The biochemistry and medical significance of the flavonoids.

The small GTP-binding protein rho regulates the assembly of focal adhesions and actin stress fibers in response to growth factors

Epidemiological studies have revealed that a diet rich in plant-derived foods has a protective effect on human health. Identifying bioactive dietary constituents is an active area of scientific investigation that may lead to new drug discovery. 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). Some epidemiological studies have found a positive association between the consumption of foods containing kaempferol and a reduced risk of developing several disorders such as cancer and cardiovascular diseases. Numerous preclinical studies have shown that kaempferol and some glycosides of kaempferol have a wide range of pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial, anticancer, cardioprotective, neuroprotective, antidiabetic, anti-osteoporotic, estrogenic/antiestrogenic, anxiolytic, analgesic and antiallergic activities. In this article, the distribution of kaempferol in the plant kingdom and its pharmacological properties are reviewed. The pharmacokinetics (e.g. oral bioavailability, metabolism, plasma levels) and safety of kaempferol are also analyzed. This information may help understand the health benefits of kaempferol-containing plants and may contribute to develop this flavonoid as a possible agent for the prevention and treatment of some diseases.

A review on the dietary flavonoid kaempferol.

Thematic review series: glycerolipids. DGAT enzymes and triacylglycerol biosynthesis.

Flavonoids are small molecular secondary metabolites synthesized by plants with various biological activities. Due to their physical and biochemical properties, they are capable of participating in plants' interactions with other organisms (microorganisms, animals and other plants) and their reactions to environmental stresses. The majority of their functions result from their strong antioxidative properties. Although an increasing number of studies focus on the application of flavonoids in medicine or the food industry, their relevance for the plants themselves also deserves extensive investigations. This review summarizes the current knowledge on the functions of flavonoids in the physiology of plants and their relations with the environment.

Flavonoids as Important Molecules of Plant Interactions with the Environment

Coumarins reduce biofilm formation and the virulence of Escherichia coli O157:H7.

Ginkgolic acids and Ginkgo biloba extract inhibit Escherichia coli O157:H7 and Staphylococcus aureus biofilm formation.

Nuclear factor (NF)-cB is a transcription factor regulating the expression of inflammatory and immune genes. In the present study, an extract from stem bark of Cinnamomum cassia Blume(Lauraceae) was discovered to have an inhibitory effect on LPS-induced NF-KB transcriptional activity, which was determined using macrophages RAW 264.7 transfected stably with an alkaline phosphatase reporter construct containing four copies of the NF-KB binding KB sequence. Following activity-guided fractionation, trans-cinnamaldehyde and 2-methoxycinnamaldehyde were identified as the NF-KB inhibitors from C cassia with IC50 values of 43 MM and 31 pM, respectively. As a positive control, caffeic acid phenethyl ester (CAPE) showed an IC50 value of 2 uM on NF-KB transcriptional activity. Both trans-cinnamaldehyde and 2-methoxycinnamaldehyde inhibited LPS-induced DNA binding activity of NF-KB in addition to NF-KB transcription-al activity.

Cinnamaldehyde and 2-Methoxycinnamaldehyde as NF-κB Inhibitors from Cinnamomum cassia

Staphylococcal biofilms are problematic and play a critical role in the persistence of chronic infections because of their abilities to tolerate antimicrobial agents. Thus, the inhibitions of biofilm formation and/or toxin production are viewed as alternative means of controlling Staphylococcus aureus infections. Here, the antibiofilm activities of 560 purified phytochemicals were examined. Alizarin at 10 μg/ml was found to efficiently inhibit biofilm formation by three S. aureus strains and a Staphylococcus epidermidis strain. In addition, two other anthraquinones purpurin and quinalizarin were found to have antibiofilm activity. Binding of Ca(2+) by alizarin decreased S. aureus biofilm formation and a calcium-specific chelating agent suppressed the effect of calcium. These three anthraquinones also markedly inhibited the hemolytic activity of S. aureus, and in-line with their antibiofilm activities, increased cell aggregation. A chemical structure-activity relationship study revealed that two hydroxyl units at the C-1 and C-2 positions of anthraquinone play important roles in antibiofilm and anti-hemolytic activities. Transcriptional analyses showed that alizarin repressed the α-hemolysin hla gene, biofilm-related genes (psmα, rbf, and spa), and modulated the expressions of cid/lrg genes (the holin/antiholin system). These findings suggest anthraquinones, especially alizarin, are potentially useful for controlling biofilm formation and the virulence of S. aureus.

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Calcium-chelating alizarin and other anthraquinones inhibit biofilm formation and the hemolytic activity of Staphylococcus aureus.

A bioassay-guided fractionation of the root extract of Angelica dahurica (Umbelliferae) led to the isolation of six furanocoumarins as active ingredients responsible for the antitumoral property The hexane soluble part of the extract demonstrated a significant inhibition on the proliferation of cultured human tumor cells such as A549 (non small cell lung), SK-OV-3 (ovary), SK-MEL-2 (melanoma), XF498 (central nervous system) and HCT-15 (colon) in vitro, whereas the remaining water soluble part exhibited poor inhibition Intensive investigation of the hexane soluble part of the extract yielded six furanocoumarins, ie isoimperatorin, cnidicin, imperatorin, oxypeucedanin, byakangelicol, oxypeucedanin hydrate, all of which exhibited a significant inhibition on cell proliferation in a dose-dependent manner

Shi Yong Ryu

Papers

Coumarins reduce biofilm formation and the virulence of Escherichia coli O157:H7.

Ginkgolic acids and Ginkgo biloba extract inhibit Escherichia coli O157:H7 and Staphylococcus aureus biofilm formation.

Cinnamaldehyde and 2-Methoxycinnamaldehyde as NF-κB Inhibitors from Cinnamomum cassia

Calcium-chelating alizarin and other anthraquinones inhibit biofilm formation and the hemolytic activity of Staphylococcus aureus.

Antiproliferative effect of furanocoumarins from the root of Angelica dahurica on cultured human tumor cell lines.