Abstracts
Antioxidants (Quercetin)
Antioxidants
The efficacy of oxidation inhibition of five natural and synthetic antioxidants (BHT, BHA, nordihydroguaiaretic acid [NDGA], quercetin and rutin) was studied in O/W emulsions. Linoleic acid was used as a reference molecule; the reaction was initiated by an azo-compound. The kAH characterizing the reaction of the antioxidant with the peroxyl radical decreases in the following order: (BHA) > (BHT) > (NDGA) > (quercetin) > (rutin).
Carlotti-ME; Gallarate-M; Gasco-MR; Trotta-M: Inhibition of lipoperoxidation of linoleic acid by five antioxidants of different lipophilicity. Pharmazie. 1994 Jan; 49(1): 49-52.
Electrochemistry (Quercetin)
Electrochemistry
The electrochemical properties of four structurally related flavonoids, quercetin, quercetin-3-O-rhamnose (quercitrin), quercetin-3-O-rutinose (rutin) and luteolin were investigated.
Hendrickson-HP; Kaufman-AD; Lunte-CE: Electrochemistry of catechol-containing flavonoids. J-Pharm-Biomed-Anal. 1994 Mar; 12(3): 325-34
Immunotoxicity
Immunotoxicity
To test the effect of purified polyunsaturated fatty acids on immune cells in vitro
Linoleic and linolenic acids inhibited all of the immune responses
Inhibition of lipid mediator production by indomethacin, quercetin, rutin, or nordihydroguariaretic acid, and addition of vitamins C and E with anti-oxidant activity failed to reverse the effects of linoleic acid. Thus, linoleic and linolenic acids appear to directly inhibit immune and tumor cells, at least under these conditions.
Immunotoxicity of polyunsaturated fatty acids in serum-free medium. Tezabwala-BU; Bennett-M; Grundy-SM. Immunopharmacol-Immunotoxicol. 1995 May; 17(2): 365-83.
Tumorigenesis
Tumorigenesis
The effect of dietary supplementation of flavonoidal compounds such as quercetin, rutin, luteolin and (+)-catechin on the incidence of tumorigenesis in male Swiss albino mice was observed.
Subcutaneous administration of 20-MC along with the flavonoidal compounds (quercetin, luteolin) was found to have significant effect on tumor expression. The possible mode of action of the flavonoidal compounds may be through their influence on the initiation and promotion phases of the carcinogenic process coupled with enhancement of the detoxification process.
Elangovan-V; Sekar-N; Govindasamy-S: Chemopreventive potential of dietary bioflavonoids against 20-methylcholanthrene-induced tumorigenesis. Cancer-Lett. 1994 Nov 25; 87(1): 107-13.
Gastric Cancer & Quercetin
Gastric cancer
According to this study conducted on 354 gastric cancer patients and 354 controls, quercetin may lower the risk of stomach cancer. A dietary history questionnaire was used to assess the usual food intake of all particpants, and the results were adjusted for several dietary factors. The beneficial effects of quercetin may be due to its flavonoid properties, and may contribute to the well-established protective effect of fruits and vegetables against gastric cancer.
Garcia-Closas R, Gonzalez CA, Agudo A, Riboli E: Intake of specific carotenoids and flavonoids and the risk of gastric cancer in Spain, Cancer Causes Control 1999 Feb;10(1):71-5
Cancer Cell Growth
Cancer cell growth
Quercetin may inhibit cancer cell growth and tolerance to heat shock, according to this study conducted on both quercetin and sunphenon. Quercetin was found to be more effective than sunphenon in combined therapy with hyperthermia for cancer. The study indicates that quercetin may inhibit cell growth by delaying the reorganization of F-actin during the recovery period after heat shock to cancer cells.
Kudo M, Naito Z, Yokoyama M, Asano G: Effects of quercetin and sunphenon on responses of cancer cells to heat shock damage, Exp Mol Pathol 1999 Apr;66(1):66-75
Allergy Control
Allergy Control
Recommends: quercitin (1-3 gms), "vitamin C" ("magnesium" "ascorbate" 600-1,800 mgs) and "bromelain" (300 - 900 mgs) divided into 3 - 6 doses a day as effective against "allergic" and "asthmatic" reactions to pollens, cat hair and auto exhaust.
South, J.: Quercitin for "allergy" control.
Brain Neurons
Brain Neurons
The antioxidant action of myricetin and quercetin, the "flavonoid" constituents of the extract of "Ginkgo" biloba (EGb), on "oxidative" "metabolism" of "brain" "neurons" dissociated from the rats was examined. Incubation with myricetin or quercetin reduced the oxidation of DCFH in resting brain neurons, more profoundly than EGb. Such an antioxidant action of myricetin or quercetin may be responsible for a part of the beneficial effects of EGb on brain neurons subject to "ischemia".
