Design, Synthesis, and In Vivo Evaluation of Isosteviol Derivatives as New SIRT3 Activators with Highly Potent Cardioprotective Effects

Cardiovascular diseases (CVDs) persist as the predominant cause of mortality, urging the exploration of innovative pharmaceuticals. Mitochondrial dysfunction stands as a pivotal contributor to CVDs development. Sirtuin 3 (SIRT3), a prominent mitochondrial deacetylase known for its crucial role in protecting mitochondria against damage and dysfunction, has emerged as a promising therapeutic target for CVDs treatment. Utilizing isosteviol, a natural ent-beyerene diterpenoid, 24 derivatives were synthesized and evaluated in vivo using a zebrafish model, establishing a deduced structure-activity relationship. Among these, derivative 5v exhibited significant efficacy in doxorubicin-induced cardiomyopathy in zebrafish and murine models. Subsequent investigations revealed that 5v selectively elevated SIRT3 expression, leading to the upregulation of SOD2 and OPA1 expression, effectively preventing mitochondrial dysfunction, mitigating oxidative stress, and preserving cardiomyocyte viability. As a novel structural class of SIRT3 activators with robust therapeutic effects, 5v emerges as a promising candidate for further drug development.

Oridonin suppresses gastric cancer SGC-7901 cell proliferation by targeting the TNF-alpha/androgen receptor/TGF-beta signalling pathway axis

Statistics provided by GLOBOCAN list gastric cancer as the sixth most common, with a mortality ranking of third highest for the year 2020. In China, a herb called Rabdosia rubescens (Hemsl.) H.Hara, has been used by local residents for the treatment of digestive tract cancer for hundreds of years. Oridonin, the main ingredient of the herb, has a curative effect for gastric cancer, but the mechanism has not been previously clarified. This study mainly aimed to investigate the role of TNF-alpha/Androgen receptor/TGF-beta signalling pathway axis in mediating the proliferation inhibition of oridonin on gastric cancer SGC-7901 cells. MTT assay, cell morphology observation assay and fluorescence assay were adopted to study the efficacy of oridonin on cell proliferation. The network pharmacology was used to predict the pathway axis regulated by oridonin. Western blot assay was adopted to verify the TNF-α/Androgen receptor/TGF-β signalling pathway axis regulation on gastric cancer by oridonin. The results showed Oridonin could inhibit the proliferation of gastric cancer cells, change cell morphology and cause cell nuclear fragmentation. A total of 11signaling pathways were annotated by the network pharmacology, among them, Tumour necrosis factor alpha (TNF-α) signalling pathway, androgen receptor (AR) signalling pathway and transforming growth factor (TGF-β) signalling pathway account for the largest proportion. Oridonin can regulate the protein expression of the three signalling pathways, which is consistent with the results predicted by network pharmacology. These findings indicated that oridonin can inhibit the proliferation of gastric cancer SGC-7901 cells by regulating the TNF-α /AR /TGF-β signalling pathway axis.

Oridonin enhances cytotoxic activity of natural killer cells against lung cancer

BACKGROUND

Oridonin is a Chinese herbal medicine exhibiting anti-tumor properties; however, its immune modulation capacity has yet to be elucidated. Our objective in this study was to determine whether oridonin enhances the anti-tumor activity of natural killer (NK) cells against lung cancer cells.

METHODS

LDH-releasing assays were used to investigate the effects of oridonin on NK-92MI cell activity against lung cancer cells. Flow cytometry and real-time PCR were used to examine the effects of oridonin on degranulation markers, cytotoxic factors, activating receptors on NK-92MI cells, and ligands in lung cancer cells. Western blot analysis provided insight into the mechanisms underlying the observed effects.

RESULTS

Oridonin enhanced the cytotoxic effects of NK-92MI cells against A549 lung cancer cells. This effect involved upregulating the expression of the degranulation marker CD107a and IFN-γ as well as activating receptors on NK cells and their ligand MICA/B. Oridonin also inhibited STAT3 phosphorylation in A549 cells and NK-92MI cells. A lung cancer mouse model confirmed the anti-tumor effects of oridonin and NK-92MI cells, wherein both treatments alone suppressed tumor growth. Oridonin was also shown to have a synergistic effect on the anti-tumor activity of NK-92MI cells.

CONCLUSIONS

The ability of oridonin to enhance the cytotoxic effects of NK cells indicates its potential as a novel therapeutic agent for the treatment of lung cancer.

Oridonin Protects against Myocardial Ischemia-Reperfusion Injury by Inhibiting GSDMD-Mediated Pyroptosis

Pyroptosis serves a crucial function in various types of ischemia and reperfusion injuries. Oridonin, a tetracycline diterpene derived from Rabdosia rubescens, can significantly inhibit the aggregation of NLRP3-mediated inflammasome. This experiment is aimed at investigating the effect of oridonin on pyroptosis in mice cardiomyocytes. Based on the models of myocardial ischemia/reperfusion (I/R) and hypoxia/reoxygenation (H/R), Evans Blue/TTC double staining, TUNEL staining, and Western blotting were applied to determine the effects of oridonin on myocardial damage, cellular activity and signaling pathways involved in pyroptosis. During I/R and H/R treatments, the extent of gasdermin D-N domains was upregulated in cardiomyocytes. Apart from that, oridonin improved cell survival in vitro and decreased the myocardial infarct size in vivo by also downregulating the activation of pyroptosis. Finally, the expression levels of ASC, NLRP3 and p-p65 were markedly upregulated in cardiomyocytes after H/R treatment, whereas oridonin suppressed the expression of these proteins. The present experiment revealed that myocardial I/R injury and pyroptosis can be alleviated and inhibited by oridonin pretreatment via NF-κB/NLRP3 signaling pathway, both in vivo and in vitro. Therefore, oridonin may serve as a potentially novel agent for the clinical treatment of myocardial ischemia-reperfusion injuries.

Anti-Cancer Properties of Stevia rebaudiana; More than a Sweetener

Stevia rebaudiana Bertoni is a perennial shrub from Paraguay that is nowadays widely cultivated, since it is increasingly being utilized as a sugar substitute in various foodstuffs due to its sweetness and minimal caloric content. These properties of the plant’s derivatives have spurred research on their biological activities revealing a multitude of benefits to human health, including antidiabetic, anticariogenic, antioxidant, hypotensive, antihypertensive, antimicrobial, anti-inflammatory and antitumor actions. To our knowledge, no recent reviews have surveyed and reported published work solely on the latter. Consequently, our main objective was to present a concise, literature-based review of the biological actions of stevia derivatives in various tumor types, as studied in in vitro and in vivo models of the disease. With global cancer estimates suggesting a 47% increase in cancer cases by 2040 compared to 2020, the data reviewed in this article should provide a better insight into Stevia rebaudiana and its products as a means of cancer prevention and therapy within the context of a healthy diet.

Isosteviol Sodium Ameliorates Dextran Sodium Sulfate-Induced Chronic Colitis through the Regulation of Metabolic Profiling, Macrophage Polarization, and NF-κB Pathway

Inflammatory bowel diseases (IBDs) constitute a group of chronic intestinal conditions prominently featuring deranged metabolism. Effective pharmacological treatments for IBDs are lacking. Isosteviol sodium (STV-Na) exhibits anti-inflammatory activity and may offer therapeutic benefits in chronic colitis. However, the associated mechanism remains unclear. This study is aimed at exploring the therapeutic effects of STV-Na against chronic colitis in terms of metabolic reprogramming and macrophage polarization. Results show that STV-Na attenuated weight loss and colonic pathological damage and restored the hematological and biochemical parameters in chronic colitis mice models. STV-Na also restored intestinal permeability by increasing the goblet cell numbers, which was accompanied by lowered plasma lipopolysaccharide and diamine oxidase levels. Metabolomic analysis highlighted 102 candidate biomarkers and 5 vital pathways that may be crucial in the potential pharmacological mechanism of STV-Na in regulating intestinal inflammation and oxidative stress. These pathways were glycerophospholipid metabolism, phenylalanine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, the pentose phosphate pathway, and phosphonate and phosphinate metabolism. Furthermore, STV-Na significantly decreased M1 macrophage polarization in the spleen and colon. The mRNA and protein levels of IL-1β, TNF-α, and NF-κB/p65 in colonic tissue from the colitis mice were decreased after the STV-Na treatment. Overall, STV-Na could alleviate chronic colitis by suppressing oxidative stress and inflammation levels, reprogramming the metabolic profile, inhibiting macrophage polarization, and suppressing the NF-κB/p65 signaling pathway. STV-Na remains a promising candidate drug for treating IBDs.

