Kitasetaline, a novel β-carboline alkaloid from Kitasatospora setae NBRC 14216T

With the genetically modified Kitasatospora setae NBRC 14216(T) strain, a new β-carboline alkaloid, kitasetaline (1), was produced on solid medium. The structure was elucidated on the basis of physicochemical evidence. This is the first report of this type of alkaloid found in the genus Kitasatospora.     

Determination of six lignans in Schisandra chinensis (Turcz.) Baill. Fruits and related Chinese multiherb remedies by HPLC

A simple, rapid and specific HPLC method was established for simultaneous determination of six major lignans in Schisandra chinensis and related Chinese multiherb remedies (CMRs) containing this herb. The six lignans were successfully separated on a C₁₈ column by gradient elution using acetonitrile and water as the mobile phase, and detection wavelength was set at 225 nm. The method was validated through the following performance criteria: linearity, precision, repeatability, stability, accuracy, limit of detection (LOD) and quantification (LOQ). This assay was successfully used for determination of six lignans in 10 raw herbs collected from different regions in China and five Chinese multiherb remedies. Significant variations were demonstrated in the contents of six compounds in these samples. This HPLC method established is suitable for routine quantitative analysis of S. chinensis and multiherb remedies containing this herb.     

Preparative separation of gingerols from Zingiber officinale by high-speed counter-current chromatography using stepwise elution

Following an initial clean-up step on silica column, high-speed counter-current chromatography (HSCCC) was used to purify gingerols from an extract of the dried rhizome of Zingiber officinale. The sample was separated with petroleum ether–ethyl acetate–methanol–water (1:0.2:0.5:0.7, v/v) and petroleum ether–ethyl acetate–methanol–water (1:0.2:0.7:0.5, v/v) in a stepwise elution and yielded 132 mg of 6-gingerol, 31 mg of 8-gingerol and 61 mg of 10-gingerol from 360 mg of pre-purified sample. The purity of each compound was over 98% as determined by HPLC. The structures of the three compounds have been identified by LC-ESI-MS, ¹H NMR and ¹³C NMR.     

Separation and quantification of component monosaccharides of the tea polysaccharides from Gynostemma pentaphyllum by HPLC with indirect UV detection

A reversed-phase high-performance liquid chromatographic (HPLC) method is described for the simultaneous determination of aldoses and uronic acids. The separation was carried out on a RP-C₁₈ column (4.6 mm i.d. × 250 mm, 5 μm, Venusil, USA) using precolumn derivatization with 1-phenyl-3-methyl-5-pyrazolone (PMP) and UV detection at 250 nm, and the 10 PMP derivatives of mannose, ribose, rhamnose, glucuronic acid, galacturonic acid, glucose, xylose, galactose, arabinose and fucose were baseline separated within 40 min. Furthermore, the described method was applied to the quantitative analysis of component monosaccharides in the water-soluble polysaccharides extracted from Gynostemma pentaphyllum Makino tea and the result showed that the tea polysaccharide was a typical heteropolysaccharide and consisted of mannose, ribose, rhamnose, glucuronic acid, galacturonic acid, glucose, xylose, galactose and arabinose in the molar contents of 16.3, 10.3, 47.1, 5.6, 24.0, 128.4, 25.0, 101.4 and 71.1 μM, respectively. Quantitative recoveries of the component monosaccharides in the tea polysaccharide were in the range of 94.6–108.0% and the RSD values were lower than 4.9%. The results demonstrated that the proposed HPLC method was precise and practical for the analysis of the G. pentaphyllum tea polysaccharide.     

Application of preparative high-speed counter-current chromatography for separation and purification of lignans from Taraxacum mongolicum

Apart from being used as a pharmaceutical, the inflorescences, leaves and roots of Taraxacum mongolicum are processed into different food products. However, only few phytochemical investigations on this plant have been performed. In the present study, a preparative high-speed counter-current chromatography (HSCCC) for the separation and purification of bioactive compounds from T. mongolicum was developed. Two lignans, mongolicumin A and rufescidride, were obtained. The target compounds were finally isolated and purified with a solvent system composed of ethyl acetate–n-butanol–water (2:5:7, v/v/v). The lower phase was used as the mobile phase in the head to tail elution mode. By injecting 500 mg of the enriched extract of T. mongolicum, one-step HSCCC procedure yielded 36.7 mg of mongolicumin A and 43.9 mg of rufescidride with the purity of 98.7% and 98.5%, respectively, as determined by high-performance liquid chromatography (HPLC). The chemical structures of the two lignans were confirmed by UV, IR, HRESIMS, 1D and 2D NMR. Among them, mongolicumin A is a new compound, and rufescidride was obtained from genus Taraxacum for the first time. Furthermore, lignans were first isolated and identified from genus Taraxacum.     

