A Green Extraction Method to Achieve the Highest Yield of Limonin and Hesperidin from Lime Peel Powder (Citrus aurantifolia)

Green extraction is aimed at reducing energy consumption by using renewable plant sources and environmentally friendly bio-solvents. Lime (Citrus aurantifolia) is a rich source of flavonoids (e.g., hesperidin) and limonoids (e.g., limonin). Manufacturing of lime products (e.g., lime juice) yields a considerable amount of lime peel as food waste that should be comprehensively exploited. The aim of this study was to develop a green and simple extraction method to acquire the highest yield of both limonin and hesperidin from the lime peel. The study method included ethanolic-aqueous extraction and variable factors, i.e., ethanol concentrations, pH values of solvent, and extraction temperature. The response surface methodology was used to optimize extraction conditions. The concentrations of limonin and hesperidin were determined by using UHPLC-MS/MS. Results showed that the yields of limonin and hesperidin significantly depended on ethanol concentrations and extraction temperature, while pH value had the least effect. The optimal extraction condition with the highest amounts of limonin and hesperidin was 80% ethanol at pH 7, 50 °C, which yields 2.072 and 3.353 mg/g of limonin and hesperidin, respectively. This study illustrates a green extraction process using food waste, e.g., lime peel, as an energy-saving source and ethanol as a bio-solvent to achieve the highest amount of double bioactive compounds.

Kirenol, darutoside and hesperidin contribute to the anti-inflammatory and analgesic activities of Siegesbeckia pubescens makino by inhibiting COX-2 expression and inflammatory cell infiltration

ETHNOPHARMACOLOGICAL RELEVANCE

The Chinese traditional medicine of Siegesbeckia pubescens Makino (SM), which has the effect of healing rheumatism and promoting joint health, is often used to treat rheumatoid arthritis and ischemic stroke.

AIM OF THE STUDY

To clarify the mechanisms underlying the anti-inflammatory and analgesic influence of active components in the ethanol extract of Siegesbeckia pubescens Makino (ESM).

MATERIALS AND METHODS

The active ingredients in the ESM were identified practicing high-performance liquid chromatography-diode array detection (HPLC-DAD). Four models including xylene-induced ear oedema, complete Freund's adjuvant (CFA)-induced hind paw oedema, acetic acid-induced pain writhing and lipopolysaccharide (LPS)-induced RAW264.7 cell migration, were used to clarify the anti-inflammatory and analgesic mechanisms of the active ingredients in the ESM.

RESULTS

(1) Three active ingredients of kirenol, darutoside and hesperidin were identified in the ESM, with relative proportion of 0.6%, 0.2% and 0.01%, respectively; hesperidin was reported for the first time in the ESM. (2) Both the ESM and its active ingredients could effectively alleviate the degree of swelling of the auricle and toes, increase the threshold of heat pain, decrease the overexpression of inflammatory protein cyclooxygenase-2 (COX-2) in the skin tissue of the tested parts of the toes, and reduce the number of writhes induced by acetic acid in mice. (3) ESM and its active ingredients also dose-dependently inhibited the migration of RAW264.7 cells.

CONCLUSIONS

ESM and its active ingredients can effectively attenuate the expression of inflammatory factors induced by chemical inflammation, prevent the infiltration of inflammatory cells, and exert good anti-inflammatory and antinociceptive activities.

Green synthesis of hesperidin coated silver nanoparticles for colorimetric detection of gentamicin sulfate in real samples

Gentamicin sulfate (GEN), a well-known broad-spectrum antibiotic is mostly administered through intramuscular injections and entirely excreted in un-metabolized form through urination from patient's body. Quantitative detection of GEN by direct UV absorption is usually challenging due to lack of chromophores and fluorophores in structure. The current study described the hesperidin coated silver nanoparticles (HSPAgNPs) based novel colorimetric quantitative assay for GEN. HSPAgNPs, based colorimetric detection involved a transition from characteristic yellow colour to blackish brown upon addition of GEN, accompanied by a significant quenching in localized surface plasmon resonance (LSPR) band at λ_max 398 nm. Moreover, the synthesized HSPAgNPs were employed to rapid and quantitative detection of GEN in concentration range of 5 to 100 μM. Limit of detection (LOD) and limit of quantification (LOQ) was calculated by standard deviation of the ordinate intercept and slope of the regression line and estimated to be 6.89 μM and 20.88 μM respectively, with a linear correlation factor R² equal to 0.9990 which strictly followed Beer's law. Furthermore, the utility and effectiveness of HSPAgNPs was also explored for selective recognition of GEN in tap water, serum, human blood plasma and urine.

A High-Yield Process for Production of Biosugars and Hesperidin from Mandarin Peel Wastes

In this research, novel biorefinery processes for obtaining value-added chemicals such as biosugar and hesperidin from mandarin peel waste (MPW) are described. Herein, three different treatment methods were comparatively evaluated to obtain high yields of biosugar and hesperidin from MPW. Each method was determined by changes in the order of three processing steps, i.e., oil removal, hesperidin extraction, and enzymatic hydrolysis. The order of the three steps was found to have a significant influence on the production yields. Biosugar and hesperidin production yields were highest with method II, where the processing steps were performed in the following order: oil removal, enzymatic hydrolysis, and hesperidin extraction. The maximum yields obtained with method II were 34.46 g of biosugar and 6.48 g of hesperidin per initial 100 g of dry MPW. Therefore, the methods shown herein are useful for the production of hesperidin and biosugar from MPW. Furthermore, the utilization of MPWs as sources of valuable materials may be of considerable economic benefits and has become increasingly attractive.

The Effects of Different Varieties of Aurantii Fructus Immaturus on the Potential Toxicity of Zhi-Zi-Hou-Po Decoction Based on Spectrum-Toxicity Correlation Analysis

In accordance with the provision in China Pharmacopoeia, Citrus aurantium L. (Sour orange-SZS) and Citrus sinensis Osbeck (Sweet orange-TZS) are all in line with the requirements of Aurantii Fructus Immaturus (ZS). Both kinds of ZS are also marketed in the market. With the frequent occurrence of depression, Zhi-Zi-Hou-Po decoction (ZZHPD) has attracted wide attention. Currently, studies have shown that ZZHPD has a potential toxicity risk, but the effect of two commercial varieties of ZS on ZZHPD has not been reported. In this study, the toxicity differences of ZZHPD prepared by SZS and TZS were revealed through repeated administration experiments in rats. This indicated that different varieties of ZS could affect the toxicity of the prescription. In order to further study the chemical material basis of the toxicity difference, the fingerprints of ZZHPD prepared by different varieties of ZS were established by high-performance liquid chromatography (HPLC). Five different characteristic peaks were screened by non-target chemometrics. They were identified as geniposide, neoeriocitrin, naringin, hesperidin, and neohesperidin using an HPLC-time-of-flight mass spectrometry analyzer (TOF/MS) and an HPLC-triple stage quadrupole mass spectrometry analyzer (QqQ-MS/MS). Combined with a quantitative analysis and previous studies on promoting the intestinal absorption of geniposide, it is speculated that the synergistic effects of the components may be the main reason for the difference of toxicity among the different medicinal materials. This study provides a reference for the clinical, safe use of ZZHPD, and also provides a new perspective for the study of the potential toxic substances of traditional Chinese medicine compound preparations.