Protective effect of isosteviol sodium against LPS-induced multiple organ injury by regulating of glycerophospholipid metabolism and reducing macrophage-driven inflammation

Sepsis is a severe inflammatory disorder that can lead to multiple organ injury. Isosteviol sodium (STV-Na) is a terpenoid derived from stevioside that exerts anti-inflammatory, antioxidant and antiapoptotic activities. However, the influence of STV-Na on sepsis remains unknown. Here, we assessed the potential effects of STV-Na on sepsis and multiple organ injury induced by lipopolysaccharide (LPS). We found that STV-Na increased the survival rate of mice treat with LPS, significantly improved the functions of the heart, lung, liver, and kidney, reduced the production of inflammatory cytokines and decreased macrophage infiltration. Moreover, Multiorgan metabolomics analysis demonstrated that glutathione metabolism, purine metabolism, glycerophospholipid metabolism and pantothenate and CoA biosynthesis, were significantly altered by STV-Na. This study provides novel insights into the metabolite changes of multiple organ injury in septic mice, which may help characterize the underlying mechanism and provide an improved understanding of the therapeutic effects of STV-Na on sepsis.

Glaucocalyxin A suppresses osteoclastogenesis induced by RANKL and osteoporosis induced by ovariectomy by inhibiting the NF-κB and Akt pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Glaucocalyxin A (GLA), the most abundant active component of the aboveground sections of Rabdosia japonica (Burm. f.) Hara var. glaucocalyx (Maxim.) Hara, possesses various pharmacological activities, such as antioxidant, antithrombosis, anticoagulation, antibacterial, antitumor, anti-inflammatory activities. According to previous studies, inflammation is closely associated with osteoclast differentiation and activity. Although GLA has demonstrated effective anti-inflammatory properties, its effects on osteoclast differentiation remain unclear.

AIM OF THE STUDY

To examine the possible inhibitory effects of GLA and its molecular mechanisms in osteogenesis induced by RANKL as well as ovariectomy (OVX)-induced osteoporosis (OP) in mice.

MATERIALS AND METHODS

Tartrate-resistant acid phosphatase (TRAP) staining, F-actin staining, and a bone resorption pit assay were applied for identifying the effects of GLA on the differentiation of osteoclasts and the function of bone resorption. The mRNA expression of the genes related to osteoclast differentiation was measured by quantitative PCR. Protein expression of nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), c-fos and phosphorylation of inhibitor of nuclear factor kappa B (IκBα), protein kinase B (AKT), c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38 in RANKL-induced osteoclasts was determined using western blotting. The effect of GLA on OP was studied using a mouse model of OVX.

RESULTS

At nontoxic concentrations ≤0.5 μM in vitro, GLA suppressed the formation of osteoclasts induced by RANKL with the decreased number and area size of TRAP-positive multinuclear osteoclasts, and the resorption of bone function by reducing F-actin ring number and bone resorption pit areas. It also reduced the expression of the genes specific for osteoclasts, which included genes encoding NFATc1, cathepsin K, c-fos, TRAP, vacuolar-type ATPase d2, and dendritic cell-specific transmembrane protein. Moreover, GLA repressed NF-κB and Akt pathway activation induced by RANKL. Micro-CT analysis of femur samples indicated decreased bone loss and greater trabecular bone density after GLA treatment, which showed that GLA played a protective role by inhibiting bone loss in OVX-induced OP mice in vivo.

CONCLUSIONS

Our study is the first to show that GLA has significant therapeutic potential in OP, which is the disease of osteoclast increase caused by estrogen deficiency.

Evidence of an antidepressant-like effect of xylopic acid mediated by serotonergic mechanisms

BACKGROUND

Depression causes significant debilitating symptoms and economic burden. Current management is challenged by slow onset of action and modest efficacies of antidepressants; thus, the search for newer antidepressants remains relevant. We evaluated the antidepressant effects of a kaurene diterpene, xylopic acid (XA), in zebrafish and mouse models.

METHODS

The chronic unpredictable stress (CUS) protocol in zebrafish and the tail suspension test (TST), forced swim test (FST), lipopolysaccharide-induced depression-like behaviour test (LID) and repeated open space swimming test (OSST) in mice were used. We further examined the impact of depleting monoamines on XA's antidepressant effects. The contribution of glutamatergic and nitrergic pathways on the antidepressant effect of XA in mice and XA's effects on 5-HT receptors and monoamine oxidase (MAO) enzymes were also evaluated. Finally, XA's influence on neuroprotection was evaluated by measuring BDNF and oxidative stress enzymes in whole brain. XA doses (1-10 μM) in zebrafish and (10, 30, 100 mg kg-1) in mice exerted potent antidepressant-like potential in FST, TST, LID and showed fast-onset antidepressant-like property in the OSST.

RESULTS

The antidepressant-like properties in mice were reversed by blocking synthesis/release of serotonin but not noradrenaline using p-chlorophenylalanine and α-methyl-p-tyrosine, respectively. This antidepressant-like effect was potentiated by D-cycloserine and Nω-Nitro-L-arginine methyl ester (L-NAME) but not by D-serine and L-arginine. XA also evoked partial agonist-like effects on 5-hydroxytrptamine receptors on the rat fundus but it did not have MAO inhibition effect. It also increased BDNF, glutathione and antioxidant enzymes.

CONCLUSION

Therefore, xylopic acid possesses antidepressant-like effects largely mediated by serotonergic and neuroprotective mechanisms.

Oridonin ameliorates noise-induced hearing loss by blocking NLRP3 - NEK7 mediated inflammasome activation

Inflammation is involved in noise-induced hearing loss (NIHL), but the mechanism is still unknown. The NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, which triggers the inflammatory cascade, has been implicated in several inflammatory diseases in response to oxidative stress. However, whether the NLRP3 inflammasome is a key factor for permanent NIHL is still unknown. In this study, quantitative real-time polymerase chain reaction (qPCR), western blot, and enzyme-linked immunosorbent assays (ELISAs) demonstrated that the expression levels of activated caspase-1, interleukin (IL)-1β, IL-18, and NLRP3 were significantly increased in the cochleae of mice exposed to broadband noise (120 dB) for 4 h, compared with the control group. These results indicate that the activation of inflammasomes in the cochleae of mice during the pathological process of NIHL as well as NLRP3, a sensor protein of reactive oxygen species (ROS), may be key factors for inflammasome assembly and subsequent inflammation in cochleae. Moreover, many recent studies have revealed that NEK7 is an important component and regulator of NLRP3 inflammasomes by interacting with NLRP3 directly and that these interactions can be interrupted by oridonin. Here, we further determined that treatment with oridonin could indeed interrupt the interaction between NLRP3 and NEK7 as well as inhibit the downstream inflammasome activation in mouse cochleae after noise exposure. Furthermore, we tested anakinra, another inflammatory inhibitor, and it was shown to partially alleviate the degree of hearing impairment in some frequencies in an NIHL mouse model. These discoveries suggest that inhibiting NLRP3 inflammasomes and the downstream signaling pathway may provide a new strategy for the clinical treatment of NIHL.

Glaucocalyxin A induces cell cycle arrest and apoptosis via inhibiting NF-κB/p65 signaling pathway in melanoma cells

AIMS

Melanoma is a malignant tumor of the skin with a high metastasis rate and poor prognosis. Glaucocalyxin A (GLA), isolated from Rabdosia japonica, is a diterpenoid compound with anticancer properties. Here, we investigated the anticancer properties and explored the mechanisms underlying GLA activity in melanoma cells in vitro and in vivo.

MAIN METHODS

Cell Counting Kit-8 and colony formation assays were used to assess the effects of GLA on cell proliferation. Flow cytometry was used to evaluate the cell cycle, apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS), and western blot analysis and immunofluorescence staining were used to examine protein expression. Immunohistochemical analysis was performed to examine animal tissues and tumors in mice.

KEY FINDINGS

GLA could effectively inhibit cell proliferation and induce cell apoptosis. GLA induced an overproduction of cellular ROS, decreased MMP, and upregulated the Bax/Bcl-2 ratio, which is an indicator of apoptosis. Phosphorylation of nuclear factor κB (NF-κB)/p65 and NF-κB/p65 nuclear expression decreased after GLA treatment in vitro and in vivo, suggesting that the anticancer effects of GLA are mediated through the NF-κB/p65 pathway. Moreover, we observed that GLA was effective in inhibiting tumor growth without obvious toxicity to major organs in mice.

