naphthoquinones and isovalerylshikonin

In this study, besides isovaleryl shikonin, another shikonin derivative, tigloylshikonin, was also isolated from the roots of Onosma hookeri Clarke. var. longiforum Duthie as a main naphthoquinone constituent for the first time. Then optimization of the ultrasonic-assisted extraction was done by Box-Behnken design-response surface methodology on the basis of single-factor experiments. The optimized conditions were 72% (v/v) ethanol and the material to solution ratio was 1:37(g/mL) at 52 °C for 77 min. Under these conditions, the extraction yield of ethanol extract was 36.74 ± 0.32%, the contents of isovaleryl shikonin and tigloylshikonin reached 0.094 ± 0.003% and 0.223 ± 0.006%, respectively. Notably, in that optimized condition, the yield of isovaleryl shikonin increased by approximately 7.64-fold than the previous report. In the in vitro antioxidant activity assay, the optimal ethanol extract exhibited similar 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity as butylated hydroxy toluene (BHT), but slightly weaker 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) scavenging activity and total antioxidant capacity than that of BHT. However, the active polar fraction, the ethyl acetate fraction, which is enriched with naphthoquinone constituents, performs as a better antioxidant agent than BHT. Therefore, both of them could be considered as a naturally sourced antioxidants compared to commercially available synthetic drugs. PRACTICAL APPLICATION: Onosma hookeri Clarke. var. longiforum Duthie, a traditional Chinese medicine and food item, has been in use since a long time. A systematic determination of the main naphthoquinones, and antioxidant capacity of the naphthoquinones-enriched ethanol extract and different polar fractions, was carried out in the present study. The results may provide theoretical basis for the claim that naphthoquinones-enriched ethanol extract and ethyl acetate fraction from the roots of Onosma hookeri Clarke. var. longiforum Duthie could be used as potential natural antioxidants in the pharmaceutical, food, and cosmetic industries.

Topics: Antioxidants; Boraginaceae; Free Radical Scavengers; Naphthoquinones; Pentanoic Acids; Plant Extracts; Plant Roots; Ultrasonics

Recycling counter-current chromatography (CCC) has been developed and widely used in preparative separation. Due to increasingly broader peaks with longer elution times, recycling elution must be stopped before a peak overlap occurs, resulting in the insufficient separation of target compounds. In this study, the concept of in situ concentration was proposed, and the corresponding technique was designed to compress the effluents with the reserved separation effect (peak resolution). By combining this technique with multi-stage recycling elution, a novel unlimited recycling CCC (URCCC) strategy was developed to overcome the recycling time limitation to improve the resolution. The URCCC strategy was successfully applied in the preparative separation of naturally occurring naphthaquinones, where the in situ concentration was used two times with three-stage recycling CCC elution. Finally, isobutyrylshikonin (1), β, β-dimethylacrylshikonin (2) and isovalerylshikonin (3) were separated with high resolutions (R

Topics: Biological Products; Countercurrent Distribution; Naphthoquinones; Pentanoic Acids

Topics: Animals; Anti-Bacterial Agents; Boraginaceae; Drug Synergism; Mice; Microbial Sensitivity Tests; Naphthoquinones; Pentanoic Acids; Peritonitis; Sepsis; Staphylococcal Infections; Staphylococcus aureus

In this work, electrogenerated anion and dianion species from shikonin and its ester derivative isovalerylshikonin were characterized by means of ESR/UV-Vis spectroelectrochemistry. Analysis of the spectra supported the proposal that stepwise dissociative electron transfer (DET) takes place during the second reduction process of the esterified compound. Quantum chemical calculations were performed for validating the occurrence of this mechanistic pathway and for obtaining thermodynamic information on the electron transfer process; ΔG(cleavage)(0) was estimated to be -0.45 eV, considering that the two possible products of the overall reaction scheme are both a quinone and carboxylate anions.

Topics: Electrochemical Techniques; Electron Spin Resonance Spectroscopy; Electron Transport; Electrons; Esters; Naphthoquinones; Pentanoic Acids; Quantum Theory; Spectrophotometry, Ultraviolet; Thermodynamics

Topics: Anthraquinones; Drugs, Chinese Herbal; Ions; Naphthoquinones; Pentanoic Acids; Spectrometry, Mass, Electrospray Ionization

A new, fast and sensitive high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) method was developed and validated for isovalerylshikonin in rat plasma using emodin as internal standard (IS). The analyte was extracted from rat plasma with ethyl acetate, after 10% HCl treatment and protein precipitated by methanol. The compound was separated on an Ultimate XB-C(18) analytical column using a mobile phase of methanol-10 mM ammonium acetate in water-acetonitrile containing 0.05% formic acid (45 : 10 : 45, v/v/v) with isogradient elution. The analyte was detected in negative ion mode using multiple-reaction monitoring. The method was validated and the specificity, linearity, lower limit of quantitation (LLOQ), precision, accuracy, recoveries and stability were determined. LLOQ was 9 ng/mL for isovalerylshikonin. Correlation coefficient (r) value for the linear range of the analyte was greater than 0.99. The intra-day and inter-day precision and accuracy were better than 8.52%. The relative and absolute recovery was above 86% and no matrix effects were observed for isovalerylshikonin. This validated method provides a modern, rapid and robust procedure for the pharmacokinetic study of the two compounds in rats after intravenous administration to rats (n = 4).

Topics: Animals; Boraginaceae; Chromatography, High Pressure Liquid; Drug Stability; Drugs, Chinese Herbal; Emodin; Injections, Intravenous; Naphthoquinones; Pentanoic Acids; Plant Roots; Rats; Reproducibility of Results; Sensitivity and Specificity; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry