Schisandrin B stereoisomers protect against hypoxia/reoxygenation‐induced apoptosis and associated changes in the Ca2+‐induced mitochondrial permeability transition and mitochondrial membrane potential in AML12 hepatocytes

The effects of the schisandrin B stereoisomers, (±)γ‐schisandrin [(±)γ‐Sch] and (?)schisandrin B [(?)Sch B], on hypoxia/reoxygenation‐induced apoptosis were investigated in AML12 hepatocytes. Changes in cellular reduced glutathione (GSH) levels, Ca²⁺‐induced mitochondrial permeability transitions (MPTs) and mitochondrial membrane potentials (Δψ_m values) were also examined in (±)γ‐Sch‐ and (?)Sch B‐treated cells, without or with hypoxia/reoxygenation challenge. The (±)γ‐Sch/(?)Sch B pretreatments (2.5–5.0 µm ) protected against hypoxia/reoxygenation‐induced apoptosis in AML12 cells in a concentration‐dependent manner, with the (?)Sch B effect being more potent. Drug antiapoptotic effects were further evidenced by suppression of hypoxia/reoxygenation‐induced mitochondrial cytochrome c release and subsequent cleavage of caspase 3 and poly‐ADP‐ribose polymerase by (?)Sch B pretreatment. Whereas hypoxia/reoxygenation challenge increased the extent of Ca²⁺‐induced MPT pore opening, and Δψ_m, in AML12 hepatocytes, cytoprotection afforded by (±)γ‐Sch/(?)Sch B pretreatment against hypoxia/reoxygenation‐induced apoptosis was associated with a decreased sensitivity to Ca²⁺‐induced MPT and an increased Δψ_m in both unchallenged and challenged cells, compared with the drug‐free control. The results indicate that (±)γ‐Sch/(?)Sch B pretreatment protected against hypoxia/reoxygenation‐induced apoptosis in AML12 hepatocytes and that the cytoprotection afforded by (±)γ‐Sch/(?)Sch B may at least in part be mediated by a decrease in sensitivity to Ca²⁺‐induced MPT, which may in turn result from enhancement of cellular GSH levels by drug pretreatments. Copyright © 2009 John Wiley & Sons, Ltd.     

Genistein inhibits Aβ25–35‐induced SH‐SY5Y cell damage by modulating the expression of apoptosis‐related proteins and Ca2+ influx through ionotropic glutamate receptors

In this study, we investigated the protective effects of genistein against SH‐SY5Y cell damage induced by β‐amyloid 25–35 peptide (Aβ_25–35) and the underlying mechanisms. Aβ‐induced neuronal death, apoptosis, glutamate receptor subunit expression, Ca²⁺ ion concentration, amino acid transmitter concentration, and apoptosis‐related factor expression were evaluated to determine the effects of genistein on Aβ‐induced neuronal death and apoptosis. The results showed that genistein increased the survival of SH‐SY5Y cells and decreased the level of apoptosis induced by Aβ_25–35. In addition, genistein reversed the Aβ_25–35‐induced changes in amino acid transmitters, α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate (AMPA) receptors, and N‐methyl‐d ‐aspartate (NMDA) receptor subunits in SH‐SY5Y cells. Aβ_25–35‐induced changes in Ca²⁺ and B‐cell lymphoma‐2 (Bcl‐2) and Bcl‐2‐associated X (Bax) protein and gene levels in cells were also reversed by genistein. Our data suggest that genistein protects against Aβ_25–35‐induced damage in SH‐SY5Y cells, possibly by regulating the expression of apoptosis‐related proteins and Ca²⁺ influx through ionotropic glutamate receptors.     

Xanthorrhizol Induces Apoptosis Through ROS‐Mediated MAPK Activation in Human Oral Squamous Cell Carcinoma Cells and Inhibits DMBA‐Induced Oral Carcinogenesis in Hamsters