SIGNIFICANCE

This is the first study to show that GLA inhibits cell proliferation, arrests the cell cycle in the G2/M phase, and induces mitochondrial apoptosis via the NF-κB/p65 pathway in melanoma cells. Overall, our results demonstrate that GLA may be a potential anticancer agent for the treatment of melanoma.

An Insight into the Anti-Angiogenic and Anti-Metastatic Effects of Oridonin: Current Knowledge and Future Potential

Cancer is one of the leading causes of death worldwide, with a mortality rate of more than 9 million deaths reported in 2018. Conventional anti-cancer therapy can greatly improve survival however treatment resistance is still a major problem especially in metastatic disease. Targeted anti-cancer therapy is increasingly used with conventional therapy to improve patients' outcomes in advanced and metastatic tumors. However, due to the complexity of cancer biology and metastasis, it is urgent to develop new agents and evaluate the anti-cancer efficacy of available treatments. Many phytochemicals from medicinal plants have been reported to possess anti-cancer properties. One such compound is known as oridonin, a bioactive component of Rabdosia rubescens. Several studies have demonstrated that oridonin inhibits angiogenesis in various types of cancer, including breast, pancreatic, lung, colon and skin cancer. Oridonin's anti-cancer effects are mediated through the modulation of several signaling pathways which include upregulation of oncogenes and pro-angiogenic growth factors. Furthermore, oridonin also inhibits cell migration, invasion and metastasis via suppressing epithelial-to-mesenchymal transition and blocking downstream signaling targets in the cancer metastasis process. This review summarizes the recent applications of oridonin as an anti-angiogenic and anti-metastatic drug both in vitro and in vivo, and its potential mechanisms of action.

Stevioside protects against rhabdomyolysis-induced acute kidney injury through PPAR-γ agonism in rats

We explored the potential role of peroxisome proliferator activated receptor-γ (PPAR-γ) in stevioside-mediated renoprotection using rhabdomyolysis-induced acute kidney injury (AKI) model in rats. Rhabdomyolysis refers to intense skeletal muscle damage, which further causes AKI. Glycerol (50% w/v, 8 ml/kg) was injected intramuscularly in rats to induce rhabdomyolysis. After 24 hr, AKI was demonstrated by quantifying serum creatinine, urea, creatinine clearance, microproteinuria, and electrolytes in rats. Further, oxidative stress was measured by assaying thiobarbituric acid reactive substances, generation of superoxide anion, and reduced glutathione levels. Additionally, serum creatine kinase (CK) level was assayed to determine glycerol-induced muscle damage in rats. Pathological changes in rat kidneys were studied using hematoxylin-eosin and periodic acid Schiff staining. Moreover, the expression of apoptotic markers (Bcl-2, Bax) in rat kidneys was demonstrated by immunohistochemistry. Stevioside (10, 25, and 50 mg/kg) was administered to rats, prior to the induction of AKI. In a separate group, bisphenol A diglycidyl ether (BADGE, 30 mg/kg), a PPAR-γ receptor antagonist was given prior to stevioside administration, which was followed by rhabdomyolysis-induced AKI in rats. The significant alteration in biochemical and histological parameters in rats indicated AKI, which was attenuated by stevioside treatment. Pretreatment with BADGE abrogated stevioside-mediated renoprotection, which is suggestive of the involvement of PPAR-γ in its renoprotective effect. In conclusion, stevioside protects against rhabdomyolysis-induced AKI, which may be attributed to modulation of PPAR-γ expression.

15β-Senecioyl-oxy-ent-kaur-16-en-19-oic Acid, a Diterpene Isolated from Baccharis lateralis, as Promising Oral Compound for the Treatment of Schistosomiasis

Praziquantel is the only available drug to treat schistosomiasis, and therefore, urgent studies must be performed to identify new anthelmintic agents. This study reports the anthelmintic evaluation of two related ent-kaurane diterpenes isolated from aerial parts of Baccharis lateralis (Asteraceae), ent-kaur-16-en-19-oic acid (1) and 15β-senecioyl-oxy-ent-kaur-16-en-19-oic acid (2) against Schistosoma mansoni in vitro and in a murine model of schistosomiasis. Both compounds exhibited in vitro activity with lethal concentration 50% (LC₅₀) values of 26.1 μM (1) and 11.6 μM (2) as well as reduced toxicity against human cell lines, revealing a good selectivity profile, mainly with compound 2 (selectivity index > 10). Compound 2 also decreased egg production and caused morphological alterations in the parasite reproductive system. In mice infected with S. mansoni, oral treatment with compound 2 at 400 mg/kg, the standard dose used in this model of schistosomiasis, caused a significant reduction in a total worm burden of 61.9% (P < 0.01). S. mansoni egg production, a key mechanism for both transmission and pathogenesis, was also markedly reduced. In addition, compound 2 achieved a significant reduction in hepatosplenomegaly. Therefore, the diterpene 15β-senecioyl-oxy-ent-kaur-16-en-19-oic acid (2) has an acceptable cytotoxicity profile and is orally active in a murine schistosomiasis model.

Oridonin triggers G2/M cell cycle arrest, cellular apoptosis and autophagy in human gastric cancer cells

PURPOSE

Gastric carcinoma is the fourth principal cause of cancer-related deaths throughout the globe. There are inadequate clinical therapies for gastric cancer due to lack of operational drugs and ambiguity in molecular mechanisms. As such there is a persistent requirement for novel and effective anticancer drugs for gastric cancer. The main purpose of the current study was to investigate the antitumor effects of a plant diterpenoid, namely Oridonin, against SGC-7901 human gastric cancer cells along with examining its effects on cellular apoptosis, cell autophagy and cell cycle phase distribution.

METHODS

WST-1 cell proliferation assay was used to evaluate cell viability of SGC-7901 human gastric cancer cells. Apoptosis was evaluated by using DAPI and comet assays using fluorescence microscopy. Autophagy was evaluated by transmission electron microscopy (TEM) and western blot method. Effects on cell cycle phase distribution were studied by flow cytometry.

RESULTS

Oridonin molecule led to considerable and dose-dependent antiproliferative effects on SGC-7901 human gastric cancer cells exerting only mild cytotoxic effects in normal cells thus exhibiting selective toxicity. The number of gastric cancer cell colonies decreased significantly as oridonin dose increased. DAPI and comet assays revealed that oridonin induced powerful apoptotic effects in these cells, triggering significant DNA damage and both these effects exhibited dose-dependence. TEM indicated that oridonin induced autophagy in SGC-7901 cells by creating autophagosomes and autophagic vacuoles. Oridonin also targeted G2/M phase cell cycle in these gastric cancer cells along with targeting some key cell cycle related proteins including cyclin-B1, cyclin D1 and cyclin E.

CONCLUSION

In conclusion, the results show that oridonin showed strong anticancer effects in SGC-7901 human gastric cancer cells by triggering apoptosis and autophagy, and targeting cell cycle at G2/M phase.

Oridonin inhibits 4T1 tumor growth by suppressing Treg differentiation via TGF-β receptor

The Chinese herbal medicine oridonin has potent anti-inflammatory and antitumor activities. In addition, oridonin treatment effectively suppresses breast cancer growth. However, the underlying mechanisms are poorly defined. Here, we reported that oridonin decreased Treg differentiation in vitro and in vivo. Oridonin inhibition of Treg differentiation was dependent on decreasing TGF-β receptor expression. Oridonin attenuated Tregs' immunosuppressive ability; thus, oridonin did not inhibit CD8⁺ T cell proliferation very well in vitro. Oridonin greatly delayed the progression of 4T1 tumors in vivo. In addition, oridonin combined with anti-PD-1 activated a robust antitumor immune response and suppressed 4T1 tumor growth. Therefore, our results indicate that oridonin inhibits TNBC growth by modulating Treg differentiation, which provides new directions for the clinical treatment of TNBC.

