Fourier Transform Infrared (FTIR) Spectroscopic Characterisation of Selected Marine Macroalgae from The Ratnagiri Coast, Maharashtra, India

Marine macroalgae are recognised as a rich reservoir of bioactive compounds with potential pharmaceutical and nutraceutical applications. This study characterised the biochemical profiles of Gracilaria sp. (Rhodophyta), Padina sp. (Phaeophyta), and Caulerpa sp. (Chlorophyta) collected from the Ratnagiri coast using Fourier Transform Infrared (FTIR) spectroscopy. Spectra revealed common functional groups including O-H/N-H stretching (3270–3285 cm⁻¹), C-H stretching (2920–2925 cm⁻¹), amide I/II (1638–1542 cm⁻¹), carboxylate (1408–1361 cm⁻¹), and polysaccharides (1240–1020 cm⁻¹). Low-frequency absorptions (595–581 cm⁻¹) indicated sulphate. Comparative analysis revealed species-specific variations in polysaccharide and sulphate-related functional groups. Species-specific traits included sulphated polysaccharides in Gracilaria sp. (581 cm⁻¹), alginate-like bands in Padina sp. (1240–1151 cm⁻¹), and glycosidic linkages in Caulerpa sp. (1161–907 cm⁻¹). These findings highlight biochemical diversity, supporting the potential of these macroalgae as sources of bioactive polysaccharides and protein-associated biomolecules.