Tese
Avaliação da atividade antioxidante de diferentes classes de compostos contra a oxidação de lipoproteínas de baixa densidade
Fecha
2011-10-04Registro en:
PORTELLA, Rafael de Lima. Evaluation of antioxidant activity of different classes of compounds against low density lipoprotein oxidation. 2011. 147 f. Tese (Doutorado em Bioquímica) - Universidade Federal de Santa Maria, Santa Maria, 2011.
Autor
Portella, Rafael de Lima
Institución
Resumen
Abnormalities of lipid metabolism often lead to pathologic lipid accumulation in the
vessel wall, oxidative and chronic inflammatory sequelae and the formation of atherosclerotic
lesions, ultimately leading to clinical events. Low density lipoprotein (LDL) oxidative
modification in the vascular wall seems to be a key factor in atherosclerosis development.
Following the oxidation hypothesis of atherosclerosis the role of antioxidants has been
investigated in a large number of epidemiological, clinical and experimental studies.
Therefore, we investigated the antioxidant activity of three compounds of different classes in
preventing the low density lipoprotein oxidation. In the guaraná study, we showed that
subjects who habitually ingested guaraná (GI) demonstrated lower conjugated dienes
production than did subjects who never ingested guaraná (NG; reduction of 27%, p <
0,0014), independent of other variables. However, in the GI group the conjugated dienes
production was positively associated with glucose levels. The GI group also showed a total
cholesterol level significantly lower than NG group. Also, guaraná demonstrated a high
antioxidant activity in vitro, mainly at concentrations of 1 and 5 μg/mL, demonstrated by
suppression of CDs and TBARS productions, tryptophan destruction and high TRAP activity.
Guaraná, similar to other foods rich in caffeine and catechins such as green tea, has some
effect on LDL oxidation that could partially explain the protective effects of this food in
cardiometabolic diseases. In the thiosemicarbazone study, salicylaldehyde-4-
phenylthiosemicarbazone (SPTS) may have antioxidant activity against Cu2+- and 2,2′-
Azobis(2-methylpropionamidine) dihydrochloride (AAPH)-induced LDL and serum oxidation.
Additionally, SPTS was effective at preventing tryptophan destruction. SPTS also showed
significant total radical-trapping antioxidant activity and could prevent thiobarbituric acid
reactive substances (TBARS) formation induced by sodium nitroprusside in different rat
tissues and by Cu2+ in human LDL and serum. These results indicate that the antioxidant
effect of SPTS is caused by a combination of transition metal chelation and free-radicalscavenging
activity. In the organotellurium study, the 2-phenyl-2-tellurophenyl
vinylphosphonate (DPTVP) may have antioxidant activity against Cu2+- and 2,2′-azobis(2-
methylpropionamidine) dihydrochloride (AAPH)-induced LDL and serum oxidation.
Additionally, DPTVP was effective at preventing tryptophan oxidation. DPTVP also showed
significant total radical-trapping antioxidant activity and could prevent thiobarbituric acid
reactive substance (TBARS) formation induced by Cu2+ in human LDL and serum.
Additionally, DPTVP exhibited no toxicity in rat aorta slices. The results presented here
indicate that the antioxidant effect of DPTVP is caused by a combination of free-radicalscavenging
activity and possible blockade of the copper binding sites of LDL. Considering
these preliminary results, we can conclude that the three compounds presented a potential
antioxidant activity and could prevent the oxidative modifications of LDL. These data
encourage us to evaluate these compounds in in vivo studies and investigate additional
properties in preventing the atherogenic process.