Chromatographic determination of polysaccharides in Lycium barbarum Linnaeus

Polysaccharides in Lycium barbarum Linnaeus have been shown to be effective in preventing cancer. The objectives of this study were to develop an appropriate method for molecular weight determination of polysaccharides in L. barbarum. The most suitable analytical condition was: a volume-ratio of L. barbarum sample to deionized water at 1:10, followed by shaking in a 100 °C water bath for 30 min, concentrating to 50 mL and adding 250 mL of 95% ethanol for precipitation at −20 °C for 8 h, hydrolysing protein with 2.5 U/mL of proteinase at pH 8 and 60 °C for 4 h and separating polysaccharide into five fractions by high-performance size exclusion chromatography (HPSEC) with the molecular weight of two major fractions being 79,250 and 24,468 Da. Analysis of monosaccharides by gas chromatography (GC) indicated the presence of rhamnose, arabinose, xylose, mannose, glucose and galactose, with the molar ratio at 0.3:2.7:0.3:0.2:2.7:0.9, respectively.     

Determination of the change of flavonoid components as the defence materials of Citrus unshiu Marc. fruit peel against Penicillium digitatum by liquid chromatography coupled with tandem mass spectrometry

A healthy fruit peel of Citrus unshiu Marc. and one infected by Penicillium digitatum were analysed for flavonoids via high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC–MS/MS) in the positive mode with selected ion monitoring (SIM). Among 16 flavonoid components characterised in C. unshiu Marc., four flavanones and nine flavones were identified for the first time. The identified compounds were quantified by HPLC–UV. To investigate the function of the flavonoids as defence materials, the flavonoid content change of the fruit peel inoculated with P. digitatum was monitored by HPLC. The flavonoid concentration in the infected fruit peel decreased initially after the infection and then gradually increased before finally progressively decreasing.     

Thermally-induced geometrical isomerisation of lycopene and its potential influence on functional activity

About 90–98% of native lycopene exists in the all-E form, but 79–88% of the lycopene found in the human body are Z-isomeric forms. Thermally-induced geometrical isomerisation of lycopene occurred within 24 h of refluxing in ethyl acetate and the proportion of Z-isomers increased from 5.8% to 49.9%. Accordingly, the concentration of lycopene required to double quinone reductase (QR) activity in Hepa 1c1c7 cells decreased from >100 to ∼22 μg/mL following thermo-isomerisation, while cell viability was retained at >87% at levels up to 50 μg/mL. The inhibition of nitric oxide (NO) production in activated RAW 264.7 macrophages was 50% at ∼100 μg/mL thermo-isomerised lycopene and increased to >80% when the concentration in the medium was increased to 500 μg/mL. No significant inhibition of NO evolution by macrophages occurred with native (∼94% all-E) lycopene. Both QR induction and NO inhibition bioassays revealed that the structural changes evoked by thermo-isomerisation were accompanied by enhanced biological functionality.     

Fingerprint profile of active components for Artemisia selengensis Turcz by HPLC–PAD combined with chemometrics

An approach was proposed to develop enhanced fingerprint by means of high-performance liquid chromatography (HPLC) with photodiode array detection. The approach was applied to establish enhanced chromatographic fingerprints of various Artemisia selengensis Turcz which is a traditional Chinese medicine (TCM). In comparison with common fingerprint at a fixed wavelength, enhanced fingerprint compiled additional spectral data and was more informative. So it could be used to conduct the quality control of this TCM comprehensively. Thereafter, the chromatographic fingerprint data set was submitted for classification to a suite of chemometrics methods viz. similarity analysis (SA), hierarchical clustering analysis (HCA) and principal component analysis (PCA). Each method highly lighted different properties of the data matrix according to the fingerprints from different types of A. selengensis Turcz. It provided comprehensive information for matching and discrimination of the fingerprints, and appeared to be suited for quality assurance purposes for these similar types of sample.     

Development and validation of an HPLC-FLD method for rapid determination of histamine in skipjack tuna fish (Katsuwonus pelamis)

This study compared and validated two methods of high-performance liquid chromatography: fluorescence detection (HPLC-FLD) and UV–Vis detection. Recoveries greater than 55% at all spiking levels using UV–Vis detection could not be obtained. However, derivatization with pre-column o-phthalaldehyde (OPA) was found to efficiently enhance the method sensitivity. The analytical method was validated based on the following criteria: linearity, sensitivity, accuracy, precision, repeatability, and recovery. For fluorescence detection, excellent linear correlation with R² = 0.9977 was observed over the range of 5.0 to 100.0 mg/L. The minimum detection limit was calculated to be 1.5 mg/kg, while the limit of quantification (LOQ) value of the validated method was determined to be 4.5 mg/kg. Good recoveries (RSD% = 1.35) were obtained at all spiking levels ranging between 0 and 200 mg/kg. The proposed method was found to be suitable, selective, and rapid for the determination of histamine.     

