The anti-cancer activities of Vernonia amygdalina extract in human breast cancer cell lines are mediated through caspase-dependent and p53-independent pathways

Breast cancer is currently the leading cause of cancer-related deaths among women globally. Notably, medicinal plant extracts may be a potential source for treatments of breast cancer. Vernonia amygdalina (VA) is a woody shrub reported to have not only diverse therapeutic effects but also anti-cancer properties. However, current research about the mechanisms of the anti-cancer potential of VA has been limited. This study aimed to investigate the mechanisms of action of VA that underlie its anti-cancer effects in human breast cancer cell lines (MCF-7 and MDA-MB-231 cells). Results from MTT assay revealed that VA inhibits the proliferation of MCF-7 and MDA-MB-231, in a time- and dose-dependent manner. The underlying mechanism of this growth inhibition involved the stimulation of cell-type specific G1/S phase cell cycle arrest in only MCF-7 cells, and not in MDA-MB-231 cells. While the growth arrest was associated with increased levels of p53 and p21, and a concomitant decrease in the levels of cyclin D1 and cyclin E, it was shown that VA causes cell cycle arrest through a p53-independent pathway as tested by the wild type p53 inhibitor, pifithrin-α. Furthermore, this study revealed that VA induces apoptosis in the two cell lines, as indicated by the increase in Annexin V-positive cells and sub-G1 population, and that this VA-induced apoptosis occurred through both extrinsic and intrinsic apoptotic pathways. The apoptosis in MCF-7 cells was also likely to be caspase-dependent and not p53 transcriptional-dependent. Given that approximately 70% of diagnosed breast cancers express ER-α, a crucial finding was that VA inhibits the expression of ER-α and its downstream player, Akt, highlighting the potential clinical significance of VA. Moreover, VA exhibits synergism when combined with doxorubicin, suggesting that it can complement current chemotherapy. Overall, this study demonstrates the potential applications of VA as an anti-cancer drug for breast cancer treatment.

Chlorogenic acid stimulates glucose transport in skeletal muscle via AMPK activation: a contributor to the beneficial effects of coffee on diabetes

Chlorogenic acid (CGA) has been shown to delay intestinal glucose absorption and inhibit gluconeogenesis. Our aim was to investigate the role of CGA in the regulation of glucose transport in skeletal muscle isolated from db/db mice and L6 skeletal muscle cells. Oral glucose tolerance test was performed on db/db mice treated with CGA and soleus muscle was isolated for 2-deoxyglucose transport study. 2DG transport was also examined in L6 myotubes with or without inhibitors such as wortmannin or compound c. AMPK was knocked down with AMPKα1/2 siRNA to study its effect on CGA-stimulated glucose transport. GLUT 4 translocation, phosphorylation of AMPK and Akt, AMPK activity, and association of IRS-1 and PI3K were investigated in the presence of CGA. In db/db mice, a significant decrease in fasting blood sugar was observed 10 minutes after the intraperitoneal administration of 250 mg/kg CGA and the effect persisted for another 30 minutes after the glucose challenge. Besides, CGA stimulated and enhanced both basal and insulin-mediated 2DG transports in soleus muscle. In L6 myotubes, CGA caused a dose- and time-dependent increase in glucose transport. Compound c and AMPKα1/2 siRNA abrogated the CGA-stimulated glucose transport. Consistent with these results, CGA was found to phosphorylate AMPK and ACC, consistent with the result of increased AMPK activities. CGA did not appear to enhance association of IRS-1 with p85. However, we observed activation of Akt by CGA. These parallel activations in turn increased translocation of GLUT 4 to plasma membrane. At 2 mmol/l, CGA did not cause any significant changes in viability or proliferation of L6 myotubes. Our data demonstrated for the first time that CGA stimulates glucose transport in skeletal muscle via the activation of AMPK. It appears that CGA may contribute to the beneficial effects of coffee on Type 2 diabetes mellitus.

