Cytotoxic biflavones from Stellera chamaejasme

Terpenoids from the Roots of Stellera chamaejasme (L.) and Their Bioactivities

An undescribed diterpene, stellerterpenoid A (1), and two undescribed sesquiterpenoids, stellerterpenoids B and C (2-3), together with six known compounds, prostratin (4) stelleraguaianone B (5), chamaejasnoid A (6), auranticanol L (7), wikstronone C (8), and oleodaphnone (9), were isolated from the roots of Stellera chamaejasme L. Their structures were elucidated by extensive spectroscopic data (1D, 2D NMR, IR, UV, and HR-ESI-MS). The absolute configuration of 1-3 was elucidated based on ECD calculation. Among them, stellerterpenoid A was a rare 13, 14-seco nortigliane diterpenoid and stellerterpenoid B was a guaiacane-type sesquiterpenoid with an unusual 1, 2-diketone moiety. The known stelleraguaianone B (5) exhibited moderate activity for suppressing NO production in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages cells with an IC50 value of 24.76 ± 0.4 μM. None of the compounds showed anti-influenza virus or anti-tumor activity in vitro.

Daphnane-type diterpenoids from Stellera chamaejasme L. and their inhibitory activity against hepatocellular carcinoma cells

Daphnane-type diterpenoids, which are scarce in nature, exhibit potent growth-inhibitory activities against various cancer cells. To identify more daphnane-type diterpenoids, the phytochemical components in the root extracts of Stellera chamaejasme L. were analysed in this study using the Global Natural Products Social platform and the MolNetEnhancer tool. Three undescribed 1α-alkyldaphnane-type diterpenoids (1-3; named stelleradaphnanes A-C) and 15 known analogues were isolated and characterised. The structures of these compounds were determined using ultraviolet and nuclear magnetic resonance spectroscopy. The stereo configurations of the compounds were determined using electronic circular dichroism. Next, the growth-inhibitory activities of isolated compounds against HepG2 and Hep3B cells were examined. Compound 3 exhibited potent growth-inhibitory activities against HepG2 and Hep3B cells with half-maximal inhibitory concentration values of 9.73 and 15.97 μM, respectively. Morphological and staining analyses suggested that compound 3 induced apoptosis in HepG2 and Hep3B cells.

Chemical constituents from leaves of Jatropha curcas

Objective

To investigate the chemical constituents from the leaves of Jatropha curcas and evaluate their inhibition on lipopolysaccharide (LPS)-activated BV-2 microglia cells.

Methods

The n-BuOH extract of the leaves of J. curcas was isolated by macroporous adsorption resin, silica gel, ODS, column chromatography and semi-preparative HPLC. The structures of the compounds were identified by MS, NMR, ECD, and other spectroscopic methods. In addition, anti-neuroinflammatory effects of isolated compounds were evaluated by measuring the production of nitric oxide (NO) in over-activated BV-2 cells.

Results

Seventeen compounds, including (7R,8S)-crataegifin A-4-O-β-D-glucopyranoside (1), (8R,8'R)-arctigenin (2), arctigenin-4'-O-β-D-glucopyranoside (3), (-)-syringaresinol (4), syringaresinol-4'-O-β-D-glucopyranoside (5), (-)-pinoresinol (6), pinoresinol-4'-O-β-D-glucopyranoside (7), buddlenol D (8), (2R,3R)-dihydroquercetin (9), (2S,3S)-epicatechin (10), (2R,3S)-catechin (11), isovitexin (12), naringenin-7-O-β-D-glucopyranoside (13), chamaejasmin (14), neochamaejasmin B (15), isoneochamaejasmin A (16), and tomentin-5-O-β-D-glucopyranoside (17) were isolated and identified. Compounds 2, 4 and 8 significantly inhibited the release of NO in BV-2 microglia activated by LPS, with IC50 values of 18.34, 29.33 and 26.30 μmol/L, respectively.

Conclusion

Compound 1 is a novel compound, and compounds 2, 3, 8, 14-17 are isolated from Jatropha genus for the first time. In addition, the lignans significantly inhibited NO release and the inhibitory activity was decreased after glycosylation.

