Ikuo Nishigaki

Beneficial effects of green tea: A literature review

The health benefits of green tea for a wide variety of ailments, including different types of cancer, heart disease, and liver disease, were reported. Many of these beneficial effects of green tea are related to its catechin, particularly (-)-epigallocatechin-3-gallate, content. There is evidence from in vitro and animal studies on the underlying mechanisms of green tea catechins and their biological actions. There are also human studies on using green tea catechins to treat metabolic syndrome, such as obesity, type II diabetes, and cardiovascular risk factors.Long-term consumption of tea catechins could be beneficial against high-fat diet-induced obesity and type II diabetes and could reduce the risk of coronary disease. Further research that conforms to international standards should be performed to monitor the pharmacological and clinical effects of green tea and to elucidate its mechanisms of action.

Lipid peroxide levels of serum lipoprotein fractions of diabetic patients

Abstract The elevation of lipid peroxide level has been considered as a cause of the degeneration of organs or tissues (1–6). It was also considered that the lipid peroxide formed in the primary site would be transferred via blood to other organs or tissues where the damage would be provoked by the propagation of lipid peroxidation (7,8). Recently, it was reported from our laboratory that plasma lipid peroxide levels of diabetic patients were significantly higher than those of control subjects and that the levels in diabetics with angiopathy were markedly higher than those in diabetics without angiopathy (9). From these results, we suspected that a high level of lipid peroxide in plasma would be, at least partly, the cause of angiopathy in patients suffering from diabetes, and that it would be worthwhile to obtain further information on the lipid peroxides of blood plasma of diabetic patients. The present paper deals with the lipid peroxide levels of serum lipoprotein fractions of diabetic patients examined in relation to some abnormal features of lipid metabolism.

Antioxidants and human diseases

Oxidative stress plays a pivotal role in the development of human diseases. Reactive oxygen species (ROS) that includes hydrogen peroxide, hyphochlorus acid, superoxide anion, singlet oxygen, lipid peroxides, hypochlorite and hydroxyl radical are involved in growth, differentiation, progression and death of the cell. They can react with membrane lipids, nucleic acids, proteins, enzymes and other small molecules. Low concentrations of ROS has an indispensable role in intracellular signalling and defence against pathogens, while, higher amounts of ROS play a role in number of human diseases, including arthritis, cancer, diabetes, atherosclerosis, ischemia, failures in immunity and endocrine functions. Antioxidants presumably act as safeguard against the accumulation of ROS and their elimination from the system. The aim of this review is to highlight advances in understanding of the ROS and also to summarize the detailed impact and involvement of antioxidants in selected human diseases.

Effect of thermal injury on lipid peroxide levels of rat

Abstract Since the report of Cannon and Bayliss (1) who believed that fluid loss from circulation was not sufficient to account for the circulatory failure commonly seen in battle casualties, occurrence of “toxic factor” has gathered much attention. In fact, in these cases fluid therapy is very successful in acute phase, but late death often occurs. Accordingly, many investigations on toxic factor after burn injury have been carried out. Among them, the following reports drew our attention. Allgower et al. (2) claimed to have identified the toxin as a lipid-protein polymer formed from a component of cell walls of the skin. Helmkamp et al. (3) found significant reduction in the levels of polyunsaturated fatty acids such as linoleate, arachidonate, and docosahexaenoate in red cell membrane phospholipid of severely burned humans. Loebl et al. (4) suggested that erythrocyte destruction in early postburn period would be due to a substance circulating in thermally injured patients. Rai and Courtemanche (5) described that with an increase in burn index, the fall in vitamin A level became greater. Sugiyama et al. (6) recently reported that extensive release of prostaglandins into the blister a few hours after burn injury would partly explain general symptoms of the burn syndrome. From these reports, we suspected that burn toxin might be similar to lipid peroxides. In the present study, therefore, the levels of lipid peroxides in animal tissues and serum of postburn period were measured.