Hydrogen sulfide regulates Na+/H+ exchanger activity via stimulation of phosphoinositide 3-kinase/Akt and protein kinase G pathways

Intracellular pH (pH(i)) is an important endogenous modulator of cardiac function. Inhibition of Na(+)/H(+) exchanger-1 (NHE-1) protects the heart by preventing Ca(2+) overload during ischemia/reperfusion. Hydrogen sulfide (H(2)S) has been reported to produce cardioprotection. The present study was designed to investigate the pH regulatory effect of H(2)S in rat cardiac myocytes and evaluate its contribution to cardioprotection. It was found that sodium hydrosulfide (NaHS), at a concentration range of 10 to 1000 μM, produced sustained decreases in pH(i) in the rat myocytes in a concentration-dependent manner. NaHS also abolished the intracellular alkalinization caused by trans-(±)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]benzeneacetamide methane-sulfonate hydrate (U50,488H), which activates NHEs. Moreover, when measured with an NHCl(4) prepulse method, NaHS was found to significantly suppress NHE-1 activity. Both NaHS and cariporide or [5-(2-methyl-5-fluorophenyl)furan-2-ylcarbonyl]guanidine (KR-32568), two NHE inhibitors, protected the myocytes against ischemia/reperfusion injury. However, coadministration of NaHS with KR-32568 did not produce any synergistic effect. Functional study showed that perfusion with NaHS significantly improved postischemic contractile function in isolated rat hearts subjected to ischemia/reperfusion. Blockade of phosphoinositide 3-kinase (PI3K) with 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), Akt with Akt VIII, or protein kinase G (PKG) with (9S,10R,12R)-2,3,9,10,11,12-hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]]enzodiazocine-10-carboxylic acid, methyl ester (KT5823) significantly attenuated NaHS-suppressed NHE-1 activity and/or NaHS-induced cardioprotection. Although KT5823 failed to affect NaHS-induced Akt phosphorylation, Akt inhibitor did attenuate NaHS-stimulated PKG activity. In conclusion, this work demonstrated for the first time that H(2)S produced cardioprotection via the suppression of NHE-1 activity involving a PI3K/Akt/PKG-dependent mechanism.

Polyphenols-rich Vernonia amygdalina shows anti-diabetic effects in streptozotocin-induced diabetic rats

AIM OF THE STUDY

This study aims to investigate the hypoglycemic properties of Vernonia amygdalina Del. (VA) and its possible mechanisms of action in a single-dose STZ induced diabetic rat model.

MATERIALS AND METHODS

A dose-response study was conducted to determine optimum dose for the hypoglycemic effect of VA in STZ-induced diabetic rats. The optimum dose (400 mg/kg) was used throughout the 28-day chronic study. Body weight, food and water intakes of the rats were monitored daily. Fasting blood serum, pancreas, liver and soleus muscle were collected for biochemical analyses. Chemical composition of VA was analysed using HPLC and LC-ESI-MS.

RESULTS

The study reveals that ethanolic extract of VA contains high level of polyphenols mainly 1,5-dicaffeoyl-quinic acid, dicaffeoyl-quinic acid, chlorogenic acid and luteolin-7-O-glucoside. In an oral glucose tolerance test, 400 mg/kg VA exhibited a significant improvement in glucose tolerance of the STZ-induced diabetic rats. 28-day treatment with 400 mg/kg VA resulted in 32.1% decrease in fasting blood glucose compared to diabetic control. VA also caused significant decrease (18.2% and 41%) in triglyceride and total cholesterol level. Besides, VA showed protective effect over pancreatic β-cells against STZ-induced damage, causing a slight increase in insulin level compared to diabetic control. VA administration also showed positive regulation of the antioxidant system, both enzymatic and non-enzymatic. Furthermore, VA was found to increase expression of GLUT 4 (24%) in rat skeletal muscle. Further tissue fractionation revealed that it can increase the GLUT 4 translocation (35.7%) to plasma membrane as well, suggesting that VA may stimulate skeletal muscle's glucose uptake. This observation is in line with the restoration in skeletal muscle glycogenesis of VA-treated group. However, no alteration was observed in GLUT 1 expression. In addition, VA also suppressed (40% inhibition) one of the key hepatic gluconeogenic enzymes, glucose-6-phosphatase (G6Pase).

