Catherine Guyon

Glyphosate-induced antioxidant imbalance in HaCaT: The protective effect of Vitamins C and E

Roundup 3 plus(®), a glyphosate-based herbicide, is widely used in the ground, but its extensive use has posed a health risk in man. The aim of this study was firstly to investigate how glyphosate alone or included in Roundup 3 plus(®) affected the antioxidant defense system and lipid peroxidation of human cutaneous cells, and secondly, to evaluate the ameliorating effects of antioxidants, as Vitamin C (VitC) and Vitamin E (VitE), against Roundup 3 plus(®)-induced epidermal antioxidant impairment. Our results showed that glyphosate alone or included in Roundup 3 plus(®), induced significant changes in cellular antioxidant status as a glutathione depletion, enzymatic (catalase, glutathione-peroxidase and superoxide dismutase) disorders, and increased lipid peroxidation. VitC or VitE supplementation increased superoxide dismutase, glutathione-reductase and -peroxidase activities and reduced lipid peroxidation in Roundup 3 plus(®)-treated keratinocytes. These in vitro data indicated that VitC and VitE might have preventive effects against deleterious cutaneous cell damage caused by Roundup 3 plus(®).

Dietary vitamin C supplementation decreases blood pressure in DOCA-salt hypertensive male Sprague Dawley rats and this is associated with increased liver oxidative stress

The effects of a vitamin C supplemented diet on blood pressure, body and liver weights, liver antioxidant status, iron and copper levels were investigated in DOCA-salt treated and untreated Sprague-Dawley (SD) male rats after 8 weeks of treatment. Vitamin C supplementation had no effect on blood pressure in SD rats but induced a significant decrease in blood pressure in DOCA-salt treated rats, the decrease being more efficient at 50 mg/kg of vitamin C than at 500 mg/kg. Hepatic lipid peroxidation and iron levels were significantly increased in DOCA-salt hypertensive rats whereas total hepatic antioxidant capacity (HAC), glutathione peroxidase (GSH-Px) and catalase (CAT) activities were decreased. Vitamin C supplementation did not affect the overall antioxidant defences of control SD rat livers. In contrast, vitamin C supplementation accentuated the DOCA-salt induced accumulation of liver iron and lipid peroxidation. This occurred without any notable aggravation in the antioxidant deficiency of vitamin C supplemented DOCA-salt treated rat livers. Our data suggest that DOCA-salt treatment induces an accumulation of iron in rat livers which is responsible for the prooxidant effect of vitamin C. The normalization of blood pressure in DOCA-salt treated rats by vitamin C supplementation appears thus independent from liver antioxidant status.

Chemical Composition and in vitro Cytotoxic Activity of Essential Oils from Two Tropical Lamiaceae: Aeollanthus pubescens Benth. and Ocimum gratissimum L

Abstract Essential oils of Aeollanthus pubescens Benth. and Ocimum gratissimum L. (Lamiaceae) from Togo were investigated for their percentage composition and in vitro cytotoxicity. The GC and GC-MS analyses indicated that the major constituents of both essential oils were thymol, p-cymene and γ-terpinene. Testing of these volatile oils and their major constituents from commercial origin in vitro for possible cytotoxicity on the human epidermic cell line HaCat showed that the toxicity of the essential oil of A. pubescens (IC50: 1800µg.ml−1) was higher than that of the essential oil of O. gratissimum (IC50: 2400 µg.ml−1). Pure commercial thymol standard showed a cytotoxicity (IC50: 1800 µg.ml−1) identical to that of the A. pubescens essential oil. Conversely, p-cymene and γ-terpinene standards were found almost non-toxic (IC50 >3000 µg.ml−1). These findings support the assumption that the cytotoxic activities of the tested essential oils were basically due to their high level content in thymol.

A biochromatographic framework to evaluate the calcium effect on the antihypertensive molecule-human serum albumin binding.

The Ca(2+) cation effect on the antihypertensive molecule binding on human serum albumin (HSA) was studied by biochromatography. The thermodynamic parameters corresponding to this binding were determined for a wide range of Ca(2+) concentration (x). For the two antihypertensive molecules under study, their binding to HSA can be divided into two Ca(2+) cation concentration regions due to a HSA phase transition. This result was confirmed by an enthalpy-entropy investigation. For a low x value (below x(c)=1.6 mmol l(-1)), the HSA cavity was in an ordered solid-like state leading to an increase in the interactions between the antihypertensive drugs and the HSA cavity and consequently, a solute-HSA affinity increase. For x above x(c), the HSA cavity was in a disordered solid-like state, implying a decrease in the antihypertensive drug-HSA binding.

Chemical Composition and In Vitro Cytotoxic Activity of Xylopia aethiopica (Dun) A. Rich. (Annonaceae) Fruit Essential Oil from Togo

Abstract Essential oil extracted (4.4% in yield) from air-dried fruits of Xylopia aethiopica harvested in Togo was investigated for percentage composition and in vitro cytotoxicity. The chemical composition of the essential oil was examined by GC and GC/MS. Thirty-five compounds were identified representing 89.9% of total oil. The major constituents were β-pinene (23.6%), α-pinene (11%), sabinene (9.8%), germacrene D (8.3%) and 1,8 cineole (8.2%). The cytotoxicity of the volatile oil was evaluated in vitro on the human epidermal cell line HaCaT. The tested sample did not show any cytotoxicity (IC50 >3000 μg.ml-1) effect at concentrations around 3000 μg.ml-1. Further testing in bioassay would probably help in validating some of medicinal uses of X. aethiopica in topical drugs and/or in cosmetics as natural products.

Evolution of Liver Antioxidant Status and Iron Implication During the Development of Deoxycorticosterone-Saline Hypertension in Rats

Hypertension is known to be associated with an oxidative stress resulting from an imbalance of antioxidant defense mechanisms in various tissues. The purpose of this study was to investigate the relationship between the increase of arterial blood pressure, measured during the gradual development of experimental hypertension in deoxycorticosterone (DOCA)-salt-treated rats, and an early imbalance of liver antioxidant status. The levels of liver oxidant/antioxidant markers and iron were studied during the induction of hypertension in 3-, 6-, and 8-wk DOCA-salt-treated Sprague-Dawley rats. Hepatic antioxidant defenses were decreased as early as 3 wk of hypertensive treatment: the decrease of peroxidase-reductase-transferase and catalase activities was associated with a significant increase of thiobarbituric acid reactive substances (TBARS) levels. Liver oxidative stress increased until 6 wk, and remained stable at 8 wk of DOCA-salt treatment. Concurrently, liver iron levels were increased at 6 wk and returned to normal values after 8 wk of hypertensive treatment. Iron seems to be an inductor of liver oxidative stress and responsible for the persistent oxidative stress, most likely through secondary free-radical release. Thus, our data (1) confirm that hypertension in DOCA-salt-treated rats might be a free-radical-dependent disease where hepatic oxidant/antioxidant imbalance is obviously involved from the beginning of blood pressure elevation and (2) suggest that the use of suitable iron chelators might reverse liver oxidative stress associated with the increase of blood pressure.