Peer Review Report For: Toxicology Study and MMP-1 and COL1A1 Expression of Malang Green Apple Juice Fermented by Lactobacillus plantarum DAD-13 and Saccharomyces cerevisiae Fermipan on Human Fibroblast: Potential Modality of Anti-aging [version 2; peer review: 1 approved with reservations]

Background Continuous exposure to sunlight and pollution without adequate protection can damage skin, making it prone to premature aging. One of the natural ingredients for anti-aging is antioxidant. Malang green apple ( Malus sylvestris Mill) contains bioactive compounds that can act as antioxidants, but its use is still limited to only as food ingredient. Furthermore, some studies show the potency of fruit fermentation to increase these bioactive compounds. Thus, this study is a preliminary study to examine the anti-aging potency of fermented Malang green apples. Methods Human foreskin fibroblasts were treated with fermented Malang green apple juice extract (FAJ) by Lactobacillus plantarum DAD-13 and Saccharomyces cerevisiae Fermipan and its unfermented (AJ) for 24, 48, and 72 hours. Cell viability was measured using the MTT assay and collagen deposition was measured using the Sirius red staining method. The expression of matrix metalloproteinase 1 (MMP-1) and collagen type 1 alpha 1 chain (COL1A1) was measured in fibroblasts after treatment with extracts. Results Cell viability and collagen deposition of fibroblasts tended to be higher after 48 h of extract exposure. Fibroblasts that received FAJ 62.5 μg/mL showed higher cell viability than negative control (p