Application potential of Lysimachia christinae Hance polysaccharides in kidney stone prevention/treatment: a multidimensional comparison between ultrasonic-assisted extraction and hot water extraction

Lysimachia christinae Hance (LCH), a traditional Chinese herbal medicine, possesses the effects of "clearing heat and promoting diuresis, relieving stranguria and expelling stones, and detoxifying and protecting the kidneys". This study for the first time developed an efficient, green, and economical ultrasonic-assisted extraction (UAE) process for extracting LCH polysaccharides (LCHP-UAE). Meanwhile, it systematically investigated the mechanisms of action of UAE and hot water extraction (HWE) technologies for extracting LCH polysaccharides. Finally, it comparatively analyzed the differences in physicochemical properties, functional characteristics, and bioactivities between LCHP-UAE and LCH polysaccharides obtained by HWE (LCHP-HWE). It was found that under the optimal operating conditions of UAE obtained by response surface methodology optimization, the extraction yield of LCHP-UAE reached 8.25 ± 0.13 %. Compared with HWE, UAE strongly disrupted the cell walls of raw materials through cavitation effect and mechanical vibration, thereby improving mass transfer capacity. Compared with LCHP-HWE, LCHP-UAE exhibited characteristics such as lower M_W and smaller particle size, increased content of uronic acid, better thermal stability, and stronger water- and oil-holding capacities.Owing to its unique structural advantages, LCHP-UAE showed superior antioxidant activity and kidney stone inhibitory effect. In conclusion, this study establishes a robust theoretical foundation for the efficient utilization of LCH and the deployment of LCHP-UAE in contexts including the food industry and kidney stone intervention.