## 3 Results and Discussion
### Antioxidant Effects of PCB, SP, WB, and SPWB  
We evaluated the antioxidant effects of SP, WB, SPWB, and PCB by measuring the DPPH free-radical scavenging activities and compared them to the activity of 50 \(\upmu\)g/mL Trolox, which was used as a positive control (Figure 3). Treatment with 23.3 \(\upmu\)g/mL PCB, which corresponded to the concentration present in 0.5 mg/mL of SPWB, resulted in \(68.46\pm 2.02\%\) of free radical-scavenging activity, and a similar effect of 59.02 \(\pm\) 1.59% antioxidant activity was also observed for 0.1 mg/mL SP. Both WB and SPWB exhibited much higher effects than the same concentration of SP, which implied that WB had a synergistic effect on the antioxidant activity of SP. Indeed, the antioxidant effects of wheat bran and its extracts have been demonstrated previously [25]. Therefore, these findings indicate that WB may increase the antioxidant effects of SP, which was expected because the addition of WB also lowered cytotoxicity (Figure 2). These promising results could be due to the higher amounts of phenolic substances in WB and, more probably, because of several types of proteins, such as soluble globulins, which are composed of multiple polypeptide chains and have molecular weights in the 10-100 kDa range. Wheat albumin in the WB could stabilize PCB by preventing or decreasing the breakage of its bonds with soluble albumin in WB [26; 27]. This hypothesis is supported by other studies showing that various proteins, such as bovine serum albumin, beta-lactoglobulin, and whey proteins, prevent the digestion of PCB by protecting the cysteine bonding between them, and bilirubin, which has a very similar structure to PCB, is known to be stabilized by the complex of human serum albumin in human blood [18; 19; 28]. Therefore, the addition of WB enhanced the antioxidant effects of SP and protected against the death of human skin fibroblasts, possibly due to the synergistic effects of various phenolic compounds and binding with soluble globulin-like wheat albumins present in WB. Various factors, such as visible light, environmental pollution, and solar UV light, increase ROS generation, leading to skin aging. Continuous accumulation of intracellular ROS in skin cells leads to oxidative stress, which ultimately causes cell death and induces cellular senescence [29]. To evaluate the inhibitory effects of the extracts on intracellular ROS production, we measured ROS levels using DCF-DA staining of UVB-irradiated human skin fibroblast cells treated with the extracts (Figure 4). Figure 3: DPPH free radical-scavenging activity of the extracts. Human fibroblasts were subjected to different treatments, as indicated. PCB, PCB standard; SP, the PCB extract from _Arthrospira maxima_, prepared by water extraction using ultrasonication at room temperature followed by ethanolic extraction at 70 \({}^{\circ}\)C; WB, the wheat bran extract prepared by water extraction at 4 \({}^{\circ}\)C for eight hours; SPWB, a mixture of SP and WB containing the same amounts of PCB and SP. Trolox (50 \(\upmu\)g/mL) was used as a positive control. The mean \(\pm\) SD values for triplicate experiments are shown; error bars represent the SD. \(\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\mathbf{\  
As expected, SPWB substantially inhibited ROS production. Considering the ROS levels in the UV(\(-\)) group to be 100%, the levels were increased to 187.23 \(\pm\) 9.71% in the UV(+) group but only to 107.46 \(\pm\) 5.06%, 149.61 \(\pm\) 5.27%, and 121.58 \(\pm\) 7.25% in the SPWB, 0.1 mg/mL SP, and 1 mg/mL WB treatments, respectively. Notably, the reduction in ROS production by WB and SPWB was concentration-dependent, except for a similar decrease at the highest concentrations of 1 and 0.5 mg/mL, respectively. These results indicated that the optimal concentration of SPWB was approximately 0.5 mg/mL for high antioxidant activities and inhibition of ROS generation.