A new liquid–liquid extraction method for determination of 6 azo-dyes in chilli products by high-performance liquid chromatography

A liquid–liquid extraction method was developed for purifying and enriching the sample of 6 azo-dyes (including Para red, Sudan red G, Sudan I, Sudan II, Sudan III and Sudan IV) by formic acid and chloroform. The results indicated that formic acid can facilitate the solution of fat-soluble azo-dyes, which was helpful for the separation of the fat-soluble interferences from the samples. The extracting conditions of 6 azo-dyes were also optimised. And the proposed extraction method was evaluated by the determination of 6 azo-dyes in chilli products. The mean recoveries of 6 azo-dyes were from 94.1% to 99.2% for chilli powder and from 94.2% to 98.6% for chilli spice. The CCα and CCβ obtained for 6 azo-dyes were in the range of 1.7–2.1 and 2.8–3.4 μg/kg for chilli spice and chilli powder. The inexpensive and simple method was acceptable for routine monitoring 6 azo-dyes in chilli products.     

薄层色谱-薄层扫描法测定发酵液中 L-亮氨酸的研究

用层析硅胶G板进行薄层色谱分离发酵液中L-亮氨酸与L-缬氨酸,经茚三酮显色得到完整的L-亮氨酸色斑;用CS-9301薄层扫描仪测定L-亮氨酸色斑峰面积;根据公式C=(Y-97.286)×n/(2559.5×V)计算发酵液L-亮氨酸浓度.结果表明该方法平均回收率为97.3%,重现性试验的变异系数为0.045%,说明本方法的准确性和重现性良好,能满足大批量测定发酵液中L-亮氨酸含量的要求.     

Simple procedure for fatty acid analysis of glycerophospholipids in Escherichia coli and Saccharomyces cerevisiae

Rapid, convenient methods have been developed for fatty acid analysis of membrane glycerophospholipids in microorganisms. Fatty acid methyl esters derived from glycerophospholipids have been prepared directly from wet pellets of Escherichia coli cells or Saccharomyces cerevisiae spheroplasts without lipid extraction and fractionation in high yields under mild temperature conditions for analysis by gas chromatography.     

Chemical composition and in vitro antioxidative activity of a lemon balm (Melissa officinalis L.) extract

The leaf material of lemon balm (Melissa officinalis L.) was extracted with 450 ml/l aqueous ethanol by medium pressure liquid-solid extraction. The total phenolic content of the extract was estimated as gallic acid equivalents by Folin-Ciocalteu reagent method and a qualitative-quantitative compositional analysis was carried out using high performance liquid chromatography coupled with photodiode array detection. The lemon balm extract contained hydroxycinnamic acid derivatives and flavonoids with caffeic acid, m-coumaric acid, eriodictyol-7-O-glucoside, naringin, hesperidin, rosmarinic acid, naringenin, hesperetin being identified based on their chromatographic behaviour and spectral characteristics. The extract was also investigated for potential in vitro antioxidant properties in iron(III) reduction, iron(II) chelation, 1,1-diphenyl-2-picrylhydrazyl, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonate), superoxide anion and nitric oxide free-radical scavenging, and inhibition of β-carotene-linoleic acid bleaching assays. The extract demonstrated antioxidant activity in all the assays. However, it was not as potent as the positive controls except in the β-carotene-linoleic acid bleaching assay, where its activity was superior to that of gallic and caffeic acids and statistically indistinguishable from quercetin and BHA. The exceptionally high antioxidant activity and the fact that this assay is of biological relevance warrants further investigation of lemon balm extract in ex vivo and in vivo models of oxidative stress.     

Phenolic compounds from the edible seeds extract of Chinese Mei (Prunus mume Sieb. et Zucc) and their antimicrobial activity

Prunus mume seeds have been used as a healthy food and traditional drug in China. The present study investigated the phenolic compounds and antimicrobial activity of ethanolic extract from seeds of P. mume. Total phenolic content was determined as gallic acid equivalents by the Folin-Ciocalteu method. The antibacterial activity was measured by a filter paper disc method. Three chlorogenic acid isomers, namely, 3-O-caffeoylquinic acid, 5-O-caffeoylquinic acid and 4-O-caffeoylquinic acid, were identified from P. mume seeds for the first time. The contents of these isolated compounds were quantified by HPLC. Results showed that 3-O-caffeoylquinic acid was of the highest level in these three isomers. The ethanolic extract exhibited inhibition activity against bacteria and fungi obviously. The isolated phenolic compounds also exhibited inhibition activity against bacteria significantly, but showed weak or no inhibition activity against yeasts and mold. The results exhibited that the antimicrobial activity of P. mume seeds may be partly due to the phenolic compounds.     

