Redox Reactions between Kaempferol and Illuminated Chloroplasts

Takahama, Umeo

doi:10.1104/pp.71.3.598

Cited by 51 publications

(29 citation statements)

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“…These codominant genes code for the addition of (2,27), we suspected that K9 might also be inhibitory in vivo. In an attempt to circumvent the problem of flavonoid contamination during chloroplast isolation (see "Introduction"), we examined whole mesophyll cells from soybeans to determine if the kaempferol glycosides, especially K9, were present in this photosynthetic tissue.…”

Section: Discussionmentioning

confidence: 97%

“…The inhibitory effects of kaempferol aglycone on photosynthesis in vitro are well characterized (2,27), but its glycosides are less effective (2). There are reports that flavonoid glycosides occur in plastids isolated from several species (19,26,28,29) including soybean (26), but it is difficult to rule out plastid contamination by vacuolar flavonoids during subcellular fractionation.…”

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confidence: 99%

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Kaempferol Glycosides and Enzymes of Flavonol Biosynthesis in Leaves of a Soybean Strain with Low Photosynthetic Rates

Cosio

McClure²

1984

Plant Physiol.

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Soybean (Glycine max L.) strains which accumulate kaempferol 3-(2G-glucosylgentiobioside) in their leaves fix CO2 at rates significantly lower than those lacking this compound (Buttery, Buzzell 1976 Crop Sci 16: 547-550), and kaempferol aglycone is a well known inhibitor of photosynthesis in vitro. However, since neither kaempferol nor any of its glycosides could be detected in mesophyll cells isolated from mature soybean leaves we suspect that kaempferol 3420-glucosylgentiobioside) has no direct inhibitory effect on photosynthesis. The most rapid stage of flavonoid accumulation, and the highest level of activity for several enzymes of phenolic biosynthesis, occurs in leaflets 2.5 to 3 centimeters long. Mesophyll cells isolated from these leaflets contain about 70% of the whole leaf activity for shikimate dehydrogenase, 24% of the 4-coumarate:CoA ligase activity, 35% of the activity for chalcone-flavanone isomerase, but no demonstrable activity for phenylalanine ammonialyase. Our results suggest a highly tissue-specific pattern of secondary phenolic metabolism in soybean leaves.

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Section: Discussionmentioning

confidence: 97%

mentioning

confidence: 99%

Kaempferol Glycosides and Enzymes of Flavonol Biosynthesis in Leaves of a Soybean Strain with Low Photosynthetic Rates

Cosio

McClure²

1984

Plant Physiol.

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Section: Salivary Polymorphonuclear Leukocytes (Spmn) Produce Omentioning

confidence: 99%

“…The enhancement of H 2 O 2 production is possible by the stimulation of leukocytes in the oral cavity. H 2 O 2 formation usually accompanies the formation of O 2 -and it is known that flavonol aglycones like kaempferol and quercetin reduce O 2 -to H 2 O 2 (Takahama 1983(Takahama , 1987Bors et al, 1997).Blackburn Jr. et al (1987) reported that quercetin can inhibit O 2 -production, degranulation and phosphorylation of specific proteins, which are observed in plasma neutrophils when stimulated.…”

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confidence: 99%

Oxydation of Quercetin by Salivary Components II. Effects of Quercetin on Reactive Oxygen Metabolism by Salivary Polymorphonuclear Leukocytes.

Hirota¹,

Takahama²,

Ansai³

et al. 2002

FSTR

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Salivary polymorphonuclear leukocytes (SPMN) produce O 2-and H 2 O 2 reducing molecular oxygen, and quercetin is a phenolic compound found in vegetables and fruits. The aim of the present study was to elucidate the interaction between SPMN and quercetin. The oxygen consumption by SPMN, which was stimulated by phorbol myristate acetate (PMA), was suppressed by quercetin. Half-inhibition was observed at about 20 M quercetin. During inhibition of the oxygen uptake, quercetin was oxidized; the oxidation was inhibited by superoxide dismutase and enhanced by horseradish peroxidase. We showed previously that when onion soup is ingested, quercetin glucosides in the soup are hydrolyzed to quercetin in the oral cavity to bind to the epithelial tissues, and that quercetin can be a hydrogen donor to peroxidase in saliva to scavenge H 2 O 2 (Hirota et al., 2001). It was discussed then that the H 2 O 2 scavenging function may be important when H 2 O 2 production is enhanced. The enhancement of H 2 O 2 production is possible by the stimulation of leukocytes in the oral cavity. H 2 O 2 formation usually accompanies the formation of O 2 -and it is known that flavonol aglycones like kaempferol and quercetin reduce O 2 -to H 2 O 2 (Takahama 1983(Takahama , 1987Bors et al., 1997).Blackburn Jr. et al. (1987) reported that quercetin can inhibit O 2 -production, degranulation and phosphorylation of specific proteins, which are observed in plasma neutrophils when stimulated. The inhibition of O 2 -production may be in part due to inhibition of the NADPH oxidase system of leukocytes that is located on the cell membranes (Tauber et al., 1984). In addition, quercetin can also inhibit the activation of phospholipases that is induced on the stimulation of leukocytes (Takemura et al., 1997;Tordera et al., 1994). Berton et al. (1980) discussed that quercetin can regulate inflammatory processes taking account of quercetin-dependent inhibition of O 2 -production by stimulated leukocytes. It is known that some flavonoids including quercetin have an anti-inflammatory function (Pietta, 1997;Tordera et al., 1994). These reports using plasma leukocytes prompted us to study the effects of quercetin which can stay in the oral cavity for 4-5 h after ingestion of onion soup (Hirota et al., 2001), on the stimulation of salivary polymorphonuclear leukocytes (SPMN) and on the scavenging of O 2 -and H 2 O 2 that are formed by SPMN. In addition, as some phenolics might decrease the risk of caries (Haslam, 1998), the effects of quercetin on bacteria which cause caries and periodontal diseases were also studied. The results obtained in this study are quercetin-dependent inactivation of SPMN, scavenging of O 2 -and H 2 O 2 generated by SPMN and inhibition of the growth of P. gingivalis. These results suggest that quercetin might suppress the growth of P. gingivalis attenuating the production of reactive oxygen species by stimulated SPMN in the oral cavity and tissues. Materials and MethodsReagents Quercetin and 3,4-dihydroxybenzoic acid were obtained from Wako ...

