Anticancer activity in vitro of a fucoidan from the brown alga Fucus evanescens and its low-molecular fragments, structurally characterized by tandem mass-spectrometry

► Fucoidan FeF1 was isolated from the brown alga Fucus evanescens. ► FeF1 was depolymerized to low-molecular-weight fragments FeF1-AHL by autohydrolysis. ► MS analysis revealed that FeF1-AHL was a mixture of sulfated (1-5) oligosaccharides (DP 2-6). ► FeF1 possesses anticancer activities in melanoma SK-MEL-28 and SK-MEL-5 cell lines. ► FeF1-AHL inhibits the colony formation of SK-MEL-28 cell lines likely to FeF1 fucoidan.