Publications by authors named "Hoi-Yan Leung"

Allergic rhinitis and asthma are common chronic allergic diseases of the respiratory tract, which are accompanied by immunoglobulin E (IgE)-mediated inflammation and the involvement of type 2 T helper cells, mast cells, and eosinophils. (Berk.) Sacc is a fungal parasite on the larva of Lepidoptera.

View Article and Find Full Text PDF

Xiao-Er-An-Shen Decoction (XEASD) has been used clinically for the treatment of Tourette syndrome (TS) in children for more than 20 years in mainland China. The biochemical mechanism underlying the therapeutic action produced by XEASD treatment against TS remains unknown. However, a previous study has shown that pre-incubation of PC12 neuronal cells with XEASD can induce neurite outgrowth and protect against oxidative stress.

View Article and Find Full Text PDF

Background: HCY2, a triterpenoid-enriched extract of Cynomorii Herba, has been shown to reduce body weight and adiposity and attenuate manifestations of the associated metabolic syndrome in high-fat-diet (HFD)-fed mice.

Purpose: The current study aimed to investigate the biochemical mechanism underlying the anti-obesity effect produced by HCY2.

Study Design: An HCY2-containing extract was examined for its effects on the regulation of adenosine monophosphate-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor gamma co-activator-1 (PGC1) pathways and the protein expression related to mitochondrial uncoupling and biogenesis in skeletal muscle using an HFD-induced obese mouse model.

View Article and Find Full Text PDF

Mitochondrial biogenesis, which involves an increase in mitochondrial number and the overall capacity of oxidative phosphorylation, is a critical determinant of skeletal muscle function. Recent findings have shown that some natural products can enhance mitochondrial adaptation to aerobic exercise, which in turn improves exercise performance, presumably by delaying muscle fatigue. Ursolic acid (UA), a natural triterpene, is commonly found in various vegetables and fruits.

View Article and Find Full Text PDF

8th Day superoxide dismutase (SOD)-Like Supreme (SOD-Like Supreme, a free radical scavenging health product) is an antioxidant-enriched fermentation preparation with free radical scavenging properties. In the present study, the cellular/tissue protective actions of SOD-Like Supreme against menadione toxicity in cultured H9c2 cardiomyocytes and in AML12 hepatocytes as well as oxidant-induced injury in the mouse myocardium and liver were investigated. SOD-Like Supreme was found to possess potent free radical scavenging activity in vitro as assessed by an oxygen radical absorbance capacity assay.

View Article and Find Full Text PDF

Schisandrin A (Sch A) and schisandrin B (Sch B) are active components of Schisandrae Fructus. We compared the biochemical mechanism underlying the anti-inflammatory action of Sch A and Sch B, using cultured lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and concanavalin (ConA)-stimulated mouse splenocytes.

View Article and Find Full Text PDF

Previous studies have demonstrated that HCF1, a semipurified fraction of Cistanches Herba, causes weight reduction in normal diet- and high fat diet-fed mice. The weight reduction was associated with the induction of mitochondrial uncoupling and changes in metabolic enzyme activities in mouse skeletal muscle. To further investigate the biochemical mechanism underlying the HCF1-induced weight reduction, the effect of HCF1 and its active component, β-sitosterol (BSS), on C2C12 myotubes was examined.

View Article and Find Full Text PDF

In the practice of traditional Chinese medicine, many Yang-tonic herbs have been used for retarding the decline in bodily function and delaying the onset of age-related diseases. Our earlier studies have demonstrated that Yang-invigorating herbs/formulations protect against oxidative injury in various organs and also extend the median lifespan in mice. This lifespan extension was associated with an upregulation of cellular antioxidant status including that of mitochondria whose functional capacity is also increased by "Yang-invigorating" herbs/formulations.

View Article and Find Full Text PDF

Previous findings have demonstrated that β-sitosterol (BSS), an active component of Cistanches Herba, protected against oxidant injury in H9c2 cardiomyocytes and in rat hearts by enhancing mitochondrial glutathione redox cycling, possibly through the intermediacy of mitochondrial reactive oxygen species production. We therefore hypothesized that BSS pretreatment can also confer tissue protection against oxidant injury in other vital organs such as liver and kidney of rats. In this study, the effects of BSS pretreatment on rat models of carbon tetrachloride (CCl4) hepatotoxicity and gentamicin nephrotoxicity were investigated.

