Optimisation of isolation of polyphenols from Malus pumila Mill. Leaves by high-speed countercurrent chromatography using response surface methodology.

Considering comprehensive utilization of natural products, isolation and activity determination processes of bioactive compounds are essential. In this study, a combined high-speed countercurrent chromatography (HSCCC) with preparative HPLC method was developed to isolate the five antioxidant polyphenols from 75% ethanol extract of Malus pumila Mill. leaves. The HSCCC conditions were optimized by response surface methodology (RSM) considering two response indexes including retention of stationary phase and analysis time. The optimal HSCCC conditions were flow rate of 2.11 mL/min, revolution speed of 717 rpm, and temperature of 25℃, with a solvent system of ethyl acetate/methanol/water (10:1:10, v/v/v). The unseparated fractions obtained from HSCCC were subjected to preparative HPLC for further isolation. As a result, phloridzin (15.3 mg), isoquercitrin (2.1 mg), quercetin 3-O-xyloside (1.9 mg), quercetin-3-O-arabinoside (4.0 mg), and quercitrin (2.0 mg) were isolated from 200.0 mg extracts. The purities of these compounds were all above 92%. Their chemical structures were identified by mass spectrometer and nuclear magnetic resonance. The five isolated compounds were further investigated for their rat hippocampal neuroprotective effects against hydrogen peroxide-induced oxidative stress. No cytotoxicity was observed in all tested concentrations. While all five compounds except phloridzin showed significantly neurogenic activities and neuroprotective effects, especially at the concentration of 0.5 mg/L. These results demonstrate that RSM is a suitable technique for optimisation of HSCCC and the isolated polyphenols can be used as antioxidants in pharmaceutical and food products.

[Chemical composition analysis of Eucalyptus essential oil and allelopathic effects of α-terpineol]. / æ¡‰æ ‘æ²¹åŒ–å­¦æˆåˆ†åˆ†æžåŠα-松油醇的化感作用.

We extracted Eucalyptus essential oil by steam distillation and analyzed its chemical components by GC-MS. The inhibitory effects of α-terpineol, a component in Eucalyptus essential oil, were tested in Petri dishes on the germination and growth of Amaranthus retroflexus. The allelopathic effects of α-terpineol on A. retroflexus were examined with a pot experiment by measuring germination rate and biomass. The yield of essential oil was 0.04%. Ninety-two chemical components were detected from the essential oil. In Petri dish experiment, the germination inhibitory effect under 5 µL and 7.5 µL of α-terpineol per dish reached 100%. In pot experiment, germination, aboveground fresh and dry weights of A. retroflexus were significantly affected by α-terpineol. At the concentration of 1.6 µL·cm-3, the inhibition effect was strongest, with the allelopathic response index being -0.51 for germination, -0.62 for aboveground fresh weight, and -0.44 for aboveground dry weight, and the inhibition ratio being 51%, 62% and 44%, respectively.

Isolation and purification of alkaloids from the fruits of Macleaya cordata by ionic-liquid-modified high-speed counter-current chromatography.

Macleaya cordata (Willd) R. Br. is a medicinal plant. The most important bioactive compounds of M. cordata are alkaloids that have many biological activities including antifungal, anti-inflammatory, and antitumor. In this study, an ionic-liquid-modified high-speed counter-current chromatography method was established to obtain alkaloids from the fruits of M. cordata. The conditions of ionic-liquid-modified high-speed counter-current chromatography, including solvent systems, the content of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate [C4 mim][BF4 ]), and the posttreatment of the ionic liquid, were investigated. Five alkaloids protopine, allocryptopine, sanguinarine, 8-O-demethylchelerythrine, and chelerythrine were separated from the extract of the fruits using a high speed counter-current chromatography with two-phase solvent system composed of dichloromethane/methanol/0.3 mol/L hydrochloric acid aqueous solution/[C4 mim][BF4 ] (4:2:2:0.015, v/v). Their purities were 96.33, 95.56, 97.94, 96.22, and 97.90%, respectively. The results indicated that a small amount of ionic liquids as modifier of the two-phase solvent system could shorten the separation time and improve the separation efficiency of the alkaloids from the fruits. The ionic-liquid-modified high-speed counter-current chromatography would provide a feasible way for highly effective separation of alkaloids from natural products.

A strategy of rapidly screening out herbicidal chemicals from Eucalyptus essential oils.

BACKGROUND: To enhance discovering efficiency of new herbicidal compounds, a strategy for rapidly screening out strongly herbicidal chemical components from natural resources is necessary. RESULTS: Seventeen essential oils selected from 14 Eucalyptus species and hybrids were evaluated for their herbicidal activities on annual ryegrass. A feasible strategy was established for rapidly pinpointing the chemicals contributing to strong herbicidal activities without the process of isolation and purification of individual compounds. This strategy was based on gas chromatography-mass spectrometry (GC-MS) coupled with principal component analysis (PCA) and verified by the bioassay results using several individual compounds. Two strong herbicidal compounds trans-pinocarveol and α-terpineol were screened out using the strategy. The strong herbicidal activity of trans-pinocarveol was discovered for the first time. CONCLUSION: The established strategy of screening herbicidal compounds from natural resources is simple, feasible and reliable. © 2019 Society of Chemical Industry.

Synthesis of fluorescent ionic liquid-functionalized silicon nanoparticles with tunable amphiphilicity and selective determination of Hg2.

Fluorescent silicon nanoparticles have attracted much attention in recent years due to their superior optical properties, strong photostability, low toxicity, and favorable biocompatibility. In this paper, we have prepared imidazolium ionic liquid-functionalized silicon nanoparticles (IL@SiNPs) via a simple one-pot hydrothermal route from 1-(trimethoxysilyl)propyl-3-methylimidazolium chloride that was denoted as [SmIm]Cl and sodium citrate. The synthetic IL@SiNPs could be a novel label-free sensing probe for sensitive and selective detection of Hg2+ ions with energy transfer from IL@SiNPs to Hg2+. A good linear relationship was obtained from 0 to 40 µmol L-1 with a detection limit of 0.45 µM. Furthermore, the solubility of the IL@SiNPs can be facilely converted by anion exchange without complex chemical modification. The ionic liquid-modified SiNPs may show great promise in biological and environmental applications due to their excellent biocompatibility and optical performance.