Studies on lipid peroxidation in biological systems. I. Effects on various factors on lipid peroxide level on blood

Antioxidative and anti-diabetic effects of amaranth (Amaranthus esculantus) in streptozotocin-induced diabetic rats

The anti-diabetic and antioxidative effect of amaranth grain (AG) and its oil fraction (AO) was studied in streptozotocin-induced diabetic rats. Male Sprague-Dawley rats were divided into four groups after induction of STZ-diabetes: normal control; diabetic control; diabetic-AG supplement (500 g kg(-1) diet); diabetic-AO supplement (100 g kg(-1) diet) and fed experimental diets for 3 weeks. Serum glucose, insulin, activities of serum marker enzymes of liver function and liver cytosolic antioxidant enzymes were measured. The AG and AO supplement significantly decreased the serum glucose and increased serum insulin level in diabetic rats. Serum concentration of liver function marker enzymes, GOT and GPT, were also normalized by AG and AO treatment in diabetic rats. Liver cytosolic SOD and GSH-reductase activities were significantly increased, and catalase, peroxidase and GSH-Px activities were decreased in diabetic rats. AG and AO supplement reverted the antioxidant enzyme activities to near normal values. Hepatic lipid peroxide product was significantly higher, and GSH content was decreased in diabetic rats. However, AG and AO supplement normalized these values. Our data suggest that AG and AO supplement, as an antioxidant therapy, may be beneficial for correcting hyperglycaemia and preventing diabetic complications.

Antioxidant effect of Phaseolus vulgaris in streptozotocin-induced diabetic rats

The antioxidant effect of an aqueous extract of Phaseolus vulgaris pods, an indigenous plant used in Ayurvedic medicine in India, was studied in rats with streptozotocin-induced diabetes. Oral administration of Phaseolus vulgaris pod extract (PPEt; 200 mg/kg body weight) for 45 days resulted in a significant reduction in thiobarbituric acid reactive substances and hydroperoxides. The extract also causes a significant increase in reduced glutathione, superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase in the liver and kidneys of rats with streptozotocin-induced diabetes. These results clearly show the antioxidant property of PPEt. The effect of PPEt at 200 mg/kg body weight was more effective than glibenclamide.

Antioxidant action of Tinospora cordifolia root extract in alloxan diabetic rats

Tinospora cordifolia is widely used in Indian Ayurvedic medicine for the treatment of diabetes mellitus. Oral administration of 2.5 g and 5.0 g/kg body weight of the aqueous extract of the roots for 6 weeks resulted in a significant reduction in thiobarbituric acid reactive substances (TBARS) and an increase in reduced glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD) in alloxan diabetic rats. The effect of Tinospora cordifolia root extract (TCREt) was most prominently seen in the case of rats given 5.0 g/kg body weight. The effect of TCREt was more effective than glibenclamide. Thus our study shows that TCREt exhibits antioxidant action in alloxan diabetes.

Ovariectomy Accelerates Photoaging of Rat Skin¶

We have previously reported the formation of wrinkles, a decrease in skin elasticity and a loss in the linearity of dermal elastic fibers in rat hind limb skin irradiated with ultraviolet radiation in wavelength ranging 290-320 nm (UVB) at a suberythemal dose for 6 weeks. Estrogens are considered effective in preventing photoaging in postmenopausal females, but the role of estrogen in the skin remains unclear. In this study we have evaluated the influence of short-term chronic UVB irradiation at a suberythemal dose on the skin of ovariectomized rats. An ovariectomy or a sham operation was performed on each 3 week-old female Sprague-Dawley rat. Starting 1 week after the operation the hind limb skin of each rat was irradiated with UVB at a suberythemal dose (130 mJ/cm2) three times a week for 3 or 6 weeks. Decreases in elasticity and wrinkle formation in the skins of ovariectomized animals were induced more quickly than in the skins of sham-operated animals following UVB irradiation. The linearity of elastic fibers in the ovariectomy group decreased significantly compared with the sham-operation group, but erythema in the ovariectomy group was induced more readily than in the sham-operation group following UVB irradiation. These findings suggest that decreases in the estrogen levels after ovariectomy accelerate photoaging in terms of the morphology and physical properties of the skin surface and the three-dimensional structure of elastic fibers.