Xanthorrhizol, a natural sesquiterpenoid compound isolated from Curcuma xanthorrhiza Roxb, has been known to inhibit the growth of human colon, breast, liver and cervical cancer cells. In this study, xanthorrhizol decreased cell viability, induced apoptosis and decreased the level of full‐length PARP in SCC‐15 oral squamous cell carcinoma (OSCC) cells. A decrease in cell viability and PARP degradation was not prevented by treatment with the caspase inhibitor Z‐VAD‐fmk in xanthorrhizol‐treated cells. Xanthorrhizol treatment elevated intracellular Ca²⁺ and ROS levels in SCC‐15 cells. Treatment with a Ca²⁺ chelator, EGTA/AM, did not affect xanthorrhizol‐ induced cytotoxicity, but cell viability was partly recovered by treatment with endogenous antioxidant, GSH, or hydroxy radical trapper, MCI‐186. Furthermore, the viability of xanthorrhizol‐treated SCC‐15 cells was significantly restored by treatment with SB203580 and/or SP600125 but not significantly by PD98059 treatment. Xanthorrhizol‐induced activation of p38 MAPK and JNK was blocked by MCI‐186. Finally, xanthorrhizol suppressed the number of tumors in buccal pouches and increased the survival rate in hamsters treated with 7,12‐dimethylbenz[a]anthracene. In conclusion, xanthorrhizol may induce caspase‐independent apoptosis through ROS‐mediated p38 MAPK and JNK activation in SCC‐15 OSCC cells and prevent chemical‐induced oral carcinogenesis. Therefore, xanthorrhizol seems to be a promising chemopreventive agent. Copyright © 2012 John Wiley & Sons, Ltd.     

Bisabololoxide A,One of the Constituents in German Chamomile Extract,Attenuates Cell Death Induced by Calcium Overload

Bisabololoxide A (BSBO), main constituents in German chamomile extract, is responsible for antipruritic effect. In previous study, the incubation with 30–100 μM BSBO for 24 h exerted cytotoxic and proapoptotic effects on rat thymocytes. To further characterize BSBO cytotoxicity, the effect on the cells suffering from calcium overload by calcium ionophore A23187 was examined. A23187 induced Ca²⁺‐dependent cell death. Contrary to our expectation, 1–10 μM BSBO inhibited A23187‐induced increase in cell lethality of rat thymocytes. BSBO attenuated A23187‐induced increases in populations of shrunken living cells, phosphatidylserine‐exposed living cells, and dead cells, without affecting the increase in intracellular Ca²⁺ concentration and the Ca²⁺‐dependent hyperpolarization. The effect of BSBO on A23187‐treated cells may be unique because the activation of Ca²⁺‐dependent K⁺ channels is required for cell shrinkage, externalization of phosphatidylserine, and cell death in some cells. The cell death induced by A23187 was not inhibited by Z‐VAD‐FMK, a pan‐inhibitor of caspases. Thus, the cell death may be a necrosis with some features observed during an early stage of apoptosis. These results suggest that BSBO at low micromolar concentrations is cytoprotective against calcium overload. Copyright © 2013 John Wiley & Sons, Ltd.     

Astragalosides rescue both cardiac function and sarcoplasmic reticulum Ca²⁺ transport in rats with chronic heart failure

The study investigated the beneficial effects of astragalosides (AS) on cardiac performance in rats with chronic heart failure. Chronic heart failure was produced by left anterior descending coronary artery ligation, and the therapeutic efficacy of astragalosides at 10, 20 and 40 mg/kg was evaluated. Five weeks after the operation, cardiac function was deficient and sarcoplasmic reticulum Ca²⁺‐ATPase (SERCA) activity was significantly reduced. Moreover, SERCA mRNA decreased, while expression of the SERCA down‐regulator phospholamban (PLB) was significantly increased. Phosphorylated phospholamban (P‐PLB), the form that does not inhibit SERCA, was also reduced by chronic heart failure. Treatment with AS improved left ventricle function and cardiac structure, reversed the depression of SERCA activity, and increased P‐PLB. These results suggest that the cardioprotective effect of AS may be due to the increase in P‐PLB protein, which disinhibits SERCA activity. Rescue of sarcoplasmic reticulum Ca²⁺ cycling by astragalosides could normalize excitation–contraction coupling and improve overall cardiac function. Copyright © 2011 John Wiley & Sons, Ltd.     