The onjisaponin B metabolite tenuifolin ameliorates dopaminergic neurodegeneration in a mouse model of Parkinson's disease

Onjisaponin B (OB) is the main active ingredient of the traditional Chinese medicinal herb polygala, which is effective against neurodegenerative disorders. However, the target of OB is currently unknown. Neuroinflammation and oxidative stress are both risk factors for the pathogenesis and progression of Parkinson's disease (PD). Here, we used a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced subacute mouse model of PD to explore the efficacy and neuroprotective mechanism of OB in PD. Immunohistochemistry was used to mark dopaminergic (DA) neurons and microglia in the substantia nigra pars compact. Administration of OB (20 and 40 mg/kg) prevented the degeneration of DA neurons and improved motor impairment in the rotarod test. Furthermore, OB attenuated microglia over-activation and reduced the secretion of inflammatory factors including tumor necrosis factor-alpha, interleukin-1 beta (IL-1β) and interleukin-6 (IL-6), as determined by ELISA. Meanwhile, the activities of superoxide dismutase and malondialdehyde were used to measure the level of oxidative stress in brain homogenates and suppression of excessive lipid epoxidation and increased antioxidant enzyme activity were found in OB-treated PD mice. Finally, OB inhibits the expression of the p65 subunit of NF-κB in the nucleus and attenuated expression of the RhoA and ROCK2 proteins in PD mice. Consequently, our results show that OB ameliorates DA neurodegeneration in a MPTP-induced mouse model of PD through anti-oxidant and anti-inflammatory activities mediated via the RhoA/ROCK2 signaling pathway. This finding demonstrates that OB may be a promising drug for DA neuron degeneration, which may provide a new therapeutic agent for future discovery of drugs for PD.See video abstract: http://links.lww.com/WNR/A580.

Beneficial effects of Oridonin on myocardial ischemia/reperfusion injury: Insight gained by metabolomic approaches

Oridonin is a diterpenoid isolated from Rabdosia rubescens (Hemsl.) Hara, a well-known herbal tea in China with many health benefits. To provide a better understanding of the potential cardioprotective effect of Oridonin, we investigated the metabolic alterations in heart tissue and serum of rat subjected to myocardial ischemia/reperfusion (MI/R) injury with or without pretreatment of Oridonin by UPLC-MS/MS metabolomics approach. Rats were randomly divided into groups as follows: Control, Sham, MI/R and pretreated with Oridonin (10 mg/kg)+MI/R. After 24 h of reperfusion, heart tissue and serum were collected for biochemical and metabolomic analysis. Pretreatment with Oridonin significantly decreased infarct size and reversed the abnormal elevated myocardial zymogram in serum. Moreover, Oridonin regulated several metabolic pathways, including glycolysis, branched chain amino acid, kynurenine, arginine, glutamine and bile acid metabolism. Our results suggest that Oridonin indeed displays outstanding cardioprotective effect mainly by regulating energy and amino acid metabolism.

Oridonin inhibits the proliferation, migration and invasion of human osteosarcoma cells via suppression of matrix metalloproteinase expression and STAT3 signalling pathway

PURPOSE

Oridonin, a diterpenoid, has been reported to exhibit anticancer activity against a wide range of cancer types.In this study, the effect Oridonin was examined against human osteosarcoma cells.

METHODS

The human osteosarcoma cells U2OS were treated with various concentrations of Oridonin from 0-200 μM for 24 h. The anti-proliferative effects of Oridonin were measured by cell viability assay. DAPI and annexin V/propidium iodide (PI) assays were employed to examine the induction of apoptosis. Transwell assay was performed to examine the cell migration and invasion. Expression analysis was performed by western blot.

RESULTS

Oridonin inhibited the proliferation of U2OScells and exhibited an IC50 of 30 µM. The antiproliferative effects were mainly found to be due to induction of apoptosis as indicated by DAPI staining. Moreover, the annexin V/PI staining showed that the percentage of the apoptotic cells increased with increase in the concentration of Oridonin. The induction of apoptosis was also related with upregulation of Bax, Caspase 3 and 9 expression and downregulation of Bcl-2. Oridonin was also found to cause significant decrease in the expression of MMP-2, 3 and 9 concentration-dependently. Transwell assay showed that Oridonin inhibited the migration and invasion of the U2OS cells.

CONCLUSION

It is concluded that Oridonin exhibits significant antiproliferative effects on the osteosarcoma cells and may prove essential in the development of systemic therapy for osteosarcoma.

Isosteviol ameliorates diabetic cardiomyopathy in rats by inhibiting ERK and NF-κB signaling pathways

Diabetes-induced injury of myocardium, defined as diabetic cardiomyopathy (DCM), accounts for significant mortality and morbidity in diabetic population. Alleviation of DCM by a potent drug remains considerable interests in experimental and clinical researches because hypoglycemic drugs cannot effectively control this condition. Here, we explored the beneficial effects of isosteviol sodium (STVNa) on type 1 diabetes-induced DCM and the potential mechanisms involved. Male Wistar rats were induced to diabetes by injection of streptozotocin (STZ). One week later, diabetic rats were randomly grouped to receive STVNa (STZ/STVNa) or its vehicle (STZ). After 11 weeks of treatment or 11 weeks treatment following 4 weeks of removal of the treatment, the cardiac function and structure were evaluated and related mechanisms were investigated. In diabetic rats, oxidative stress, inflammation, blood glucose and plasma advanced glycation end products (AGEs) were significantly increased, whereas superoxide dismutase 2 (SOD-2) expression and activity were decreased. STVNa treatment inhibited cardiac hypertrophy, fibrosis and inflammation, showed similar ratio of heart to body weight and antioxidant capacities almost similar to the normal controls, which can be sustained at least 4 weeks. Moreover, STVNa inhibited diabetes-inducted stimulation of both extracellular signal-regulated kinase (ERK) and nuclear factor κB (NF-κB) signal pathways. However, blood glucose, plasma AGE and insulin levels were not altered by STVNa treatment. These results indicate that STVNa may be developed into a potent therapy for DCM. The mechanism underlying this therapeutic effect involves the suppression of oxidative stress and inflammation by inhibiting ERK and NF-κB without changing blood glucose or AGEs.

Oridonin protects against the inflammatory response in diabetic nephropathy by inhibiting the TLR4/p38-MAPK and TLR4/NF-κB signaling pathways

Inflammation plays a pivotal role in the development and progression of diabetic nephropathy (DN). Oridonin (Ori), a component isolated from Rabdosia rubescens, possesses remarkable anti-inflammatory, immunoregulatory and antitumor properties. However, the renoprotective effects of Ori and the underlying molecular mechanisms have not been explored in DN. In this study, we aimed to investigate the protective effects and potential mechanisms responsible for the anti-inflammatory effects of Ori in diabetes-induced renal injury in vivo and in vitro. Our results showed that Ori significantly attenuated diabetes-induced renal injury and markedly decreased urinary protein excretion levels, serum creatinine concentrations and blood urea nitrogen concentrations in rats. Ori also significantly alleviated infiltration of inflammatory cells (cluster of differentiation (CD)68) in kidney tissues and reduced the levels of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-1β and monocyte chemotactic protein 1 (MCP-1), both in vivo and in vitro. TLR4 is a principal mediator of innate immune and inflammatory responses and participates in the development of DN. Our molecular studies indicated that Ori administration significantly down-regulated TLR4 overexpression in DN. Additional studies were conducted to investigate the effect of Ori on the p38-mitogen-activated protein kinase (p38-MAPK) and nuclear factor (NF)-κB pathways. The results showed that Ori inhibited IκBα, p65, and p38 phosphorylation, as well as NF-κB DNA-binding activity. In conclusion, these results demonstrated that Ori exerts protective effects in diabetes-induced renal injury in vivo and in vitro. These effects may be ascribed to its anti-inflammatory and modulatory effects on the TLR4/p38-MAPK and TLR4/NF-κB signaling pathways.

Oridonin protects the lung against hyperoxia-induced injury in a mouse model

Hyperoxic acute lung injury (HALI) is caused by prolonged exposure to high oxygen partial pressure. This study was undertaken to investigate the protective effects of oridonin on HALI in a mouse model. Mice were randomly divided into three groups: the control group, HALI group and oridonin (ORI) group. HALI was induced by exposing mice to pure oxygen at 2.5 atmospheres absolute (ATA) for six hours in the HALI and ORI groups. In the ORI group, mice were intraperitoneally injected with ORI at 10 mg/kg twice daily after hyperoxic exposure. Animals were sacrificed 24 hours after the hyperoxia exposure, followed by bronchoalveolar lavage fluid (BALF). Lungs were then collected. Each lung was processed for HE staining and detection of wet-to-dry weight ratio. The lactate dehydrogenase (LDH) activity and protein content of BALF were determined, and the contents of malonaldehyde (MDA), glutathione (GSH), tumor necrosis factor alpha (TNF-?) and interleukin-10 (IL-10) in the lung were measured. Our results showed prolonged exposure to hyperoxia significantly damaged the lung, caused lung edema, increased MDA and TNF-?, and reduced GSH and IL-10 in the lung. However, post-exposure treatment with oridonin was able to improve lung pathology, attenuate lung edema, reduce MDA and TNF-?, and increase GSH and IL-10 in the lung. These findings suggest that oridonin can protect the lung against hyperoxia-induced injury in mice.