Effects of physicochemical parameters on the production of phenolic acids from palm oil mill effluent under liquid-state fermentation by Aspergillus niger IBS-103ZA

The present investigation is an effort to develop an environmentally friendly and cost-effective liquid-state fermentation process by introducing a new locally isolated fungal strain of Aspergillus niger (IBS-103ZA) for the production of phenolics from a new source, palm oil mill effluent (POME). Sucrose, manganese sulphate (MnSO₄) and temperature were identified as the most significant variables in improving phenolics production. Optimisation increased the total phenolic content from 856 ± 2.22 to 941 ± 3.72 GAE mg/l at 35.0 °C, 6.0% (w/v) sucrose, 2.7% (w/v) MnSO₄, and with other parameters fixed. The fermented extract (FE) with IC₅₀ value of 0.45 mg/ml showed the strongest antioxidant potency, compared to unfermented extract (UFE), with IC₅₀ of 1.13 mg/ml, and the synthetic antioxidant, BHT, with IC₅₀ of 0.63 mg/ml. The phenolic compounds were identified and quantified by HPLC.     

Characterization and in vitro antioxidation of papain hydrolysate from black-bone silky fowl (Gallus gallus domesticus Brisson) muscle and its fractions

Black-bone silky fowl (Gallus gallus domesticus Brisson) (BSF) muscle was hydrolyzed by papain, and the hydrolysate was separated by preparative high performance liquid chromatography (HPLC). The amino acid composition of the BSF hydrolysate (BSFH) and its fractions was determined by HPLC precolumn derivation with 2,4-dinitrofluorobenzene. The molecular weight (MW) distribution of the BSFH and its fractions was measured by a peptide column on an HPLC system. Antioxidant activities of the BSFH and its fractions were studied by testing the reducing power and four radical scavenging systems: superoxide anion (O₂⁻), hydroxyl (·OH), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS⁺) radicals. The results demonstrated that the BSFH had strong antioxidant capacity to scavenge O₂⁻, DPPH and ABTS⁺, and displayed strong reducing power, but revealed less powerful ability to scavenge ·OH. Fraction II of the BSFH exhibited the highest activity in scavenging O₂⁻ and DPPH, and reducing power, whereas fraction I displayed the strongest ·OH scavenging ability. Besides Glu, Asp and Gly, the rich amino acids of Ala and Leu played an important role in antioxidant activity. The small-size peptides with MW ranging from approximately 200-6000 Da probably contributed to higher antioxidant activity. Results from this study indicated that BSFH and its fractions could be used as food additives and diet nutrients.     

Heat-induced degradation of inulin

Dry heating of inulin from chicory for up to 60 min at temperatures between 135 and 195 °C resulted in a significant degradation of the fructan ranging from 20 to 100%. The choice of the analytical method has a significant influence on inulin quantification especially in heat-treated samples. The amount of inulin found after thermal treatment measured as fructose after acidic hydrolysis was significantly higher compared with corresponding data obtained with a method based on enzymatic hydrolysis. Using high-performance anion-exchange chromatography with pulsed amperometric detection as well as high-performance thin-layer chromatography, it was found that thermal treatment of inulin leads to a degradation of the long fructose chains and formation of new products, most likely di-D-fructose dianhydrides. These degradation products of inulin are cleavable by acid to fructose monomers, but their glycosidic bonds are no longer accessible for -fructosidase, thus explaining the discrepancies in inulin quantification with respect to the method used. Inulin degradation must be taken into account when fructan is used as a prebiotic ingredient in thermally treated foods like bakery products.     

Determination of anthocyanins in four Croatian cultivars of sour cherries (Prunus cerasus)

The anthocyanins were characterised and quantified in four cultivars of sour cherries by means of high-performance liquid chromatography and mass spectrometry. Column chromatography on XAD-2 Amberlite was the method used for isolation of anthocyanins. A diode-array detector was employed. For anthocyanins determination was chosen wavelength of 518 nm. Cyanidin-3-glucosylrutinoside and cyanidin-3-rutinoside were major anthocyanins. The total anthocyanin content in sour cherries, (expressed as cyanidin-3-glucosylrutinoside) varied from 2.7 to 28.0 mg/100 g of fresh weight, with the highest content being observed in Oblainska cultivar.