Antiproliferative Activity of Phenylpropanoids Isolated from Lagotis brevituba Maxim

The aim of the present study was to evaluate the antiproliferative effect of phenylpropanoids isolated from the n‐BuOH‐soluble fraction of an ethanolic extract of Lagotis brevituba Maxim. The phenylpropanoids were identified as echinacoside, lagotioside, glucopyranosyl(1–6)martynoside, plantamoside, and verbascoside. Three of the compounds, lagotioside, glucopyranosyl(1–6)martynoside, and plantamoside, were isolated from L. brevituba for the first time. The antiproliferative activity of the isolates was evaluated in human gastric carcinoma (MGC‐803), human colorectal carcinoma (HCT116), human hepatocellar carcinoma (HepG2), and human lung cancer (HCT116) cells using an 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. Plantamoside showed promising activity against MGC‐803 cells, with a half maximal inhibitory concentration value of 37.09 μM. The mechanism of the pro‐apoptosis effect of plantamoside was then evaluated in MGC‐803 cells. Changes in cell morphology, including disorganization of the architecture of actin microfilaments and formation of apoptotic bodies, together with cell cycle arrest in G2/M phases, were observed after treatment of plantamoside. The antiproliferative and pro‐apoptotic effects were associated with a decrease in the ratio of Bcl‐2/Bax and reduced mitochondrial membrane potential, which was accompanied by the release of reactive oxygen species and Ca²⁺ into the cytoplasm. Taken together, the results indicated that plantamoside promotes apoptosis via a mitochondria‐dependent mechanism. Copyright © 2017 John Wiley & Sons, Ltd.     

Concentration Dependent Effect of (−)‐Epicatechin on Na+/K+‐ATPase and Ca2+‐ATPase Inhibition Induced by Free Radicals in Hypertensive Patients: Comparison with L‐ascorbic Acid

Although the antioxidant properties of flavonoids are well documented, it is still unclear whether these effects are dependent on radical scavenging or iron chelating activities. Oxidative stress, a state of excessive reactive oxygen species (ROS) activity, is associated with vascular disease conditions such as hypertension. Both the anti‐ and pro‐oxidant effects of tea catechins have been implicated in the alterations of cellular functions that determine their chemoprotective and therapeutic potentials in health and diseases. The present study examined the concentration dependent (10^?7 to 10^?4 m ) effects of (?)‐epicatechin and L‐ascorbic acid on Na⁺/K⁺‐ATPase and Ca²⁺‐ATPase activity in hypertensive patients and normal subjects. L‐ascorbic acid has been used as a positive control to compare the effect of (?)‐epicatechin. A significant (p < 0.0001) decrease in the activities of Na⁺/K⁺‐ATPase and Ca²⁺‐ATPase was observed in hypertensive patients compared with normal subjects. We report that (?)‐epicatechin shows a significant (p < 0.001) dose‐dependent protective effect against oxidative stress induced by tert‐butyl hydroperoxide (t‐BHP), which is manisfested as a decrease in the activity of erythrocyte Na⁺/K⁺‐ATPase and Ca²⁺‐ATPase, in hypertensive patients as well as normal subjects. The effect of L‐ascorbic acid was also significant (p < 0.001) and was comparable with that of (?)‐epicatechin. Copyright © 2012 John Wiley & Sons, Ltd.     

Alkali‐Soluble Polysaccharide,Isolated from Lentinus edodes,Induces Apoptosis and G2/M Cell Cycle Arrest in H22 Cells Through Microtubule Depolymerization

The aim of the study was to evaluate the pro‐apoptotic effects of polysaccharides derived from Lentinus edodes and further elucidated the mechanisms of this action. Our results demonstrated that marked morphological changes of apoptosis were observed after treatment of L. edodes polysaccharides [Lentinan (LTN)]. Moreover, LTN‐induced cell apoptosis was characterized by a rapid stimulation of reactive oxygen species production, the loss of mitochondrial membrane potential and an increase in intracellular concentration of Ca²⁺. In addition, the results of the haematoxylin and eosin and TUNEL assay further confirmed that LTN‐induced apoptosis in vivo. Furthermore, flow cytometry analysis showed that LTN could arrest the cell cycle at G2/M phase, and immunofluorescence showed LTN caused disruption of microtubule. These results suggest that disruption of cellular microtubule network, arrest of the cell cycle at G2/M phase and induction of apoptosis may be one of the possible mechanisms of anti‐tumour effect of LTN. Copyright © 2014 John Wiley & Sons, Ltd.     

