Preparation and structure characterization of a natural acetylated fructooligosaccharide from Polygonatum sibiricum and its alleviative effect on colitis by inhibiting NLRP3 pathway

This study aimed to isolate oligosaccharides from P. sibiricum, analyze its structure, and elucidate the pharmacological mechanism for colitis improvement. First, a homogeneous oligosaccharide PSO-A was isolated and its structure was characterized. Then, the colitis model was induced with 3 % dextran sulfate sodium (DSS) and intervened with PSO-A. The results show that PSO-A was an agavin-type acetylated fructooligosaccharide with a molecular weight of 2.12 kDa. PSO-A consisted of (2 → 6)-β-D-Fruf residue backbone with an internal α-D-Glcp residue and (2 → 1)-β-D-Fruf residue side chains. Further, PSO-A increased mucin content, protected intestinal barrier integrity of colitis mice, and significantly inhibited the levels of inflammatory factors. Moreover, the protein expressions of NLRP3, ASC, and Caspase-1 in colitis mice was statistically inhibited by PSO-A. In summary, PSO-A could alleviate colitis by inhibiting NLRP3 inflammasome pathway, which provides a basis for the development and application of P. sibiricum oligosaccharides as drug or functional food to relieve colitis

Timing and forcing mechanism of the final Neotethys seawater retreat from Central Iran in response to the Arabia-Asia collision in the late early Miocene

The Iranian Plateau lies in the middle of the Neotethys tectonic domain; to the east it connects with the Tibetan Plateau, and to the west with the Anatolian Plateau and the Alpine orogenic belts. In the Cenozoic it underwent land/sea changes and tectonic uplift in response to the Arabia-Asia plate collision. One of the most prominent geological consequences of the collision was the disappearance of an epicontinental sea in Central Iran, which was a northeastern branch of the Neotethys seaway in the Oligocene-early Miocene. The timing of the final seawater retreat from Central Iran and its forcing mechanism are important for understanding the effects of Arabia-Asia plate collision as well as global eustatic sea-level changes. In this paper we present new magnetostratigraphy, U-Pb ages of one tuffaceous bed, and stable isotopic records of carbonates. The results of this multidisciplinary study indicate that a shallow open sea in the Qom back-arc basin ended at 17 Ma, but the final seawater retreat from a restricted marine environment was at 16.8 Ma. The final regression was just before the Middle Miocene Optimum, implying that it was not related to a climatic factor, but driven by the Arabia-Asia plate collision. Moreover, the delta O-18 record of fine-grained lacustrine carbonates indicates an isotopic shift towards more positive isotopes after 13 Ma, suggesting an enhanced aridification in Central Iran. This climatic deterioration was a response to reduced transport of moisture by westerlies from a retreating Neotethys Sea driven by a global eustatic sea-level drop in response to the East Antarctica ice-sheet expansion after the middle Miocene Optimum