CA : A Cancer Journal for Clinicians

OBJECTIVE — To systematically review the incidence of posttransplantation diabetes (PTD), risk factors for its development, prognostic implications, and optimal management. RESEARCH DESIGN AND METHODS — We searched databases (MEDLINE, EMBASE, the Cochrane Library, and others) from inception to September 2000, reviewed bibliographies in reports retrieved, contacted transplantation experts, and reviewed specialty journals. Two reviewers independently determined report inclusion (original studies, in all languages, of PTD in adults with no history of diabetes before transplantation), assessed study methods, and extracted data using a standardized form. Meta-regression was used to explain between-study differences in incidence. RESULTS — Nineteen studies with 3,611 patients were included. The 12-month cumulative incidence of PTD is lower (10% in most studies) than it was 3 decades ago. The type of immunosuppression explained 74% of the variability in incidence (P 0.0004). Risk factors were patient age, nonwhite ethnicity, glucocorticoid treatment for rejection, and immunosuppression with high-dose cyclosporine and tacrolimus. PTD was associated with decreased graft and patient survival in earlier studies; later studies showed improved outcomes. Randomized trials of treatment regimens have not been conducted. CONCLUSIONS — Physicians should consider modification of immunosuppressive regimens to decrease the risk of PTD in high-risk transplant recipients. Randomized trials are needed to evaluate the use of oral glucose-lowering agents in transplant recipients, paying particular attention to interactions with immunosuppressive drugs. Diabetes Care 25:583–592, 2002

A systematic review of the literature

The antioxidant activities and total phenolics of 28 plant products, including sunflower seeds, flaxseeds, wheat germ, buckwheat, and several fruits, vegetables, and medicinal plants were determined. The total phenolic content, determined according to the Folin−Ciocalteu method, varied from 169 to 10548 mg/100 g of dry product. Antioxidant activity of methanolic extract evaluated according to the β-carotene bleaching method expressed as AOX (Δ log A470/min), AA (percent inhibition relative to control), ORR (oxidation rate ratio), and AAC (antioxidant activity coefficient) ranged from 0.05, 53.7, 0.009, and 51.7 to 0.26, 99.1, 0.46, and 969.3, respectively. The correlation coefficient between total phenolics and antioxidative activities was statistically significant. Keywords: Antioxidant activity; phenolics; medicinal plants; oilseeds; buckwheat; vegetables; fruits; wheat products

Antioxidant Activity and Total Phenolics in Selected Fruits, Vegetables, and Grain Products

Flavonoids are a class of secondary plant phenolics with significant antioxidant and chelating properties. In the human diet, they are most concentrated in fruits, vegetables, wines, teas and cocoa. Their cardioprotective effects stem from the ability to inhibit lipid peroxidation, chelate redox-active metals, and attenuate other processes involving reactive oxygen species. Flavonoids occur in foods primarily as glycosides and polymers that are degraded to variable extents in the digestive tract. Although metabolism of these compounds remains elusive, enteric absorption occurs sufficiently to reduce plasma indices of oxidant status. The propensity of a flavonoid to inhibit free-radical mediated events is governed by its chemical structure. Since these compounds are based on the flavan nucleus, the number, positions, and types of substitutions influence radical scavenging and chelating activity. The diversity and multiple mechanisms of flavonoid action, together with the numerous methods of initiation, detection and measurement of oxidative processes in vitro and in vivo offer plausible explanations for existing discrepancies in structure-activity relationships. Despite some inconsistent lines of evidence, several structure-activity relationships are well established in vitro. Multiple hydroxyl groups confer upon the molecule substantial antioxidant, chelating and prooxidant activity. Methoxy groups introduce unfavorable steric effects and increase lipophilicity and membrane partitioning. A double bond and carbonyl function in the heterocycle or polymerization of the nuclear structure increases activity by affording a more stable flavonoid radical through conjugation and electron delocalization. Further investigation of the metabolism of these phytochemicals is justified to extend structure-activity relationships (SAR) to preventive and therapeutic nutritional strategies.

Flavonoid antioxidants: chemistry, metabolism and structure-activity relationships.

