An efficient procedure for preparing high-purity pingyangmycin and boanmycin from Streptomyces verticillus var. pingyangensis fermentation broth via macroporous cation-exchange resin and subsequent reversed-phase preparative chromatography

Preparative separation of iridoid glucosides and crocins from Gardeniae Fructus using sequential macroporous resin column chromatography and evaluation of their anti-inflammatory and antioxidant activities

Iridoid glycosides (geniposide (GP), genipin-1-gentiobioside (GB), etc.) and crocins (crocin Ⅰ (CR1), crocin Ⅱ(CR2), etc.) are two main bioactive components in Gardeniae Fructus (GF), which is a famous traditional Chinese medicine. Iridoid glycosides exhibit many activities and are used to manufacture gardenia blue pigment for the food industry. Crocins are rare natural water-soluble carotenoids that are often used as food colorants. A sequential macroporous resin column chromatography technology composed of HC-500B and HC-900B resins was developed to selectively separate iridoid glucosides and crocins from GF. The adsorption of GP on HC-900B resin was an exothermic process. The adsorption of CR1 on HC-500B resin was an endothermic process. The two kinds of components were completely separated by a sequential resin column. GB and GP were mainly found in product 1 (P1) with purities of 11.38% and 46.83%, respectively, while CR1 and CR2 were mainly found in product 2 (P2) with purities of 12.32% and 1.40%, respectively. The recovery yields of all the compounds were more than 80%. The above results showed that sequential resin column chromatography technology achieved high selectivity and recovery yields. GF extract, P1 and P2 could significantly inhibit the secretion of nitric oxide (NO), tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) in lipopolysaccharide (LPS)-induced RAW264.7 cells, indicating that iridoid glycosides and crocins provide a greater contribution to the anti-inflammatory activity of GF. At the same time, compared to the GF extract and P1, P2 exhibited stronger scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals, indicating that crocins may provide a significant contribution to the antioxidant activity of GF.

Adsorption Properties and Preparative Separation of Flavonoids from Rhizoma Smilacis Glabrae Using Macroporous Resins

Astilbin (AST), isoastilbin (ISO), and engeletin (ENG) are the main flavonoids in Rhizoma Smilacis Glabrae (RSG) and have many biological activities. In this study, the adsorption kinetics of AST, ISO, and ENG on HPD-300 resin was investigated and their adsorption processes conformed to a pseudo-second-order kinetics equation. The fitting curves of the intraparticle diffusion model showed three linear stages and did not pass through the origin, meaning the adsorption process of the three flavonoids was controlled by boundary layer diffusion and intraparticle diffusion. Their adsorption isotherms were also constructed and could be well-fitted by the Langmuir equation. A low temperature was favorable for their adsorption. The relative adsorption capacity of ENG was significantly higher than those of the other two compounds, indicating that the substitution pattern on ring B has an important impact on the adsorption of flavonoids with resin. The separation process was optimized by dynamic adsorption/desorption experiments. After separation, the purities of AST, ISO, and ENG increased from 5.55%, 1.22%, and 0.45% to 27.46%, 6.14%, and 2.27%, respectively, and all the recoveries exceeded 75%. After that, the three compounds were further separated by preparative HPLC and silica gel chromatography. In the final product, the purities of AST, ISO, and ENG could reach above 98%.

Preparative separation of 1,1-diphenyl-2-picrylhydrazyl inhibitors originating from Saxifraga sinomontana employing medium-pressure liquid chromatography in combination with reversed-phase liquid chromatography

Traditional Tibetan medicines elaborately document the health benefits of Saxifraga sinomontana. However, there have been limited reports on its chemical make-up, presumably because of the complicated separation and purification process. In this work, a methanolic extract of Saxifraga sinomontana was utilized for targeted separation of 4 key 1,1-diphenyl-2-picrylhydrazyl inhibitors employing the medium-pressure liquid chromatography, reversed-phase liquid chromatography in combination with on-line reversed-phase liquid chromatography-1,1-diphenyl-2-picrylhydrazyl detection. Pre-treatment of the sample was carried out by employing medium-pressure liquid chromatography using MCI GEL® CHP20P as the stationary phase, furnishing 2.4 g of fraction Fr3 and 3.4 g of fraction Fr4 (the percentage retrieval was 32.7%). The 1,1-diphenyl-2-picrylhydrazyl inhibitors contained in fractions Fr3 and Fr4 were subjected to additional separation using a C18 (ReproSil-Pur C18 AQ) column and yielded 106.2 mg of Fr3-1, 246.9 mg of Fr3-2, 248.5 mg of Fr4-1 and 41.8 mg of Fr4-2. The degree of purity, structures and 1,1-diphenyl-2-picrylhydrazyl inhibition activity of the isolated DPPH inhibitors were determined, and four 1,1-diphenyl-2-picrylhydrazyl inhibitors including two new diarylnonanoids (3-methoxy-4-hydroxyphenol-(6'-O-galloyl)-1-O-β-d-glucopyrano side with IC₅₀ of 39.6 μM, 3,4,5-trimethoxyphenyl-(6'-O-galloyl)-1-O-β-d-glucopyranoside with IC₅₀ of 46.9 μM, saximonsin A with IC₅₀ of 11.4 μM, and saximonsin B with IC₅₀ of 20.6 μM) were isolated with a percentage purity above 95%. The methodology thus evolved has good efficacy for preparatively isolating high-purity 1,1-diphenyl-2-picrylhydrazyl inhibitors from extracts of Saxifraga sinomontana and could be efficiently utilized for rapidly isolating 1,1-diphenyl-2-picrylhydrazyl inhibitors from other natural products.

Large-scale preparative isolation of bergenin standard substance from Saxifraga atrata using polyamide coupled with MCI GEL® CHP20P as stationary phases in medium pressure chromatography

In this study, polyamide and MCI GEL® CHP20P were employed as stationary phases in medium pressure chromatography (MPC) for the efficient preparative separation of bergenin from Saxifraga atrata. Ethanol-water, methanol-water, and acetonitrile-water mobile phases all showed good enrichment capacity for bergenin fraction when polyamide was used as a stationary phase. After 5 cycles of polyamide MPC using acetonitrile/water, 1.2 g of bergenin fraction was isolated from 180 g Saxifraga atrata herb. Further purification of this fraction was conducted using MCI GEL® CHP20P styrene-divinylbenzene beads. The bergenin fraction was separated into two fractions, and after three runs of MPC, 714.2 mg of bergenin with purity above 99% was obtained. The results demonstrate that the combination of polyamide and styrene-divinylbenzene MPC can be utilized for preparative isolation of compounds from natural products with high yield and purity.