Oridonin Attenuates Synaptic Loss and Cognitive Deficits in an Aβ1-42-Induced Mouse Model of Alzheimer's Disease

Synaptic loss induced by beta-amyloid (Aβ) plays a critical role in the pathophysiology of Alzheimer’s disease (AD), but the mechanisms underlying this process remain unknown. In this study, we found that oridonin (Ori) rescued synaptic loss induced by Aβ_1–42in vivo and in vitro and attenuated the alterations in dendritic structure and spine density observed in the hippocampus of AD mice. In addition, Ori increased the expression of PSD-95 and synaptophysin and promoted mitochondrial activity in the synaptosomes of AD mice. Ori also activated the BDNF/TrkB/CREB signaling pathway in the hippocampus of AD mice. Furthermore, in the Morris water maze test, Ori reduced latency and searching distance and increased the number of platform crosses in AD mice. These data suggest that Ori might prevent synaptic loss and improve behavioral symptoms in Aβ_1–42-induced AD mice.

[Chemical biology and novel molecular-targeted agents in cancer therapy]

Target-based screening and cell-based screening are major approaches to identify anticancer drug candidates. Cell-based screening often contributes to the discovery of first-in-class drugs, but identification of the cellular targets of obtained compounds is a time-consuming step. To overcome this problem, affinity purification with small-molecule probes, which is a classic, but still the most common approach, has become more sophisticated and diversified. In addition, recent advances in omics studies and imaging analyses have allowed us to profile the biological effects of small molecules globally and quantitatively. Consequently, new therapeutic targets/drug leads involved in cancer cell cycle, transcription and redox regulation have been discovered.

Stevioside plays an anti-inflammatory role by regulating the NF-κB and MAPK pathways in S. aureus-infected mouse mammary glands

Mastitis is an inflammatory disease caused by microbial infection. Staphylococcus aureus is one of the primary bacteria responsible for mastitis. Stevioside is isolated from Stevia rebaudiana and is known to have therapeutic functions. This study was designed to evaluate the effects of stevioside in a mouse model of S. aureus-induced mastitis. In this study, the mouse mammary gland was infected with S. aureus to induce the mastitis model. The stevioside was administered intraperitoneally after the S. aureus infection was established. Hematoxylin-eosin (HE) staining, ELISA, Western blot, and q-PCR methods were used. The results show that stevioside significantly reduced the inflammatory cell infiltration and the levels of TNF-α, IL-1β, and IL-6 and the respective expression of their messenger RNAs (mRNAs). Further studies revealed that stevioside downregulated the TLR2, NF-κB, and (mitogen-activated protein kinase) MAPK signaling pathways in the S. aureus-infected mouse mammary gland. Our results demonstrate that stevioside reduced the expression of TNF-α, IL-1β, and IL-6 by inhibiting the phosphorylation of proteins in the NF-κB and MAPK signaling pathways dose-dependently, but that their mRNA expression was not obviously changed.

Oridonin inhibits tumor growth in glioma by inducing cell cycle arrest and apoptosis

Glioma is the most common malignant intracranial tumors. Despite newly developed therapies, these treatments mainly target oncogenic signals, and unfortunately, fail to provide enough survival benefit in both human patients and mouse xenograft models, especially the first-generation therapies. Oridonin is purified from the Chinese herb Rabdosia rubescens and considered to exert extensive anti-cancer effects on human tumorigenesis. In this study, we systemically investigated the role of Oridonin in tumor growth and the underlying mechanisms in human glioma. We found that Oridonin inhibited cell proliferations in a dose- and time-dependent manner in both glioma U87 and U251 cells. Moreover, these anti-cancer effects were also confirmed in a mouse model bearing glioma. Furthermore, cell cycle arrest in S phase was observed in Oridonin-mediated growth inhibition by flow cytometry. Cell cycle arrest in S phase led to eventual cell apoptosis, as revealed by Hoechst 33342 staining and annexin V/PI double-staining. The cell apoptosis might be accomplished through a mitochondrial manner. In all, we were the first to our knowledge to report that Oridonin could exert anti-cancer effects on tumor growth in human glioma by inducing cell cycle arrest and eventual cell apoptosis. The identification of Oridonin as a critical mediator of glioma growth may potentiate Oridonin as a novel therapeutic strategies in glioma treatments.

Oridonin attenuates Aβ1-42-induced neuroinflammation and inhibits NF-κB pathway

Neuroinflammation induced by beta-amyloid (Aβ) plays a critical role in the pathogenesis of Alzheimer’s disease (AD), and inhibiting Aβ-induced neuroinflammation serves as a potential strategy for the treatment of AD. Oridonin (Ori), a compound of Rabdosia rubescens, has been shown to exert anti-inflammatory effects. In this study, we demonstrated that Ori inhibited glial activation and decreased the release of inflammatory cytokines in the hippocampus of Aβ_1–42-induced AD mice. In addition, Ori inhibited the NF-κB pathway and Aβ_1–42-induced apoptosis. Furthermore, Ori could attenuate memory deficits in Aβ_1–42-induced AD mice. In conclusion, our study demonstrated that Ori inhibited the neuroinflammation and attenuated memory deficits induced by Aβ_1–42, suggesting that Ori might be a promising candidate for AD treatment.

Anti-rotavirus effects by combination therapy of stevioside and Sophora flavescens extract

Anti-rotaviral activities of Sophora flavescens extract (SFE) and stevioside (SV) from Stevia rebaudiana Bertoni either singly or in various combinations were examined in vitro and in vivo using a porcine rotavirus G5[P7] strain. Combination of SFE and SV inhibited in vitro virus replication more efficiently than each single treatment. In the piglet model, SV had no effect on rotavirus enteritis, whereas SFE improved but did not completely cure rotaviral enteritis. Interestingly, combination therapy of SFE and SV alleviated diarrhea, and markedly improved small intestinal lesion score and fecal virus shedding. Acute toxicity tests including the piglet lethal dose 50, and body weight, organ weight and pathological changes for the combination therapy did not show any adverse effect on the piglets. These preliminary data suggest that the combination therapy of SV and SFE is a potential curative medication for rotaviral diarrhea in pigs. Determination of the efficacy of this combination therapy in other species including humans needs to be addressed in the future.

The remarkable structural diversity achieved in ent-Kaurane Diterpenes by fungal biotransformations

The use of biotransformations in organic chemistry is widespread, with highlights of interesting applications in the functionalization of natural products containing unactivated carbons, like the kaurane diterpenes. A number of compounds with kaurane skeletons can be isolated in large amounts from several plant species and a myriad of biological activities has been related to these compounds. Studies on structure versus activity have showed that, in most cases, in kaurane diterpenes, activity increases with the increase of functionalization. Since naturally occurring kaurane diterpenes usually have limited functional groups to be used as targets for semi-synthetic modifications, production of more polar derivatives from kaurane diterpenes have been achieved mostly through the use of fungal biotransformations. In this review, selected examples the wonderful chemical diversity produced by fungi in kaurane diterpenes is presented. This diversity includes mainly hydroxylation of nearly all carbon atoms of the kaurane molecule, many of them carried out stereoselectively, as well as ring rearrangements, among other chemical modifications. Sources of starting materials, general biotransformation protocols employed, fungi with most consistent regioselectivity towards kaurane skeleton, as well as biological activities associated with starting materials and products are also described.

Anti-inflammatory and immunomodulatory activities of stevioside and steviol on colonic epithelial cells

BACKGROUND

Stevioside is a natural non-caloric sweetener isolated from Stevia rebaudiana Bertoni leaves. We have proposed its effect on attenuation of tumour necrosis factor α (TNF-α) and interleukin 1β (IL-1β) release in lipopolysaccharide (LPS)-stimulated monocytes. In this study, the anti-inflammatory and immunomodulatory activities of stevioside and its metabolite, steviol, on human colon carcinoma cell line (Caco-2) were evaluated.

RESULTS

Stevioside and steviol, in the doses used in this study, had no cytotoxicity on Caco-2 cells. Anti-inflammatory activities of these two compounds were observed by potentially suppressed LPS-mediated TNF-α, IL-1β and IL-6 release. In addition, stevioside and steviol showed immunomodulatory effects on IκBα activation and nuclear factor kappa B (NF-κB) suppression in western blotting.

CONCLUSION

Stevioside and steviol attenuate LPS-induced pro-inflammatory cytokine productions by affecting cytokine gene expression via IκBα/NF-κB signalling pathway.

