Antioxidant activity of different species and varieties of turmeric (Curcuma spp): Isolation of active compounds.

There are >80 species of turmeric (Curcuma spp.) and some species have multiple varieties, for example, Curcuma longa (C. longa) has 70 varieties. They could be different in their chemical properties and biological activities. Therefore, we compared antioxidant activity, total phenolic and flavonoid content of different species and varieties of turmeric namely C. longa [variety: Ryudai gold (RD) and Okinawa ukon], C. xanthorrhiza, C. aromatica, C. amada, and C. zedoaria. The antioxidant activity was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, oxygen radical absorbance capacity (ORAC), reducing power and 2-deoxyribose (2-DR) oxidation assay. Our results suggested that RD contained significantly higher concentrations of total phenolic (157.4 mg gallic acid equivalent/g extract) and flavonoids (1089.5 mg rutin equivalent/g extract). RD also showed significantly higher DPPH radical-scavenging activity (IC50: 26.4 µg/mL), ORAC (14,090 µmol Trolox equivalent/g extract), reducing power absorbance (0.33) and hydroxyl radical scavenging activity (IC50: 7.4 µg/mL). Therefore, RD was chosen for the isolation of antioxidant compounds using silica gel column, Toyopearl HW-40F column, and high-performance liquid chromatography. Structural identification of the compounds was conducted using 1H NMR, 13C NMR, and liquid chromatography-tandem mass spectrometry. The purified antioxidant compounds were bisabolone-9-one (1), 4-methyllene-5-hydroxybisabola-2,10-diene-9-one (2), turmeronol B (3), 5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)-1-hepten-3-one (4), 3-hydroxy-1,7-bis(4-hydroxyphenyl)-6-hepten-1,5-dione (5), cyclobisdemethoxycurcumin (6), bisdemethoxycurcumin (7), demethoxycurcumin (8) and curcumin (9). The IC50 for DPPH radical-scavenging activity were 474, 621, 234, 29, 39, 257, 198, 47 and 18 µM and hydroxyl radical-scavenging activity were 25.1, 24.4, 20.2, 2.1, 5.1, 17.2, 7.2, 3.3 and 1.5 µM for compound 1, 2, 3, 4, 5, 6, 7, 8 and 9, respectively. Our findings suggested that the RD variety of C. longa, developed by the University of the Ryukyus, Okinawa, Japan, is a promising source of natural antioxidants.

Determination of the Marker Diarylheptanoid Phytoestrogens in Curcuma comosa Rhizomes and Selected Herbal Medicinal Products by HPLC-DAD.

A method for quantification of diarylheptanoids in Curcuma comosa rhizomes and selected pharmaceutical preparations was established by using HPLC-diode array detector (DAD). The chromatographic separation of three diarylheptanoids [(3S)-1-(3,4-dihydroxy-phenyl)-7-phenyl-(6E)-6-hepten-3-ol (1), (3R)-1,7-diphenyl-(4E,6E)-4,6-heptadien-3-ol (2), and (3S)-1,7-diphenyl-(6E)-6-hepten-3-ol (3)] was performed on a Luna C18 analytical column using gradient elution with 0.5% acetic acid in water and acetonitrile with a flow rate of 1 mL/min and a column temperature of 35°C. The calibration curves for the analytes showed good linearity (R2>0.999), high precision (relative standard deviation (RSD) <2%) and acceptable recovery (98.35-103.90%, RSD <2%). The limit of detection (LOD) and limit of quantification (LOQ) were 0.06-0.22 and 0.18-0.69 µg/mL, respectively. The results of all validated parameters were within the limits according to the International Conference on Harmonization (ICH) Guidelines. The established method was successfully applied for qualitative and quantitative determination of the three constituents in different samples of C. comosa and some commercial products in capsules. The simplicity, rapidity, and reliability of the method could be useful for the fingerprint analysis and standardization of diarylheptanoids, which are responsible for the estrogenic activity in raw materials and herbal medicinal products of C. comosa.

[Study on diarylheptanoids from green peel of Juglans sigillata].

The chemical constituents from green peel of Juglans sigillata were isolated by column chomatographies over silica gel, Sephadex LH-20, and MCI. Four diarylheptanoids were isolated and their structures were characterized as dihydropterocarine(1), 3',4″-epoxy-1-(4'-hydroxy-phenyl)-7-(3″-methoxyl-phenyl)-heptan-3α-ol(2), pterocarine(3), and 1-(4'-hydroxy-phenyl)-7-(3″-methoxy-4″-hydroxyphenyl)-heptan-3α-ol(4). Compound 1 is a new compound, named as dihydropterocarine. Compounds 2-4 were isolated from the plant of J. sigillata for the first time.

Characterisation of diarylheptanoid- and flavonoid-type phenolics in Corylus avellana L. leaves and bark by HPLC/DAD-ESI/MS.

