Oxidative Stress and DNA Lesion Reduction of a Polyphenolic Enriched Extract of Thymus marschallianus Willd. in Endothelial Vascular Cells Exposed to Hyperglycemia

Abstract

The present study aimed to compare two polyphenolic-enriched extracts obtained from the Thymus marschallianus Willd. (Lamiaceae) species, harvested from culture (TMCE in doses of 0.66 μg GAE/mL and 0.066 μg GAE/mL) and from spontaneous flora (TMSE in doses of 0.94 μg GAE/mL and 0.094 μg GAE/mL) by assessing their biological effects on human umbilical vein endothelial cells (HUVECs) exposed to normoglycemic (137 mmol/L glucose) and hyperglycemic conditions (200 mmol/L glucose). Extracts were obtained by solid phase extraction (SPE) and analyzed by chromatographical (HPLC-DAD) and spectrophotometrical methods. Their effects on hyperglycemia were evaluated by the quantification of oxidative stress and NF-ĸB, pNF-ĸB, HIF-1α, and γ-H2AX expressions. The HPLC-DAD analysis highlighted significant amounts of rosmarinic acid (ranging between 0.18 and 1.81 mg/g dry extract), luteolin (ranging between 2.04 and 17.71 mg/g dry extract), kaempferol (ranging between 1.85 and 7.39 mg/g dry extract), and apigenin (ranging between 4.97 and 65.67 mg/g dry extract). Exposure to hyperglycemia induced oxidative stress and the activation of NF-ĸ increased the expression of HIF-1α and produced DNA lesions. The polyphenolic-enriched extracts proved a significant reduction of oxidative stress and γ-H2AX formation and improved the expression of HIF-1α, suggesting their protective role on endothelial cells in hyperglycemia. The tested extracts reduced the total NF-ĸB expression and diminished its activation in hyperglycemic conditions. The obtained results bring evidence for the use of the polyphenolic-enriched extracts of T. marschallianus as adjuvants in hyperglycemia.

Biological Activities and Chemical Profile of Gentiana asclepiadea and Inula helenium Ethanolic Extracts

“…The absorbance was determined at 500 nm, and TPA content was expressed as g CAE per 100 g of dry material. All the determinations were performed using a UV–V is spectrophotometer (Specord 200 Plus, Analytik Jena, Germany) [ 58 , 59 , 60 , 61 ].…”

“…The absorbance of obtained solutions was read at 450 nm, using Trolox as standard for the calibration curve (R2 = 0.992). The results of FRAP assay were expressed as μmol of Trolox Equivalents (TE) per 100 mL of extract [ 58 , 59 , 60 , 61 ]…”

“…The results of the DPPH assay were expressed as IC 50 value (μg/mL), representing the concentration of antioxidant capable of reducing the DPPH radical concentration by half [ 58 , 59 , 60 , 61 ].…”

Evaluation of the Cytotoxic, Antioxidative and Antimicrobial Effects of Dracocephalum moldavica L. Cultivars

“…The aerial parts were air-dried after collection and grounded using a Grindomix GM 200 knife mill (Éragny, France). Subsequently, the obtained powder was macerated for 10 days with 70% v / v ethanol in water and 2–3 shakes/day, and the obtained ethanolic extract was filtered at the end of the maceration period [ 58 , 59 , 60 , 61 ].…”

“…Results were expressed as µM of Trolox equivalent/g of dry plant material. All assays were performed in triplicate [ 60 , 71 ].…”