Deep eutectic solvent as a green solvent for enhanced extraction of narirutin, naringin, hesperidin and neohesperidin from Aurantii Fructus

INTRODUCTION

In the present study, a green and efficient extraction method using deep eutectic solvents as extraction solvent was developed for extracting the four major active compounds narirutin, naringin, hesperidin and neohesperidin from Aurantii Fructus.

METHODOLOGY

A series of tunable deep eutectic solvents were prepared and investigated by mixing choline chloride or betaine to different hydrogen-bond donors, and betaine/ethanediol was found to be the most suitable extraction solvent. To achieve the best extraction yield, the primary factors affecting the extraction efficiency, such as hydrogen-bond acceptor/hydrogen-bond donor ratio, water content in deep eutectic solvents, extraction temperature, solid/liquid ratio and extraction time, were investigated.

RESULTS

The optimal extraction conditions were 40% of water in betaine/ethanediol (1:4) at 60°C for heated extraction of 30 min and solid/liquid ratio 1:100 g/mL. Under the optimum extraction condition, the extraction yields of narirutin, naringin, hesperidin, and neohesperidin were 8.39 ± 0.61, 83.98 ± 1.92, 3.03 ± 0.35 and 35.94 ± 0.63 mg/g, respectively, which were much higher than those of methanol as extraction solvent (5.5 ± 0.48, 64.23 ± 1.51, 2.16 ± 0.15 and 30.14 ± 0.62 mg/g).

CONCLUSION

The present results showed that deep eutectic solvents could be promising green and efficient solvents for extraction of the bioactive ingredients from traditional Chinese medicine.

Scrophularia lucida L. as a valuable source of bioactive compounds for pharmaceutical applications: In vitro antioxidant, anti-inflammatory, enzyme inhibitory properties, in silico studies, and HPLC profiles

The genus Scrophularia has received much interest with regards to its traditional uses against eczema, psoriasis, and mastitis. Yet, the medicinal properties of some species still need to be scientifically validated. The present study was designed to investigate into the biological properties of various solvent extracts (ethyl acetate, methanol, and aqueous) of the roots and aerial parts of Scrophularia lucida based on its antioxidant, anti-inflammatory, and enzyme inhibitory activities together with phytochemical screening. Our results revealed that the solvent extracts differed in their biological effectiveness. The root ethyl acetate extract showed the highest ABTS scavenging, FRAP, CUPRAC, and inhibitory activity against AChE and α-glucosidase. The ethyl acetate extract of the aerial parts displayed the highest BChE and α-amylase inhibition and antioxidant effect in the phosphomolybdenum assay, while the methanol extracts of both parts were the most effective DPPH• scavengers and tyrosinase inhibitors. The methanol extracts of the root and aerial parts also inhibited NO production in lipopolysaccharide (LPS)-stimulated murine leukemic monocyte-macrophage cell (4.99% and 10.77%, respectively), at 31.25 μg/mL concentration. The highest TPC (34.98 mg GAE/g extract) and TFC (48.33 mg RE/g extract) were observed in the ethyl acetate extract of the root and aerial parts, respectively. The most abundant compounds in the root ethyl acetate extract were luteolin (852 μg/g extract), rosmarinic acid (522 μg/g extract), and hesperidin (394 μg/g extract) while kaempferol was most abundant in the ethyl acetate extract of the aerial parts (628 μg/g extract). In silico experiments were conducted on tyrosinase and the higher docking values were observed for rosmarinic acid and hesperidin. The present findings provide base line information which tend to support the potential use of S. lucida in the management of several chronic diseases, including Alzheimer's disease and diabetes mellitus.

In Silico Docking and In Vitro Approaches towards BACE1 and Cholinesterases Inhibitory Effect of Citrus Flavanones

Alzheimer’s disease (AD) is the most prevalent neurodegenerative disease, distinctively characterized by senile plaques, neurofibrillary tangles, and synaptic loss, finally resulting in neuronal death. β-Site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) and cholinesterases have been identified as therapeutic targets for AD, and the discovery of their inhibitors is of critical importance for developing preventive strategies for AD. To discover natural multi-target compounds possessing BACE1, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibitory properties, major citrus flavanones including hesperetin, naringenin, and hesperidin were evaluated. In vitro anti-AD activities were performed via BACE1 and cholinesterases inhibition assays, as well as enzyme kinetic predictions. For the design of potential inhibitors of AD-related enzymes, molecular docking analysis was performed. Based on the biological evaluation, hesperidin demonstrated the best inhibitory properties toward BACE1, AChE, and BChE, with IC₅₀ values of 10.02 ± 1.12, 22.80 ± 2.78, and 48.09 ± 0.74 µM, respectively. Kinetic studies revealed that all tested compounds were found to be noncompetitive inhibitors against BACE1 and cholineseterases. In addition, molecular docking studies of these compounds demonstrated negative binding energies for BACE1, AChE, and BChE, indicating high affinity and tight binding capacity for the target enzymes. The present study suggested that the selected citrus flavanones could act together as multiple inhibitors of BACE1, AChE, and BChE, indicating preventive and therapeutic potential against AD.

Chemical Evidence for Potent Xanthine Oxidase Inhibitory Activity of Ethyl Acetate Extract of Citrus aurantium L. Dried Immature Fruits

Xanthine oxidase is a key enzyme which can catalyze hypoxanthine and xanthine to uric acid causing hyperuricemia in humans. Xanthine oxidase inhibitory activities of 24 organic extracts of four species belonging to Citrus genus of the family Rutaceae were assayed in vitro. Since the ethyl acetate extract of C. aurantium dried immature fruits showed the highest xanthine oxidase inhibitory activity, chemical evidence for the potent inhibitory activity was clarified on the basis of structure identification of the active constituents. Five flavanones and two polymethoxyflavones were isolated and evaluated for inhibitory activity against xanthine oxidase in vitro. Of the compounds, hesperetin showed more potent inhibitory activity with an IC₅₀ value of 16.48 μM. For the first time, this study provides a rational basis for the use of C. aurantium dried immature fruits against hyperuricemia.

