https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

Eating five servings of fruits and vegetables per day! This is what is highly recommended and heavily advertised nowadays to the general public to stay fit and healthy! Drinking green tea on a regular basis, eating chocolate from time to time, as well as savoring a couple of glasses of red wine per day have been claimed to increase life expectancy even further! Why? The answer is in fact still under scientific scrutiny, but a particular class of compounds naturally occurring in fruits and vegetables is considered to be crucial for the expression of such human health benefits: the polyphenols! What are these plant products really? What are their physicochemical properties? How do they express their biological activity? Are they really valuable for disease prevention? Can they be used to develop new pharmaceutical drugs? What recent progress has been made toward their preparation by organic synthesis? This Review gives answers from a chemical perspective, summarizes the state of the art, and highlights the most significant advances in the field of polyphenol research.

Plant Polyphenols: Chemical Properties, Biological Activities, and Synthesis

Biological activities and distribution of plant saponins.

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.

There has been considerable public and scientific interest in the use of phytochemicals derived from dietary components to combat human diseases. They are naturally occurring substances found in plants. Ferulic acid (FA) is a phytochemical commonly found in fruits and vegetables such as tomatoes, sweet corn and rice bran. It arises from metabolism of phenylalanine and tyrosine by Shikimate pathway in plants. It exhibits a wide range of therapeutic effects against various diseases like cancer, diabetes, cardiovascular and neurodegenerative. A wide spectrum of beneficial activity for human health has been advocated for this phenolic compound, at least in part, because of its strong antioxidant activity. FA, a phenolic compound is a strong membrane antioxidant and known to positively affect human health. FA is an effective scavenger of free radicals and it has been approved in certain countries as food additive to prevent lipid peroxidation. It effectively scavenges superoxide anion radical and inhibits the lipid peroxidation. It possesses antioxidant property by virtue of its phenolic hydroxyl group in its structure. The hydroxy and phenoxy groups of FA donate electrons to quench the free radicals. The phenolic radical in turn forms a quinone methide intermediate, which is excreted via the bile. The past few decades have been devoted to intense research on antioxidant property of FA. So, the present review deals with the mechanism of antioxidant property of FA and its possible role in therapeutic usage against various diseases.

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Ferulic Acid: Therapeutic Potential Through Its Antioxidant Property

Methanol extracts of 11 kinds of commonly available vegetables were examined for hydroxyl radical scavenging potency using the bleomycin−Fe method. In this method, the iron ion and bleomycin in water form hydroxyl radicals, and the scavenging activity is monitored by the modified thiobarbituric acid method. All extracts showed scavenging capacity, even though the activity of some of them was lower than that of l-ascorbic acid. Those vegetables were classified into three groups according to their activity, groups showing strong activity, moderate activity, and weak activity, as compared to the activity of l-ascorbic acid at the same concentration. Among them, the methanol extract of radish sprout (Japanese name “kaiware-daikon”) exhibited the highest potency (1.8 times as l-ascorbic acid). Then, we investigated the constituents of the methanol extract of radish sprout and the contribution to the overall activity of each compound by examining their activity. As the result, several kinds of sinapinic acid es...

Antioxidant constituents of radish sprout (Kaiware-daikon), Raphanus sativus L.

Powerful antioxidative agents based on garcinoic acid from Garcinia kola

Biomimic transformation of resveratrol

A novel flavonol glycoside, 7-O-methylmearnsitrin (7,4‘-O-dimethylmyricetin 3-O-α-l-rhamnopyranoside), and myricetrin, kaempferol 3-O-α-l-rhamnopyranoside, europetin 3-O-α-l-rhamnoside, and 7-O-methyl quercetin 3-O-α-l-rhamnopyranoside were isolated from the leaves of Sageretia theezans, and their chemical structures were identified by spectroscopic analyses including two-dimensional NMR (HSQC, HMBC). Whereas myricetrin, europetin 3-O-α-l-rhamnoside, and 7-O-methylquercetin 3-O-α-l-rhamnopyranoside showed stronger activities than ascorbic acid and α-tocopherol, 7-O-methylmearnsitrin showed very weak antioxidant activities by ESR and LDL oxidation inhibition tests. Keywords: Flavonol glycosides; 7-O-methylmearnsitrin; Sageretia theezans; ESR; LDL oxidation

Novel flavonol glycoside, 7-O-methyl mearnsitrin, from Sageretia theezans and its antioxidant effect.

Plant peroxidases were found to play an important role in plant physiology such as the metabolism and transformation of small complexes. In the present research, a novel Momordica charantia peroxidase (MCP) from fruits was purified to electrophoretic homogeneity by combining consecutive treatment of ammonium sulfate fractionation, ion exchange chromatography on DEAE-Sepharose FF, affinity chromatography on concanavalin A (Con A) Sepharose and gel filtration on Sephadex G-150. The physical and chemical characters of MCP were also investigated. MCP catalyzed the oxidation of ferulic acid (FA) to dehydrodimer (FA-2) in aqueous acetone system at pH 5.0. Its structure was identified by spectral analyses including IR, 1H-, 13C-NMR and electrospray ionization mass spectroscopy (ESI-MS). The anti-inflammatory activities of FA, FA-2 and other derivatives were examined. FA-2 significantly inhibited the release of proinflammatory factors such as TNF-alpha, NO and proliferation of spleen cells induced by phytohemagglutinin (PHA) and Con A and promoted a greater DNA fragmentation of spleen cells than that of other complexes. These results suggested that MCP as a tool enzyme transformed some complexes such as FA to more active derivatives, and that FA-2 was a potential inhibitor on inflammation through interference with immune response in the process of inflammation, which maybe was associated with apoptosis of immune related cells induced by FA-2.

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Masatake Niwa

Papers

Antioxidant constituents of radish sprout (Kaiware-daikon), Raphanus sativus L.

Powerful antioxidative agents based on garcinoic acid from Garcinia kola

Biomimic transformation of resveratrol

Novel flavonol glycoside, 7-O-methyl mearnsitrin, from Sageretia theezans and its antioxidant effect.

Oxidation of ferulic acid by Momordica charantia peroxidase and related anti-inflammation activity changes.