Abstract
Natural polysaccharides derived from plants have demonstrated significant antidiabetic properties by effectively alleviating hyperglycemia, improving insulin resistance, and preventing diabetes-associated complications. In this study, polysaccharides were extracted from Centella asiatica (L.) leaves via hot water extraction, followed by 50% (v/v) alcohol precipitation and Sevag deproteinization. Using DEAE-52 cellulose chromatography, the crude Centella asiatica polysaccharide (CAP) was separated into three fractions: P50-1, P50-2, and P50-3. P50-2 showed the greatest inhibition of α-amylase and α-glucosidase. Consequently, P50-2 was further purified using Sephacryl S-400 high-resolution (HR) gel chromatography to yield a single fraction, designated P50-2 A. An evaluation of the composition demonstrated that the compound P50-2 A, characterized as an acidic heteropolysaccharide, possesses a molecular mass of 3014 kDa. Its structure comprises fucose, rhamnose, mannose, arabinose, galactose, glucose, glucuronic acid, and galacturonic acid, arranged in a molar proportion of 0.83:1.21:6.32:24.36:37.16:19.29:5.48:5.35. Fourier transform infrared spectroscopy (FT-IR) and methylation analysis confirmed that P50-2 A is an arabinogalactan with a pyranose ring structure and 14 methylated sugar residues. Scanning electron microscopy (SEM) revealed an irregular, spongy morphology, while X-ray diffraction (XRD) analysis indicated a semi-crystalline structure comprising both amorphous and crystalline phases. In conclusion, this investigation offers the first thorough structural characterisation of CAP, providing a strong basis for further research into the links between its structure and activity as well as its uses in a variety of domains. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1038/s41598-026-35232-y.