Deciphering the multifunctional bioactivities of ulvan from Ulva lactuca: structural insights with emphasis on antibiofilm and cytotoxic properties

BackgroundThe increasing prevalence of antimicrobial resistance (AMR), alongside the growing incidence of cancer, diabetes and adverse effects associated with antibiotics, chemotherapy and synthetic drugs, encourages researchers to find out natural products as a potential solution. In this context, a systematic approach was applied to extract ulvan from the edible green algae Ulva lactuca, known for its rich biochemical composition and to determine its multifunctional biomedicinal properties.MethodsIn this study, sulphated polysaccharide ulvan was extracted from U. lactuca through hot water extraction and the purified ulvan was characterized by various spectral analysis. Biomedical properties of the ulvan were determined through in vitro assays approaches. The biocompatibility of the ulvan was assessed by Artemia cytotoxicity and anticancer activity against human skin cancer (A431) cells.ResultsThe organoleptic characteristics of ulvan revealed that it is odourless, whitish in colour, polar, powdery, and possesses gelling ability. Biochemical analysis indicated that ulvan exhibited high thermal stability under conditions ranging from 103.6 to 600 °C, with a near-neutral pH of 6.7–7.4, and contained substantial amounts of carbohydrates, alongside sulfate groups, uronic acids, and proteins. Spectroscopic analysis revealed the structural makeup and functional groups of the ulvan. The extracted ulvan exhibited promising free-radical scavenging activity (DPPH, FRAP, HPO, and TAA). Antimicrobial studies revealed that ulvan inhibited both bacterial and Candida strains, with MICs in the range of 50 to 90 µg/mL. It had also exhibited notable antibiofilm activity, as evidenced by inhibition of exopolysaccharide production, increased protein leakage, and ROS production in the tested pathogens, along with microscopic visualization confirming eradication of microbial adherence on glass surface. In vitro antidiabetic activity of ulvan showed promising α-amylase inhibitory activity, with an IC50 of 78.43 µg/mL. The safety assessment of ulvan revealed minimal toxicity to Artemia salina nauplii (LC50: 147.8 µg/mL). The cytotoxicity of ulvan on A431 cells recorded an IC50 value of 82.44 µg/mL.ConclusionOverall, this study elucidated the structural and biomedicinal attributes of ulvan, notably revealing its pronounced antibiofilm activity and selective cytotoxic effects against human skin cancer (A431) cells remains comparatively underexplored. Hence, this study substantiates its potential as a promising multifunctional therapeutic applications.