Antihyperglycaemic activity of Musa sapientum flowers: effect on lipid peroxidation in alloxan diabetic rats

Musa sapientum commonly known as 'banana' is widely used in Indian folk medicine for the treatment of diabetes mellitus. Oral administration of 0.15, 0.20 and 0.25 g/kg body weight of the chloroform extract of the flowers for 30 days resulted in a significant reduction in blood glucose and glycosylated haemoglobin and an increase in total haemoglobin. The extract prevented a decrease in body weight, and also resulted in a decrease in free radical formation in the tissues. Thus the study shows that banana flower extract (BFEt) has an antihyperglycaemic action. The decrease in thiobarbituric acid reactive substances (TBARS) and the increase in reduced glutathione (GSH), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) clearly shows the antioxidant property of BFEt. The effect of BFEt was more prominently seen in the case of animals given 0.25 g/kg body weight. BFEt was more effective than glibenclamide.

A decrease of free radical production near critical targets as a cause of maximum longevity in animals

A comprehensive study was performed on the brains of various vertebrate species showing different life energy potentials in order to find out if free radicals are important determinants of species-specific maximum life span. Brain superoxide dismutase, catalase, Se-dependent and independent GSH-peroxidases, GSH-reductase, and ascorbic acid showed significant inverse correlations with maximum longevity, whereas GSH, uric acid, GSSG/GSH, in vitro peroxidation (thiobarbituric acid test), and malondialdehyde (measured by HPLC), did not correlate with maximum life span. Superoxide dismutase, catalase, GSH-peroxidase, GSH and ascorbate results agree with those previously reported in various independent works using different animal species. GSSG/GSH, and true malondialdehyde (HPLC) results are reported for the first time in relation to maximum longevity. The results suggest that longevous species simultaneously show low antioxidant concentrations and low levels of in vivo free radical production (a low free radical turnover) in their tissues. The "free radical production hypothesis of aging" is proposed: a decrease in oxygen radical production per unit of O2 consumption near critical DNA targets (mitochondria or nucleus) increases the maximum life span of extraordinarily long-lived species like birds, primates, and man. Free radical production near these DNA sites would be a main factor responsible for aging in all the species, in those following Pearl's (Rubner's) metabolic rule as well as in those not following it.

Urinary profiles of organic acids and volatile metabolites during the starvation process in rats

Capillary gas chromatographic procedures were used to quantify the volatile and acidic compound profiles in the urinary samples of Sprague-Dawley rats during the starvation and refeeding periods. Numerous metabolites, identified through mass spectrometry, showed significant variations due to these physiological processes. Correlations are attempted with the previously studied biochemical processes in diabetic animals.

Quantitative alterations in the metabolism of carbonyl compounds due to diet-induced lipid peroxidation in rats

Following the dietary induction of lipid peroxidation in rats (verified by the levels of malonaldehyde and glutathione peroxidase), the urinary carbonyl compounds were followed chromatographically. Through a headspace gas chromatographic procedure, increases of several aldehydes and furan derivatives were noticed. Liquid chromatography of the dinitrophenylhydrazone derivatives of urinary carbonyls provided a more definitive experiment, in which the increased-peroxidation animals could be compared to those maintained on a control diet. Several carbonyl metabolites, identified by mass spectrometry, were elevated following the lipid peroxidation induction.

Chromatographic profiling of urinary volatile and organic acid metabolites of normal and diabetic C57BL/Ks mice

Capillary gas chromatography and gas chromatography-mass spectrometry were used to examine the urinary volatile and organic acid metabolites in normal and diabetic C57BL/Ks male mice. Quantitative differences in the excretion of these metabolites were assessed in the animals from 5 to 24 weeks of age. Statistically significant differences were examined with respect to known metabolic abnormalities in the diabetic animals and to the possible toxic effects of elevated levels of certain metabolites. A number of aldehyde metabolites and aromatic acids, as well as most other organic acids, were found at consistently higher levels in diabetic urine. Several ketone metabolites, linalool, and 2-sec.-butylthiazoline were found at consistently low levels throughout the study.