INTRODUCTION: The leaves of Corylus avellana L. (common hazel, Betulaceae), a plant with a wide distribution in Europe, have been used in folk medicine for various diseases, but phytochemical exploration of C. avellana is still incomplete. To the best of our knowledge there is no previous report concerning diarylheptanoids in C. avellana, although these compounds show a frequent occurrence among Betulaceae plants. OBJECTIVE: To improve existing online chromatographic methods for the investigation of the phenolic compounds in C. avellana leaves and bark, focusing on diarylheptanoid-type molecules. METHODS: Dried and powdered leaves and bark of C. avellana were extracted with increasing polarity solvents (n-hexane, chloroform, ethyl acetate and methanol) in Soxhlet extractor apparatus. For the characterisation of the phenolic compounds in the ethyl acetate and methanolic extracts, UV spectral data, obtained by LC with a diode-array detector (DAD), accurate molecular mass and formula, acquired by LC and electrospray ionisation (ESI) with time-of-flight (TOF) MS and fragmentation pattern, given by LC-ESI/MS/MS analyses were used. Quantitation of the compounds was performed by LC-MS/MS. RESULTS: In the methanolic and ethyl acetate extracts of C. avellana bark four flavonoid glycosides and a caffeoyl hexoside derivative were detected and characterised, while in C. avellana leaves, seven diarylheptanoid-type molecules were tentatively identified in addition to six flavonoid components. As far as we know this is the first study where the presence of diarylheptanoids in C. avellana is reported. CONCLUSION: The improved HPLC/DAD-ESI/MS method was successfully utilised for the characterisation and quantitation of the phenolic compounds in C. avellana bark and leaves extracts.

Separation and identification of diarylheptanoids in supercritical fluid extract of Alpinia officinarum by UPLC-MS-MS.

In the present study, ultra-performance liquid chromatography (UPLC) coupled to electrospray ionization (ESI(+)) tandem mass spectrometry (MS) was developed to identify and characterize the diarylheptanoids in the supercritical fluid extract (SFE) of Alpinia officinarum. The method established provides good reproducibility of UPLC and shows high precision with all the mass accuracy of less than 5 ppm. The ESI-MS-MS fragmentation behavior of every group and their appropriate characteristic pathways were proposed. On the basis of analyzing the fragmentation pathways, elemental composition provided by software Masslynx, mass data of the standard compounds and the information regarding polarity obtained from retention time data, in all, 23 diarylheptanods were characterized. All of them have been reported in Alpinia officinarum. They were classified into six distinct groups (homologous series). Compared to the references, the fragmentation pathways of the first and second group were detailed much more and complementary. Further more, the fragmentation pathways of the last four groups were firstly discussed. The fragmentation rules deduced and the data provided could aid in the characterization of other diarylheptanoids of these types and would be useful for the further research of diarylheptanoids in Alpinia officinarum or the other plants.

Capillary zone electrophoresis for separation and analysis of four diarylheptanoids and an alpha-tetralone derivative in the green walnut husks (Juglans regia L.).

A fast capillary zone electrophoresis (CZE) method for the simultaneous determination of four cyclic diarylheptanoids (rhoiptelol, RH; juglanin A, JA; juglanin B, JB; juglanin C, JC) and an alpha-tetralone derivative (sclerone, SC) in the extract of the green walnut husks (Juglans regia L.) was developed. The optimized buffer was composed of 25 mM sodium tetraborate at pH 10.3. The applied voltage was 20 kV and the capillary temperature was kept constant at 20 degrees C. The detection wavelength was set at 220 nm using a photodiode array detection. The effects of several CE parameters, including pH value, buffer concentration, applied voltage and separation temperature on the separation were investigated systematically. Regression equations showed good linear relationships (correlation coefficients: 0.9996-0.9999) between the peak area of each compound (RH, JA, JB, JC and SC) and its concentration accordingly. The relative standard deviations (R.S.D.) of the migration time and peak area were less than 0.57 and 3.44% (intra-day), and 0.97 and 3.71% (inter-day), respectively. The contents of the five active compounds in the green walnut husks (J. regia L.) from different origins were determined with satisfactory repeatability and recovery.

NMR-based metabolic profiling of Anigozanthos floral nectar.

Nuclear magnetic resonance spectroscopic methods have been used to characterize the chemical composition of floral nectar of Anigozanthos species with a minimum of sample preparation and without derivatization. The nectar of this passerine-pollinated plant is largely dominated by glucose and fructose, while sucrose occurs only at a minor level. Tyrosine, several additional amino acids, and a variety of carboxylic acids were identified and their concentrations estimated. A linear diarylheptanoid was detected as a trace component, marking the first time this type of secondary product in Hemodoraceae has been found.

Characterization and identification of diarylheptanoids in ginger (Zingiber officinale Rosc.) using high-performance liquid chromatography/electrospray ionization mass spectrometry.

In our continuing investigation of diarylheptanoids in Zingiberaceae plants using liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS/MS), 26 diarylheptanoids were identified from fresh ginger rhizome. Of the 26 compounds, 15 diarylheptanoids appear to be new compounds. In addition, the majority of these compounds (18) were acetylated, which is different from our investigation of diarylheptanoids from turmeric, another member of the Zingiberaceae, which did not possess any acetylated diarylheptanoids. In all, five distinct groups (homologous series) of diarylheptanoids were found in extracts from ginger rhizome. These groups were differentiated by structural differences on the heptane skeletons, whereas homologs within each group differed by substitution patterns on the aromatic rings. Diagnostic fragmentation behavior in (+)- and (-)ESI-MS/MS analyses for each group of homologs, as well as information regarding polarity obtained from retention time data, allowed us to classify compounds by group and identify them based on key structural features.