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“…5). It has already been reported that quercetin was oxidized by O2 and radicals formed during lipid peroxidation and that the oxidation was accompanied by the absorbance decrease at 380 nm (19,20 …”

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confidence: 99%

Hydrogen Peroxide-Dependent Oxidation of Flavonols by Intact Spinach Chloroplasts

Takahama

1984

Plant Physiol.

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ABSTRACIExternally added quercetin (100 micromolar) was oxidized by intact spinach chloroplasts at a rate of 30 micromoles per mg chlorophyll per hour in the presence of 100 micromolar H202. The oxidation rate was increased by about 20% in a hypotonic reaction mixture. The thylakoid fraction also oxidized the flavonol in the presence of H202, and the rate was about 25% of that by intact chloroplasts. The oxidation of quercetin was inhibited by KCN and NaN3. Ascorbate, which permeates slowly across chloroplast envelope, only slightly suppressed the initial rate of quercetin oxidation by intact chloroplasts, while the oxidation by ruptured chloroplasts was suppressed by ascorbate by about 60%. Quercetin glycosides, quercitrin and rutin, were also oxidized by chloroplasts in the presence of H202. These results suggest that flavonols are oxidized by peroxidase-like activity in chloroplasts and that externally added flavonols can permeate into the stroma through the envelope of intact chloroplasts.Flavonols are widely distributed pigments in vascular plants. Their subcellular localization has been investigated and they were found in chloroplasts (12,(14)(15)(16) MATERIALS AND METHODSIntact chloroplasts were isolated from spinach leaves obtained from a local market. Depetiolated spinach leaves were homogenized by a Waring Blendor in a medium which contained 0.5 mM KH2PO4, 1 mM MnCl2, 1 mM MgC12, 2 mm EDTA, 10 mM NaCl, 330 mM sorbitol, and 25 mM Mes-NaOH (pH 6.3). The homogenate was filtered through eight layers of gauze. The filtrate was centrifuged at 3,000 rpm for 1 min. The sediment was suspended into the above buffer solution, centrifuged at 3,000 rpm for 45 s, and suspended again into the same buffer solution. To separate intact chloroplasts from broken chloroplasts, the obtained chloroplast fraction was centrifuged in a Percoll density gradient. Percoll and the above buffer solution were mixed to obtain Percoll density gradient. At the bottom of the centrifugation tube, 2 ml of 40% Percoll (v/v) was added. Two ml of 30% and 20% Percoll were layered successively onto the 40% Percoll. Chloroplast suspension was layered onto 20% Percoll. After centrifugation at 4,000 rpm for 10 min, chloroplasts were separated into two bands. Chloroplasts between 20% and 30% Percoll were broken chloroplasts and chloroplasts between 30% and 40% Percoll were intact chloroplasts. The lower band was collected by a syringe and used for experiments. The intactness of the chloroplasts at the lower band was more than 80% by a ferricyanide test (6). Thylakoids were obtained from intact chloroplasts; hypotonically ruptured intact chloroplasts in the buffer solution without sorbitol were collected by centrifugation at 10,000g for 10 min, and suspended into the above buffer solution to use in experiments.Rates of flavonol oxidation were followed at 380 nm with a Hitachi 557 spectrophotometer at 25C. The basic reaction mixture (1 ml) contained chloroplasts equivalent to 5 to 9 pg of Chl, 0.5 mM KH2PO4, 1 mM MgC92, 10 mm NaCl, and 50 mM HepesNa...

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Redox Reactions between Kaempferol and Illuminated Chloroplasts

Cited by 51 publications

References 12 publications

Kaempferol Glycosides and Enzymes of Flavonol Biosynthesis in Leaves of a Soybean Strain with Low Photosynthetic Rates

Kaempferol Glycosides and Enzymes of Flavonol Biosynthesis in Leaves of a Soybean Strain with Low Photosynthetic Rates

Oxydation of Quercetin by Salivary Components II. Effects of Quercetin on Reactive Oxygen Metabolism by Salivary Polymorphonuclear Leukocytes.

Hydrogen Peroxide-Dependent Oxidation of Flavonols by Intact Spinach Chloroplasts

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