Thesis submitted in fulfillment of the requirements for the degree Master of Technology: Biomedical Technology In the Faculty of Health and Wellness Sciences At the Cape Peninsula University of Technology, 2012 / Human and experimental animal studies have shown that biomarkers of oxidative damage are elevated in subjects with certain diseases or risk factors. Consequently, it is hypothesized that oxidative stress plays an important role in the pathogenesis of these diseases and that dietary intake of, or supplementation with antioxidants may be protective or be useful therapeutic targets. This study was designed to investigate the modulatory effect of Camellia sinensis (Chinese green tea), Aspalathus linearis (rooibos herbal tea) and the two commercial supplements on the antioxidant status of the liver and kidney of tert-butyl hydroperoxide (t-BHP)-induced oxidative stress male Wistar rats. Rooibos and green tea are beverages well-known for their antioxidant content. Based on the specific beverage consumed, sixty male Wistar rats were randomly assigned into six groups, i.e. fermented rooibos (FRT), unfermented rooibos (URT), Chinese green tea (CGT), rooibos supplement (RTS), Chinese green tea supplement (GTS) and control (CTL). The animals had free access to the respective beverages and standard diet for 10 weeks, while oxidative stress was induced during the last 2 weeks via intraperitoneal injection of 30 μM of t-BHP per 100 g body weight. Among all the beverage and/or supplement preparations, the commercial rooibos supplement had the highest total polyphenol content and antioxidant activity while fermented rooibos, as previously shown, had a lower antioxidant content and potency when compared to its unfermented counterpart. The ability of these beverages and/or supplements to modulate the antioxidant status in tissues was organ specific and varied according to the assessment method. When considering the liver, the intake of unfermented rooibos, Chinese green tea and the commercial rooibos supplement significantly (P<0.05) restored the t-BHP-induced reduction and increased the antioxidant status with regards to oxygen radical absorbance capacity and trolox equivalent antioxidant capacity (TEAC) levels. All the beverages and/or supplements also significantly (P<0.05) enhanced the renal antioxidant capacity as assessed by the TEAC assay. In what may be an indication of decreased oxidative stress, all the beverages were associated with a general decline in activities of the antioxidant enzymes which reached significant levels in renal superoxidase dismutase activity. Generally, the beverages did not impact significantly on lipid peroxidation (LPO) although there were differing trends in the two LPO markers assessed. While thiobarbituric acid reactive substances levels showed a declining trend in both tissues, the conjugated dienes were generally elevated. In conclusion, this study confirms Camellia sinensis and Aspalathus linearis as well as their two supplements as good sources of dietary antioxidants and results demonstrated that rooibos and green tea improved the liver and kidney antioxidant capacity of oxidative stress-induced rats. Their impact on antioxidant status in rats was shown to vary between organs and according to the method of assessment. Hence multi-method, multi-organ assessment may be a more informative approach in in vivo antioxidant studies.

Indiana University-Purdue University Indianapolis (IUPUI) / Down syndrome (DS), a genetic disorder that affects ~1 in 700 live births, is caused by trisomy of human chromosome 21 (Hsa21). Individuals with DS are affected by a wide spectrum of phenotypes which vary in severity and penetrance. However, cognitive and skeletal impairments can be commonly observed in all individuals with DS. To study these phenotypes, we utilized the Ts65Dn mouse model that carries three copies of approximately half the gene orthologs found on Hsa21 and exhibit similar phenotypes as observed in humans with DS. Individuals with DS and Ts65Dn mice have deficits in bone mineral density (BMD), bone architecture, bone strength, learning and memory. Over-expression of DYRK1A, a serine-threonine kinase encoded on Hsa21, has been linked to deficiencies in DS bone homeostasis and cognition. Epigallocatechin-3-gallate (EGCG), an aromatic polyphenol found in high concentrations in green tea, is a selective inhibitor of DYRK1A activity. Normalization of DYRK1A activity by EGCG therefore may have the potential to ameliorate skeletal and cognitive deficits. We hypothesized that supplements containing EGCG obtained from health food stores/ online vendors will not be as effective as EGCG from a chemical company in correcting bone deficits associated with DS. Our results suggest that EGCG improves the bone mineral density of trisomic femurs significantly better than the supplements while the EGCgNOW supplement from NOW FOODS improves trabecular and cortical bone structure. The results from HPLC analysis of supplements showed the presence of other catechins in EGCgNOW and degradation analysis revealed the rapid degradation of supplements. Therefore we hypothesize that the presence of EGCG degradation products and other green tea catechins in supplements may play a role in the differential skeletal effects we observed. We further hypothesized that a three week treatment of adolescent mice with EGCG will lead to an improvement in the learning and memory deficits that are observed in trisomic animals in comparison to control mice. However, our results indicate that three weeks of low-dose EGCG treatment during adolescence is insufficient to improve hippocampal dependent learning and memory deficits of Ts65Dn mice. The possibility remains that a higher dose of EGCG that begins at three weeks but lasts throughout the behavioral test period may result in improvement in learning and memory deficit of Ts65Dn mice.