CONCLUSIONS

VA possesses antihyperglycemic effect, most probably through increasing GLUT 4 translocation and inhibiting hepatic G6Pase. The polyphenols in the extract may be the candidates that are responsible for the above-mentioned biological activities.

Leonurine protects middle cerebral artery occluded rats through antioxidant effect and regulation of mitochondrial function

BACKGROUND AND PURPOSE

Oxidative stress is known to be involved in ischemic stroke. Intense interest is drawn to the therapeutic potential of Chinese herbs on ischemic stroke because many of them contain antioxidant properties. Leonurine, 1 of the active compounds from purified Herba Leonuri, was studied to evaluate its possible therapeutic effects on ischemic stroke. Method-Middle cerebral artery occlusion was selected as our model of study. The animals were pretreated with Leonurine orally for 7 days and the surgery was done. One day after surgery, 2,3,5-triphenyltetrazolium chloride staining and neurological deficit score were carried out to evaluate the functional outcome of animals, whereas levels of superoxide dismutase, glutathione peroxidase, and malondialdehyde were analyzed for oxidative stress analysis. For mitochondrial studies, 3 hours after surgery, mitochondria were isolated for analysis of reactive oxygen species production, adenosine triphosphate biosynthesis, oxygen consumption, and respiratory control ratio value. Result-In in vivo experiments, Leonurine pretreatment reduced infarct volume, improved neurological deficit in stroke groups, increased activities of antioxidant enzymes superoxide dismutase and glutathione peroxidase, and decreased levels from the lipid peroxidation marker malondialdehyde. In terms of mitochondrial modulation, Leonurine inhibited mitochondrial reactive oxygen species production and adenosine triphosphate biosynthesis. Animal studies also demonstrated that the mitochondrial function and redox state were restored by Leonurine treatment.

CONCLUSIONS

Leonurine has neuroprotective effects and carries a therapeutic potential of stroke prevention.

Activation of macrophages by polysaccharide-protein complex from Lycium barbarum L

Macrophages play crucial roles in innate immunity. This paper reports that a polysaccharide-protein complex isolated from Lycium barbarum (LBP) is able to activate macrophages. LBP was isolated from Lycium barbarum fruit and separated to five homogenous fractions, designated LBPF1, LBPF2, LBPF3, LBPF4 and LBPF5. It was found that LBP (50 mg/kg, i.p.) markedly upregulated the expressions of CD40, CD80, CD86 and MHC class II molecules on peritoneal macrophages. In vitro studies showed that LBP and LBPF1-5 activated transcription factors NF-kappaB and AP-1 by RAW264.7 macrophage cells, induced TNF-alpha, IL-1beta, IL-12p40 mRNA expression, and enhanced TNF-alpha production in a dose-dependent manner. Furthermore, LBP (50 mg/kg, i.p.) significantly enhanced macrophage endocytic and phagocytic capacities in vivo. These results indicate that LBP enhances innate immunity by activating macrophages. The mechanism may be through activation of transcription factors NF-kappaB and AP-1 to induce TNF-alpha production and upregulation of MHC class II costimulatory molecules.

Cerebral protection of purified Herba Leonuri extract on middle cerebral artery occluded rats

AIM OF STUDY

Oxidative stress is involved in stroke. In particular, Chinese Herbal Medicine with antioxidant properties is believed to have potential therapeutic effect. In this study, neuroprotective effects of purified Herba Leonuri (pHL) were evaluated in Wistar rats undergone middle cerebral artery occlusion (MCAO).

MATERIALS AND METHODS

The rats were treated with their respective treatments for 2 weeks prior to the MCAO, continually treated for another 7 days after MCAO. During the post-surgery treatment period, neurological deficit score was measured. At the end of treatment, animals were sacrificed and samples were collected for analysis of infarct volume, apoptosis and antioxidant analysis.

RESULTS

Under the treatment of pHL, the infarct volume was reduced significantly from 20.75+/-0.03% to 15.19+/-0.02% (p<0.05). The neurological impairment was alleviated to 1.82 as compared to vehicle (2.43). Plasma antioxidant concentration was increased from 0.31+/-0.03 mM to 0.42+/-0.05 mM (p<0.05). DNA oxidative damage was reduced to 1.19+/-0.03 in stroke pHL treated group (p<0.05 as compared to vehicle group, 1.78+/-0.03). pHL could reduce the level of apoptosis and also the pro-apoptotic proteins, but increase the level of anti-apoptotic proteins.