Exposure to polycyclic aromatic hydrocarbons with special focus on cancer

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are a group of compounds consisting of two or more fused aromatic rings. Most of them are formed during incomplete combustion of organic materials such as wood and fossil fuels, petroleum products, and coal. The composition of PAH mixtures varies with the source and is also affected by selective weathering effects in the environment. PAHs are ubiquitous pollutants frequently found in a variety of environments such as fresh water and marine sediments, the atmosphere, and ice. Due to their widespread distribution, the environmental pollution due to PAHs has aroused global concern. Many PAHs and their epoxides are highly toxic, mutagenic and/or carcinogenic to microorganisms as well as to higher forms of life including humans. The main aim of this review is to provide contemporary information on PAH sources, route of exposure, worldwide emission rate, and adverse effects on humans, especially with reference to cancer.

Kaempferol, a potential cytostatic and cure for inflammatory disorders

Kaempferol (3,5,7-trihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) is a flavonoid found in many edible plants (e.g., tea, broccoli, cabbage, kale, beans, endive, leek, tomato, strawberries, and grapes) and in plants or botanical products commonly used in traditional medicine (e.g., Ginkgo biloba, Tilia spp, Equisetum spp, Moringa oleifera, Sophora japonica and propolis). Its anti-oxidant/anti-inflammatory effects have been demonstrated in various disease models, including those for encephalomyelitis, diabetes, asthma, and carcinogenesis. Moreover, kaempferol act as a scavenger of free radicals and superoxide radicals as well as preserve the activity of various anti-oxidant enzymes such as catalase, glutathione peroxidase, and glutathione-S-transferase. The anticancer effect of this flavonoid is mediated through different modes of action, including anti-proliferation, apoptosis induction, cell-cycle arrest, generation of reactive oxygen species (ROS), and anti-metastasis/anti-angiogenesis activities. In addition, kaempferol was found to exhibit its anticancer activity through the modulation of multiple molecular targets including p53 and STAT3, through the activation of caspases, and through the generation of ROS. The anti-tumor effects of kaempferol have also been investigated in tumor-bearing mice. The combination of kaempferol and conventional chemotherapeutic drugs produces a greater therapeutic effect than the latter, as well as reduces the toxicity of the latter. In this review, we summarize the anti-oxidant/anti-inflammatory and anticancer effects of kaempferol with a focus on its molecular targets and the possible use of this flavonoid for the treatment of inflammatory diseases and cancer.

D-Pinitol Promotes Apoptosis in MCF-7 Cells via Induction of p53 and Bax and Inhibition of Bcl-2 and NF-κB

Development of drugs from natural products has been undergoing a gradual evoluation. Many plant derived compounds have excellent therapeutic potential against various human ailments. They are important sources especially for anticancer agents. A number of promising new agents are in clinical development based on their selective molecular targets in the field of oncology. D-pinitol is a naturally occurring compound derived from soy which has significant pharmacological activitites. Therefore we selected D-pinitol in order to evaluate apoptotic potential in the MCF-7 cell line. Human breast cancer cells were treated with different concentrations of D-pinitol and cytotoxicity was measured by MTT and LDH assays. The mechanism of apoptosis was studied with reference to expression of p53, Bcl-2, Bax and NF-kB proteins. The results revealed that D-pinitol significantly inhibited the proliferation of MCF-7 cells in a concentration-dependent manner, while upregulating the expression of p53, Bax and down regulating Bcl-2 and NF-kB. Thus the results obtained in this study clearly vindicated that D-pinitol induces apotosis in MCF-7 cells through regulation of proteins of pro- and anti-apoptotic cascades.

Mangiferin in cancer chemoprevention and treatment: pharmacokinetics and molecular targets.

