Triterpenoids from Momordica charantia Fruit on Lipopolysaccharide-Stimulated Pro-Inflammatory Cytokine Production in Bone Marrow-Derived Dendritic Cells

The bitter melon, Momordica charantia L., was once an important food and medicinal herb. Various studies have focused on the potential treatment of stomach disease with M. charantia and on its anti-diabetic properties. However, very little is known about the specific compounds responsible for its anti-inflammatory activities. In addition, the in vitro inhibitory effect of M. charantia on pro-inflammatory cytokine production by lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells (BMDCs) has not been reported. Phytochemical investigation of M. charantia fruit led to the isolation of 15 compounds (1-15). Their chemical structures were elucidated spectroscopically (one- and two-dimensional nuclear magnetic resonance) and with electrospray ionization mass spectrometry. The anti-inflammatory effects of the isolated compounds were evaluated by measuring the production of the pro-inflammatory cytokines interleukin IL-6, IL-12 p40, and tumor necrosis factor α (TNF-α) in LPS-stimulated BMDCs. The cucurbitanes were potent inhibitors of the cytokines TNF-α, IL-6, and IL-12 p40, indicating promising anti-inflammatory effects. Based on these studies and in silico simulations, we determined that the ligand likely docked in the receptors. These results suggest that cucurbitanes from M. charantia are potential candidates for treating inflammatory diseases.

A link between chemical structure and biological activity in triterpenoids

BACKGROUND

Plants with triterpenoid compounds in nature have various biological activities and are reported in many scientific works of literature. Triterpenoids are compounds that draw the attention of scientists because of their wide source, wide variety, high medicinal value, and anti-tumor properties. However, a lack of approach to understand their chemical structures has limited the fundamental comprehension of these compounds in cancer cell therapy.

OBJECTIVE

To seek anti-cancer activity of the structures of triterpenoid compounds and their derivatives, we summarized a number of plants and their derivatives that are a source of potential novel therapeutic anti-cancer agents.

METHODS

This work focuses on relevant 1036 patents and references that detail the structure of organic compounds and derivatives for the treatment of tumors.

RESULT

Compared to tetracyclic triterpenoid, pentacyclic triterpenoid has contributed more to improve the autophagic signaling pathways of cancer cells.

CONCLUSION

The heterogenous skeleton structure of triterpenoids impaired the programmed cell death signaling pathway in various cancers.

Cucurbitacin IIb induces apoptosis and cell cycle arrest through regulating EGFR/MAPK pathway

Epidermal growth factor receptor (EGFR) is considered as a valid target in the clinical trials of anticancer therapy and tyrosine kinase inhibitors (TKIs) of EGFR are approved for cancer treatments. In present work, cucurbitacin IIb (CuIIb) was confirmed to exhibit the proliferation inhibitory activity in A549 cells. CuIIb induced apoptosis via STAT3 pathway, which was mitochondria-mediated and caspase-dependent. CuIIb also suppressed the cell cycle and induced G2/M phase cell cycle arrest. CuIIb was capable of suppressing the signal transmitting of the EGFR/mitogen-activated protein kinase (MAPK) pathway which was responsible for the apoptosis and cell cycle arrest. Homogeneous time-resolved fluorescence (HTRF) analysis demonstrated that the kinase activity of EGFR was inhibited by CuIIb. Molecular docking suggested that the CuIIb-EGFR binding fundamentally depends on the contribution of both hydrophobic and hydrogen-bonding interactions. Hence CuIIb may serve as a potential EGFR TKI.

Lipid-Lowering Activities of Cucurbitacins Isolated from Trichosanthes cucumeroides and Their Synthetic Derivatives

In the ongoing efforts to discover natural cholesterol-lowering compounds, dihydrocucurbitacin B, isolated from Trichosanthes cucumeroides roots, was found to promote LDL uptake by upregulating LDLR protein in a PCSK9-dependent process. In this study, an in-depth investigation of T. cucumeroides roots afforded 27 cucurbitacins (1-27), including seven new cucurbitacins (1-7), and their structures were elucidated by spectroscopic data analyses. In order to gain insight into their structure-activity relationship, cucurbitacin derivatives (B1-11 and DB1-11) were synthesized. Evaluation of lipid-lowering activities of these cucurbitacins by an LDL uptake assay in HepG2 cells revealed that most of the compounds improved the LDL uptake rate, among which hexanorisocucurbitacin D (6) and isocucurbitacin D (21) exhibited the highest activities (rates of 2.53 and 2.47, respectively), which were comparable to that of the positive control, nagilactone B (rate of 2.07). According to a mechanistic study by Western blot analysis, compounds 6 and 21 dose-dependently increased LDLR protein levels and reduced PCSK9 protein levels, representing promising new lipid-lowering drug candidates.