CONCLUSION

pHL is believed to have promising therapeutic effect for stroke treatment through antioxidant mechanisms.

Scutellarin sensitizes drug-evoked colon cancer cell apoptosis through enhanced caspase-6 activation

BACKGROUND

We have reported that resveratrol (RSV) and 5-fluorouracil (5-FU) evoked apoptosis through caspase-6 activation in wild-type (p53+/+) and knockout (p53(-/-)) HCT116 human colon cancer cells. In this study, we investigated the sensitization effects of scutellarin (SC), a compound isolated from the traditional Chinese herb Erigeron breviscapus, on RSV and 5-FU-evoked apoptosis of these cancer cells.

MATERIALS AND METHODS

The drug-induced apoptosis was qualified by TUNEL staining under fluorescence microscopy, before being quantified by propiodium iodide staining through flow cytometric assay.

RESULTS

SC (100 microM) sensitized RSV- (200 microM) and 5-FU (500 microM)-evoked apoptosis in p53+/+ but not p53(-/-) cells. RSV- and 5-FU-elicited caspase-6 activation was promoted by SC in a time-dependent manner. SC itself did not trigger apoptosis or caspase-6 activation at the concentration tested.

CONCLUSION

SC is a novel sensitizing agent for both RSV- and 5-FU-evoked apoptosis, through the enhancement of caspase-6 activation in a p53-dependent manner.

Polysaccharide-protein complex from Lycium barbarum L. is a novel stimulus of dendritic cell immunogenicity

Dendritic cell (DC) immunogenicity correlates with its maturation, which can be induced by toxic microbial products such as LPS. In this study, we report that a nontoxic polysaccharide-protein complex isolated from a Chinese medicinal herb, Lycium barbarum (LBP), induces phenotypic and functional maturation of DCs with strong immunogenicity. LBP up-regulated DC expression of CD40, CD80, CD86, and MHC class II molecules; down-regulated DC uptake of Ag; enhanced DC allostimulatory activity; and induced IL-12p40 and p70 production. All of its five fractions were active. LBP developed enhanced Th1 response, and LBP-treated DCs enhanced Th1 and Th2 responses in vitro and in vivo. Our study provides evidence and rationale on using LBP in various clinical conditions to enhance host immunity and suggests LBP as a potent adjuvant for the design of DC-based vaccines.

Activation of T lymphocytes by polysaccharide-protein complex from Lycium barbarum L

T lymphocytes play central roles in adaptive immunity. Lycium barbarum L. (L. barbarum), also known as wolfberry, is a Chinese herbal medicine with various biological activities, such as enhancing immunity, protecting liver damage, and reducing the side effects of chemotherapy and radiotherapy. Here, we report that polysaccharide-protein complex from L. barbarum (LBP) is able to activate T cells. LBP was isolated from L. barbarum and separated to five homogenous fractions, designated LBPF1, LBPF2, LBPF3, LBPF4, and LBPF5. We found that LBP, LBPF4, and LBPF5 significantly stimulated mouse splenocyte proliferation. The proliferation proved to be of T cells, but not B cells. Cell cycle profile analysis indicated that LBP, LBPF4, and LBPF5 markedly reduced sub-G1 cells. LBP, LBPF4, and LBPF5 could activate transcription factors NFAT and AP-1, prompt CD25 expression, and induce IL-2 and IFN-gamma gene transcription and protein secretion. LBP (i.p. or p.o.) significantly induced T cell proliferation. Our results suggest that activation of T lymphocytes by LBP may contribute to one of its immuno-enhancement functions.