Cholinergic Involvement and Synaptic Dynamin 1 Expression in Yokukansan‐mediated Improvement of Spatial Memory in a Rat Model of Early Alzheimer's Disease

The aim of this study was to investigate the effect of Yokukansan (YKS) on the impairment of spatial memory and cholinergic involvement in a rat model of early‐phase Alzheimer's disease (AD). In this model, rats underwent four‐vessel transient cerebral ischemia and then were treated with beta amyloid oligomers injected intracerebroventricularly once daily for 7 days. These animals showed memory impairment in an eight‐arm radial maze task without histological evidence of apoptosis but with a decrease in expression of hippocampal dynamin 1, an important factor in synaptic vesicle endocytosis. Oral administration of YKS for 2 weeks significantly increased the number of correct choices and decreased the number of error choices in the eight‐arm radial maze task (P < 0.05). Moreover, YKS significantly increased high K⁺‐evoked potentiation of acetylcholine (ACh) release (P < 0.05) and significantly increased the expression of dynamin 1 (P < 0.01) in the hippocampus. The ameliorative effect of YKS on spatial memory impairment in our rat model of early‐phase AD may be mediated in part by an increase in ACh release and modulation of dynamin 1 expression, leading to improved synaptic function. Future studies will determine whether YKS is similarly useful in the treatment of memory defects in patients diagnosed with early‐stage AD. Copyright © 2012 John Wiley & Sons, Ltd.     

Effects of Total Flavones from Acanthopanax senticosus on L‐type Calcium Channels,Calcium Transient and Contractility in Rat Ventricular Myocytes

Acanthopanax senticosus (Rupr. et Maxim.) Harms (AS), a traditional herbal medicine, has been widely used to treat ischemic heart disease. However, the underlying cellular mechanisms of its benefits to cardiac function remain unclear. The present study examined the effects of total flavones from AS (TFAS) on L‐type Ca²⁺ channel currents (I_Ca‐L) using the whole cell patch‐clamp technique and on intracellular calcium ([Ca²⁺]_i) handling and cell contractility in rat ventricular myocytes with the aid of a video‐based edge‐detection system. Exposure to TFAS resulted in a concentration‐ and voltage‐dependent blockade of I_Ca‐L, with the half‐maximal inhibitory concentration (IC₅₀) of 283.12 µg/mL and the maximal inhibitory effect of 36.49 ± 1.95%. Moreover, TFAS not only increased the maximum current in the current–voltage relationship but also shifted the activation and inactivation curves of I_Ca‐L toward the hyperpolarizing direction. Meanwhile, TFAS significantly reduced amplitudes of myocyte shortening and [Ca²⁺]_i with an increase in the time to 10% of the peak (Tp) and a decrease in the time to 10% of the baseline (Tr). Thus, the cardioprotective effects of TFAS may be attributed mainly to the attenuation of [Ca²⁺]_i through the direct inhibition of I_Ca‐L in rat ventricular myocytes and consequent negative effect on myocardial contractility. Copyright © 2015 John Wiley & Sons, Ltd.     

Anti‐platelet Activity of Erythro‐(7S,8R)‐7‐acetoxy‐3,4,3′,5′‐tetramethoxy‐8‐O‐4′‐neolignan from Myristica fragrans

Platelets play a critical role in pathogenesis of cardiovascular disorders and strokes. The inhibition of platelet function is beneficial for the treatment and prevention of these diseases. In this study, we investigated the anti‐platelet activity of erythro‐(7S,8R)‐7‐acetoxy‐3,4,3′,5′‐tetramethoxy‐8‐O‐4′‐neolignan (EATN), a neolignan isolated from Myristica fragrans, using human platelets. EATN preferentially inhibited thrombin‐ and platelet‐activating factor (PAF)‐induced platelet aggregation without affecting platelet damage in a concentration‐dependent manner with IC₅₀ values of 3.2 ± 0.4 and 3.4 ± 0.3 μM, respectively. However, much higher concentrations of EATN were required to inhibit platelet aggregation induced by arachidonic acid. EATN also inhibited thrombin‐induced serotonin and ATP release, and thromboxane B₂ formation in human platelets. Moreover, EATN caused an increase in cyclic AMP (cAMP) levels and attenuated intracellular Ca²⁺ mobilization in thrombin‐activated human platelets. Therefore, we conclude that the inhibitory mechanism of EATN on platelet aggregation may increase cAMP levels and subsequently inhibit intracellular Ca²⁺ mobilization by interfering with a common signaling pathway rather than by directly inhibiting the binding of thrombin or PAF to their receptors. This is the first report of the anti‐platelet activity of EATN isolated from M. fragrans. Copyright © 2013 John Wiley & Sons, Ltd.     

