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Summary Acute toxicity in Wistar rat and the impact of hydrolysed collagen (HC) from seabass skin on in vitro cell proliferation and collagen production were studied using L929 fibroblasts. HC was rich in glycine (326 residue/1000 residue) and imino acids (196 residue/1000 residue). MALDI mass spectrum of HC showed several low MW peptides with MW range of 1050–1330 Da as the major components. Based on acute oral cytotoxicity test in Wistar rat, HC was considered as safe with LD50 value higher than 5000 mg kg−1 body. HC could promote L929 cell growth, especially when used in combination with vitamin C (VitC) at a ratio of 2:1. HC/VitC (2:1) mixture also exhibited the higher enhancement effect on collagen production of L929 cells, compared with HC or VitC alone. Thus, HC could be a promising candidate for biological applications, especially in combination with VitC, as nutraceuticals for skin care.

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BACKGROUND: Clown featherback (Chitala ornata) skin, a by-product from the filleting process line, could serve as a good aquatic collagenous source. Nevertheless, the typical collagen extraction method is a time-consuming process providing a relatively low yield. Ultrasound had been reported to be an alternative technique for enhancing the extraction efficiency of several compounds, although the harsh conditions of ultrasound could affect their physicochemical and molecular characteristics. Thus, the application of ultrasonication under appropriate conditions could comprise a promising means for improving the extraction efficiency of collagen from clown featherback skin. RESULTS: Ultrasonication using different amplitudes (20-80%) and times (10-30 min) was implemented during extraction. An ultrasound-assisted process (UAP) was able to increase the yield of collagen (P < 0.05) and could also result in a collagen purity decrease as evaluated by hydroxyproline content. There was no dramatic change in the solubility of resulting collagens. UAP induced protein degradation, particularly with an increasing amplitude and time, where slight changes in the isoelectric point value of collagen were observed. UAP had no adverse effect on molecular structure, where a triple-helical structure was still retained when an 80% amplitude was employed for 10 min (UAP-80/10-C). The amino acid composition of UAP-80/10-C reconfirmed the unique characteristic of collagen containing imino acid. CONCLUSION: An UAP under appropriate conditions could be used to improve the extraction yield with minimal effects on the molecular integrity of the resulting collagen. In addition, fish skin waste from the cutting process line, particularly clown featherback skin, could be exploited as a value-added product, comprising fish skin collagen.