Oligomeric Flavonoids Research Articles

Beer constituents as potential cancer chemopreventive agents

Beer is a complex alcoholic beverage made from barley (malt), hop, water and yeast. Phenolic constituents of beer are derived from malt (70–80%) and hop (20–30%). Structural classes include simple phenols, benzoic- and cinnamic acid derivatives, coumarins, catechins, di-, tri- and oligomeric proanthocyanidins, (prenylated) chalcones and flavonoids as well as alpha- and iso-alpha-acids derived from hop. Compounds belonging to different structural classes have distinct profiles of biological activity in in vitro test systems, and in combination might lead to enhanced effects. Scientific evidence has accumulated over the past 10 years pointing to the cancer preventive potential of selected hop-derived beer constituents, i.e., prenylflavonoids including xanthohumol and isoxanthohumol, and hop bitter acids. Chemopreventive activities observed with these compounds relevant to inhibition of carcinogenesis at the initiation, promotion and progression phases, as well as results from in vivo studies on metabolism, bioavailability and efficacy are summarised in this review.

プロアントシアニジンの立体選択的合成研究とその生物活性

The proanthocyanidins are known as condensed tannins and/or oligomeric flavonoids, and their many biological activities, powerful antioxidant activity, free-radical-scavenging activity and an anti-tumor-promoting effect, have been reported. Proanthocyanidins have been obtained from many kinds of plants, but because they are usually obtained as a complex mixture of structurally related compounds, it is very difficult to isolate them in a pure form. Consequently, we planned to develop efficient synthetic methods leading to procyanidins with a high level of purity and stereoselectivity for biological assay. We developed stereoselective condensation method under TMSOTf-catalyzed intermolecular and intramolecular conditions for procyanidin synthesis. The relationships between the structure of proanthocyanidins and their bioactivities (SAR) against the Maillard reaction inhibitory activity, antioxidant activity, DPPH radical scavenging activity, DNA polymerase inhibitory activity and DNA metabolic enzymes inhibitory activity using synthesized procyanidin oligomers including 3-substituted oligomers, were investigated.

Role of anthocyanidin reductase, encoded by BANYULS in plant flavonoid biosynthesis.

Condensed tannins (CTs) are flavonoid oligomers, many of which have beneficial effects on animal and human health. The flavanol (-)-epicatechin is a component of many CTs and contributes to flavor and astringency in tea and wine. We show that the BANYULS (BAN) genes from Arabidopsis thaliana and Medicago truncatula encode anthocyanidin reductase, which converts anthocyanidins to their corresponding 2,3-cis-flavan-3-ols. Ectopic expression of BAN in tobacco flower petals and Arabidopsis leaves results in loss of anthocyanins and accumulation of CTs.

Chocolate: Modern Science Investigates an Ancient Medicine

HOCOLATE HAS BEGUN TO ATTRACT ATTENTION not only for its unique sensory attributes but also for potential health benefits related to its interesting phytochemical profile. Specifically, a group of flavonoids has been identified and isolated in certain cocoas and chocolates. Recently completed in vitro studies and pilot clinical trials suggest that these flavonoids possess a variety of biological activities that may be beneficial to cardiovascular health and cancer prevention. During the 2000 Annual Meeting and Science Innovation Exposition of the American Association for the Advancement of Science, on February 19, 2000, John W. Erdman, Jr., PhD, University of Illinois, and Norman K. Hollenberg, MD, PhD, Harvard Medical School, organized Symposium Session 4131, at which recent research on chocolate was presented and discussed. As a class, dietary flavonoids have received considerable attention in the scientific literature during the past decade due to their association with certain health benefits (cardiovascular health and cancer prevention). The focus of flavonoid research reported at this Symposium was expanded to include oligomeric flavonoids, found in foods such as certain cocoas and chocolates. A brief review was made of new findings about the history of chocolate use in Central American civilizations as both a food and a medicine, and then the new research evidence suggesting that certain cocoa flavonoids may have cardiovascular health benefits was discussed.