Acacetin‐induced cell apoptosis in head and neck squamous cell carcinoma cells: Evidence for the role of muscarinic M3 receptor

Aacacetin, a plant flavone has shown antitumor efficacy recently. However, its associated mechanisms are poorly known. We hypothesized that the muscarinic M3 receptor (M₃R), which is highly expressed in some cancer tissue, is related to the antitumor effect of acacetin in head and neck squamous cell carcinoma (HNSCC) cells. Our results showed that 12.5‐ to 200‐μM acacetin inhibited cell viability in dose‐ and time‐dependent manners in HNSCC cells, but a relative higher concentration was needed for oral adenoid cystic carcinoma cells. M₃R expression level was higher in HNSCC cells than that in adenoid cystic carcinoma cells. Flow cytometry and electron microscopy confirmed acacetin‐induced cell apoptosis in 22B cells, a HNSCC cell line. Acacetin promoted mitochondrial cytochrome c release and caspase 9, 3 processing. Knocking down of M₃R expression by specific siRNA significantly prevented the acacetin‐induced cell viability damage, cell apoptosis, and caspase 3 activation. Besides, M₃R was also involved in acacetin‐induced elevation of reactive oxygen species and intracellular calcium ([Ca²⁺]_i). These data indicate that acacetin‐induced cell apoptosis in HNSCC cells may through M₃R related calcium signaling and caspase 3 activation. Acacetin is a potent natural antitumor reagent especially for the tumor cells, which highly expressed M₃R.     

New Findings on the Effects of Tannic Acid: Inhibition of L‐Type Calcium Channels,Calcium Transient and Contractility in Rat Ventricular Myocytes

Tannic acid (TA) is a group of water‐soluble polyphenolic compounds that occur mainly in plant‐derived feeds, food grains and fruits. Many studies have explored its biomedical properties, such as anticancer, antibacterial, antimutagenic, antioxidant, antidiabetic, antiinflammatory and antihypertensive activities. However, the effects of TA on the L‐type Ca²⁺ current (I_Ca‐L) of cardiomyocytes remain undefined. The present study examined the effects of TA on I_Ca‐L using the whole‐cell patch‐clamp technique and on intracellular Ca²⁺ handling and cell contractility in rat ventricular myocytes with the aid of a video‐based edge detection system. Exposure to TA resulted in a concentration‐ and voltage‐dependent blockade of I_Ca‐L, with the half maximal inhibitory concentration of 1.69 μM and the maximal inhibitory effect of 46.15%. Moreover, TA significantly inhibited the amplitude of myocyte shortening and peak value of Ca²⁺ transient and increased the time to 10% of the peak. These findings provide new experimental evidence for the cellular mechanism of action of TA and may help to expand clinical treatments for cardiovascular disease. Copyright © 2016 John Wiley & Sons, Ltd.     

环维黄杨星D对心肌细胞缺氧/复氧损伤的保护作用和对心肌细胞内游离钙浓度的影响

目的:研究环维黄杨星D(CVB-D)对培养乳鼠心肌细胞缺氧/复氧损伤的保护作用和对急性分离大鼠心肌细胞内游离Ca²⁺浓度的影响。方法:采用培养的乳鼠心肌细胞建立缺氧/复氧损伤模型,测定心肌细胞搏动频率、细胞存活率、肌酸激酶(CK)的含量;应用特异性荧光指示剂Fluo-3/AM负载急性分离的大鼠心肌细胞,用激光共聚焦显微镜检测胞内游离钙的变化。结果:缺氧/复氧损伤+环维黄杨星D组(H/R+CVB-D)乳鼠心肌细胞搏动频率、细胞存活率与缺氧/复氧损伤组比较明显升高,CK含量与缺氧/复氧损伤组比较明显下降。对急性分离大鼠心肌细胞内[Ca²⁺]i逐步升高,并呈剂量依赖性;在有外钙和无外钙时,CVB-D对胞内钙的升高有显著差异(P<0.05);在无外钙并加入内罗啶孵育后,CVB-D引起的胞内[Ca²⁺]i轻度升高,但与无钙组相比无显著性差异(P>0.05)。结论:环维黄杨星D对培养乳鼠心肌细胞缺氧/复氧损伤有保护作用,对急性分离大鼠有升高心肌细胞内游离钙离子浓度的作用,[Ca²⁺]的升高既源于内钙释放又源于外钙内流。     