Chamaejasmenin E from Stellera chamaejasme induces apoptosis of hepatocellular carcinoma cells by targeting c-Met in vitro and in vivo

Hepatocellular carcinoma (HCC), the most prevalent liver cancer, is considered one of the most lethal malignancies with a dismal outcome. There is an urgent need to find novel therapeutic approaches to treat HCC. At present, natural products have served as a valuable source for drug discovery. Here, we obtained five known biflavones from the root of Stellera chamaejasme and evaluated their activities against HCC Hep3B cells in vitro. Chamaejasmenin E (CE) exhibited the strongest inhibitory effect among these biflavones. Furthermore, we found that CE could suppress the cell proliferation and colony formation, as well as the migration ability of HCC cells, but there was no significant toxicity on normal liver cells. Additionally, CE induced mitochondrial dysfunction and oxidative stress, eventually leading to cellular apoptosis. Mechanistically, the potential target of CE was predicted by database screening, showing that the compound might exert an inhibitory effect by targeting at c-Met. Next, this result was confirmed by molecular docking, cellular thermal shift assay (CETSA), as well as RT-PCR and Western blot analysis. Meanwhile, CE also reduced the downstream proteins of c-Met in HCC cells. In concordance with above results, CE is efficacious and non-toxic in tumor xenograft model. Taken together, our findings revealed an underlying tumor-suppressive mechanism of CE, which provided a foundation for identifying the target of biflavones.

Bioactivity of natural biflavonoids in metabolism-related disease and cancer therapies

Natural biflavonoids, such as amentoflavone, bilobetin, ginkgetin, isoginkgetin, taiwaniaflavone, morelloflavone, delicaflavone, hinokiflavone, and other derivatives (~ 40 biflavonoids), are isolated from Selaginella sp., Ginkgo biloba, Garcinia sp., and several other species of plants. They are able to exert therapeutic benefits by regulating several proteins/enzymes (PPAR-γ, CCAAT/enhancer-binding protein α [C/EBPα], STAT5, pancreatic lipase, PTP1B, fatty acid synthase, α-glucosidase [AG]) and insulin signaling pathways (via PI3K-AKT), which are linked to metabolism, cell growth, and cell survival mechanisms. Deregulated insulin signaling can cause complications of obesity and diabetes, which can lead to cognitive disorders such as Alzheimer's, Parkinson's, and dementia; therefore, the therapeutic benefits of these biflavones in these areas are highlighted. Since biflavonoids have shown potential to regulate metabolism, growth- and survival-related protein/enzymes, their relation to tumor growth and metastasis of cancer associated with angiogenesis are highlighted. The translational role of biflavones in cancer with respect to the inhibition of metabolism-related processes/pathways, enzymes, or proteins, such as STAT3/SHP-1/PTEN, kinesins, tissue kallikreins, aromatase, estrogen, protein modifiers, antioxidant, autophagy, and apoptosis induction mechanisms, are discussed. Finally, considering their observed bioactivity potential, oral bioavailability studies of biflavones and related clinical trials are outlined.

Guaiane-type sesquiterpenoids from the roots of Stellera chamaejasme L. and their neuroprotective activities

Nine undescribed guaiane-type sesquiterpenoids stelleraterpenoids A‒I, along with seven reported congeners, were isolated and identified from the 70% EtOH extract of the roots of Stellera chamaejasme L. Their chemical structures were elucidated on the basis of various spectral data. The relative configurations were determined by their NOESY spectra and comparison between their experimental and calculated NMR data. The absolute configurations were established by the comparison between the experimental and calculated ECD spectra and further by X-ray single-crystal diffraction analysis. The neuroprotective effects of these compounds on the H₂O₂-induced damage in human neuroblastoma SH-SY5Y cells were evaluated. Stelleraguaianone B exhibited the better activity with 71.62% cell viability compared to the positive control Trolox (65.05%) at 12.5 μM, which might be achieved by inhibiting the apoptosis of SH-SY5Y cells based on an annexin V-FITC/PI staining experiment.

Biflavanones, Chalconoids, and Flavonoid Analogues from the Stem Bark of Ochna holstii

Two new biflavanones (1 and 2), three new bichalconoids (3-5), and 11 known flavonoid analogues (6-16) were isolated from the stem bark extract (CH3OH-CH2Cl2, 7:3, v/v) of Ochna holstii. The structures of the isolated metabolites were elucidated by NMR spectroscopic and mass spectrometric analyses. The crude extract and the isolated metabolites were evaluated for antibacterial activity against Bacillus subtilis (Gram-positive) and Escherichia coli (Gram-negative) as well as for cytotoxicity against the MCF-7 human breast cancer cell line. The crude extract and holstiinone A (1) exhibited moderate antibacterial activity against B. subtilis with MIC values of 9.1 μg/mL and 14 μM, respectively. The crude extract and lophirone F (14) showed cytotoxicity against MCF-7 with EC50 values of 11 μg/mL and 24 μM, respectively. The other isolated metabolites showed no significant antibacterial activities (MIC > 250 μM) and cytotoxicities (EC50 ≥ 350 μM).

