Antioxidant activity applying an improved ABTS radical cation decolorization assay.

Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

The use of and search for drugs and dietary supplements derived from plants have accelerated in recent years. Ethnopharmacologists, botanists, microbiologists, and natural-products chemists are combing the Earth for phytochemicals and “leads” which could be developed for treatment of infectious diseases. While 25 to 50% of current pharmaceuticals are derived from plants, none are used as antimicrobials. Traditional healers have long used plants to prevent or cure infectious conditions; Western medicine is trying to duplicate their successes. Plants are rich in a wide variety of secondary metabolites, such as tannins, terpenoids, alkaloids, and flavonoids, which have been found in vitro to have antimicrobial properties. This review attempts to summarize the current status of botanical screening efforts, as well as in vivo studies of their effectiveness and toxicity. The structure and antimicrobial properties of phytochemicals are also addressed. Since many of these compounds are currently available as unregulated botanical preparations and their use by the public is increasing rapidly, clinicians need to consider the consequences of patients self-medicating with these preparations.

Plant Products as Antimicrobial Agents

http://www.dietcan.net/docs/Polifenoles%20en%20alimentos%20y%20biodisponibilidad.pdf

Polyphenols: food sources and bioavailability

This review summarizes the multifaceted aspects of antioxidants and the basic kinetic models of inhibited autoxidation and analyzes the chemical principles of antioxidant capacity assays. Depending upon the reactions involved, these assays can roughly be classified into two types:  assays based on hydrogen atom transfer (HAT) reactions and assays based on electron transfer (ET). The majority of HAT-based assays apply a competitive reaction scheme, in which antioxidant and substrate compete for thermally generated peroxyl radicals through the decomposition of azo compounds. These assays include inhibition of induced low-density lipoprotein autoxidation, oxygen radical absorbance capacity (ORAC), total radical trapping antioxidant parameter (TRAP), and crocin bleaching assays. ET-based assays measure the capacity of an antioxidant in the reduction of an oxidant, which changes color when reduced. The degree of color change is correlated with the sample's antioxidant concentrations. ET-based assays include th...

The Chemistry behind Antioxidant Capacity Assays

Argylia radiata (L.) D. Don (Bignoniaceae) represents an important source of secondary metabolites, largely unexplored. The paper presents the isolation from the plant root of two new monoterpene alkaloids, 10-acetoxy-actinidine and 4-nor-7,8-dehydro-10-hydroxy-skytanthine, whose structures were elucidated by Mass spectrometry and 1 H-NMR data.

Monoterpene alkaloids from Argylia radiata.

Phenylpropanoid glycosides in Italian Orobanche spp., sect. Orobanche.

Oxidative stress might play an important role in the development of osteoarthritis, but not much is known about the effect of antioxidants on osteoarthritis risk. We, therefore, aimed to investigate the effect of dietary vitamin C, E, beta-carotene, and non-enzymatic antioxidant capacity (NEAC), which measures overall antioxidant activity from the diet, on the risk of osteoarthritis. For this study 43,865 men and women from the Swedish National March Cohort (SNMC) were followed for up to 19 years. We computed dietary intake of vitamin C, E and beta-carotene using information from a Food Frequency Questionnaire (FFQ). To estimate dietary NEAC we combined the information from the FFQ with food item-specific antioxidant capacity values from an antioxidant food database. Cases of osteoarthritis were identified through the Swedish National Patient Registers. We categorized all exposure variables into sex-specific quartiles and used multivariable-adjusted Cox proportional hazards regression models to estimate hazard ratios (HRs) with 95% confidence intervals (95% CIs). In total, we observed 5976 cases of OA during 469,148 person-years of follow-up. After adjusting for potential confounders, we did not find any association between vitamin C, beta-carotene and NEAC (p-values for trend > 0.5), but a positive association was found with higher dietary vitamin E intake (HR Q4 vs Q1: 1.11; 95% CI 1.02–1.21; p for trend = 0.01) and the risk of OA. Our findings do not provide evidence for dietary antioxidants to protect from the development of OA, and a higher dietary vitamin E intake might even increase the risk.

Mauro Serafini

Papers

Monoterpene alkaloids from Argylia radiata.

Phenylpropanoid glycosides in Italian Orobanche spp., sect. Orobanche.

Dietary antioxidants, non-enzymatic antioxidant capacity and the risk of osteoarthritis in the Swedish National March Cohort.

Phytochemical analysis on the seeds of a new Iranian Plantago ovata Forssk. population specimen.

The Occurrence of Iridoid Glycosides in Cymbalaria Spp. in Italy