The antioxidant paradox

Comparative analysis of antioxidant status in diabetic patients with and without insulin resistance

Diabetes mellitus (DM) is a metabolic disorder characterized by insulin resistance, where hyperglycemia is believed to trigger oxidative stress, contributing to insulin function impairment. This study aimed to assess and compare levels of malondialdehyde (MDA), glutathione (GSH), and uric acid in diabetic patients with and without insulin resistance and to assess the correlation with fasting blood sugar (FBS) and lipid profiles. Significant variations were found in MDA, uric acid, and GSH levels between insulin-resistant and non-resistant diabetic groups (p<0.0001). FBS, hemoglobin A1C (HbA1C), insulin activity, and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) significantly differed between the groups (p<0.0001). Total cholesterol, triglyceride, high-density lipoprotein (HDL), very-low-density lipoprotein (VLDL), and low-density lipoprotein-cholesterol (LDL-C) concentrations were higher in the insulin resistance group than the non-insulin resistance group (p<0.0001). Uric acid also exhibited a significant correlation (p<0.01) with LDL levels, while HDL levels showed a negative correlation with both MDA and uric acid (p<0.001). Diabetes mellitus, characterized by chronic hyperglycemia, may play a role in the development of oxidative stress. This oxidative stress is a significant factor that could potentially lead to the onset of insulin resistance, a condition strongly associated with dyslipidemia. The results of this study indicate that the decrease in GSH levels and the increase in MDA and uric acid levels are particularly noteworthy in the context of insulin resistance among patients with diabetes.

Antioxidative properties of phenolic compounds and their effect on oxidative stress induced by severe physical exercise

Extensive research has found strongly increased generation of reactive oxygen species, free radicals, and reactive nitrogen species during acute physical exercise that can lead to oxidative stress (OS) and impair muscle function. Polyphenols (PCs), the most abundant antioxidants in the human diet, are of increasing interest to athletes as antioxidants. Current literature suggests that antioxidants supplementation can effectively modulate these processes. This overview summarizes the actual knowledge of chemical and biomechanical properties of PCs and their impact as supplements on acute exercise-induced OS, inflammation control, and exercise performance. Evidence maintains that PC supplements have high potency to positively impact redox homeostasis and improve skeletal muscle's physiological and physical functions. However, many studies have failed to present improvement in physical performance. Eleven of 15 representative experimental studies reported a reduction of severe exercise-induced OS and inflammation markers or enhancement of total antioxidant capacity; four of eight studies found improvement in exercise performance outcomes. Further studies should be continued to address a safe, optimal PC dosage, supplementation timing during a severe training program in different sports disciplines, and effects on performance response and adaptations of skeletal muscle to exercise.

Flaxseed Ethanol Extract Effect in Acute Experimental Inflammation

Background and Objectives: Previous studies demonstrated antioxidant activities for flaxseed and flaxseed oil. The aim of the present study was to evaluate the prophylactic and therapeutic anti-inflammatory and antioxidant effects of flaxseed ethanol extract in acute experimental inflammation. Materials and Methods: The in vivo anti-inflammatory and antioxidant activity was evaluated on a turpentine-induced acute inflammation (6 mL/kg BW, i.m.) by measuring serum total oxidative status, total antioxidant reactivity, oxidative stress index, malondialdehyde, total thiols, total nitrites, 3-nitrotyrosine, and NFkB. The experiment was performed on nine groups (n = 5) of male rats: negative control; inflammation; three groups with seven days of flaxseed extract (100%, 50%, 25%) pretreatment followed by inflammation on day eight; three groups of inflammation followed by seven days of treatment with flaxseed extract (100%, 50%, 25%); inflammation followed by seven days of treatment with diclofenac (20 mg/kg BW). Results: Flaxseed extract anti-inflammatory activity was better in the therapeutic plan than in the prophylactic one, and consisted of NO, 3NT, and NF-κB reduction in a dose dependent way. ROS was reduced better in the therapeutic flaxseed extracts administration, and antioxidants were increased by the prophylactic flaxseed extracts administration. Both, ROS and antioxidants were influenced more by the total flaxseed extract, which was also more efficient than diclofenac. Conclusions: flaxseed extract prophylaxis has a useful antioxidant activity by increasing the antioxidants, and flaxseed extract therapy has anti-inflammatory and antioxidant activities by reducing NF-κB, RNS, and ROS.

