Unprecedented diterpenoid dimers with soluble epoxide hydrolase inhibitory effect from Euphorbia fischeriana.

Biseuphoids A (1) and B (2), two unprecedented ent-abietane-type diterpenoid dimers linked by monomeric blocks through C-17-C-12' and C-17-C-11', respectively, were isolated from Euphorbia fischeriana, along with their biogenesis related diterpenoid monomers, 17-hydroxyjolkinolide B (3), caudicifolin (4), and fischeriabietane C (5). Their structures were elucidated by extensive spectroscopy assisted by quantum chemical NMR and ECD calculations. The unusual dimeric skeletons are possibly derived from the adduct of diterpenoid monomers through Michael-like reactions. The novel dimers 1 and 2 exhibited inhibitory activities on soluble epoxide hydrolase (sEH) with IC50 values of 8.17 and 5.61 µM, respectively. Molecular dynamics studies illustrated that both 1 and 2 can occupy the catalytic pocket of sEH by forming stable hydrogen bonds with the key amino acid residues including Gln384, Asn378, Pro361, Ala365, Asn366, and Asn472.

Cytotoxic diterpenoid dimer containing an intricately caged core from Euphorbia fischeriana.

Bislangduoids A and B, a novel class of dimeric diterpenoids based on ent-abietanes tethered by C-17-C-15' bridge, were identified as trace components from a traditional Chinese medicine Euphorbia fischeriana (Langdu). Bislangduoid A features a highly oxidized scaffold incorporating a cage-like pentacyclic core. Their structures were elucidated by extensive spectroscopic techniques, electronic circular dichroism, and NMR calculations. The biosynthetic pathway for the dimeric skeleton and the unique caged moiety via Michael and acetal-formation reactions was proposed. Bislangduoid A showed pronounced cytotoxicity against HepG2 cells through the mitochondria-dependent apoptosis pathway.

The nature compound dehydrocrenatidine exerts potent antihepatocellular carcinoma by destroying mitochondrial complexes in vitro and in vivo.

Cumulative evidence indicates that mitochondria dysfunction plays an important role in tumour treatment. Given the limited efficacy and toxicity of current mitochondria-targeted drugs, research into effective mitochondria-targeted anticancer agents remains an irresistible general trend. In this study, it was found that dehydrocrenatidine (DEC), a ß-carbolin alkaloid isolated from Picrasma quassiodes, displays a promising growth inhibitory effect in vitro and in vivo by inducing apoptosis of hepatocellular carcinoma (HCC) cells. Mechanistically, we provided that the possible target of DEC against HCC cells was determined by isobaric labels for relative and absolute quantification assay and validated them using further experiments. The results suggested that DEC can target and regulate the function of mitochondrial complexes I, III and IV, affecting oxidative phosphorylation and ultimately leading to mitochondrial dysfunction to exert its anti-HCC effects. In addition, the combination of DEC and sorafenib showed a synergistic effect and was also associated with mitochondrial dysfunction. Importantly, DEC did not show significant toxicity in mice. This study provided a new insight into underlying mechanisms in DEC-treated HCC cells, suggesting that DEC might be a mitochondrial targeting lead compound.

Bisfischoids A and B, dimeric ent-abietane-type diterpenoids with anti-inflammatory potential from Euphorbia fischeriana Steud.

Two undescribed ent-abietane-type diterpenoid dimers with nonacyclic backbone formed by intermolecular [4 + 2] cycloaddition into a spirocyclic skeleton, bisfischoids A (1) and B (2), along with a known one fischdiabietane A (3), were identified from Euphorbia fischeriana Steud. Their structures were elucidated by extensive spectroscopic analysis, ECD and NMR calculation combined with DP4+ probability analysis, as well as X-ray diffraction. The anti-inflammatory potential of dimers 1-3 were examined using their inhibitory effects on soluble epoxide hydrolase (sEH), which revealed that 1 and 2 exhibited promising activities with inhibition constant (Ki) of 3.20 and 1.95 µM, respectively. Further studies of molecular docking and molecular dynamics indicated that amino acid residue Tyr343 in the catalytic cavity of sEH was the key site for their inhibitory function.

Alisma genus: Phytochemical constituents, biosynthesis, and biological activities.