双苯氟嗪对大鼠脑缺血再灌注损伤后胞浆[Ca2+]i的影响

 目的研究双苯氟嗪(Dip)对大鼠局灶性脑缺血再灌注损伤后脑神经细胞胞浆Ca²⁺浓度([Ca²⁺]_i)变化的影响。方法将400pmol的内皮素-1(ET-1)灌注到大鼠大脑中动脉附近制备大鼠局灶性脑缺血再灌注模型,以Fura-2/AM作为钙荧光指示剂,双波长荧光分光光度法检测灌注ET-1后不同时间大鼠大脑皮层和纹状体神经细胞胞浆[Ca²⁺]_i的变化及Dip对灌注ET-1后4h胞浆[Ca²⁺]_i变化的影响,并采用TYC染色法观察了Dip对灌注ET-1后24h脑梗死范围的影响。结果灌注400pmolET-1诱发大鼠局灶性脑缺血再灌注损伤后,大鼠大脑皮层和纹状体神经细胞胞浆[Ca²⁺]_i明显升高,并于灌注EF-1后4h达峰值,随着再灌注时间的延长,胞浆[Ca²⁺]_i逐渐降低;Dip20,40mg·kg^-1可以明显降低灌注ET-1后4h大脑皮层和纹状体神经细胞胞浆[Ca²⁺]_i的升高(P<0.01),Dip10mg·kg^-1组虽表现出一定的降低胞浆[Ca²⁺]_i的作用,但与溶剂组比较,差异无显著性(P>0.05);对脑梗死范围的测定结果显示,Dip可以缩小脑梗死范围,其作用呈现明显的剂量依赖关系(r=0.9797,P<0.01)。结论Dip对抗脑缺血再灌注损伤后胞浆[Ca²⁺]_i升高可能是其产生神经保护作用的重要机制。     

附子水溶性生物碱对心衰细胞模型的治疗作用

目的:研究附子水溶性生物碱对心力衰竭大鼠心肌细胞膜ATP酶以及相关离子的影响,以揭示其对急性心力衰竭细胞的治疗作用。方法:取新生大鼠心室肌细胞原代培养5 d至细胞成熟,用0.8%戊巴比妥钠作用5 min造模后,分别给予附子水溶性生物碱0.01,0.02,0.04 g·L-1,以及阳性药物去乙酰毛花苷注射液4 mL·L-1,作用1.5 h后检测心肌细胞ATP酶活性以及各相关离子浓度。结果:模型组与正常组比较,心肌细胞活力明显减小,细胞内Ca2+-ATP酶和Ca2+-Mg2+-ATP酶的活性与Na+,Mg2+含量降低,K+,Ca2+的含量与Na+-K+-ATP酶的活性上升;去乙酰毛花苷4 mL·L-1以及附子水溶性生物碱各剂量组均能提高心衰细胞的细胞活性,并能升高模型细胞Na+,Mg2+含量,提高细胞内Ca2+-ATP酶和Ca2+-Mg2+-ATP酶的活性,降低K+,Ca2+的含量与Na+-K+-ATP酶的活性。结论:附子水溶性生物碱能调节心衰细胞内酶的活力与离子浓度使之趋于正常,对戊巴比妥钠致心衰细胞模型具有一定的治疗作用。     

Cognitive Ameliorating Effect of Acanthopanax koreanum Against Scopolamine‐Induced Memory Impairment in Mice