Phytochemical analysis, antimicrobial, antioxidant activities and total phenols of Ferulago carduchorum in two vegetative stages (flower and fruit)

Ferulago carduchorum (Apiaceae family) is an endemic plant of Iran. The crude extract and four fractions of aerial parts of F. carduchorum in two vegetative stages (flower and fruit) were studied for their total phenolic contents, antimicrobial and antioxidant activities using folin-ciocalteu assay, micro dilution method and DPPH assay, respectively. The results indicated that the best antioxidant activity was determined in flower crude extract (IC50=0.44 mg/mL). The flower ethyl acetate fraction (FLE) showed better antimicrobial and antifungal activities than other fractions. So, FLE was selected for phytochemical investigations, resulting in isolation of a flavonoid (hesperetin). Hesperetin showed antimicrobial activity. The results showed that the antimicrobial and antioxidant effects during the flowering are obviously more than the fruit season.

Isolation and identification of chemical constituents from Origanum majorana and investigation of antiproliferative and antioxidant activities

BACKGROUND

Origanum majorana L., belonging to the Lamiaceae family, has great potential and has been used as a folk medicine against asthma, indigestion, headache and rheumatism; in addition, the essential oils of this plant have been used widely in the food industry. Plant materials have been harvested from the Medicinal and Aromatic Plant Field of Gaziosmanpasa University. Air-dried plant materials were boiled in water, filtered, and the solvent part subsequently extracted with hexane and ethyl acetate. The chromatographic method was applied to the ethyl acetate extract to isolate bioactive secondary metabolites, the structures of which were elucidated by spectroscopic techniques: basically one-dimensional and two-dimensional nuclear magnetic resonance and quadrupole time-of-flight liquid chromatography. Antiproliferative and antioxidant activities of isolated secondary metabolites were determined.

RESULTS

5,6,3'-Trihydroxy-7,8,4'-trimethoxyflavone, hesperetin, hydroquinone, arbutin and rosmarinic acid were isolated from the water-soluble ethyl acetate extract of aerial parts of O. majorana. Antioxidant activities of isolated compounds and water-soluble ethyl acetate extract were investigated using assays of DPPH(•), ABTS(•+), reducing power and total phenolic content. Antiproliferative activities of the isolated compounds and plant extracts were investigated against C6 and HeLa cell lines using BrdU cell proliferation enzyme-linked immunosorbent assay and xCELLigence assay, respectively. Both hesperetin and hydroquinone were determined to have stronger antiproliferative activities against C6 and HeLa cells than the other isolated compounds and 5-fluorouracil.

CONCLUSION

The results showed that the extract and isolated compounds exhibited significant antioxidant activities. Hence this plant has the potential to be a natural antioxidant in the food industry and an anticancer drug.

Comparison of Ensemble Strategies in Online NIR for Monitoring the Extraction Process of Pericarpium Citri Reticulatae Based on Different Variable Selections

Different ensemble strategies were compared in online near-infrared models for monitoring active pharmaceutical ingredients of Traditional Chinese Medicine. Bagging partial least square regression and boosting partial least square regression were adopted to near-infrared models, to determine hesperidin and nobiletin content during the extraction process of Pericarpium Citri Reticulatae in a pilot scale system. Different pretreatment methods were investigated, including Savitzky-Golay smoothing, derivatives, multiplicative scatter correction, standard normal variate, normalize, and combinations of them. Two different variable selection methods, including synergy interval partial least squares and backward interval partial least squares algorithms, were performed. Based on the result of the synergy interval partial least squares algorithm, bagging partial least square regression and boosting partial least square regression were adopted into the quantitative analysis. The results demonstrated that the established approach could be applied for rapid determination and real-time monitoring of hesperidin and nobiletin in Pericarpium Citri Reticulatae (Citrus reticulata) during the extraction process. Comparing the results, the boosting partial least square regression provided a slightly better accuracy than the bagging partial least square regression. Finally, this paper provides a promising ensemble strategy on online near-infrared models in Chinese medicine.

Development of new reference material neohesperidin for quality control of dietary supplements

BACKGROUND

Neohesperidin is an important natural flavanone glycoside distributed in several citrus species. This compound is widely used as a raw material for food additives in the food industry. The request for certified reference materials (CRMs) in dietary supplements was stipulated by the National Administrative Committee for CRMs and was underpinned by the need to improve the accuracy and comparability of measurement data and to establish metrological traceability of analytical results.

RESULTS

This paper reports the sample preparation methodology, homogeneity and stability studies, value assignment and uncertainty estimation of a new certified reference material of neohesperidin (GBW09522). Differential scanning calorimetry, coulometric titration and mass balance methods proved to be sufficiently reliable and accurate for certification purposes. The certified value of neohesperidin CRM is 994 g kg(-1) with an expanded uncertainty of 4 g kg(-1) (k = 2). The reference material described above was homogeneous and stable for 12 months at a storage temperature of 25 °C.

CONCLUSION

The new CRM of neohesperidin can be used to validate analytical methods and improve the accuracy of measurement data as well as quality control of neohesperidin-related dietary supplements, foods, traditional herbs and pharmaceutical formulations.

In situ detection and identification of hesperidin crystals in satsuma mandarin (Citrus unshiu) peel cells

INTRODUCTION

Hesperidin, a flavonoid known to have important pharmacological effects, accumulates particularly in the peels of satsuma mandarin (Citrus unshiu). Although histochemical studies have suggested that hesperidin forms crystals in some tissues of the Rutaceae and Umbelliferae, there has been no rigorous in situ detection or identification of hesperidin crystals in C. unshiu.

OBJECTIVE

To characterise the chemical component of the crystals found in C. unshiu peels using Raman microscopy.

METHODS

Sections of C. unshiu peels were made. The distribution and morphology of crystals in the sections were analysed microscopically. Raman microscopy was used to detect hesperidin in the sections directly.

RESULTS

The crystals were more abundant in immature peel and were observed particularly in areas surrounding vascular bundles, around the border between the flavedo and albedo layers and just below the epidermal cells. In the morphological analysis by scanning electron microscopy, needle-shaped crystals aggregated and formed clusters of spherical crystals. Spectra obtained by Raman microscopy of the crystals in the peel sections were consistent with those of the hesperidin standard.

CONCLUSION

This study showed the detailed distribution of crystals in C. unshiu peels and their main component was identified using Raman microscopy to be hesperidin for the first time.