Effect of Rebaudioside A, a diterpenoid on glucose homeostasis in STZ-induced diabetic rats

Rebaudioside A (Reb A), a major constituent of Stevia rebaudiana, was recently proposed as an insulinotropic agent. The aim of this investigation was to evaluate the antihyperglycemic effect of Reb A on the activities of hepatic enzymes of carbohydrate metabolism in streptozotocin (STZ)-induced diabetic rats. Diabetes was induced in adult male Albino Wistar rats, weighing 180-200 g, by a single intraperitoneal injection at a dose of STZ (40 mg/kg body weight). Diabetic rats showed significant (P<0.05) increase in the levels of plasma glucose and glycosylated hemoglobin and significant (P<0.05) decrease in the levels of plasma insulin and hemoglobin. Activities of gluconeogenic enzymes such as glucose-6-phosphatase and fructose-1,6-bisphosphatase were significantly (P<0.05) increased while hexokinase and glucose-6-phosphate dehydrogenase were significantly (P<0.05) decreased in the liver along with glycogen. Oral treatment with Reb A to diabetic rats significantly (P<0.05) decreased blood glucose and reversed these hepatic carbohydrate metabolizing enzymes in a significant manner. Histopathology changes of pancreas confirmed the protective effects of Reb A in diabetic rats. Thus, the results show that Reb A possesses an antihyperglycemic activity and provide evidence for its traditional usage in the control of diabetes.

Proteomic identification of proteins involved in the anticancer activities of oridonin in HepG2 cells

Oridonin is the main bioactive constituent of the Chinese medicinal herb Isodon rubescens and has been shown to have anti-neoplastic effects against a number of cancers in vitro and in vivo. Here we report the proteomic identification of proteins involved in the anticancer properties of oridonin in hepatocarcinoma HepG2 cells. Cell viability assay showed that oridonin dose-dependently inhibited cell growth with an IC(50) of 41.77μM. Treatment with oridonin at 44μM for 24h induced apoptosis and G2/M cell cycle arrest, which were associated with nine differentially expressed proteins identified by proteomic analysis. The proteomic expression patterns of Hsp70.1, Sti1 and hnRNP-E1 were confirmed by quantitative real-time PCR and/or immunoblotting. Eight of the nine identified proteins are shown, for the first time, to be involved in the anticancer activities of oridonin. Up-regulation of Hsp70.1, STRAP, TCTP, Sti1 and PPase, as well as the down-regulation of hnRNP-E1 could be responsible for the apoptotic and G2/M-arresting effects of oridonin observed in this study. Up-regulation of HP1 beta and GlyRS might contribute to inhibitory effects of oridonin on telomerase and tyrosine kinase, respectively. These findings shed new insights into the molecular mechanisms underlying the anticancer properties of oridonin in liver cancer cells.

Anxiolytic and sedative-hypnotic activities of polygalasaponins from Polygala tenuifolia in mice

In the present study, the anxiolytic and sedative-hypnotic activities of polygalasaponins extracted from Polygala tenuifolia Willdenow (Polygalaceae) were determined in mice using hole-board, elevated plus maze, open field, and sodium pentobarbital-induced hypnosis tests. Moreover, the acute toxicity of polygalasaponins was also estimated in mice. Sixty minutes after p.o. administration of polygalasaponins (40, 80, 160 mg/kg) in mice, the central crossing counts and percentage of central/total ambulation significantly increased and the number of rearings and defecations was evidently inhibited in the open field test. Polygalasaponins also increased the head-dips of mice in the hole-board test and the time spent by mice in the open arms of the X-maze, prolonged sleep duration and shortened sleep latency in the test of synergetic effect on sodium pentobarbital (45 and 25 mg/kg, respectively). Acute toxic study showed the oral median lethal dose (LD(50)) of polygalasaponins was 3.95 g/kg and 0% lethal dose 2.6 g/kg. These results suggest that polygalasaponin possesses evident anxiolytic and sedative-hypnotic activities and has a relatively safe dose range, which supports the use of Polygala tenuifolia root as an anxiolytic and sedative-hypnotic drug in folk medicine.

Ent-kaurane diterpenoids from Rabdosia rubescens and their cytotoxic effects on human cancer cell lines

Two new ent-kaurane diterpenoids, 16,17-exo-epoxide-oridonin ( 1) and 11,15- O,O-diacetyl-rabdoternins D ( 2), together with thirteen known ones, were isolated from the aerial parts of Rabdosia rubescens. Their structures were established on the basis of high-field 1D and 2D NMR methods supported by HRMS. All diterpenoids were tested for cytotoxicity against human Hep G2, COLO 205, MCF-7, and HL-60 cancer cells. The compounds oridonin ( 3), 14- O-acetyl-oridonin ( 4), 1,14- O,O-diacetyl-oridonin ( 5), rosthorin ( 6), effusanin E ( 7), and ponicidin ( 8), as well as six alpha-methylene gamma-ketone bearing diterpenoids, were modestly active in these assays.

Cytotoxic ent-kaurane diterpenoids from Isodon sinuolata

Five (1-5) ent-kaurane diterpenoids and 17 other known ones, were isolated from the leaves and stems of Isodon sinuolata. Their structures were determined on the basis of spectroscopic methods including 1D and 2D NMR spectroscopic analysis. All compounds were evaluated for cytotoxicity against a small panel of cell lines. Some compounds exhibited significant cytotoxicity.

Stevioside and related compounds: therapeutic benefits beyond sweetness

Stevioside, an abundant component of Stevia rebaudiana leaf, has become well-known for its intense sweetness (250-300 times sweeter than sucrose) and is used as a non-caloric sweetener in several countries. A number of studies have suggested that, beside sweetness, stevioside along with related compounds, which include rebaudioside A (second most abundant component of S. rebaudiana leaf), steviol and isosteviol (metabolic components of stevioside) may also offer therapeutic benefits, as they have anti-hyperglycemic, anti-hypertensive, anti-inflammatory, anti-tumor, anti-diarrheal, diuretic, and immunomodulatory actions. It is of interest to note that their effects on plasma glucose level and blood pressure are only observed when these parameters are higher than normal. As steviol can interact with drug transporters, its role as a drug modulator is proposed. This review summarizes the current knowledge of the pharmacological actions, therapeutic applications, pharmacokinetics and safety of stevioside and related compounds. Although much progress has been made concerning their biological and pharmacological effects, questions regarding chemical purity and safety remain unsolved. These issues are discussed to help guide future research directions.

Isosteviol increases insulin sensitivity and changes gene expression of key insulin regulatory genes and transcription factors in islets of the diabetic KKAy mouse

AIMS

Isosteviol (ISV), a diterpene molecule, is an isomer of the backbone structure of a group of substances with recently proven antidiabetic capabilities in both man and rodents. The aim of this study was to investigate if ISV possesses beneficial effects on the metabolism in the diabetic KKAy mouse and to establish the long-term in vivo effects of ISV on the gene expression profile of key insulin regulatory genes in islets.

METHODS

Twenty KKAy mice, aged 5 weeks, were divided into two groups and treated for 9 weeks with either (i) standard chow diet (control) or (ii) chow + 20 mg/kg body weight of ISV. Blood samples were collected before and after intervention and were subsequently analysed. As a non-diabetic control group, 10 normal C57BL mice were fed with standard chow diet. Gene expression was determined in islets by quantitative real-time RT-PCR and Affymetrix microarray.

RESULTS

We demonstrated that long-term treatment with ISV improves glucose homeostasis, increases insulin sensitivity, lowers plasma triglycerides and lowers weight in the diabetic KKAy mice. Furthermore, ISV markedly changes the gene expression profile of key insulin regulatory genes GLUT2, Ins1, Ins2, Pdx1/Ipf1, Beta2/Neurod1, Pax6 and 11-beta-HSD-1 and beta-cell transcription factors Nkx2-2, Nkx6-1, C/EBPalpha and FoxA2 in isolated islets of the KKAy mice.

CONCLUSIONS

The results indicate that ISV improves glucose and insulin sensitivity as well as improving the lipid profile and upregulates the gene expression of key beta-cell genes, including insulin regulatory transcription factors.

