Antioxidant and anti-aging potential of a peptide formulation (Gal₂-Pep) conjugated with gallic acid

Skin is highly vulnerable to premature aging due to external stress, therefore, in this study, a peptide formulation, (galloyl)₂-KTPPTTP (Gal₂-Pep) was synthesized by combining TPPTTP peptide, and gallic acid (GA). All peptides were synthesized on 2-chlorotrityl chloride resin using solid-phase peptide synthesis (SPPS), and analyzed on an electrospray ionization (ESI)/quadrupole-time-of-flight (Q-TOF) tandem mass spectroscopy (MS) system. Initially, Gal₂-Pep showed no toxicity below the concentration 100 μM with cell survival rate of 88% for keratinocytes and fibroblasts. The reactive oxygen species (ROS) scavenging activity of Gal₂-Pep was more stable compared to GA alone; and after four weeks at room temperature, its ROS scavenging activity remained higher than 50%. Moreover, the peptide formulation, Gal₂-Pep also exhibited elastase inhibitory effect in CCD-1064Sk fibroblast cells. Based on the results of RT-qPCR, it was proved in this study that Gal₂-Pep increased the expression of PGC-1α to prevent oxidative stress, and validated its potential as an anti-aging agent through increasing the expression of type I collagen and by decreasing the expression of matrix metalloproteinase-1 (MMP1). The findings obtained reinforce the suggestion that the peptide formulation synthesized in this study could be used as a natural antioxidant and anti-aging agent for its cosmetic applications.