Novel cucurbitane-type triterpene saponins from Hemsleya amabilis

The rhizomes of the medicinal plant Hemsleya amabilis (Cucurbitaceae) yielded three new cucurbitane-type triterpene saponins xuedanosides K-M (1-3) by silica gel column, ODS column, and pre-HPLC techniques. The structure was determined by spectroscopic analysis and examined alongside existing data from prior studies. Compounds 1-3 were evaluated for cytotoxic activity against HeLa and HCT-8 human cancer cell lines and showed significant cytotoxicity with IC₅₀ values of 2.01-14.56 and 8.94-27.48 μM, respectively.

Plant triterpenoid saponins: biosynthesis, in vitro production, and pharmacological relevance

The saponins are a diverse class of natural products, with a broad scale distribution across different plant species. Chemically characterized as triterpenoid glycosides, they posses a 30C oxidosqualene precursor-based aglycone moiety (sapogenin), to which glycosyl residues are subsequently attached to yield the corresponding saponin. Based on the chemically distinct aglycone moieties, broadly, they are divided into triterpenoid saponins (dammaranes, ursanes, oleananes, lupanes, hopanes, etc.) and the sterol glycosides. This review aims to present in detail the biosynthesis patterns of the different aglycones from a common precursor and their glycosylation patterns to yield the functionally active glycoside. The review also presents recent advances in the pharmacological activities of these saponins, particularly as potent anti-neoplastic pharmacophores, antioxidants, or anti-viral/antibacterial agents. Since alternate production pedestals for these pharmacologically important triterpenes via cell and tissue cultures are an attractive option for their sustainable production, recent trends in the variety and scale of in vitro production of plant triterpenoids have also been discussed.

Polyhydroxy cucurbitane triterpenes from Hemsleya penxianensis tubers

Ten new cucurbitane triterpenoids, hemsleyacins A-J (1-10), together with three known cucurbitane triterpenoids, dihydrocucurbitacin F (11), scandenogenin D (12), and jinfushanencin F (13), were separated from ethanolic tuber extracts of Hemsleya penxianensis. The absolute configurations of the new compounds were established based on NMR, HRESIMS, and CD spectra. Compounds 7 and 10-12 were evaluated in terms of their antifeedant activity against Plutella xylostella larvae. The result showed that compound 10 exhibited potent antifeedant activity against P. xylostella larvae after 48 h of treatment. Furthermore, the MTT test showed that compound 11 exhibited potent inhibition toward the UMUC-3 and T24 cell lines with IC₅₀ values of 29.12 and 35.62 μM, respectively, compared to the positive control cisplatin IC₅₀ values of 8.27 and 13.72 μM. Western blot analysis revealed that compound 11 treatments substantially inhibited the phosphorylation of IκBα.

Five New Cucurbitane-Type Triterpenoid Glycosides from the Rhizomes of Hemsleya penxianensis with Cytotoxic Activities

Five new cucurbitane-typetriterpenoid glycosides, named Xuedanoside F–J (1–5), were obtained from the rhizomes of Hemsleya penxianensis (Xue dan), which belongs to the family of Cucurbitaceae. These new compounds were elucidated byspectroscopic analysis, including 1D, 2D NMR, and HR-ESI-MS spectra. Additionally, all the isolates were evaluated for cytotoxicity against three human cancer cell lines (Hela, MCF-7, and A-549) with the IC₅₀ ranging from 2.25 to 49.44 µM in vitro with treatment 48 h and showed low cytotoxicity in human normal liver L-02 cells (IC₅₀ > 50 µM). Compound 5 showed the most significant cytotoxic activity with the IC₅₀ value of 2.25, 4.72, and 5.33 µM in 48 h, respectively.

Molecular Networking-Based Analysis of Cytotoxic Saponins from Sea Cucumber Holothuria atra

The saponin composition of a specimen of black sea cucumber, Holothuria atra collected in the Persian Gulf was studied by a combined approach including LC-MS/MS, Molecular Networking, pure compound isolation, and NMR spectroscopy. The saponin composition of Holothuria atra turned out to be more complex than previously reported. The most abundant saponins in the extract (1⁻4) were isolated and characterized by 1D- and 2D-NMR experiments. Compound 1 was identified as a new triterpene glycoside saponin, holothurin A5. The side chain of the new saponin 1, unprecedented among triterpene glycosides, is characterized by an electrophilic enone function, which can undergo slow water or methanol addition under neutral conditions. The cytotoxic activity of compounds 1⁻4, evaluated on the human cervix carcinoma HeLa cell line, was remarkable, with IC50 values ranging from 1.2 to 2.5 µg/mL.

Novel Cucurbitane Triterpenes from the Tubers of Hemsleya amabilis with Their Cytotoxic Acitivity

Chemical research of the medicinal plant Hemsleya amabilis (Cucurbitaceae) yielded five new cucurbitane-type triterpenes hemslelis A–E (1–5) by silica gel column, ODS column, and semi-HPLC techniques. Their structures were determined by spectroscopic analysis and examined alongside existing data from prior studies. Compounds 1–5 were evaluated for their cytotoxic activities against three human tumor cell lines, Hela, HCT-8, and HepG-2, with the IC₅₀ ranging from 5.9 to 33.9 μM compared to Cisplatin.