The neuroprotective effects of isosteviol against focal cerebral ischemia injury induced by middle cerebral artery occlusion in rats

Occlusion of a cerebral artery impairs blood flow leading to neuronal death. Reperfusion of the tissue is associated with inflammation, increased reactive oxygen species, necrosis and apoptosis. Hence, damage to the brain will continue even after the blood flow is restored. Isosteviol has been demonstrated to have protective effects against ischemia-reperfusion (IR) injury in the rat heart and the current study was undertaken to determine whether it is also effective in preventing IR injury in the brain. Rats were divided into six groups: a sham-operation control group and 5 IR groups that were pre-treated with either isosteviol 5 mg.kg (-1), 10 mg.kg (-1), 20 mg.kg (-1), nimodipine 5 mg.kg (-1), or saline. Cerebral ischemia was induced for 2 hours. Twenty-two hours after re-perfusion the rats were assessed for neurobehavioral deficit, infarct volume, histological changes, and malondialdehyde, superoxide dismutase (SOD), Bcl-2 and NF-kappaB levels in brain tissue. Pre-treatment with isosteviol reduced infarct volume, ameliorated cell death and infiltration of neutrocytes, improved neuro-locomotor activity, increased SOD activity, induced Bcl-2, suppressed lipid superoxidation and the expression of NF-kappaB, and therefore retarded necrosis and apoptosis of neurons and inflammation. These positive effects were dose-dependent with an isosteviol dose of 20 mg.kg (-1), thus being as effective as nimodipine.

Novel ent-Beyeran-19-oic acids from biotransformations of isosteviol metabolites by Mortierella isabellina

Biotransformations of ENT-16beta-hydroxybeyeran-19-oic acid ( 1) by Mortierella isabellina produced hydroxylated metabolites. The isolated metabolites included three new compounds, ent-14beta,16beta-dihydroxybeyeran-19-oic acid ( 3), ent-12beta-hydroxy-16-oxobeyeran-19-oic acid ( 4), and ent-7alpha,12beta-dihydroxy-16-oxobeyeran-19-oic acid ( 5), and one known compound, ent-7alpha,16beta-dihydroxybeyeran-19-oic acid ( 2). The structural elucidation was achieved by detailed analysis of LC-MS chromatograms, and MS and NMR spectroscopic data. In this study, M. isabellina hydroxylated the basic skeleton beyeran-19-oic acid at the 7beta-, 12alpha-, and 14alpha-positions, and oxidized the skeleton at the 16-position. All compounds were evaluated with the cell viability assay. The results of the bioassay indicated that MTT formazan exocytosis occurs upon treatment of the cells with 1.

THE EFFECTS OF ISOSTEVIOL AGAINST MYOCARDIUM INJURY INDUCED BY ISCHAEMIA?REPERFUSION IN THE ISOLATED GUINEA PIG HEART

1. This study aimed to investigate the protective effects of isosteviol against myocardial ischaemia-reperfusion (IR) injury and its effects on mitochondrial adenosine triphosphate (ATP)-sensitive potassium channel (mitoK(ATP)) activity in vitro. 2. Groups of eight guinea pigs were treated as follows: constant perfusion control (PC), IR control, ischaemic preconditioning (IPC) + IR, isosteviol (50, 250 or 500 nmol) + IR, 5-hydroxydecanoate acid (5-HD) (5 micromol) + isosteviol (500 nmol) + IR. The guinea pig heart was isolated and perfused in Langendorff mode with modified Tyrode solution at a flow rate of 10 mL/min. Ischaemia was introduced for 30 min followed by reperfusion for 20 min. Cardiac function, coronary arterial flow rate, lactate dehydrogenase (LDH) and creatine kinase (CK) activities in the perfusate were measured prior to ischaemia and at the end of reperfusion. 3. There were no significant (P > 0.05) changes in cardiac function or markers of cell damage (i.e. activities of LDH and CK) in the PC group. In contrast, cardiac function was adversely affected in the IR group, with significant (P < 0.05) decreases in left ventricular developing pressure (LVDevP), dP/dt(max) and dP/dt(min) compared with baseline and the PC group. In addition, there were increases in activity of LDH (20%) and CK (67%) compared with baseline and the PC group. 4. Ischaemic preconditioning and pretreatment with isosteviol, at all dose levels, resulted in a significant (P < 0.05) attenuation of IR injury. Lactate dehydrogenase and CK activities were not significantly (P < 0.05) different compared with baseline. Isosteviol did not increase coronary flow, suggesting that the protective effect of isosteviol on the myocardium was not mediated by dilation of the coronary blood vessels. 5. Pretreatment with the mitoK(ATP) blocker 5-HD partially antagonized the effects of 500 nmol isosteviol, with a statistically significant attenuation of its protective effects on HR, LVDevP, dP/dt(max) and dP/dt(min) compared with isosteviol alone pretreatment. 6. The IR injury on the Langendorff perfused guinea pig heart was alleviated by isosteviol, which appears to mediate its effects through mitoK(ATP) channels. Future research might aim to investigate the interaction of isosteviol with mitoK(ATP) channels in order to clarify its mechanism of action.

The cardioprotective effect of isosteviol on rats with heart ischemia-reperfusion injury

This study was designed to assess the cardioprotective effect of isosteviol on rats with heart ischemia-reperfusion (IR) injury and to explore the mechanism of action of the compound. Sprague Dawley rats were divided into 8 groups (n=10-12): a sham-operated control and 7 ischemia-reperfusion groups (IR control, 3 isosteviol pre-treated (0.5, 1.0 and 2.0 mg kg(-1)), ligustrazine pre-treated, 5-hydroxydecanoate (5-HD) pre-treated and 5-HD+ isosteviol pre-treated groups). IR was produced by occluding the left coronary artery for 30 min followed by re-opening the artery for 90 min. The compounds under investigation were administered intravenously 10 min prior to occluding the artery. Hemodynamic parameters (+/-dp/dt(max), LVSP, LVDevP, MAP), heart rate, ventricular tachycardia (VT) and ventricular fibrillation (VF) were determined during the IR period. The myocardial infarct size, activities of serum lactate dehydrogenase and creatine kinase were determined at the end of the experiment. In the isosteviol pre-treated groups, the hemodynamic parameters were improved and the myocardial infarct size, the activities of serum enzymes, and the incidences of VT and VF were all decreased when compared to the control group. These effects of isosteviol were similar to that of a traditional cardioprotective agent, ligustrazine. The 5-HD+ isosteviol group displayed parameters that were between those in the equivalent isosteviol pre-treated group and the IR control group. In conclusion, damage due to a standard rat heart IR injury was reduced by pretreatment with intravenous isosteviol, and this effect was partly attenuated by a mitochondrial ATP-sensitive potassium channel blocker, 5-HD.

Antiproliferative ent-Kauranoids from Isodon parvifolius

Nine new 7alpha,20-epoxy- ENT-kaurane diterpenoids, parvifolines O - W (1 - 9), together with five known analogues, lasiocarpanin (10), rosthorin A (11), longikaurin E (12), adenolin D (13) and longikaurin B (14), were isolated from the leaves of Isodon parvifolius. Their structures were determined by means of spectroscopic analysis. Selected diterpenoids (1 - 10) were tested for their antiproliferative activity against A549, HT-29 and K562 cells. Compounds 3, 7, 8 and 10 showed moderate inhibitory activity against all three cell lines.

Comparative effects of Stevia rebaudiana leaves and stevioside on glycaemia and hepatic gluconeogenesis

The purpose of the present study was to compare the effect of the oral treatment (gavage) with Stevia rebaudiana (Bert.) Bertoni (SRB) and stevioside (STV) on glycaemia and gluconeogenesis of 15-h fasted rats. For this purpose, the rats received SRB (20 mg/kg x day), STV (5.5 mg/kg x day) or an equal volume of water (controls) during 15 days. To measure hepatic gluconeogenesis, liver perfusion and isolated hepatocytes were used. Glycaemia and gluconeogenesis from L-alanine (5 mM), L-glutamine (5 mM) and L-lactate (2 mM) were decreased (P < 0.05) after pre-treatment with SRB. However, the treatment with STV did not influence glycaemia and gluconeogenesis. Moreover, to get further information about the mechanism by which SRB leaves inhibit gluconeogenesis their potential role as a PPARgamma agonist was investigated. The data showed absence of activation of PPARgamma receptors. In summary, our results showed that the reduction of glycaemia promoted by the treatment with SRB leaves was mediated, at least in part, by an inhibition of hepatic gluconeogenesis. However, this effect did not involve stevioside and the activation of PPARgamma receptors.

