Antioxidant effects of flavonoids

Flavonoids are polyphenolic compounds whose main dietary source are fruits and vegetables. Epidemiological evidence has suggested that dietary flavonoids may protect against heart disease but biological effects have not hitherto been demonstrated directly in humans and there was no consistent evidence about the absorption of flavonoids. The studies performed for this thesis aimed to test antioxidant properties of flavonoids using an in vitro system, ex vivo tests on human tissue (lymphocytes) and in a dietary intervention. The main conclusions of this thesis are: 1. There is a potent antioxidant action of dietary flavonoids demonstrated by the comet assay, of potential importance in protection against cardiovascular disease and cancer. 2. The antioxidant capacities of most major dietary flavonoids are greater than vitamin C. 3. Results from the comet assay and TEAC show reasonable agreement in ranking. 4. Antioxidant activities of free flavonoids are more than the conjugated flavonoids. 5. There was a strong positive correlation between the number of hydroxyl groups of flavonoids and the antioxidant activity. 6. Dietary flavonoids are absorbed and the fasting plasma concentration can be increased 12 fold by a simple and palatable food supplement. 7. Supplementation with onions, tomato ketchup and tea led to protection of lymphocytes against free radical damage (H2O2), a biological effect of potential medical importance possibly attributable to the absorption of dietary flavonoids. 8. Dietary flavonoids intake (and specifically quercetin) can be estimated with reasonable accuracy from 24 hour urinary flavonoid excretion or fasting plasma concentration. 9. The range of dietary flavonoid consumption in ten NIDDM patients was estimated at 20-80 mg/day from their normal diets. On the basis of results in this thesis, dietary difference within this range would influence tissue antioxidant status

Studies on the genetic variation of the green unicellular alga Haematococcus pluvialis (Chlorophyceae) obtained from different geographical locations using ISSR and RAPD molecular marker.

Haematococcus pluvialis (Flotow) is a unicellular green alga, which is considered to be the best astaxanthin-producing organism. Molecular markers are suitable tools for the purpose of finding out genetic variations in organisms; however there have been no studies conducted on ISSR or RAPD molecular markers for this organism. The DNA of 10 different strains of H. pluvialis (four strains from Iran, two strains from Finland, one strain from Switzerland and three strains from the USA) was extracted. A genetic similarity study was carried out using 14 ISSR and 12 RAPD primers. Moreover, the molecular weights of the bands produced ranged from 0.14 to 3.4 Kb. The PCA and dendrogram clustered the H. pluvialis strains into various groups according to their geographical origin. The lowest genetic similarity was between the Iran2 and USA2 strains (0.08) and the highest genetic similarity was between Finland1 and Finland2 (0.64). The maximum numbers of bands produced by the ISSR and RAPD primers were 35 and 6 bands, respectively. The results showed that ISSR and RAPD markers are useful for genetic diversity studies of Haematococcus as they showed geographical discrimination