Bioassay guided fractionation and identification of active anti-inflammatory constituent from Delonix elata flowers using RAW 264.7 cells

CONTEXT

Delonix elata (L.) Gamble (Fabaceae) has been used in the Indian traditional medicine system to treat rheumatism and inflammation.

AIM

To assess the anti-inflammatory effect of Delonix elata flowers and to isolate the active principle.

MATERIALS AND METHODS

The prompt anti-inflammatory constituent was isolated from Delonix elata flower extracts using bioassay guided fractionation in liposaccharide (LPS) stimulated RAW 264.7 macrophage cell line. The anti-inflammatory activity of extracts/fractions/sub-fractions/compounds (10, 25, and 50 µg/ml) was evaluated by estimating the levels of nitric oxide (NO), TNF-α, and IL-1β after 24 h of LPS induction (1 μg/ml). The isolated active compound was subjected to NMR, IR, and UV analyses for structure determination.

RESULTS

In an attempt to search for anti-inflammatory constituents, the active pure principle was isolated and crystallized as a white compound from Delonix elata flowers methanol extract. This active compound (50 µg/ml) decreased the release of inflammatory mediators levels such as NO (0.263 ± 0.03 µM), TNFα (160.20 ± 17.57 pg/ml), and IL-1β (285.79 ± 15.16 pg/ml) significantly (p < 0.05); when compared to the levels of NO (0.774 ± 0.08 µM), TNFα (501.71 ± 25.14 pg/ml), and IL-1β (712.68 ± 52.25 pg/ml) from LPS-stimulated macrophage cells. The active compound was confirmed as hesperidin with NMR, IR, and UV spectroscopy data. This is the first report of this compound from Delonix elata flowers.

CONCLUSION

The findings of the study support the traditional use of Delonix elata flowers to treat inflammation.

Effect of hesperidin and neohesperidin from bittersweet orange (Citrus aurantium var. bigaradia) peel on indomethacin-induced peptic ulcers in rats

Hesperidin and neohesperidin are the major flavanones isolated from bittersweet orange. It was recently reported that they have potent anti-inflammatory effects in various inflammatory models. In the present study, the effects of hesperidin and neohesperidin on indomethacin-induced ulcers in rats and the underlying mechanisms were investigated. Gastric ulcers were induced in rats with a single dose of indomethacin. The effects of pretreatment with hesperidin and neohesperidin were assessed in comparison with omeprazole as reference standard. Ulcer index, gene expression of gastric cyclooxygenase-2 (COX-2), tumor necrosis factor alpha (TNF-α), lipid peroxidation product, malondialdhyde (MDA), and reduced glutathione (GSH) content in stomach were measured. Furthermore, gross and histopathological examination was performed. Our results indicated that both hesperidin and neohesperidin significantly aggravated gastric damage caused by indomethacin administration as evidenced by increased ulcer index and histopathological changes of stomach.

UPLC-MS-ELSD-PDA as a powerful dereplication tool to facilitate compound identification from small-molecule natural product libraries

The generation of natural product libraries containing column fractions, each with only a few small molecules, using a high-throughput, automated fractionation system, has made it possible to implement an improved dereplication strategy for selection and prioritization of leads in a natural product discovery program. Analysis of databased UPLC-MS-ELSD-PDA information of three leads from a biological screen employing the ependymoma cell line EphB2-EPD generated details on the possible structures of active compounds present. The procedure allows the rapid identification of known compounds and guides the isolation of unknown compounds of interest. Three previously known flavanone-type compounds, homoeriodictyol (1), hesperetin (2), and sterubin (3), were identified in a selected fraction derived from the leaves of Eriodictyon angustifolium. The lignan compound deoxypodophyllotoxin (8) was confirmed to be an active constituent in two lead fractions derived from the bark and leaves of Thuja occidentalis. In addition, two new but inactive labdane-type diterpenoids with an uncommon triol side chain were also identified as coexisting with deoxypodophyllotoxin in a lead fraction from the bark of T. occidentalis. Both diterpenoids were isolated in acetylated form, and their structures were determined as 14S,15-diacetoxy-13R-hydroxylabd-8(17)-en-19-oic acid (9) and 14R,15-diacetoxy-13S-hydroxylabd-8(17)-en-19-oic acid (10), respectively, by spectroscopic data interpretation and X-ray crystallography. This work demonstrates that a UPLC-MS-ELSD-PDA database produced during fractionation may be used as a powerful dereplication tool to facilitate compound identification from chromatographically tractable small-molecule natural product libraries.

Isolation of xanthone and benzophenone derivatives from Cyclopia genistoides (L.) Vent. (honeybush) and their pro-apoptotic activity on synoviocytes from patients with rheumatoid arthritis

A fast and efficient method for the isolation of the C-glucosidated xanthones mangiferin and isomangiferin from the South-African plant Cyclopia genistoides was developed for the first time. The procedure involved extraction, liquid-liquid partitioning with ethyl acetate and subsequent precipitation of mangiferin and isomangiferin from methanol and acetonitrile-water fractions, respectively. Additionally, two benzophenone derivatives: 3-C-β-glucosides of maclurin and iriflophenone, were isolated from C. genistoides extracts using semi-preparative HPLC. Apart from the above, the isolation procedure also yielded hesperidin and small amounts of luteolin. The structures of the compounds were determined by 1D and 2D NMR experiments and/or LC-DAD-ESI-MS. The selected Cyclopia constituents were screened for pro-apoptotic activity on TNF-α-stimulated synovial cells isolated from rheumatoid arthritis patients. The strongest effect, measured as percent of apoptotic cells, was recorded for isomangiferin (75%), followed by iriflophenone 3-C-β-glucoside (71%), hesperidin (67%) and mangiferin (65%). The results are encouraging for further studies on the use of the above compounds in the treatment of rheumatoid arthritis.

Identification of flavonoids with trypsin inhibitory activity extracted from orange peel and green tea leaves

BACKGROUND

Orange peel (Citrus sinensis) and green tea (Camellia sinensis) leaves, rich sources of food flavonoids, were analyzed for their trypsin inhibitory potential. Hesperetin, rutin and hesperidin from orange peel, and catechin from green tea leaves, were isolated and their chemical structures were analyzed. All four compounds were evaluated for their trypsin inhibitory potential.