Anti-diabetic effects of Cichorium intybus in streptozotocin-induced diabetic rats

The present study was designed to investigate the hypoglycemic and hypolipidemic properties of an ethanolic extract of Cichorium intybus (CIE) which is widely used in India as a traditional treatment for diabetes mellitus. Male Sprague-Dawley rats aged 9 weeks (160-200 g) were administered with streptozotocin (STZ, 50mg/kg) intraperitoneally to induce experimental diabetes. The Cichorium intybus whole plant was exhaustively extracted with 80% ethanol, concentrated at 40 degrees C using a rotavapor and freeze dried to get powder. Hypoglycemic effects of CIE were observed in an oral glucose tolerance test (OGTT) in which, a dose of 125 mg of plant extract/kg body weight exhibited the most potent hypoglycemic effect. Moreover, daily administration of CIE (125 mg/kg) for 14 days to diabetic rats attenuated serum glucose by 20%, triglycerides by 91% and total cholesterol by 16%. However, there was no change in serum insulin levels, which ruled out the possibility that CIE induces insulin secretion from pancreatic beta-cells. In addition, hepatic glucose-6-phosphatase activity (Glc-6-Pase) was markedly reduced by CIE when compared to the control group. The reduction in the hepatic Glc-6-Pase activity could decrease hepatic glucose production, which in turn results in lower concentration of blood glucose in CIE-treated diabetic rats. In conclusion, our results support the traditional belief that Cichorium intybus could ameliorate diabetic state.

Anti-diabetic activity of the semi-purified fractions of Averrhoa bilimbi in high fat diet fed-streptozotocin-induced diabetic rats

The present study was designed to investigate the hypoglycemic and hypolipidemic activities of the semi-purified fractions of an ethanolic leaf extract of Averrhoa bilimbi (ABe) in high fat diet (HFD)-streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats aged 10 weeks (200-250 g) were fed with a high fat diet obtained from Glen Forrest stock feeders (Western Australia) for 2 weeks prior to intraperitoneal injection with streptozotocin (STZ, 50 mg/kg). The leaves of A.bilimbi were exhaustively extracted with 80% ethanol, concentrated at 40 degrees C using a rotavapor and partitioned successively with butanol, ethylacetate and hexane to get aqueous (AF), butanol (BuF), ethylacetate (EF), and hexane fractions (HF). The fractions were freeze-dried to obtain powders of each. To investigate the effect of long term administration of the hypoglycemic fractions, diabetic animals were treated with vehicle (distilled water), AF (125 mg/kg), or BuF (125 mg/kg), twice a day for 14 days. The long term administration of AF and BuF at a dose of 125 mg/kg significantly (P < 0.05) lowered blood glucose and triglyceride concentrations when compared to the vehicle. The hepatic glycogen content was significantly higher (P < 0.05) in AF-treated rats when compared to diabetic control, however no change was found in the BuF-treated rats. Moreover, AF as well as BuF did not cause any significant change in the total cholesterol and HDL-cholesterol. There was also no difference in liver thiobarbituric acid reactive substances (TBARS) and cytochrome P450 values between AF, BuF and vehicle-treated control rats. In conclusion, the results indicate that AF is more potent than BuF in the amelioration of hyperglycemia and hyperlipidemia in HFD fed-STZ diabetic rats. Hence, AF is a potential source for the isolation of active principle(s) for oral anti-diabetic therapy.

GST-pi expression correlates with oxidative stress and apoptosis in breast cancer

Glutathione S-transferase (GST) is known to play a key role in the detoxification and reduction of reactive oxygen species (ROS). Thus, we assessed GST activity and GST-pi expression in relation to oxidative stress and apoptosis in breast cancer. Tumor tissues from 32 breast cancer patients were evaluated for GST activity and thiobarbituric acid reactive substances (TBARS) that are by-products of oxidative stress. Four-micron sections of formalin-fixed, paraffin embedded tumors were stained immunohistochemically with anti-GST-pi. Apoptotic cells were detected by in situ end labeling of DNA fragments using a commercial kit. TBARS levels were significantly higher in breast cancers of older patients. GST-pi expression was up-regulated in breast cancers that exhibited higher oxidative stress and associated with higher GST activity. Apoptosis in GST-pi negative tumors was not correlated with GST activity, but GST-pi positive tumors within the same range of oxidative stress showed a reduction in apoptosis as well as an increased GST activity. This correlation was absent in GST-pi positive tumors experiencing higher oxidative stress. GST-pi expression may influence the level of GST activity and delay apoptosis in breast cancer. However, GST-pi expression in tumors with higher levels of oxidative stress may not be sufficient to abrogate the deleterious effects of ROS.