Marsilea crenata ethanol extract prevents monosodium glutamate adverse effects on the serum levels of reproductive hormones, sperm quality, and testis histology in male rats

BACKGROUND AND AIM

Marsilea crenata is an aquatic plant that contains high antioxidants level and could prevent cell damages caused by free radicals. The present study aimed to investigate the effect of M. crenata ethanol extract on luteinizing hormone (LH), testosterone levels, sperm quality, and testis histology of adult male rats induced by monosodium glutamate (MSG).

MATERIALS AND METHODS

This study randomly divided 48 male rats into eight groups (n=6): control group; MSG group (4 mg/g body weight [b.w.] for 30 days); MS1, MS2, and MS3 groups (4 mg/g b.w. MSG and M. crenata ethanol extract at dose 0.216, 0.432, and 0.648 mg/g b.w., respectively, for 30 days); and S1, S2, and S3 groups (M. crenata ethanol extract at dose of 0.216, 0.432, and 0.648 mg/g b.w., respectively, for 30 days). The blood sample was collected on days 0 and 30 to determine the LH and testosterone levels. The animals were dissected on day 30, and the testes were isolated for morphometric, histology (spermatogenic cell number), and malondialdehyde (MDA) examination. Moreover, semen was collected to determine the sperm quality parameter.

RESULTS

The LH and testosterone levels significantly increased (p<0.05) after M. crenata administration at all doses. The higher dose of M. crenata ethanol extract demonstrated a high decrease in MDA level in MSG-treated rat testis; increase of spermatogonia, spermatocytes, spermatids, and Leydig cells number; and increase of seminiferous tubular diameter and germinal epithelium thickness.

CONCLUSION

The ethanol extract of M. crenata can improve the levels of LH, testosterone, sperm quality, number of testis morphometric, spermatogenic, and Leydig cells in MSG-treated male rats.

The Role of Circulating Lycopene in Low-Grade Chronic Inflammation: A Systematic Review of the Literature

BACKGROUND AND AIMS

In recent years, it has become clear that low-grade chronic inflammation is involved in the onset and progression of many non-communicable diseases. Many studies have investigated the association between inflammation and lycopene, however, results have been inconsistent. This systematic review aims to determine the impact of circulating lycopene on inflammation and to investigate the effect of consuming tomato products and/or lycopene supplements on markers of inflammation.

METHODS

Eligible studies, published before March 2020, were identified from PubMed, EBSCOhost and ScienceDirect. Human studies published in English, that evaluated the effect of circulating lycopene in relation to inflammation biomarkers were screened and included. Studies assessing lycopene intake or general intake of carotenoids/antioxidants without measuring circulating lycopene, as well as those not reporting inflammation biomarkers as outcomes, were excluded.

RESULTS

Out of 80 publications identified and screened, 35 met the inclusion criteria. Results from 18 cross-sectional studies suggest that lycopene levels are adversely affected during inflammation and homeostatic imbalance. Most of the 17 included intervention studies reported increased circulating lycopene levels after tomato/lycopene supplementation, but almost no changes in inflammation biomarkers were observed.

CONCLUSIONS

There is little evidence that increasing tomato intake or lycopene supplementation diminuates this inflammation. However, depletion of lycopene may be one of the first signs of low-grade inflammation. The available data thereby imply that it is beneficial to consume lycopene-rich foods occasionally to stay healthy and keep circulating lycopene at a basal level.