View Article and Find Full Text PDF

This study aimed to investigate the effects of a health product Squina (Diacylglyceryl Ether) (DAGE) on innate and adaptive immunity in mice. Both ex vivo/ in vivo mouse models and an in vitro system using cultured mouse splenocytes were recruited for the assessment of innate and adaptive immunity. For the innate immune response, DAGE extract treatment enhanced the LPS-induced IL1-β secretion by activated macrophages in vitro and long-term DAGE treatment (0.

View Article and Find Full Text PDF

High levels of reactive oxygen species inflict oxidative damage on various cellular components that eventually culminate in a variety of diseases. This study investigated the cytoprotective effects of a nucleic acid-based health product (Squina [Hong Kong, China] DNA) against oxidative stress, particularly in neuronal cells. Adult female Sprague-Dawley rats were treated with Squina DNA, and changes in mitochondrial antioxidant status and functional capacity were assessed by the activities of antioxidant enzymes and ATP generation capacity in brain, heart ventricular, kidney, skeletal muscle, and liver tissues of control and Squina DNA-treated rats.

View Article and Find Full Text PDF

Objective: Schisandrin B (Sch B) is the most abundant, active dibenzocyclooctadiene derivative isolated from the fruit of Schisandra chinensis (Turcz) Baillon (Schisandraceae). (-)Sch B was found to be the most potent stereoisomer of Sch B in producing cytoprotective action in H9c2 cardiomyocytes. The elucidation of biochemical mechanism underlying the cytoprotection of (-)Sch B has attracted much interest in the area of preventive medicine.

View Article and Find Full Text PDF

Sch B (schisandrin B), the most abundant dibenzocyclooctadiene lignan in Fructus schisandrae, can induce glutathione antioxidant and heat shock responses, as well as protect against oxidant-induced injury in various tissues, including the liver in rodents and AML12 (alpha mouse liver 12) hepatocytes. (-)Sch B is the most potent stereoisomer of Sch B in its cytoprotective action on AML12 hepatocytes. To define the role of ROS (reactive oxygen species) arising from CYP (cytochrome P450)-catalysed metabolism of (-)Sch B in triggering glutathione antioxidant and heat shock responses, the effects of a CYP inhibitor [ABT (aminobenzotriazole)] and antioxidants [DMTU (dimethylthiouracil) and TRX (trolox)] on (-)Sch B-induced ROS production and associated increases in cellular GSH level, as well as Hsp25/70 (heat-shock protein 25/70) production, were investigated in AML12 hepatocytes.

View Article and Find Full Text PDF

Danshen-Gegen (DG) Decoction, an herbal formulation containing Radix Salviae miltiorrhizae and Radix Puerariae lobatae, has been used for the treatment of coronary artery disease in Chinese medicine. In the present study, the involvement of ERK- and PKCε-mediated pathways in the cytoprotection against apoptosis afforded by DG pretreatment was investigated in H9c2 cardiomyocytes. Pretreatment with a methanol extract of aqueous DG decoction protected against hypoxia/reoxygenation-induced apoptosis in H9c2 cardiomyocytes.

View Article and Find Full Text PDF

Danshen-Gegen (DG) decoction, an herbal formulation comprising Radix Salvia Miltiorrhiza and Radix Puerariae Lobatae, is prescribed for the treatment of coronary heart disease in Chinese medicine. Experimental and clinical studies have demonstrated that DG decoction can reduce the extent of atherosclerosis. In the present study, using an ex vivo rat model of myocardial ischemia/reperfusion (I/R) injury, we investigated the myocardial preconditioning effect of an aqueous DG extract prepared from an optimized weight-to-weight ratio of Danshen and Gegen.

View Article and Find Full Text PDF

Background: Danshen-Gegen decoction (DG), a Chinese herbal formula, has been demonstrated to be effective for the treatment of coronary heart disease such as myocardial infarction. In the present study, we investigated the effect of DG post-conditioning on isoproterenol (ISO)-induced myocardial injury in rats.

Methods: ISO was injected intraperitoneally (200 mg/kg) to induce acute (2-6 hours) myocardial injury in adult female rats.

View Article and Find Full Text PDF

Danshen-Gegen (DG) decoction, an herbal formulation comprised of radix Salvia Miltiorrhiza and radix Puerariae Lobata, is prescribed for the treatment of coronary heart disease in Chinese medicine. Experimental and clinical studies have indicated that DG decoction can reduce the extent of atherosclerosis. In the present study, using an ex vivo rat model of myocardial ischemia/reperfusion (I/R) injury, we investigated the myocardial preconditioning effect of an aqueous DG extract prepared from an optimized weight-to-weight ratio of danshen and gegen.