The genus Alisma contains 11 species distributed worldwide, of which at least two species (A. orientale [Sam.] Juzep. and A. plantago-aquatica Linn.) have been used as common herbal medicines. Secondary metabolites obtained from the genus Alisma are considered to be the material basis for the various biological functions and medicinal applications. In this review, we mainly focused on the recent investigations of secondary metabolites from plants of the genus Alisma and their biological activities, with the highlighting on the diversity of the chemical structures, the biosynthesis of interesting secondary metabolites, the biological activities, and the relationships between structures and bioactivities.

The identification of alkaloids from the stems of Picrasma quassioides via computer-assisted structure elucidation and quantum chemical calculations.

Four new alkaloids (1-4) and one known alkaloid were isolated from the stems of Picrasma quassioides. The structures of these isolated compounds were elucidated by spectroscopic analyses, a combination of computer-assisted structure elucidation software (ACD/Structure Elucidator) and gauge-including atomic orbital (GIAO) calculation of 1 D NMR data. All compounds were evaluated for their cytotoxic activities against hepatocellular carcinoma HepG2 and Hep3B cells. However, they did not show obvious inhibitory activities.[Figure: see text].

A novel 15-spiro diterpenoid dimer from Andrographis paniculata with inhibitory potential against human carboxylesterase 2.

The phytochemical investigation of Andrographis paniculata resulted in the isolation of a novel 15-spiro diterpenoid dimer bisandrographolide G (1). Its structure was determined by 1D and 2D NMR, HRESIMS, electronic circular dichroism (ECD), and TD DFT calculations of ECD spectra. It showed potent inhibitory activity against human carboxylesterase 2 (CES 2) with an IC50 value of 4.61 ± 0.23 µM, and it was defined as a mixed-competitive type inhibitor with a Ki value of 8.88 µM based on the inhibition kinetics result. This finding gave us a hit to develop new generation of human CES 2 inhibitors.

Inula japonica ameliorated bleomycin-induced pulmonary fibrosis via inhibiting soluble epoxide hydrolase.

Pulmonary fibrosis is a progressive, irreversible, and fatal fibrotic lung disease with a high mortality and morbidity, and commonly nonresponsive to conventional therapy. Inula japonica Thunb. is a traditional Chinese medicine, known as "Xuan Fu Hua" in Chinese, and has been widely applied to relieve cough and dyspnea and eliminate retained phlegm with a long history. In this study, we aimed to evaluate the anti-fibrosis effect and action mechanism of I. japonica extract (IJE) for the treatment of bleomycin (BLM)-induced pulmonary fibrosis in mice. IJE treatment significantly restored BLM-induced alterations in body weight loss and lung function decline, decreased the collagen deposition induced by BLM in lung tissues, and inhibited fibrotic and inflammatory factors, such as α-SMA, TGF-ß1, TNF-α, IL-6, COX-2, NF-κB, and GSK3ß, in a dose-dependent manner. We found that IJE could enhance the concentration of 8,9-epoxyeicosatrienoic acid (8,9-EET) and decrease concentrations of 8,9-dihydroxyeicosatrienoic acid (8,9-DHET), 11,12-DHET, and 14,15-DHET in BLM-induced mice. Meanwhile, IJE suppressed protein and mRNA expression levels of soluble epoxide hydrolase (sEH), and significantly displayed the inhibition of sEH activity with an IC50 value of 0.98 µg/mL. Our results indicated that IJE exerted remarkable anti-fibrosis effect on BLM-induced pulmonary fibrosis in mice via inhibiting sEH activity, resulting in the regulation of GSK3ß signaling pathway. Our findings revealed the underlying action mechanism of I. japonica, and suggested that I. japonica could be regarded as a candidate resource for the treatment of pulmonary fibrosis.

Protostane-type triterpenoids as natural soluble epoxide hydrolase inhibitors: Inhibition potentials and molecular dynamics.

The inhibition of soluble epoxide hydrolase (sEH) is a promising therapeutic approach to treat inflammation and other disorders. In our present investigation on searching for sEH inhibitors from traditional Chinese medicines, we found that Alisma orientale displayed inhibition of sEH. We constructed a small library of protostane-type triterpenoids (1-25) isolated from A. orientale, and screened their inhibitory activities. Alismanin B (1), 11-deoxy-25-anhydro alisol E (4), 11-deoxy alisol B (5), and 25-O-ethyl alisol A (15) displayed concentration-dependently inhibitory activities against sEH with IC50 values from 3.40 ± 0.57 µM to 9.57 ± 0.88 µM. 11-Deoxy-25-anhydro alisol E (4) and 11-deoxy alisol B (5) were defined as mixed-type competitive inhibitors with Ki values of 12.6 and 3.48 µM, respectively, based on the result of inhibition kinetics. The potential interaction mechanism of 11-deoxy alisol B (5) with sEH was analyzed by molecular docking and molecular dynamics, revealing that amino acid residues Trp336 and Tyr466 were vital for its inhibitory activity.

