Anti-aging Effects and Main Chemical Constituents of <b><i>Spiraea salicifolia</i></b> Stem Extracts

Objective: To investigate the anti-aging effects and the main chemical constituents of Spiraea salicifolia stem extracts. Methods: The anti-aging effects were investigated by evaluating the antioxidant, anti-wrinkle, and anti-inflammatory properties. The 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays were used to determine the antioxidant effects. The anti-wrinkle effects were evaluated by measuring the mRNA expression of matrix metalloproteinase (MMP)-1 and MMP-12 in human skin fibroblasts. The anti-inflammatory effects were investigated by measuring the decrease in nitric oxide (NO) production, the mRNA expression of Interleukin-6 (IL-6) and the protein expression of NO synthase (iNOS) in lipopolysaccharide-induced RAW 264.7 cells. Reconstructed human epidermis and cornea-like epithelium were used to evaluate the local toxicity of the extracts. The major compounds were isolated using chromatographic separations and purification methods. The structures were identified by interpreting the measured spectroscopic data (NMR and MS) and comparing them with published values. Results: S. salicifolia stem extracts showed concentration-dependent radical-scavenging effects on DPPH and ABTS. Furthermore, they exhibited anti-wrinkle effects as they downregulated the expression of collagenase MMP-1 and elastase MMP-12 by 43% ( p &lt; 0.001) and 34% ( p &lt; 0.05), respectively, at 100 μg/mL. Moreover, they showed inhibitory effects on NO, IL-6 and iNOS of 46% ( p &lt; 0.0001), 42% ( p &lt; 0.0001) and 72% ( p &lt; 0.0001), respectively, at 100 μg/mL. The extracts were considered non-irritant to the skin and eyes (UN GHS no category). Five known compounds, luteolin 5- O- β-D-glucopyranoside (1), trans-resveratrol 3- O- β-D-glucopyranoside (2), hyperoside (3), apigenin 5- O- β-D-glucopyranoside (4), and prunioside A (5), were identified as the major chemical compounds. This is the first report of the isolation of compounds 1, 2, 4, and 5 from this species; notably, this is the second report of the isolation of 5 from nature. Conclusion: S. salicifolia stem extracts are an important source of natural antioxidant, anti-wrinkle, and anti-inflammatory ingredients that can be safely used in anti-aging cosmetic applications.