Biflavonoid-rich fraction from Daphne pseudomezereum var. koreana Hamaya exerts anti-inflammatory effect in an experimental animal model of allergic asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Daphne pseudomezereum var. koreana Hamaya is distributed in the Gangwon-do of South Korea and is traditionally used to treat chronic inflammatory diseases, including rheumatoid arthritis.

AIM OF THE STUDY

We investigated the anti-inflammatory effect of biflavonoid-rich fraction (BF) obtained from an extract of D. pseudomezereum leaves on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and mouse model of ovalbumin (OVA)-induced allergic asthma.

MATERIALS AND METHODS

Neochamaejasmin B (NB) and chamaejasmin D (CD) were spectroscopically characterized as major components of BF obtained from the leaves of D. pseudomezereum. RAW264.7 cells pretreated with NB, CD and BF and activated by LPS (500 ng/ml) were used to assess the anti-inflammatory effects of these materials in vitro. To evaluate the protective effect of BF on allergic asthma, female BALB/c mice were sensitized to OVA by intraperitoneal (i.p.) injection and treated with BF by oral administration (15 or 30 mg/kg).

RESULTS

Pretreatment with BF inhibited LPS-stimulated nitric oxide (NO), TNF-α and IL-6, and led to upregulation of heme oxygenase-1 (HO-1) in RAW264.7 macrophages. Orally administered BF significantly inhibited the recruitment of eosinophils and the production of IL-5, IL-6, IL-13 and MCP-1 as judged by the analysis of BALF from OVA-induced asthma animal model. BF also decreased the levels of IgE in the serum of asthmatic mice. BF suppressed the influx of inflammatory cells into nearby airways and the hypersecretion of mucus by the airway epithelium of asthmatic mice. In addition, the increase in Penh in asthmatic mice was reduced by BF administration. Furthermore, BF led to Nrf2 activation and HO-1 induction in the lungs of mice.

CONCLUSIONS

These data have shown the anti-asthmatic effects of BF, and therefore we expect that BF may be a potential candidate as a natural drug/nutraceutical for the prevention and treatment of allergic asthma.

Isochamaejasmin induces toxic effects on Helicoverpa zea via DNA damage and mitochondria-associated apoptosis

BACKGROUND

Stellera chamaejasme L. is a poisonous plant with rich resources and is thus highly valuable in terms of new pesticide development. Isochamaejasmin (ICM), one of the main ingredients in S. chamaejasme has drawn much attention owing to its antitumour properties. However, the toxicity and mode of action of ICM on insects are still not clear. In this article, the larva and neuronal cell (AW1) of Helicoverpa zea were used to clarify the insecticidal activity of ICM as well as its toxic mechanism at the cellular level.

RESULTS

The results confirmed that ICM has potential toxicity against H. zea both in vivo and in vitro via time- and dose-dependent manners. Moreover, we found that ICM caused DNA damage and increased the levels of γH2AX and OGG1 in AW1 cells. Results also showed decline in the mitochondrial membrane potential (MMP), upregulation of Bax/Bcl-2 expression resulting in the release of cytochrome c into the cytosol, activation of caspase-3/9, and cleavage of poly ADP-ribose polymerase (PARP) as a result of exposure to ICM. Additionally, a dose-dependent rise in the reactive oxygen species (ROS) levels, accumulation of a lipid peroxidation product, and inactivation of antioxidant enzymes were found in ICM-treated cells.

CONCLUSION

These findings confirmed the insecticidal activity of ICM. Furthermore, the results revealed that ICM could cause DNA damage and induce apoptosis via the mitochondrial pathway in AW1 cells. This study provides the basic information needed to understand the toxicity and mechanisms of action of ICM, which could potentially be used to develop it as a new insecticide.

Potent Cytotoxic Natural Flavonoids: The Limits of Perspective

BACKGROUND

Besides the numerous biologic and pharmacologic functions in the human body that act as potent antioxidants, flavonoids (flavones, flavanones, flavonols, flavanols and isoflavones) are noted as cancer preventive or therapeutic agents.

METHODS

This review summarizes the published data using PubMed, Science Direct, and Scopus.

RESULTS

In this context, recognition and introduction of the most active cytotoxic flavonoids as promising agents for cancer therapy gives insight for further evaluations. However, there are some critical points that may affect the entering of flavonoids as active cytotoxic phytochemicals in the clinical phase. Issues such as the abundance of active species in nature, the methods of extraction and purification, solubility, pharmacokinetic profile, presence of the chiral moieties, method of synthesis, and structure modification may limit the entry of a selected compound for use in humans. Although plenty of basic evidence exists for cytotoxic/antitumor activity of the versatility of flavonoids for entry into clinical trials, the above-mentioned concerns must be considered.