Growth of pediatric recipients after renal transplantation from small pediatric deceased donors weighing less than 15 kg.

RTx is currently the best treatment for children with ESRD. This study retrospectively analyzed the outcomes of growth after RTx using the pediatric-to-pediatric allocation strategy and some factors that may affect it. From March 2012 to August 2016, 8 en bloc and 38 single pediatric RTxs were performed at our center using organs from small pediatric deceased donors (weight < 15 kg). Growth before and after RTx was analyzed according to the height-for-age z-score at RTx, the 3-year follow-up, and adulthood and compared between the procedures. The chi-square test and multiple linear regression analysis were used for statistical analyses. Overall, 79.2% of children were diagnosed with chronic nephritis before RTx; 14.6% of cases were due to congenital urinary tract malformation, and 6.3% of cases were due to unknown causes. All grafts and patients survived postoperatively. The mean estimated GFRs were 92.7 ± 28.6 mL/min/1.73 m2 , 100.9 ± 32.3 mL/min/1.73 m2 , and 110.1 ± 34.8 mL/min/1.73 m2 at 1, 2, and 3 years' postoperatively, respectively. The children's postoperative growth and development, particularly during the first year postoperatively, improved but were negatively correlated with age and the height-for-age z-score before RTx. The growth of children after RTx was moderate and accelerated during prepubescence. The rate of post-RTx growth during the first year postoperatively was unrelated to the recipient's sex or duration of dialysis (P > 0.05) but was negatively correlated with age at RTx (r = -0.349, P = 0.043). Future studies on the long-term outcomes are still needed.

Quassinoids from Picrasma quassioides and Their Neuroprotective Effects.

Quassinoids are a class of highly oxygenated degraded triterpenoids exclusively discovered from plants of the Simaroubaceae family. In this study, eight new (1-8) and 15 known quassinoids (9-23) were isolated from an extract of the stems of Picrasma quassioides. The structures were elucidated by spectroscopic analysis and electronic circular dichroism spectra combined with quantum chemical calculations. Compounds 4 and 5 represent the first examples of 18-nor-quassinoids from P. quassioides. All isolates were screened for their neuroprotective activities toward H2O2-induced cell damage in SH-SY5Y cells. Further study revealed that the potential protective activities of these compounds appeared to occur via the suppression of cell apoptosis and downregulation of caspase-3 activation.

Guaiane-Type Sesquiterpenoids from the Roots of Daphne genkwa and Evaluation of Their Neuroprotective Effects.

Chromatographic purification of the roots of Daphne genkwa led to 11 new guaiane-type sesquiterpenoids (1-11), named genkwanoids A-K, and six known analogues (12-17). A comprehensive set of spectroscopic methods including IR, UV, HRESIMS, and 1D/2D NMR were used to elucidate the structures and relative configurations of 1-11. The absolute configurations were determined by the optical rotation calculations and the modified Mosher's method. The possible biosynthetic pathways for 1-11 are proposed. Furthermore, the neuroprotective effects of 1-17 on H2O2-induced damage in human neuroblastoma SH-SY5Y cells were screened using an MTT assay. Compounds 9, 10, and 16 exhibited moderate neuroprotective effects, with survival rates of 79.34%, 79.94%, and 75.64% after treatment with 12.5 µM, values that were comparable to the positive control, Trolox (78.65%). Furthermore, annexin V-FITC/PI staining of cells treated with 9, 10, and 16 showed that the neuroprotective effects of these compounds may arise from inhibiting cell apoptosis.

Uncarialins A-I, Monoterpenoid Indole Alkaloids from Uncaria rhynchophylla as Natural Agonists of the 5-HT1A Receptor.

Nine new monoterpenoid indole alkaloids, uncarialins A-I (1-9), were isolated from Uncaria rhynchophylla as well as 14 known analogues (10-23). Their structures were determined by HRESIMS, 1D and 2D NMR, and experimental and calculated electronic circular dichroism data. Compounds 5, 7, 15, and 22 displayed significant agonistic effects against the 5-HT1A receptor with EC50 values of 2.2 ± 0.1, 0.1 ± 0.1, 1.6 ± 0.3, and 2.0 ± 0.5 µM, respectively. The mechanisms of action of these four compounds with the 5-HT1A receptor were investigated by molecular docking, and the results suggested that amino acid residues Asp116, Thr196, Asn386, and Tyr390 played critical roles in the observed activity of the above-mentioned compounds.

