Increased Sulfation in Gracilaria fisheri Sulfated Galactans Enhances Antioxidant and Antiurolithiatic Activities and Protects HK-2 Cell Death Induced by Sodium Oxalate

Abstract

Urolithiasis is a common urological disease characterized by the presence of a stone anywhere along the urinary tract. The major component of such stones is calcium oxalate, and reactive oxygen species act as an essential mediator of calcium oxalate crystallization. Previous studies have demonstrated the antioxidant and antiurolithiatic activities of sulfated polysaccharides. In this study, native sulfated galactans (N-SGs) with a molecular weight of 217.4 kDa from Gracilaria fisheri were modified to obtain lower molecular weight SG (L-SG) and also subjected to sulfation SG (S-SG). The in vitro antioxidant and antiurolithiatic activities of the modified substances and their ability to protect against sodium oxalate-induced renal tubular (HK-2) cell death were investigated. The results revealed that S-SG showed more pronounced antioxidant activities (DPPH and O2− scavenging activities) than those of other compounds. S-SG exhibited the highest antiurolithiatic activity in terms of nucleation and aggregation, as well as crystal morphology and size. Moreover, S-SG showed improved cell survival and increased anti-apoptotic BCL-2 protein in HK-2 cells treated with sodium oxalate. Our findings highlight the potential application of S-SG in the functional food and pharmaceutical industries.

Optimization of Sulfated Polysaccharides Extraction from Gracilaria fisheri Obtained Through Microwave-Assisted Extraction

“…These results proved that the prediction by the Design-Expert ® was accurate and reliable. The authors emphasized that their optimized MAE technique achieves not only high extraction yield and sulfate content, but also does so using an eco-friendly method and significantly shorter extraction time compared to previously reported decoction techniques (Imjongjairak et al, 2016;Rormwong et al, 2023;Sakaew et al, 2022;Wongprasert et al, 2014). This method has the potential to reduce extraction time from hours to seconds.…”

“…Therefore, studying the techniques of extraction and the duration is a crucial step in the bioactive substance extraction process, as it significantly impacts the efficiency and quality of sulfated polysaccharide extraction (Lomartire, & Gonçalves, 2022;Wassie et al, 2021). Sulfated polysaccharides are often extracted using large amounts of water at temperatures ranging from room temperature to 100°C for several hours (Bhuyar et al, 2021;Rudtanatip et al, 2022;Yang, & Yang, 2020). Recently, the use of microwave-assisted extraction (MAE) has been extensively studied and reported as an eco-friendly, faster and more efficient method (Kanchanathawornviboon et al, 2021;Monton et al, 2022;Monton et al, 2023).…”