RESULTS

Among all the isolated compounds, rutin exhibited the highest protease inhibition activity (75.4 ± 0.9%) with IC50 = 16 ± 2 µmol L(-1), followed by catechin (65.3 ± 1.4%; IC50 = 83 ± 9 µmol L(-1)), hesperetin (62.1 ± 1.3%; IC50 = 104 ± 12 µmol L(-1)) and hesperidin (59.7 ± 1.1%; IC50 = 127 ± 14 µmol L(-1)). Lineweaver-Burk and Dixon plots and their secondary replots indicated that all four compounds possessed non-competitive inhibition. The Ki values of hesperetin, rutin, hesperidin and catechin were calculated as 90.2 ± 1.1, 17.5 ± 0.6, 84.2 ± 1.5 and 65.1 ± 1.5 µmol L(-1) respectively.

CONCLUSION

The present results suggest that the four isolated flavonoids can be used as a supplement in food for the treatment of pathologies associated with the degradation of a specific protein.

[A novel C27-steroidal glycoside sulfate from Liriope graminifolia]

An unusual novel C27-steroidal glycoside sulfate was isolated from the underground organs of Liriope graminifolia (Linn.) Baker with three known compounds. Their chemical structures were determined by spectral analysis, including HR-MS, 1D and 2D NMR as (25S)-ruscogenin 1-sulfate-3-O-alpha-L-rhamnopyranoside (1), (25S)-ruscogenin 1-O-beta-D-xylopyranosyl-3-O-alpha-L-rhamnopyranoside (2), hesperidin (3), and 4', 7-dihydroxy-5-methoxyflavanone (4). Compound 1 has cytotoxic activities against K562 and HL60 cells with IC50 values of 18.6 microg x mL(-1) and 16.5 microg x mL(-1), respectively.

[Studies on the chemical constituents of Codonopsis pilosula]

OBJECTIVE

To study the chemical constituents of Codonopsis pilosula.

METHODS

The compounds were isolated and purified by column chromatography and their structures were elucidated through spectroscopic techniques (NMR) and physicochemical properties.

RESULTS

The compounds were isolated as hesperidin(I), n-hexyl beta-sophoroside(II), atractylenolide III (III), lobetyolin(IV), lobetyolinin(V), taraxerol(VI), taraxeryl acetate(VII), alpha-spinasterol(VIII),9,10,13-trihydroxy-(E)-11-octadecenoic acid (IX),beta-sitosterol(X),beta-daucosterol(XI)and sugar(XII).

CONCLUSION

Compounds 1 -2 and 9 are isolated from this plant for the first time.

Antioxidant capacity of hesperidin from citrus peel using electron spin resonance and cytotoxic activity against human carcinoma cell lines

CONTEXT

Hesperidin is a flavonoid that has various pharmacological activities including anti-inflammatory, antimicrobial and antiviral activities.

OBJECTIVE

The aim of the study is the isolation of hesperidin from the peel of Citrus sinensis L. (Rutaceae), and the evaluation of its antioxidant capacity and cytotoxicity against different human carcinoma cell lines.

MATERIALS AND METHODS

In the present work, hesperidin is identified and confirmed using chromatographic and spectral analysis. To correlate between hesperidin concentration and antioxidant capacity of peel extracts, extraction was carried out using 1% HCl-MeOH, MeOH, alkaline solution, the concentration of hesperidin determined qualitatively and quantitatively using high performance thin layer chromatography (HPTLC), high performance liquid chromatography (HPLC) analysis, in vitro antioxidant capacity of hesperidin and the extracts against free radical diphenylpicrylhydrazyl (DPPH•) performed using an electron spin resonance spectrophotometer (ESR). Cytotoxic assay against larynx, cervix, breast and liver carcinoma cell lines was performed.

RESULTS

Hesperidin was found to be moderately active as an antioxidant agent; its capacity reached 36%. In addition, the results revealed that hesperidin exhibited pronounced anticancer activity against the selected cell lines. IC₅₀ were 1.67, 3.33, 4.17, 4.58 µg/mL, respectively.

DISCUSSION AND CONCLUSION

Orange peels are considered to be a cheap source for hesperidin which may be used in the pharmaceutical industry as a natural chemopreventive agent. Hesperidin and orange peel extract could possess antioxidant properties with a wide range of therapeutic applications.

[Determination of liquiritin, naringin, hesperidin and glycyrrhizic acid in extractive of Wendan formula by RP-HPLC]

OBJECTIVE

To develop a RP-HPLC method for simultaneous determination of liquiritin, naringin, hesperidin and glycyrrhizic acid in extraction of Wendan formula.

METHOD

DIKMA Diamonsil(2)-C18 column (4.6 mm x 250 mm, 5 microm) was used at 25 degrees C with the mobile phase of acetonitrile-0.1% phosphatic acid in a gradient manner. The flow rate was set at 1.0 mL min(-1). The detection wavelength was 237, 283 nm.

RESULT

The linear responses ranged from 0.0199-0.1191 microg for liquiritin (r = 0.9997, n = 6), 0.1800-1.0800 microg for naringin (r = 0.9997, n = 5), 0.1455-0.8730 microg for hesperidin (r = 0.9998, n = 6), 0.0393-0.2355 microg for monoammonium glycyrrhizinate (r = 0.9997, n = 6), respectively. The average recoveries were 97.7% with RSD 1.5% for liquiritin, 97.7% with RSD 2.0% for naringin, 97.1% with RSD 2.0% for hesperidin and 98.5% with RSD 1.9% for glycyrrhizic acid, respectively.

CONCLUSION

The method is quick, simple and repeatable for simultaneous determination of liquiritin, naringin, hesperidin and glycyrrhizic acid in extraction of Wendan formula.

[Study on the contents of flavonoids in Citrus reticulata 'Chachi' from various habitats and different collecting periods]

OBJECTIVE

To determine the contents of hesperidin, nobiletin and tangeretin in Citrus reticulata 'Chachi' from various habitats and different collecting periods (from October to December) and study the dynamic change of three flavonoids constituents.

METHODS

The HPLC method was used for analysis the contents of flavonoids in Citrus reticulata 'Chachi'. The system used a Diamonsil C18 column (250 mm x 4.6 mm, 5 microm) with gradient mobile phase of acetonitrile-methanol (80:20)-2% acetic acid. The monitoring wavelength was at 283 nm and 330 nm and the column temperature was at 25 degrees C with the flow rate of 1.0 ml/min.

RESULTS

The contents of hesperidin, nobiletin and tangeretin in Citrus reticulata 'Chachi' collecting from various habitats descended gradually with the mature of fruit, especially in nobiletin and tangeretin.

CONCLUSION

The method was simple, convenient and can be used to provide some foundation for the quality control of Citrus reticulata 'Chachi'.

[Study on the flavonoids constituents of Trachelospermum jasminoides]

OBJECTIVE

To study the flavonoids constituents of Trachelospemum jasminoides.