New tirucallane triterpenoids from Picrasma quassioides with their potential antiproliferative activities on hepatoma cells.

Seven new tirucallane-type triterpenoids (1-7), kumuquassin A-G, along with 20 known analogues (8-27) were isolated from the stems of Picrasma quassioides. The structures and the absolute configurations of new compounds were elucidated by spectroscopic data, electronic circular dichroism (ECD) spectroscopic analyses and quantum ECD calculations. Notably, kumuquassin A (1) contains a rare Δ17, 20 double bond, kumuquassin B (2) is the first example of tirucallane triterpenoid possessing a 5/3 biheterocyclic ring system at the side chain. All the compounds were screened for the cytotoxicity against two human hepatoma cell lines, HepG2 and Hep3B, and several compounds exhibited promising activity. The most potential compound 3 was selected for cell cycle analysis, which showed that 3 could cause an accumulation of HepG2 cells at subG1 peak. Annexin V-FITC/PI staining further confirmed that compound 3 caused death of hepatoma cells through apoptosis induction.

Effects of Enantiomerically Pure ß-Carboline Alkaloids from Picrasma quassioides on Human Hepatoma Cells.

Four pairs of ß-carboline enantiomers (1A: /1B: -4A: /4B: ), 2 ß-carboline derivatives (5:  - 6: ) with a single enantiomeric configuration, together with 2 known achiral congeners (7:  - 8: ) were isolated from the stems of Picrasma quassioides. Their structures were elucidated on the basis of extensive spectroscopic analyses and quantum mechanical calculations. Compound 5: possesses a 4,5-seco ß-carboline framework and represents the first example of this type of ß-carboline alkaloids from nature. A possible biosynthetic pathway is proposed to generate the racemate 4: and the enantiomerically pure compounds 5: and 6: . All isolates were screened for their cytotoxicity against hepatocellular carcinoma Hep3B and HepG2 cells, which revealed that enantiomeric compounds 4A: and 4B: had distinctive effects in HepG2 cells. Further investigation showed that 4B: could induce apoptosis in HepG2 cells.

Enantiomeric neolignans from Picrasma quassioides exhibit distinctive cytotoxicity on hepatic carcinoma cells through ROS generation and apoptosis induction.

Three pairs of enantiomeric neolignans 1a/1b-3a/3b were isolated from the stems of Picrasma quassioides, and separated successfully by chiral-phase HPLC. Their structures were established by comprehensive spectroscopic analyses as well as ECD spectroscopy. The in vitro cytotoxicity of the isolates was evaluated against human hepatocellular carcinoma HepG2 and Hep3B cells. Among them, 1 and its enantiomers 1a/1b, 3 and 3a/3b displayed similar cytotoxicity in pair-wise comparison against HepG2 and Hep3B cells, and the similar effects of 2 and 2a/2b were found in Hep3B cells. Interestingly, 2a and 2b had different cytotoxic activities on HepG2 cells with IC50 values of 35.6 µM and 104.4 µM, respectively. In addition, 2 exerted middle cytotoxicity against HepG2 cells with an IC50 value of 78.6 µM. The different cytotoxicity between enantiomers 2a and 2b attracted our interest. To investigate the underlying mechanisms responsible for the distinct cytotoxicity, we further assessed the effects of 2a and 2b on cell cycle distribution, cell apoptosis and reactive oxygen species (ROS) generation. The results indicated that 2a had more significant effect than 2b on apoptosis induction and ROS generation, but both had no obvious effect on cell cycle of HepG2 cells. It is concluded that the different configurations of 2a/2b determined the enantioselective cytotoxicity on HepG2 cells through apoptosis induction and ROS generation.

Stereoisomeric guaiacylglycerol-ß-coniferyl aldehyde ether induces distinctive apoptosis by downregulation of MEK/ERK pathway in hepatocellular carcinoma cells.

