Antioxidant and Pro-Oxidant Properties of Carthamus Tinctorius, Hydroxy Safflor Yellow A, and Safflor Yellow A

Abstract

(1) Carthamus Tinctorius L. (safflower) is extensively used in traditional herbal medicine. (2) The aim of this study was to investigate the bioactive properties of polyphenol extracts from flowers of Carthamus Tinctorius (CT) cultivated in Italy. We also evaluated the properties of two bioactive water-soluble flavonoid compounds, hydroxy safflor yellow A (HSYA) and safflor yellow A (SYA), contained in Carthamus Tinctorius petals. (3) The total polyphenol content was 3.5 ± 0.2 g gallic acid equivalent (GAE)/100 g, flavonoids content was 330 ± 23 mg catechin equivalent (CE)/100 g in the flowers. The extract showed a high antioxidant activity evaluated by oxygen radical absorbance capacity (ORAC) and 2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assays. In addition, flower extract, SYA, and HSYA were able to reduce the susceptibility of low-density lipoprotein to copper-induced lipid peroxidation. In order to investigate the bioactive properties of flower extract, SYA, and HSYA we also studied their modulatory effect of oxidative stress on human dermal fibroblasts (HuDe) oxidized by tert-butyl hydroperoxide (t-BOOH). The CT extract at concentrations ranging from 0.01-20 mg GAE/mL of polyphenols, exerted a protective effect against t-BOOH triggered oxidative stress. At higher concentration the extract exerted a pro-oxidant effect. Similar results have been obtained using HSYA and SYA. (4) These results demonstrate a biphasic effect exerted by HSYA, SYA, and flower extracts on oxidative stress.

Figure 1

Kinetics of LDL oxidation by 5 µM CuSO₄ as measured by the formation of conjugated dienes. Control LDL (◾), LDL incubated in the presence of Carthamus Tinctorius (CT) extract (17 µg gallic acid equivalent/mL (▲), or in the presence of 60 µg/mL of hydroxy safflor yellow A (HSYA) (⬥) or safflor yellow A (SYA) (●).

Figure 2

Viability in HuDe cells treated for 48 h in the presence of increasing concentrations of Carthamus Tinctorius (CT) extract (a) or hydroxy safflor yellow A (HSYA) (◾) and safflor yellow A (SYA) (⬥) (b). Phenolic concentrations of CT extract are expressed as µg gallic acid equivalent/mL. * p < 0.05 vs. cells incubated in the absence of CT extracts or SYA and HSYA.

Figure 3

Intracellular reactive oxygen species (ROS) formation in HuDe cells treated for 48 h in the presence of increasing concentrations of Carthamus Tinctorius (CT) extract (a) or hydroxy safflor yellow A (HSYA) (◾) and safflor yellow A (SYA) (⬥) (b). Phenolic concentrations of CT extract are expressed as µg gallic acid equivalent/mL. * p < 0.05 vs. cells incubated in the absence of CT extracts or SYA and HSYA.

Figure 4

Intracellular ROS formation in HuDe cells treated with the pro-oxidant tert-butyl hydroperoxide (t-BOOH) (50 µM) in the presence of increasing concentrations of Carthamus Tinctorius (CT) extract (a) or hydroxy safflor yellow A (HSYA) (◾) and safflor yellow A (SYA) (⬥) (b). Phenolic concentrations of CT extract are expressed as µg gallic acid equivalent/mL. * p < 0.05 vs. cells treated with t-BOOH in the absence of CT extracts or SYA and HSYA.