METHODS

The compounds were separated and purified by column chromatography with silica gel, and identified by IR, MS, NMR and 2D-NMR.

RESULTS

Six flavonoids were identified as apigenin (I), apigenin 7-O-beta-glucoside (II), apigenin 7-O-beta-neospheroside (III), luteoloside (IV), narngin (V) 6,8-di-C-glucopyanosylapigenin (VI), respectively.

CONCLUSION

Compounds V and VI are isolated from this plant for the first time.

[Study on the optimal extraction process of chaihushugan powder]

OBJECTIVE

To study the optimal extraction process of chaihushugan powder by orthogonal design.

METHODS

RP-HPLC method was developed for the determination of saikosaponin a, ferulic acid, hesperidin and paeoniflorin in chaihushugan powder. The contents of the components and the extraction yield were selected as assessment indices. Four factors were study by L9 (3(4)), including the alcohol concentration, amount of alcohol, duration of extraction and times of extraction.

RESULTS

The optimal extracting condition was 80% alcohol consumed as 10 times of crude herb amount, and extracting two times for 90 min each time.

CONCLUSION

This study supplies theoretical base for the development of chaihushugan powder formulation.

Statin-like principles of bergamot fruit (Citrus bergamia): isolation of 3-hydroxymethylglutaryl flavonoid glycosides

The 3-hydroxy-3-methylglutaryl neohesperidosides of hesperetin (brutieridin, 1) and naringenin (melitidin, 2) were isolated and detected from the fruits of bergamot (Citrus bergamia). The structures of these compounds were determined by spectroscopic and chemical methods.

[Anti-inflammatory effects and quantitative study of the combinations of active ingredients of Painong powder in mice]

OBJECTIVE

To study the anti-inflammatory effects of the combinations of active components of Painong powder, a compound traditional Chinese herbal medicine, and the quantitative analysis of their interactions.

METHODS

The mouse model of acute inflammation with increase of capillary permeability was induced by intraperitoneal injection of acetic acid. An orthogonal design with 2 levels (used and unused) was applied to assign the combinations groups of active ingredients including naringin and neohesperidin, peoniflorin, and platycodin. Aspirin and normal saline were administered as control. The pharmacodynamic interactions were analyzed by the optical density (OD) of infiltrated Evans blue.

RESULTS

The different combinations of active ingredients showed anti-inflammatory effect with different degree, and the predicted values of OD varied from 0.115 to 0.170. The maximum anti-inflammatory effect was from the combination of naringin, neohesperidin, paeoniflorin and platycodin, better than that of the saline group (P < 0.01). However, there was no significant difference as compared with the aspirin group (P > 0.05). Paeoniflorin showed a dominant contribution to the formula, and platycodin the least. The combination of all active components exhibited synergism.

CONCLUSION

The results suggest that all the ingredients are efficacious constituents of the formula, and paeoniflorin shows a dominant contribution to the formula. More information about prescription compatibility can be obtained by the orthogonal simulation method.

Hesperidin from Citrus sinensis cultivated in Dezful, Iran

This study described procedures for extracting and quantitation of hesperidin in the waste orange peel of Dezful. Two extracting procedure were used. In procedure A hesperidin was isolated from orange peel by extracting the dry peel first with petroleum ether, removing the essential oil and then with methanol. In procedure B alkaline extraction followed by acidification of the extract was used. It was purified by treatment with formamide-activated charcoal. Detailed analysis of UV, IR, 1HNMR, 13CNMR and Mass spectroscopic data confirm the structure and extent of purity of extracted hesperidin. The spectroscopic results of two extract showed that procedure A produced high extraction yield and more purified hesperidin. Pure hesperidin in gram quantity (11.7% for procedure A and 7.39% for procedure B) was obtained in one purification cycle.

HPLC separation of naringin, neohesperidin and their C-2 epimers in commercial samples and herbal medicines

Flavanone glycosides, such as naringin and neohesperidin, are distributed in some Citrus species and have a chiral center in the C-2 position of the flavanone moiety. Naringin and neohesperidin (2S-form) were separated from the corresponding C-2 epimers (2R-epi-form) by normal-phase HPLC using a polysaccaride-derived chiral stationary phases (CSPs), CHIRALPAK IB. The analyses of commercial samples of naringin revealed that the relative ratios of naringin to the C-2 epimer were 29-89%. In the case of a commercial sample of neohesperidin, the relative ratio of the neohesperidin (2S-form) is 84%. The HPLC application to Citrus species used as crude drugs in Japan (Kijitsu, Kikoku and Tohi) showed that the relative ratios of naringin to the C-2 epimer were 75-93% in Kijitsu, 74-79% in Kikoku and 54-64% in Tohi. However, there is a quite small ratio of the (2R)-epi-neohesperidin in Citrus. This result suggested that the averages of relative ratio of (2S)-naringin in Citrus species reduced according to the maturity of fruits (Kijitsu<Kikoku<Tohi). Since the relative ratios of (2S)-naringin of dry extracts of 5 Kampo formulations (including Kijitsu or Kikoku) decreased to 42-54%, the conversion from naringin to the (2R)-epimer might be enhanced during the decoction process of the formulations.

Ultrasound-assisted extraction of hesperidin from Penggan (Citrus reticulata) peel

Hesperidin, an abundant and inexpensive bioflavonoid in Penggan (Citrus reticulata) peel, has been reported to possess a wide range of pharmacological properties. Ultrasonic extraction is an effective technique for the isolation of bioactive compounds from vegetable materials. In this study, the application of ultrasonic method was shown to be more efficient in extracting hesperidin from Penggan (C. reticulata) peel than the classical method. The effects of main ultrasonic-assisted extraction conditions on extraction yields of hesperidin from Penggan (C. reticulata) peel were evaluated, including extraction solvents, solvent volume, temperature, extraction time, ultrasonic power, ultrasonic frequency. Results showed that solvent, frequency and processing temperature were the most important factors for improving the extracting yields of hesperidin. When performed at the same temperature under the same time using three frequencies, methanol as the solvent improved the extraction yield evidently compared with ethanol or isopropanol; by comparison of the frequency influence, the yield of hesperidin was higher at 60 kHz than at 20 kHz and 100 kHz. The optimum ultrasonic conditions were determined as: methanol, frequency of 60 kHz, extraction time of 60 min, and temperature of 40 degrees C. In addition, the ultrasonic power had a weak effect on the yields of hesperidin within the experimental range. Extending ultrasonic treatment times did not result in degradation of hesperidin; the rotary beaker for materials can increase the yields of hesperidin.

