Abstract
Background:
The sea cucumber Stichopus herrmanni is a marine-derived source of collagen with potential as a natural active ingredient in topical formulations. Collagen is integral to maintaining skin moisture, elasticity, and regeneration.

Aim:
This study aimed to assess the characteristics and biological activity of a sea cucumber collagen-based lotion through in vitro and in vivo testing.

Methods:
Collagen was characterized using the Hopkins–Cole test, ninhydrin test, pH measurement, water content analysis, and Fourier Transform Infrared (FTIR) spectroscopy. The lotion was formulated with varying collagen concentrations and evaluated through organoleptic testing, homogeneity, pH, spreadability, adhesion, and washability. In vivo testing was conducted on Mus musculus mice, with histological analysis of the skin, including measurements of epidermal thickness and fibroblast count, which were statistically analyzed using ANOVA.

Results:
The collagen yield and water content were 1.26% and 3.1%, respectively. The Hopkins–Cole test indicated the absence of detectable tryptophan residues, while the ninhydrin test confirmed the presence of free amino acids. FTIR analysis identified the characteristic functional groups of collagen. The F1 formulation, which incorporated 1 g of collagen, exhibited the most favorable physical characteristics and stability compared to the other formulations. In vivo results showed that F1 produced the highest epidermal thickness of 91.14 μm, compared to the positive control, which measured 75.80 μm. However, the fibroblast count in F1 (12.50) was lower than that in the positive-control group (14.25).

Conclusion:
The F1 sea cucumber collagen lotion formulation exhibited favorable physical characteristics and a superior biological response compared to the untreated and negative control groups, particularly in terms of enhancing epidermal thickness. These findings suggest the potential of S. herrmanni collagen as a natural ingredient in topical lotion formulations, although further research is required to thoroughly evaluate its biological efficacy.

Key words: Marine collagen; Skin histological evaluation; Skin regeneration; Stichopus herrmanni; Topical lotion formulation.