CONCLUSION

This review is an effort to introduce cytotoxic natural flavonoids (IC50< 10 µM) that may have the potential to be used against various tumor cells. Also, active constituents, molecular mechanisms, and related clinical trials have been discussed as well as the limitations and challenges of using flavonoids in clinic.

Neochamaejasmin A extracted from Stellera chamaejasme L. induces apoptosis involving mitochondrial dysfunction and oxidative stress in Sf9 cells

To explore the toxicity mechanisms of neochamaejasmin A (NCA), extracted from Stellera chamaejasme L., we first evaluated its cytotoxicity on the Spodoptera frugiperda (Sf9) cell line. The results confirmed that NCA inhibited Sf9 cell survival in both a dose- and time-dependent manner. Then, intracellular biochemical assays showed that NCA induced apoptosis in Sf9 cells. Evidence of apoptosis was confirmed by morphological changes and the activation of caspases-3/9. We also observed that NCA induced apoptosis via mitochondrial-dependent intrinsic apoptotic pathway by upregulating cytochrome c and proapoptotic protein (Bax) and downregulating the mitochondrial membrane potential (MMP) and antiapoptotic protein (Bcl-2). Moreover, we found a dose-dependent increase in reactive oxygen species (ROS), accumulation of lipid peroxidation product and an inactivation of the antioxidant enzymes in treated cells. Additionally, the cleavage of PARP and G2/M arrest were also detected in Sf9 cells exposed to NCA. These findings provide critical information that NCA effectively induced apoptosis in Sf9 cells through mitochondrial pathways.

Discovery of selective cystathionine β-synthase inhibitors by high-throughput screening with a fluorescent thiol probe

A high-throughput assay was developed to identify inhibitors of cystathionine β-synthase (CBS), which is one of three key enzymes involved in H₂S biosynthesis. Screening of 6491 natural compounds identified several selective CBS inhibitors, which suppressed the proliferation of HT29 cancer cells, with IC₅₀ values of less than 10 μM.

Two new peroxy fatty acids with antibacterial activity from Ophioglossum thermale Kom

Two new peroxy fatty acids, thermalic acids A (1) and B (2), together with eight known compounds, (3β)-methyl-3-hydroxy-urs-11-en-28 oate (3), luteolin (4), quercetin (5), 3-methoxyquercetin (6), ophioglonol (7), ophioglonol 4'-O-α-D-glucopyranoside (8), pedunculosumoside B (9), syringol (10), were isolated from the herba of Ophioglossum thermale Kom. The structures of 1 and 2 were identified by HRESIMS, EIMS, 1D and 2D NMR, and electronic circular dichroism (ECD) spectra. Both two acids exhibited potential antibacterial activities against Staphylococcus aureus, Bacillus subtilis, and Escherichia coli. This is the first report of peroxy fatty acids isolated from herbaceous plants of Ophioglossaceae.

Chamaejasmin B exerts anti-MDR effect in vitro and in vivo via initiating mitochondria-dependant intrinsic apoptosis pathway

Multidrug resistance (MDR) is the main obstacle limiting the efficacy of cancer chemotherapy. Looking for novel anti-MDR agents is an important way to conquer cancer drug resistance. We recently established that chamaejasmin B (CHB), a natural biflavone from Stellera chamaejasme L., is the major active component. However, its anti-MDR activity is still unknown. This study investigated the anti-MDR effect of CHB and the underlying mechanisms. First, it was found that CHB inhibited the growth of both sensitive and resistant cell lines in vitro, and the average resistant factor (RF) of CHB was only 1.26. Furthermore, CHB also displayed favorable anti-MDR activity in KB and KBV200 cancer cells xenograft mice. Subsequent study showed that CHB induced G0/G1 cell cycle arrest as well as apoptosis both in KB and in resistant KBV200 cancer cells. Further studies showed that CHB had no influence on the level of Fas/FasL and activation of procaspase 8. However, CHB-induced apoptosis was dependent on the activation of caspase 9 and caspase 3. Moreover, CHB treatment resulted in the elevation of the Bax/Bcl-2 ratio, attenuation of mitochondrial membrane potential (ΔΨ_m), and release of cytochrome c and apoptosis-inducing factor from mitochondria into cytoplasm both in KB and KBV200 cells. In conclusion, CHB exhibited good anti-MDR activity in vitro and in vivo, and the underlying mechanisms may be related to the activation of mitochondrial-dependant intrinsic apoptosis pathway. These findings provide a new leading compound for MDR therapy and supply a new evidence for the potential of CHB to be employed in clinical trial of MDR therapy in cancers.