Marine-derived polysaccharides have sparked immense interest in the nutraceutical industry as they possess a wide range of bioactivities which are highlighted in this review. These include antioxidants, anti-inflammatory, anti-cancer, gut microbiota regulator, anti-diabetic, and anti-obesity. Algae, marine invertebrates, vertebrates, and microorganisms are the main sources of marine polysaccharides, such as alginate, fucoidan, laminarin, carrageenan, chitosan, glycosaminoglycans, and exopolysaccharides. The structure and functional groups of these compounds influence their bioactive properties. Moreover, the functional properties of polysaccharides, such as gelling, thickening, and stabilising capabilities, are also crucial in product development, where they can serve as gluten substitutes in bakery goods and stabilisers in icings, sauces, and yoghurts. The potential of commercial products under development, such as marine polysaccharide supplements, is discussed, along with already commercialised products in the nutraceutical market. This review emphasises the enormous potential of marine-derived polysaccharides as bioactive compounds with health benefits and commercial value.

Limestone has always been widely used in various sectors, thus having significant economic and environmental impacts. The quarrying process is, on the one hand, essential, but on the other, harmful to the environment and people’s health, therefore, the challenge is finding a balance. This review explores the multifaceted nature of limestone, a sedimentary rock predominantly composed of calcium carbonate. The formation of limestone, along with its various types and global occurrence, is discussed to provide a basic understanding. The diverse applications of limestone range from historical uses in ancient monuments to contemporary roles in cement production, plasticized polyvinyl chloride (PVC), and soda–lime glass. The discussion extends to post-mining solutions, showcasing successful rehabilitation and innovative repurposing of former quarries into useful infrastructures, wildlife habitats, and cultural spaces. This article draws attention to the importance of sustainable practices and technological developments to balance resource use with environmental conservation. Ultimately, it emphasizes the need for responsible limestone quarrying and proactive rehabilitation strategies to ensure that no permanent ecological problems will occur.

The limestone quarrying and processing industry generates huge amounts of waste, with limestone sludge being one of the most prevalent and challenging by-products. This study aims to evaluate the potential of limestone sludge as a sustainable secondary raw material for the mechanochemical synthesis of bioceramics, specifically hydroxyapatite (HA), for high-added-value applications in bone tissue engineering. High-energy milling is innovatively used as the processing route: dry sludge (functioning as the calcium source), a phosphate source, and water were milled with the aim of producing calcium phosphates (in particular, hydroxyapatite) via mechanosynthesis. The industrial sludge was thoroughly analyzed for chemical composition, heavy metals, and mineral phases to ensure suitability for biomedical applications. The mixture of reagents was tailored to comply with Ca/P = 1.67 molar ratio. Milling was carried out at room temperature; the milling velocity was 600 rpm, and milling time ranged from 5 to 650 min. Characterization by XRD, Raman spectroscopy, and SEM confirmed the progressive transformation of calcite into hydroxyapatite through a metastable DCPD intermediate, following logarithmic reaction kinetics. The resulting powders are fine, homogeneous, and phase-pure, demonstrating that mechanosynthesis provides a low-cost and environmentally friendly pathway to convert limestone waste into functional bioceramic materials. This suggests that Moleanos sludge is a viable and sustainable source to produce tailored calcium phosphates and confirms mechanosynthesis as a cost-effective and reliable technology to activate the low-kinetics chemical reactions in the CaCO₃-H₃PO₄–H₂O system. This work highlights a novel circular economy approach for the valorization of industrial limestone sludge, turning a difficult waste stream into a high-value, sustainable resource.

This work aimed to develop bioactive films based on alginate and κ-carrageenan that were incorporated with different concentrations 0, 0.2, 0.4, 0.8, 1 and 2% (w/v) of cinnamon essential oil (CEO). The films were crosslinked with a solution of calcium chloride obtained from limestone sludge through acid dissolution. The films were characterised according to their physical, mechanical, optical, antioxidant and antimicrobial properties. The best film formulation consisted of 1.5% total carbohydrate concentration, 0.45% glycerol and 0.4% (w/v) of Tween 20. The Fourier transform infrared Spectroscopy analysis confirmed the crosslinking between the polysaccharides and the incorporation of the CEO into the polymer matrix. The addition of the CEO increased the film thickness, reduced moisture content and water vapour permeability, yet it increased solubility, due to matrix disruption invoked by the oil droplets. SEM analysis showed that CEO affected film microstructure, with moderate concentrations leading to more homogeneous structures. In terms of the mechanical properties, CEO incorporation reduced stiffness and yield strength whilst increasing film flexibility, showcasing a plasticising effect. The films were colourless and transparent; moreover, none of the samples exhibited absorbance in the visible region (400–800 nm); however, all films showed absorption in the UV region. The incorporation of the CEO into the films provided antioxidant activity. Particularly, the sample containing 2% CEO had the highest activity, with values of 97.5 ± 0.77% and 75.9 ± 1.82% in the ABTS and DPPH, respectively. Overall, these results suggest that the developed films have promising potential as sustainable food packaging materials with enhanced antioxidant functionality, although further optimisation is needed to improve antimicrobial performance and validate their effectiveness in real food packaging systems.