Acanthopanax koreanum Nakai (Araliaceae) is one of the most widely cultivated medicinal plants in Jeju Island, Korea, and the roots and stem bark of A. koreanum have been traditionally used as a tonic agent for general weakness. However, the use of A. koreanum for general weakness observed in the elderly, including those with declined cognitive function, has not been intensively investigated. This study was performed to investigate the effect of the ethanol extract of A. koreanum (EEAK) on cholinergic blockade‐induced memory impairment in mice. To evaluate the ameliorating effects of EEAK against scopolamine‐induced memory impairment, mice were orally administered EEAK (25, 50, 100, or 200 mg/kg), and several behavioral tasks, including a passive avoidance task, the Y‐maze, and a novel object recognition task, were employed. Besides, western blot analysis was conducted to examine whether EEAK affected memory‐associated signaling molecules, such as protein kinase B (Akt), Ca²⁺/calmodulin‐dependent protein kinase II (CaMKII), and cAMP response element‐binding protein (CREB). The administration of EEAK (100 or 200 mg/kg, p.o.) significantly ameliorated the scopolamine‐induced cognitive impairment in the passive avoidance task, the Y‐maze, and the novel object recognition task. The phosphorylation levels of both Akt and CaMKII were significantly increased by approximately two‐fold compared with the control group because of the administration of EEAK (100 or 200 mg/kg) (p < 0.05). Moreover, the phosphorylation level of CREB was also significantly increased compared with the control group by the administration of EEAK (200 mg/kg) (p < 0.05). The present study suggests that EEAK ameliorates the cognitive dysfunction induced by the cholinergic blockade, in part, via several memory‐associated signaling molecules and may hold therapeutic potential against cognitive dysfunction, such as that presented in neurodegenerative diseases, for example, Alzheimer's disease. Copyright © 2017 John Wiley & Sons, Ltd.     

20(S)‐ginsenoside Rg3, a neuroprotective agent,inhibits mitochondrial permeability transition pores in rat brain

Ginseng, the root of Panax ginseng C.A. Meyer (Araliaceae), is a well‐known traditional Chinese herbal medicine. Ginsenosides, which are triterpene derivatives that contain sugar moieties, are the main active ingredients of ginseng. 20(S)‐Ginsenoside Rg3, a triterpene glycoside which chemically belongs to the protopanaxadiol ginsenoside group, is effective in attenuating brain infarction after cerebral ischemia, but the detailed mechanism is not known. This study examined the effect of 20(S)‐ginsenoside Rg3 on mitochondrial permeability transition pore (MPTP) in the rat brain. 20(S)‐Ginsenoside Rg3 at 2–16 µm inhibited Ca²⁺‐ and H₂O₂‐induced swelling of mitochondria isolated from rat brains. The addition of Ca²⁺ generated reactive oxygen species (ROS) in isolated mitochondria. 20(S)‐Ginsenoside Rg3 (2–16 µm ) inhibited Ca²⁺ induced generation of ROS. At the same time, 20(S)‐ginsenoside Rg3 significantly improved mitochondrial energy metabolism, enhanced ATP levels and the respiratory control ratio. These results suggest that 20(S)‐ginsenoside Rg3 inhibits the opening of MPTP by free radical scavenging action in the brain, and this implies that inhibition of MPTP may contribute to the neuroprotective effect of 20(S)‐ginsenoside Rg3. Copyright © 2008 John Wiley & Sons, Ltd.     

Mechanisms of Vasorelaxation Induced by Hexahydrocurcuminin Isolated Rat Thoracic Aorta

This study was designed to examine the vasorelaxant effects of hexahydrocurcumin (HHC), one of the major natural metabolites of curcumin from Curcuma longa, on rat isolated aortic rings, and the underlying mechanisms. Isometric tension of the aortic rings was recorded using organ bath system. HHC (1 nM to 1 mM) relaxed the endothelium‐intact aortic rings pre‐contracted with PE and KCl in a concentration‐dependent manner. Removal of the endothelium did not alter the effect of HHC‐induced relaxation. In Ca²⁺‐free Krebs solution, HHC significantly inhibited the CaCl₂‐induced contraction in high K⁺ depolarized rings and suppressed the transient contraction induced by PE and caffeine in a concentration‐dependent manner. HHC was also observed to relax phobal‐12‐myristate‐13‐acetate (PMA), an activator of protein kinase C (PKC), precontracted aortic rings in a concentration‐dependent manner with EC₅₀ values equivalent to 93.36 ± 1.03 μM. In addition, pre‐incubation with propranolol (a β‐adrenergic receptor blocker) significantly attenuated the HHC‐induced vasorelaxation. These results suggest that the vasorelaxant effect of HHC is mediated by the endothelium‐independent pathway, probably because of the inhibition of extracellular Ca²⁺ influx through voltage‐operated Ca²⁺ channels and receptor‐operated Ca²⁺ channels, the inhibition of Ca²⁺mobilization from intracellular stores, as well as inhibition of PKC‐mediated Ca²⁺‐independent contraction. Moreover, HHC produces vasorelaxant effects probably by stimulating the β‐adrenergic receptor. Copyright © 2015 John Wiley & Sons, Ltd.