[Study on chemical constituents of Portulaca oleracea]

OBJECTIVE

To investigate chemical constituents of Portulaca oleracea.

METHODS

The constituents were isolated by various column chromatography methods, and their structures were elucidated by spectral analysis.

RESULTS

Five compounds were isolated from 70% ethanol extract and their structures were elucidated as oleracein A(1), oleracein B(2), oleracein E(3), hesperidin (4) and caffeic acid (5).

CONCLUSION

Compound 4 and 5 are isolated from Portulaca oleracea for the first time.

Simultaneous determination of flavonoid and alkaloid compounds in Citrus herbs by high-performance liquid chromatography-photodiode array detection-electrospray mass spectrometry

The major active biological constituents in Citrus herbs are flavonoids, especially hesperidin, naringin and alkaloids, mainly synephrine, with beneficial medical effects on human health. They are used as the markers to control the quality of Citrus herbs. In this paper, a new ion pairing chromatographic method was developed to exclude the most polar solute (synephrine) from the viod volume and to maintain selectivity between the two other solutes (hesperidin and naringin). Perfluorinated carboxylic acids, which are appropriate for MS detection due to their volatility, were used as ion-pairing agents. The problems of the synephrine separation, such as band tailing and low retention, were solved successfully by using perfluorinated carboxylic acids. The effect of heptafluorobutyric acid (HFBA) was the best in the three investigated perfluorinated carboxylic acids. For the flavanone glycosides, the influence of the perfluorinated acids on retention time was rather weak. The two different kinds of the analytes were separated satisfactorily in one run using an isocratic eluent and the total analysis time takes less than 10 min. The abundance of pseudomolecular ions was recorded using selected ion monitoring (SIM) mode of m/z 135.1, 273.1 and 303.1 for synephrine, naringin and hesperidin, respectively. The contents of hesperidin, naringin and synephrine in several Citrus herbs were simultaneously determined by the proposed method.

[Microwave-assisted extraction of Hesperidin from pericarpium citri reticulate]

Microwave-assisted extraction (MAE) method was studied for the extraction of Hesperidin from the pericarpium citri reticulate. Several factors, such as the concentration of extraction solvent, MAE time, MAE temperature, microwave power and liquid/ solid ratios were investigated, and the optimal conditions were obtained. The extraction percentage of hesperidiin was obtained by 2.40%, under 14 minutes extraction in 70% methanol water solvent at 65 degrees C , and the liquid/solid ratios of 25:1 (ml/g). Furthermore, compared with the other extraction methods, the MAE was more timesaving and effective. The result indicated that the MAE method is fast, efficient and energy saving, which is useful for active compounds extraction from orange peel.

Tyrosinase inhibitory effects and inhibition mechanisms of nobiletin and hesperidin from citrus peel crude extracts

The inhibitory effects of nobiletin and hesperidin from citrus peel crude extracts on tyrosinase diphenolase activity have been evaluated. IC50 of nobiletin and hesperidin were 1.49 mM and 16.08 mM, respectively and their inhibition mechanisms are competitive type with inhibition constant (Ki) 2.82 mM and noncompetitive type with Ki 9.16 mM, respectively. Crude extracts from citrus peel (C. unshiu Marc.) were extracted with 95% ethanol and fractionated by petroleum ether (PCPE). The ethanol phase (ECPE) was further desorbed from macroporous adsorption resin (FGRE). Their IC50 values were 8.09 mg/mL, 7.53 mg/mL and 4.80 mg/mL, respectively. Their inhibition of melanogenesis in B16 mouse melanoma cells was also evaluated. FGRE showed a significant inhibition (42.48% at 31.25 microg/mL, p < 0.01) while hesperidin showed almost no inhibition. Nobiletin and PCPE gave efficacious antiproliferation effects on the B16 mouse melanoma cell with IC50 values 88.6 microM and 62.96 microg/mL, respectively, through the MTT test. Hesperidin and other crude extracts showed very low cytotoxity to the B16 cell.

Tyrosinase inhibitory effects and inhibition mechanisms of nobiletin and hesperidin from citrus peel crude extracts

The inhibitory effects of nobiletin and hesperidin from citrus peel crude extracts on tyrosinase diphenolase activity are evaluated. IC50 of nobiletin and hesperidin is 1.49 mM and 16.08mM, respectively and their inhibition mechanism is competitive type with Ki = 2.82 mM and noncompetitive with Ki = 9.16 mM, respectively. Crude extracts from citrus peel (C. unshiu Marc.) were extracted with 95% ethanol and fractionated by petroleum ether (PCPE). The ethanol phase (ECPE) was further desorbed from macroporous adsorption resin (FGRE). Their IC50 values were 8.09 mg/mL, 7.53 mg/mL and 4.80 mg/mL, respectively. Their inhibition on melanogenesis in B16 mouse melanoma cells was also evaluated. FGRE showed a significant inhibition (42.5% at 31.25 microg/mL, p < 0.01) while hesperidin showed almost no inhibition. Nobiletin and PCPE give efficacious antiproliferation effects on B16 mouse melanoma cell with IC50 values 88.6 microM and 62.96 microg/mL, respectively, by the MTT test. Hesperidin and other crude extracts showed very low cytotoxity to the B16 cell.

Determination of liquiritin, naringin, hesperidin, thymol, imperatorin, honokiol, isoimperatorin, and magnolol in the traditional Chinese medicinal preparation Huoxiang-zhengqi liquid using high-performance liquid chromatography

High-performance liquid chromatography was employed to determine the contents of the eight marker components liquiritin, naringin, hesperidin, thymol, imperatorin, honokiol, isoimperatorin, and magnolol in the traditional Chinese medicinal preparation Huoxiang-zhengqi liquid. The separation was performed on a C(18) column by stepwise gradient elution with water-methanol-acetonitrile (0.01 min, 68:30:2; 20 min, 60:38:2; 50 min, 34:64:2; 65 min, 34:64:2; 75 min, 28:70:2; 85 min, 68:30:2) as the mobile phase at a flow rate of 1 ml/min, with UV detection at 283 nm. Eight regression equations showed good linear relationships between the peak area ratio of each marker to internal standard and amounts. The recoveries of the markers listed above were 97.4, 98.5, 97.4, 98.6, 97.8, 99.2, 97.0, and 97.5%, respectively. The repeatability and reproducibility (relative standard deviation) of the method were less than 2.2 and 3.0%, respectively.