An anti-inflammatory ent-kaurane from the stems of Annona squamosa that inhibits various human neutrophil functions

We have previously shown that 11 ent-kauranes isolated from the stems of Annona squamosa exhibited immunomodulating effects in leukocytes. In this study, a cellular model using isolated human neutrophils, which are important in the pathogenesis of rheumatoid arthritis, ischemia-reperfusion injury, chronic obstructive pulmonary disease, asthma and other inflammatory diseases, was established in order to elucidate the anti-inflammatory functions of 16beta,17-dihydroxy-ent-kauran-19-oic acid (1). Reactive oxygen species (ROS) and granule proteases produced by neutrophils contribute to the pathogenesis of inflammatory diseases. Compound 1 inhibited the generation of superoxide anion, the formation of ROS, and the release of elastase in formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP)-activated human neutrophils in a concentration-dependent manner with IC (50) values of 3.95 +/- 0.68, 12.20 +/- 2.16, and 12.52 +/- 2.26 microM, respectively. The anti-inflammatory actions were not attributable to cytotoxicity because incubation of the neutrophils with 1 did not result in lactate dehydrogenase release. Compound 1 did not display antioxidant or superoxide anion-scavenging activity. Furthermore, neither subcellular NADPH oxidase activity nor cAMP-dependent pathways were altered by 1. Compound 1 significantly inhibited rapid calcium release from internal calcium stores induced by FMLP but not by thapsigargin. In summary, the presented results indicate that the inhibitory effects of 1 on respiratory burst and degranulation of human neutrophils are through the inhibition of cytosolic calcium mobilization, but not via the cAMP-dependent pathways.

Increase of insulin sensitivity by stevioside in fructose-rich chow-fed rats

The intake of dietary fructose has undergone a marked increase around the world, especially the developed countries, in recent times. Stevioside, a glycoside contained in the leaves of Stevia rebaudiana Bertoni (Compositae), was used to screen the effect induced by a diet containing 60% fructose on insulin resistance in rats. Single oral administration of stevioside for 90 min decreased plasma glucose concentrations in a dose-dependent manner in rats receiving fructose-rich chow for four weeks. In addition, insulin action on glucose disposal rate was measured using the glucose-insulin index, the product of the areas under the curve of glucose, and insulin during the intraperitoneal glucose tolerance test. Oral administration of stevioside (5.0 mg/kg) in rats given four weeks of fructose-rich chow for 90 min reversed the value of glucose-insulin index, indicating that stevioside has the ability to improve insulin sensitivity in this insulin-resistant animal model. Time for the loss of plasma glucose lowering response to tolbutamide (10.0 mg/kg, i. p.) in fructose-rich chow fed rats was also markedly delayed by repeated stevioside treatment three times daily compared to the vehicle-treated group. The plasma glucose-lowering activity of tolbutamide was introduced to account for varying levels of endogenous insulin secretion, and is widely used as the indicator of insulin resistance development. Thus, it provided the supportive data that repeated oral administration of stevioside delayed the development of insulin resistance in rats on a high-fructose diet. Increased insulin sensitivity by stevioside administration was further identified using the plasma glucose-lowering action of exogenous insulin in streptozotocin-induced diabetic rats (STZ-diabetic rats). Oral administration of stevioside at 0.2 mg/kg three times daily into STZ-diabetic rats for ten days increased the response to exogenous insulin. Taken together, this demonstrated that oral administration of stevioside improves insulin sensitivity, and seems suitable as an adjuvant for diabetic patients and/or those that consume large amounts of fructose.

Two novel ent-kauranoid diterpenoids from Isodon japonica leaves

Two novel ent-kaurane diterpenoids, taihangjaponicain A (1), and taihangjaponicain B ( 2), and nine known diterpenoids, epinodosin (3), oridonin (4), epinodosinol (5), lasiokaurin ( 6), 1alpha- O-beta- D-glucopyranosylenmenol (7), lasiodonin (8), rabdosichuanin D ( 9), shikokianin (10) and rabdoternin A (11) were isolated from I. japonica leaves. The structures of the two new compounds were elucidated using 1-D and 2-D NMR spectroscopy. Compounds 1 and 3 - 11 were tested against HL-60, HO-8910 and A-549 human tumor cells. Compounds 4, 6 and 10 showed significant cytotoxicity against HL-60 cells with IC (50) values of 4.6, 2.0 and 3.4 microM, respectively, and against A-549 cells with IC (50) values of 17.5, 11.4 and 18.8 microM, respectively. Compound 6 exhibited moderate cytotoxicity against HO-8910 cells with an IC (50) value of 17.9 microM.

Activation of p38 mitogen-activated protein kinase during ent-11alpha-hydroxy-16-kauren-15-one-induced apoptosis in human leukemia HL-60 cells

Kaurene-type diterpenes possess various biological activities including antitumor and anti-inflammatory effects. Indeed, we have found that an ent-kaurene diterpene, ent-11alpha-hydroxy-16-kauren-15-one (KD), induced apoptosis via caspase-8 activation in human promyelocytic leukemia HL-60 cells. However, the mechanism of caspase-8 activation by KD is not clear. In this study, we investigated the involvement of p38 mitogen-activated protein kinase (p38 (MAPK)) in KD-induced apoptosis. p38 (MAPK) was activated by treatment with KD parallel to DNA ladder formation. Pretreatment with SB203580, a specific inhibitor of p38 (MAPK), attenuated induction of apoptosis by KD and inhibited activation of caspase-8. Cleavage of Bid, a typical substrate of caspase-8, was also inhibited by treatment with SB203580, suggesting that activation of p38 (MAPK) occurs upstream of caspase-8 during KD-induced apoptosis.

Glucose concentration in the blood of intact and alloxan-treated mice after pretreatment with commercial preparations of Stevia rebaudiana (Bertoni)

The study was concerned with the effect of mice pretreatment with two commercial products of Stevia rebaudiana Bertoni on the blood glucose concentration. One group of mice was pretreated four days with 200 mg/kg of Stevita (Stevita Co, INC, Arlington Texas) (stevia) and the other with 20 mg/kg of Clear Steviosides liquid (Stevita Co, INC, Herbal supplement, Brazil) (stevioside), whereas the animals of control group received at the same time physiological solution. Blood glucose concentration was measured before pretreatment and four days after that. The changes in glucose level were provoked by glucose-tolerance test (500 mg/kg, p.o.) and subcutaneous injection of adrenaline (0.2 mg/kg). The same procedure of measuring blood glucose was applied on the mice with alloxan-induced diabetes mellitus (two doses of 100 mg/kg with a 24-hour interval). Blood glucose levels in mice pretreated with stevia and stevioside were lower compared with control (7.82:6.82:8.01). Also, a smaller increase in this parameter compared to control was registered with pretreated mice in the glucose-tolerance test, pretreatment with stevioside being again more effective (8.68:6.36:5.82). Pretreatment with stevioside caused no significant increase in blood glucose concentration after administering adrenaline, which was not the case with the animals pretreated with stevia and control. Pretreatment with stevia, and to a greater extent with stevioside, protected test animals from the toxic action of alloxan compared with controls.

An ent-kaurene diterpene enhances apoptosis induced by tumor necrosis factor in human leukemia cells

Some antitumor agents, including tumor necrosis factor-alpha (TNF-alpha) and camptothecin (CPT), often cause resistance of tumor cells to antitumor agents through activation of the nuclear factor-kappa B (NF-kappa B) pathway that leads to up-regulation of anti-apoptotic proteins. Therefore, co-treatment of an inhibitor of the NF-kappa B pathway with antitumor agents is a useful strategy for chemotherapy. Here we report that ent-11 alpha-hydroxy-16-kauren-15-one (KD) selectively inhibits NF-kappa B-dependent gene expression due to treatment with TNF-alpha. KD in combination with TNF-alpha caused a dramatic increase in apoptosis in human leukemia cells accompanied by activation of caspases. A broad-spectrum inhibitor of caspases decreased the apoptosis induced by treatment with KD and TNF-alpha. KD in combination with CPT also caused an increase in apoptosis. These results suggest that the apoptotic potency of co-treatment of KD with TNF-alpha or CPT is elicited through selective inhibition of NF-kappa B-dependent anti-apoptotic proteins and thus may provide a basis for the development of useful approaches to the treatment of leukemia.

A novel cytotoxic oxetane ent-kauranoid from Isodon japonicus

A novel ll,20: 1,20-diepoxy-ent-kaurane diterpenoid, maoyecrystal 1 (1), was isolated from Isodan japonicus, and its structure was elucidated by spectroscopic methods and comparison with another new ent-kauranoid, rubescensin W (2) from Isodon rubescens var. taihangensis. The structure of 2 was determined by single crystal X-ray diffraction analysis. A bioassay of their cytotoxity against K562 cells showed that the oxetane group of 1 might be a bioactive moiety.