Antioxidants in Chinese herbal medicines: a biochemical perspective

Recently, intense interest has focused on the antioxidant properties of natural products. In particular, Chinese herbal medicines (CHM) have become hot topics for life science researchers since many are reported to possess cardioprotective compounds, many of which remain to be identified. Indeed, the exact mechanisms by which CHM work remain unknown. Although many of these herbal remedies are undoubtedly efficacious, few have been scientifically investigated for their active chemical constituents and biological activities. We have previously reported higher activities of antioxidant defence enzymes such as superoxide dismutase, catalase, glutathione peroxidase and glutathione S-transferases in the liver of rats treated with the herb Salvia miltiorrhiza in a model of acute myocardial infarction. Using well established in vitro antioxidant assays employing 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and diphenyl-l-picrylhydrazyl (DPPH) we have shown that in addition to elevating endogenous antioxidant enzyme activity, Salvia miltiorrhiza and other CHM traditionally used for cardiovascular disorders (such as Rhizoma ligustici, Herba leonuri, Radix achyranthis bidentatae, and Camellia sinensis) contain potent antioxidant moieties in addition to their phenolic constituents. Furthermore, these novel non-phenolic components are effective inhibitors of oxidative reactions mediated by the inflammatory oxidants, peroxynitrite,hypochlorous acid and hydroxyl radical as well as iron-dependent lipid peroxidation. In this review, we discuss the various antioxidant properties of CHM in the context of their biochemical mechanisms.

Photoactivation of hypericin down-regulates glutathione S-transferase activity in nasopharyngeal cancer cells

Photodynamic therapy (PDT) is a new modality of treatment for cancer. Hypericin is a photosensitizer, which is known to generate reactive oxygen species upon activation with light. We observed that photoactivated hypericin induces the generation of reactive oxygen intermediates in nasopharyngeal cancer (NPC) cells in vitro. There was also significant reduction of Glutathione S-transferase (GST) activity in HK1 and CNE-2 NPC cells and in tumor tissues from the NPC/HK1 murine tumor model by hypericin-mediated PDT. As antioxidants protect cells against phototoxicity, down-regulation of GST activity would potentiate the efficacy of hypericin-PDT treatment.

Evaluation of the hypoglycemic and anti-oxidant activities of Morinda officinalis in streptozotocin-induced diabetic rats

AIM OF STUDY

The aim was to investigate the hypoglycemic and anti-oxidant activities of the dried roots of Morinda officinalis in streptozotocin-induced diabetic rats.

METHODOLOGY

An ethanolic extract of the dried roots of Morinda officinalis and its three fractions (ethyl acetate, n-butanol and water) were obtained. We evaluated the hypoglycemic effects of three different single doses of the crude extract and its fractions in normal and diabetic rats for three hours after administration. Administration of the extract at 150 mg/kg twice daily for 10 days to the diabetic rats was also carried out. The effects of the 10-day treatment on the fasting serum glucose, insulin, total cholesterol, triglycerides, body weight, food intake, fluid intake, hepatic superoxide dismutase (SOD), catalase (CAT) activities, reduced glutathione (GSH), thiobarbituric acid reactive substances (TBARS) and renal TBARS levels were monitored.

RESULTS

In the three-hour dose response study, the crude ethanolic extract reduced the fasting serum glucose levels of the diabetic rats significantly at 150 mg/kg but increased those of the normal rats significantly at 600 mg/kg only. The water fraction demonstrated a dose dependent hypoglycemic effect in the diabetic rats whereas the n-butanol fraction increased the fasting serum glucose levels of the diabetic rats significantly at 50 mg/kg only within three hours after administration. The 10-day oral administration of the extract reduced the fasting serum glucose, hepatic and renal TBARS level and significantly increased the hepatic SOD and CAT activities as well as GSH levels.

CONCLUSION

The results indicate that the dried roots of Morinda officinalis possess hypoglycemic, hyperglycemic and anti-oxidant properties.