View Article and Find Full Text PDF

Wei Kang Su (WKS) is an antioxidant-enriched herbal product manufactured on the basis of Shengmai San, a well-known traditional Chinese herbal formula. In the present study, we investigated the effects of WKS co-treatment on chronic ethanol toxicity in rats. WKS co-treatment protected against chronic ethanol-induced hepatotoxicity, as evidenced by the suppression of plasma enzyme activities and reactive oxygen metabolite levels, as well as the inhibition of hepatic mitochondrial malondialdehyde production in chronic ethanol-intoxicated rats.

View Article and Find Full Text PDF

This study investigated the signal transduction pathway involved in the cytoprotective action of (-)schisandrin B [(-)Sch B, a stereoisomer of Sch B]. Using H9c2 cells, the authors examined the effects of (-)Sch B on MAPK and Nrf2 activation, as well as the subsequent eliciting of glutathione response and protection against apoptosis. Pharmacological tools, such as cytochrome P-450 (CYP) inhibitor, antioxidant, MAPK inhibitor, and Nrf2 RNAi, were used to delineate the signaling pathway.

View Article and Find Full Text PDF

Schisandrin B (Sch B) and schisandrin C (Sch C), but not schisandrin A and dimethyl diphenyl bicarboxylate, protected rat skin tissue against solar irradiation-induced oxidative injury, as evidenced by a reversal of solar irradiation-induced changes in cellular reduced glutathione and α-tocopherol levels, as well as antioxidant enzyme activities and malondialdehyde production. The cytochrome P-450-mediated metabolism of Sch B or Sch C caused ROS production in rat skin microsomes. Taken together, Sch B or Sch C, by virtue of its pro-oxidant action and the subsequent eliciting of a glutathione antioxidant response, may prevent photo-aging of skin.

View Article and Find Full Text PDF

The effect of schisandrin B (Sch B) on long-term ethanol-induced oxidative stress in various rat tissues was investigated. Long-term ethanol treatment increased reactive oxygen metabolites (ROM) level in plasma. The ethanol-induced oxidative stress was assessed by mitochondrial glutathione and α-tocopherol levels, antioxidant enzyme activities, malondialdehyde (mtMDA) production and heat shock protein (Hsp) 25/70 levels.

View Article and Find Full Text PDF

To investigate whether Vigconic 28 (VI-28), a Yang-invigorating Chinese herbal formula, could affect survival of aging animals, male and female C57BL/6J mice were given a VI-28-supplemented diet (0.05 and 0.5%, wt/wt) starting at 36 weeks of age, until death.

View Article and Find Full Text PDF

Wei Kang Su (WKS) is a commercial herbal product based on a Chinese herbal formula, Shengmai San. Here, we investigated the effects of long-term treatment with WKS on mitochondrial antioxidant status and functional ability, as well as heat shock protein (Hsp) 25/70 production, in various tissues of rats. WKS treatment enhanced mitochondrial antioxidant status and ATP generation capacity, as well as Hsp 25/70 production in various rat tissues.

View Article and Find Full Text PDF

The effects of the schisandrin B stereoisomers, (+/-)gamma-schisandrin [(+/-)gamma-Sch] and (-)schisandrin B [(-)Sch B], on hypoxia/reoxygenation-induced apoptosis were investigated in AML12 hepatocytes. Changes in cellular reduced glutathione (GSH) levels, Ca(2+)-induced mitochondrial permeability transitions (MPTs) and mitochondrial membrane potentials (Deltapsi(m) values) were also examined in (+/-)gamma-Sch- and (-)Sch B-treated cells, without or with hypoxia/reoxygenation challenge. The (+/-)gamma-Sch/(-)Sch B pretreatments (2.

View Article and Find Full Text PDF

The effects of schisandrin B stereoisomers, (+/-)gamma-schisandrin [(+/-)gamma-Sch] and (-)schisandrin B [(-)Sch B], on hypoxia/reoxygenation-induced apoptosis were investigated in H9c2 cardiomyocytes. Changes in cellular reduced glutathione (GSH) levels, Ca(2+)-induced mitochondrial permeability transition (MPT), and mitochondrial membrane potential (Deltapsi(m)) values, were examined in (+/-)gamma-Sch-pretreated and (-)Sch B-pretreated cells, without or with hypoxia/reoxygenation challenge. The (+/-)gamma-Sch and (-)Sch B (2.

View Article and Find Full Text PDF