Two 8-O-4'-type neolignan epimers erythro-guaiacylglycerol-ß-coniferyl aldehyde ether (1) and threo-guaiacylglycerol-ß-coniferyl aldehyde ether (2) were isolated from the stems of Picrasma quassioides. Further chiral separation gave two pairs of enantiomers 1a/1b and 2a/2b. The cytotoxicity assay against hepatocellular carcinoma Hep3B and HepG2 cells was evaluated by MTT assay. The results showed that 1b (IC50 = 45.56 µM) and 2b (IC50 = 39.02 µM) had more cytotoxic effect than its enantiomers 1a (IC50 = 82.66 µM) and 2a (IC50 = 67.97 µM) in Hep3B cells, respectively. Moreover, 1b and 2b could induce more apoptotic cells as well as higher reactive oxygen species (ROS) generation than 1a and 2a at 50 µM. In addition, a further study on the phosphoinositide 3-kinase (PI3K)/AKT and mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathways was investigated. The results revealed that all compounds had no significant effect on PI3K/AKT pathway, however, 1b and 2b attenuated the relative levels of p-MEK and p-ERK when compared with 1a and 2a. Taken together, the absolute configurations of guaiacylglycerol-ß-coniferyl aldehyde ether had an impact on the inhibitory effect on Hep3B cells. The inactivation of MEK/ERK signaling pathway might contribute to apoptosis induction and ROS generation in 1b- and 2b-treated cells.

Mitochondria-targeted antioxidant peptide SS31 prevents hypoxia/reoxygenation-induced apoptosis by down-regulating p66Shc in renal tubular epithelial cells.

BACKGROUND/AIMS: Ischemia/reperfusion injury plays a crucial role in renal transplantation and represents a significant risk factor for acute kidney injury and delayed graft function. Mitochondria-targeted antioxidant peptide SS31 has been shown to attenuate ischemia/reperfusion injury by inhibiting oxidative stress. The present study was carried out to investigate whether the pretreatment of SS31 could reduce hypoxia/reoxygenation (H/R)-induced injury by inhibiting p66Shc. METHODS: The cultured rat renal proximal tubular cell line NRK52E cells were exposed to 24 h hypoxia (5% CO2, 1% O2, 94% N2) followed by 6 h reoxygenation (5% CO2, 21% O2, 74% N2). SS31 was added to the culture medium 4 h prior to the treatment. Then the cell viability, apoptosis, and oxidative stress levels were determined. In addition, western blot analysis was performed to determine the expression of p66Shc, p-p66Shc, cytochrome c, and caspase-3. RESULTS: H/R induced apoptotic cell death, accompanied with activation of total and p-p66Shc in NRK52E cells. Pretreatment with SS31 or overexpression of a dominantnegative Ser36 mutant p66Shc (p66Shc S36A) or p66Shc siRNA prevented cell death, whereas the protection effect of SS31 was completely blocked by overexpression of wild-type p66Shc. Furthermore, SS31 pretreatment reduced H/R-induced intracellular oxidative stress, cytochrome c translocation to the cytoplasm, and caspase-3 activation through inhibiting p66Shc. CONCLUSION: This study revealed that SS31 pretreatment serves a protective role against H/R-induced apoptosis of human renal tubular epithelial cells, and the mechanism is related to suppression of p66Shc.

Inula japonica ameliorated the inflammation and oxidative stress in LPS-induced acute lung injury through the MAPK/NF-κB and Keap1/Nrf2 signalling pathways.

OBJECTIVES: To investigate the protective effect and underlying mechanism of Inula japonica (TEIJ) in the treatment of acute lung injury (ALI). METHODS: Protective effects of TEIJ in the inflammation and oxidative stress were studied in lipopolysaccharide (LPS)-induced ALI mice. Meanwhile, Western blot and real-time qPCR were carried out to investigate the underlying mechanism of TEIJ for ALI as well as immunohistochemistry. KEY FINDINGS: TEIJ significantly alleviated the course of ALI via suppressing the interstitial infiltrated inflammatory cells, the increase of inflammatory factors and the decrease of anti-oxidative factors. TEIJ inactivated the MAPK/NF-κB signalling pathway to suppress the transcription of its downstream target genes, such as TNF-α, IL-6, etc. Meanwhile, TEIJ activated the Keap1/Nrf2 signalling pathway to regulate expression levels of Nrf2 and its target proteins. The results of LC-QTOF-MS/MS indicated potential active constituents of I. japonica, terpenoids and flavonoids. Additionally, terpenoids and flavonoids synergistically alleviated LPS-induced ALI depending on MAPK/NF-κB and Keap1/Nrf2 signalling pathways. CONCLUSION: I. japonica could be considered a potential agent to treat ALI via regulating the MAPK/NF-κB and Keap1/Nrf2 signalling pathways.