Stereoscopic Differences in the Identification, Bioactivity, and Metabolism of C-20 and C-24 Epimeric Ginseng Saponins.

Ginseng, the roots and/or rhizomes of Panax spp.(Araliaceae), has been used as a popular herbal medicine in East Asia for at least two millennia. As a functional food and healthenhancing supplement, ginseng has been shown to have a wide range of pharmacological effects on cognition and blood circulation as well as antioxidant, antitumor, and anti-fatigue effects. The main active properties of ginseng are considered to be the triterpene saponins, often referred to as ginsenosides, which are the basis for their wide-ranging pharmacological effects. Four of these glycosides, including protopanaxadiol, protopanaxatriol, ocotillol, and oleanolic acid, are the most common saponins found in ginseng. Compared to other ginsenosides, the C-20 chimeric ginsenosides, including Rg3, Rh2, Rg2, Rh1, PF11, C-20, and C-24, as well as epimeric ocotillol-type saponins and their derivatives exhibit significant, steric differences in biological activity and metabolism. 20(R)-ginseng saponins, one class of important rare ginsenosides, have antitumor, antioxidative, antifatigue, neuroprotective and osteoclastogenesis inhibitory effects. However, 20(R)- ginsenosides are rare in natural products and are usually prepared from 20(S)-isomers through chemical differential isomerization and microbial transformation. The C20 configuration of 20(R)-ginseng saponins is usually determined by 13C NMR and X-ray single-crystal diffraction. There are regular differences in the chemical shift values of some of the carbons of the 20(S)- and 20(R)-epimers, including C-17, C-21, and C-22. Owing to their chemical structure and pharmacological and stereoselective properties, 20(R)-ginseng saponins have attracted a great deal of attention in recent years. Herein, the stereoscopic differences in the identification, bioactivity, and metabolism of C-20 and C-24 epimeric ginseng saponins are summarized.

Effect of extrusion-spheronization granulation and manganese loading on catalytic ozonation of petrochemical wastewater.

The petrochemical secondary effluent (PSE) is typical refractory wastewater derived from the petrochemical industries, which requires advanced treatment due to the strict environmental protection policies. Catalytic ozonation is one of the most widely used advanced oxidation technologies in wastewater treatment because of its high mineralization rate, in which the alumina-based catalyst usually plays an important role. Extrusion-spheronization is a promising technique for the preparation of alumina spheres because the synthesized alumina particles have high sphericity, high specific surface aera and narrow particle size distribution. In this paper, two kinds of alumina-based catalysts (catalyst A: manganese nitrate added after alumina granulation and catalyst B: manganese nitrate added into alumina powder before granulation) were prepared by the extrusion-spheronization method and used for PSE treatment by catalytic ozonation. The prepared alumina samples were characterized by Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM), while the wastewater samples were analyzed for Total organic carbon (TOC), UV254 and fluorescence spectroscopy. Results showed that manganese was uniformly distributed in both catalysts, and the specific surface area of two catalysts was 318.36 m2/g and 354.95 m2/g, respectively. Catalytic ozonation experiments were repeated nine times with each catalyst under the same conditions. The TOC removal rates for catalysts A and B in the first run were 48.88% and 49.06%, respectively, then it dropped to 28.05% for catalyst A but remained 47.81% for catalyst B after using for nine times. This implied that the long-term performance of catalyst B would be more stable than catalyst A. Similar result were found in three-dimensional fluorescence analysis. UV254 results indicated that the removal efficiency of aromatic and unsaturated substances by catalyst B was higher than catalyst A. A possible explanation is that the active component manganese oxide formed a catalyst skeleton in catalyst B, which makes it hard to dissolve. Effect of extrusion-spheronization granulation and manganese loading on advanced oxidant treatment of petrochemical wastewater.