Abstract
Carotenoids are a diverse class of biologically active compounds that contribute significantly to human health, serving vital functions in nutrition and overall well-being. Magallana bilineata, a commercially important oyster species, yields a shelf-stable powder residue possessing bioactivities with unknown specific compounds. Carotenoids are key marine bioactive compounds, but their presence in oysters remains underexplored. The present study aimed to identify the bioactive compounds from oyster powder residue through mass spectrometry for optimum utilization and value creation as a biomedical resource. The study employed solvent extraction of oyster powder residue, followed by fractionation using octadecylsilyl (ODS) column chromatography, liquid chromatography-mass spectrometry (LC-MS)-guided profiling, and ultra-high-performance liquid chromatography-ultra-high-performance liquid chromatography-elevated energy mass spectrometry-elevated energy mass spectrometry (UHPLC-MS(E)) analysis to identify carotenoids, with bioactivity assays conducted to assess the cytotoxic, antimicrobial, antioxidant, and anti-inflammatory properties. The study obtained two HPLC fractions and enabled the identification of carotenoid compounds based on retention times and UHPLC-MS(E), with elemental compositions inferred from the observed mass-to-charge ratios. The bioactivities of the two HPLC fractions, identified as zeaxanthin in fraction 1 and a zeaxanthin/lutein isomeric mixture in fraction 2, were assessed. The zeaxanthin/lutein isomeric mixture exhibited higher effectiveness in MCF-7 cancer cell inhibition (IC(50) = 93.29 ± 0.07 μg/mL) than cisplatin, but both HPLC fractions showed strong antibacterial activity against Klebsiella pneumoniae and Escherichia coli. Moreover, notable antioxidant activity was observed in both fractions for 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity assays, while zeaxanthin demonstrated anti-inflammatory activity (43.68 ± 0.11%) comparable to aspirin (43.49 ± 0.17%). These findings suggest that the observed biological activities of the HPLC fractions may be the consequences of the adaptive response and filter-feeding behaviors of oysters, which result in the accumulation of bioactive carotenoids. This study offers a promising perspective on applying mass spectrometry techniques for advanced compound extraction and identification, and on utilizing oyster powder residue as a sustainable approach to waste valorization and as a functional ingredient for biomedical applications.