Flavonoids, a group of natural substances with variable phenolic structures, are found in fruits, vegetables, grains, bark, roots, stems, flowers, tea and wine. These natural products are well known for their beneficial effects on health and efforts are being made to isolate the ingredients so called flavonoids. Flavonoids are now considered as an indispensable component in a variety of nutraceutical, pharmaceutical, medicinal and cosmetic applications. This is attributed to their anti-oxidative, anti-inflammatory, anti-mutagenic and anti-carcinogenic properties coupled with their capacity to modulate key cellular enzyme function. Research on flavonoids received an added impulse with the discovery of the low cardiovascular mortality rate and also prevention of CHD. Information on the working mechanisms of flavonoids is still not understood properly. However, it has widely been known for centuries that derivatives of plant origin possess a broad spectrum of biological activity. Current trends of research and development activities on flavonoids relate to isolation, identification, characterisation and functions of flavonoids and finally their applications on health benefits. Molecular docking and knowledge of bioinformatics are also being used to predict potential applications and manufacturing by industry. In the present review, attempts have been made to discuss the current trends of research and development on flavonoids, working mechanisms of flavonoids, flavonoid functions and applications, prediction of flavonoids as potential drugs in preventing chronic diseases and future research directions.

/pdf/flavonoids-an-overview-5gkev1wgy2.pdf

Flavonoids: an overview

The scavenging effect of methanolic extracts of peanut hulls (MEPH) on free-radical and active-oxygen species was investigated. MEPH showed marked activity as a radical scavenger in the experiment using 14,1-diphenyl-2-picrylhydrazyl radical, indicating that MEPH has effective activities as a hydrogen donor and as a primary antioxidant to react with lipid radicals. MEPH also possessed antioxidative activity toward hydrogen peroxide (H 2 O 2 ) and superoxide (O 2 .- ), indicating that MEPH has a scavenging activity on H 2 O 2 and O 2 .- . The scavenging effect of MEPH on hydroxyl radical was investigated by means of electron paramagnetic resonance spectrometry

Scavenging Effect of Methanolic Extracts of Peanut Hulls on Free-Radical and Active-Oxygen Species

The antioxidant activity of water extracts of Harng Jyur (Chrysanthemum morifolium Ramat) from four varieties, including Huang Harng Jyur (HHJ), Bai Harng Jyur (BHJ), Gan Harng Jyur (GHJ), and Kung Harng Jyur (KHJ), was investigated. The water extracts of the four Harng Jyur varieties showed strong antioxidant activity in linoleic acid and liposome model systems. Each extract at 20 mg exhibited 65.3–71.8% inhibition on malondialdehyde formation of rat liver homogenate in vitro, greater than 20 mg of tocopherol. A correlation established between the total phenolic compounds and antioxidant activity, yielded a coefficient of r2=0.934, 0.997, 0.758 and 0.983 for HHJ, BHJ, GHJ and KHJ respectively. Each extract of the four Harng Jyur varieties had effective activities as radical scavengers, metal chelators, and active oxygen scavengers. These properties may be the major reasons for the inhibition of lipid peroxidation. Of the four varieties, BHJ was the most significant antioxidative material. No mutagenicity in the four varieties was found in Salmonella typhimurium TA 98, either with or without S9 mix.

Antioxidant activity of water extract of Harng Jyur (Chrysanthemum morifolium Ramat).

Antioxidant and pro-oxidant properties of ascorbic acid and gallic acid

Chemopreventive effects of dietary phytochemicals against cancer invasion and metastasis: phenolic acids, monophenol, polyphenol, and their derivatives.

Gow-Chin Yen

Papers

Scavenging Effect of Methanolic Extracts of Peanut Hulls on Free-Radical and Active-Oxygen Species

Antioxidant activity of water extract of Harng Jyur (Chrysanthemum morifolium Ramat).

Antioxidant and pro-oxidant properties of ascorbic acid and gallic acid

Chemopreventive effects of dietary phytochemicals against cancer invasion and metastasis: phenolic acids, monophenol, polyphenol, and their derivatives.

Antioxidant activity of anthraquinones and anthrone