Abstract A variety of bioactive food components have been shown to modulate inflammatory responses and to attenuate carcinogenesis. Polyphenols isolated several years ago from various medicinal plants now seem to have a prominent role in the prevention and therapy of a variety of ailments. Mangiferin, a unique, important, and highly investigated polyphenol, has attracted much attention of late for its potential as a chemopreventive and chemotherapeutic agent against various types of cancer. Mangiferin has been shown to target multiple proinflammatory transcription factors, cell- cycle proteins, growth factors, kinases, cytokines, chemokines, adhesion molecules, and inflammatory enzymes. These targets can potentially mediate the chemopreventive and therapeutic effects of mangiferin by inhibiting the initiation, promotion, and metastasis of cancer. This review not only summarizes the diverse molecular targets of mangiferin, but also gives the results of various preclinical studies that have been performed in the last decade with this promising polyphenol.

Glycated protein-iron chelate increases lipid peroxide level in cultured aortic endothelial and smooth muscle cells

Formation of an iron chelate of glycated protein was demonstrated by the appearance of an absorption peak at approximately 270 nm after mixing glycated bovine serum albumin with FeCl3. This peak disappeared and a new peak appeared at approximately 420 nm to form an isosbestic point at approximately 340 nm by the addition of deferoxamine mesylate, an ironchelating agent, to the mixture, thus confirming the formation of the iron chelate of the glycated protein in the mixture. The lipid peroxide level was increased markedly in endothelial cells and slightly in smooth muscle cells from bovine aorta incubated in the medium containing glycated fetal bovine serum‐iron chelate. Morphological observation by phase‐contrast microscopy and scanning electron microscopy revealed that the glycated fetal bovine serumiron chelate caused intense damage to the endothelial cells. These results indicate that glycated protein‐iron chelate provokes lipid peroxidation, which explains at least in part the mechanism of atherogenesis found in diabetic patients.

Possible contributions of mastocytosis, apoptosis, and hydrolysis in pathophysiology of randomized skin flaps in humans and guinea pigs.

&NA; To understand better the pathophysiology of random skin flaps, randomized skin flaps of human (3 cases) and guinea pig (53 cases) were investigated. Proximal (normal), proximomedial (viable), mediodistal (between viable and necrotic parts), and distal (necrosis) locations of the skin flaps were biopsied. Lipid peroxidase, hvdrolytic enzymes of cytosol (Ca2+‐dependent cysteine protease: calpain), and lysosome (acid phosphatase) of skin were used as markers. Measurements were taken of the flap blood flow: the numbers of capillaries, postcapillary venules, pericapillary arterioles, leukocytes, and mast cells per unit square of dermis. Apoptotic cells were identified by specific staining. Flaps were sampled at postoperative weeks 1 and 3 (human) and hours 1 and 6, and days 1 to 7 (guinea pig). The values for normal skin were regarded as the control. Obstruction (by leukocytes) of venous microvessels, rather than arterial microvessels, was the major cause of temporary hypoxia in the proximomedial location, constant hypoxia (venous stasis) in the mediodistal location, and ischemia in the distal location. Increases in the numbers of mast cells (mastocytosis) and microvessels (angiogenesis) were significant only in the viable parts of the flaps. This phenomenon and the rate of blood flow increased with time in viable locations (guinea pig), Epidermal necrosis, dermal fibrosis, and apoptosis were evident mostly in the mediodistal location. Elevated levels of leukocytes, lipid peroxidase, acid phosphatase, and calpain, combined with necrotic changes, were seen mostly in the distal skin location. There is a strong possibility that the following factors are involved: lipid peroxidation and hydrolysis in necrosis of the distal flap location after ischemia: constant hypoxia in fibrosis and apoptosis in the mediodistal location; and initial or temporary hypoxia in mastoevtosis‐induced angiogenesis in the viable location. The results presented here indicate that guidelines for further investigations include combined suppression of leukotaxis, lipid peroxidase, and hydrolysis, or the application of mast cell growth factors in an effort to salvage the flap maximally.