Oyama-Y; Fuchs-PA; Katayama-N; Noda-K: Myricetin and quercetin, the flavonoid constituents of Ginkgo biloba extract, greatly reduce oxidative metabolism in both resting and Ca(2+)-loaded brain neurons. Brain-Res. 1994 Jan 28; 635(1-2): 125-9
Breast Cancer (Quercetin)
Breast Cancer
This study demonstrates that the flavonoid quercetin (Q), a plant-derived compound with low toxicity in vivo, greatly potentiates the growth-inhibitory activity of Adriamycin (ADR) on MCF-7 ADR-resistant human breast "cancer" cells.
These findings provide a further biological basis for the potential therapeutic application of Q as an anti-cancer drug either alone or in combination with ADR in multidrug-resistant breast "tumor" cells.
Scambia-G; Ranelletti-FO; Panici-PB; De-Vincenzo-R; Bonanno-G; Ferrandina-G; Piantelli-M; Bussa-S; Rumi-C; Cianfriglia-M; et-al: Quercetin potentiates the effect of adriamycin in a multidrug-resistant MCF-7 human breast-cancer cell line: P-glycoprotein as a possible target. Cancer-Chemother-Pharmacol. 1994; 34(6): 459-64.
Lipid Peroxidation (Quercetin)
Lipid Peroxidation
Gamma "linolenic acid" (GLA), a "polyunsaturated fatty acid", promoted lipid peroxidation in Raji "lymphoma" suspension cultures, in a dose (10 microM-100 microM) and time-dependent (4 h-48 h) manner. The increase in lipid peroxidation could be correlated to an increase in cytotoxicity. The plant flavonoids (quercetin, luteolin, butein, rutin) and the "fat"-"soluble" components ("retinol", retinoic acid, alpha-"tocopherol") by themselves did not affect lipid peroxidation in Raji cells. Quercetin, luteolin, retinol, and alpha-tocopherol were able to inhibit cell proliferation significantly. Although GLA only decreased the cytotoxicity of retinol-treated cells, the latter compound was able to block the prooxidative action of GLA by scavenging the free radicals induced by it. Quercetin at 50 and 100 microM exerted equipotent superoxide "anion" scavenging effects, but at the higher concentration it had no effect on lipid peroxidation. Although the bioactive test compounds are well known natural antioxidants, interestingly, our data showed that their potent cytotoxic actions do not involve free radicals or lipid peroxidation reactions.
Ramanathan-R; Das-NP; Tan-CH: Effects of "gamma-linolenic acid", flavonoids, and vitamins on cytotoxicity and lipid peroxidation. Free-Radic-Biol-Med. 1994 Jan; 16(1): 43-8.
Hypertension & Quercetin
Hypertension
Quercetin may reduce high blood pressure and related vascular changes, according to this animal study. Hypertensive and normotensive rats received oral quercetin daily for five weeks, after which they were tested for blood pressure, heart rate, ventricular weight index, kidney weight index, and vasodilator response. Hypertensive rats treated with quercetin experienced significant reductions in systolic, diastolic, and mean arterial blood pressure and heart rate; reduced ventricular and kidney weight index, and enhancement of endothelium-dependent relaxation. These changes were not seen in normotensive rats, or in hypertensive rats treated with vehicle alone.
Duarte J, et al: Antihypertensive effects of the flavonoid quercetin in spontaneously hypertensive rats, Br J Pharmacol 2001 May 1;133(1):117-124
Anti-tumor Effects
Anti-tumor effects
Quercetin, a bioflavonoid found in fruits and vegetables, may exert its chemoprotective effects against cancer in part by decreasing tissue inhibitor of matrix metalloproteinise-1 (TIMP-1) gene transcription, according to this study. Controversy surrounds the role of TIMP-1 in cancer progression because it has been indicated in tumor progression in cancer patients, but contradicting studies have linked high levels of TIMP-1 with decreased tumor growth.
The effect of quercetin supplementation on healthy male subjects was evaluated in this study. The subjects, whose ages ranged from 33 to 64 years, received 30 mg quercetin or placebo in a black currant drink for two weeks. Blood samples were taken prior to and after supplementation and analyzed by ELISA techniques for the following: full blood count, matrix metalloproteinase-2 (MMP-2), and TIMP-1 and -2 plasma levels.
A reverse transcriptase-polymerase chain reaction was also carried out for MMP-2, TIMP-1 and TIMP-2 gene expression determination in RNA taken from the subjects' peripheral blood lymphocytes. Quercetin supplementation was found to have no effect on the transcription of MMP-2 or TIMP-2 genes, but it did significantly decrease TIMP-1 gene transcription. The results of this study suggest that dietary quercetin may counter tumorigenesis.
Morrow DM, Fitzsimmons PE, Chopra M, McGlynn H: Dietary supplemetation with the anti-tumour promoter quercetin: its effects on matrix metalloproteinase gene regulation, Mutat Res 2001 Sep 1;480-481:269-76
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