Enantioseparation of some chiral flavanones using microbial cyclic beta-(1-->3),(1-->6)-glucans as novel chiral additives in capillary electrophoresis

Cyclic beta-(1-->3),(1-->6)-glucans, microbial cyclooligosaccharides produced by Bradyrhizobium japonicum USDA 110, were used as novel chiral additives for the enantiomeric separation of some flavanones such as eriodictyol, homoeriodictyol, hesperetin, naringenin, and isosakuranetin in capillary electrophoresis (CE). Among the flavanones, eriodictyol was separated with the highest resolution (R(s) 5.66) and selectivity factor (alpha 1.18) when 20mM cyclic beta-(1-->3),(1-->6)-glucans were added to the background electrolyte (BGE) at pH 8.3.

Antiradical and anti-H2O2 properties of polyphenolic compounds from an aqueous peppermint extract

Polyphenolic compounds such as eriocitrin, luteolin-7-O-rutinoside, diosmin, hesperidin, narirutin, isorhoifolin, rosmarinic and caffeic acids were identified in an aqueous extract (Ex) obtained from peppermint leaves (Menthae x piperitae folium). The content of polyphenols in Ex was as follows: eriocitrin 38%, luteolin-7-O-rutinoside 3.5%, hesperidin 2.9%, diosmin 0.8%, isorhoifolin 0.6%, narirutin 0.3%, rosmarinic acid 3.7% and caffeic acid 0.05%. The strongest antiradical activity (determined as DPPH* scavenging features) was observed for luteolin-7-O-rutinoside, eriocitrin and rosmarinic acid. Caffeic acid and hesperidin revealed a lower antiradical activity while isorhoifolin, narirutin and diosmin showed the lowest activity. The strongest anti-H2O2 activity was observed for eriocitrin, a little lower for rosmarinic acid. The rate of hydrogen peroxide scavenging activity displayed by luteolin-7-O-rutinoside and caffeic acid was lower than that of rosmarinic acids. Hesperidin appeared to be a very weak scavenger of hydrogen peroxide. Almost no anti-H2O2 activity was demonstrated for diosmin, narirutin and isorhoifolin. Among examined flavonoids, the strongest antiradical and anti-H2O2 activity was shown for compounds with two hydroxy groups bound to the Bring in ortho position in relation to each other. Replacement of one hydroxy group in the Bring with a methoxy group or removing one hydroxy group leads to decrease of antiradical and anti-H2O2 activity of flavonoids. Our results suggest that eriocitrin is a powerful peppermint antioxidant and a free radical scavenger.

Separation of some chiral flavonoids by microbial cyclosophoraoses and their sulfated derivatives in micellar electrokinetic chromatography

Neutral cyclosophoraoses (Cys) and highly sulfated cyclosophoraoses (HS-Cys) were successfully applied as chiral selectors with SDS for the separation of some chiral flavonoids in MEKC. HS-Cys were synthesized by the chemical modification of a family of neutral Cys isolated from a soil microorganism, Rhizobium meliloti 2011. Chiral catechin was separated with a resolution (R(s)) of 0.754 by neutral Cys and SDS. In the case of isosakuranetin and neohesperidin, resolution (R(s)) values of 1.483 and 1.306 were obtained with HS-Cys and SDS, respectively.

Analysis of flavanone-7-O-glycosides in citrus juices by short-end capillary electrochromatography

The separation of the major flavanone-7-O-glycoside constituents of Citrus was carried out by isocratic reversed phase capillary electrochromatography using a 75 microm i.d. silica fused column packed with 5 microm ODS silica gel. In comparison to HPLC mode, capillary electrochromatography resolution of flavanone glycosides was obtained with a high selectivity factor. Optimum separation conditions were found using a mixture of ammonium formate (pH 2.5)--acetonitrile (8:2, v/v) as the mobile phase by the short-end injection mode. Under these conditions all the investigated flavanones were baseline-resolved within short analysis time (i.e. between 5 and 10 min). A study, evaluating the intra- and inter-day repeatability as well as limit of detection and method linearity, was developed in accordance with the analytical procedures for method validation. The developed method was applied for the quantitative analysis of flavanone glycosides in commercial fruit juices (sweet orange, lemon and grapefruit).

HPLC separation of hesperidin and the C-2 epimer in commercial hesperidin samples and herbal medicines

Hesperidin (2S-form), the flavanone 7-O-glycoside, is the main constituent of some Citrus species. The peels of two Citrus species are used as a crude drug, Aurantii nobilis pericarpium, in the Japanese Pharmacopoeia and as components in Kampo formulae. Thus, HPLC analysis of hesperidin as a marker compound is needed for quality control of medicines. Hesperidin was separated from the corresponding C-2 epimer by normal-phase HPLC using a chiral column. Moreover, narirutin and neohesperidin were also separated from the corresponding C-2 epimer. The analyses of commercial hesperidin samples revealed that they contained the C-2 epimer and that the relative ratio of hesperidin to the epimer ranged from 92:8 to 59:41. The HPLC application to Citrus extracts suggested that naturally occurring hesperidin in Citrus has the 2S configuration; however, the dry extracts of rikkunshito and chotosan, which are Kampo formulations containing Aurantii nobilis pericarpium, were found to contain a considerable amount of the (2R)-epimer. These data suggest that the decoction process of the formulae partly converts hesperidin to the epimer. Because diastereomers differ from each other in physicochemical and biological activities, HPLC to separate hesperidin from the C-2 epimer should be introduced into the letter of approval for herbal medicines.

A validated solid-phase extraction HPLC method for the simultaneous determination of the citrus flavanone aglycones hesperetin and naringenin in urine

A simple, specific, precise, accurate, and robust HPLC assay for the simultaneous analysis of hesperetin and naringenin in human urine was developed and validated. Urine samples were incubated with beta-glucuronidase/sulphatase and the analytes were isolated by solid-phase extraction using C18 cartridges and separated on a C8 reversed phase column using a mixture of methanol/water/acetic acid (40:58:2, v/v/v) at 45 degrees C. The method was found to be linear in the 50-1200 ng/ml concentration range for both hesperetin and naringenin (r > 0.999). The accuracy of the method was greater than 94.8%, while the intra- and inter-day precision for hesperetin was better than 4.9 and 8.2%, respectively and for naringenin was better than 5.3 and 7.8%, respectively. Recovery for hesperetin, naringenin and internal standard 7-ethoxycoumarin was greater than 70.9%. The method has been applied for the determination of hesperetin and naringenin in urine samples obtained from a male volunteer following a single 300 mg oral dose of each of the corresponding flavanone glycosides hesperidin and naringin. The intra- and inter-day reproducibility through enzyme hydrolysis was less than 3.9% for both total (free + conjugated) hesperetin and naringenin. Stability studies showed urine quality control samples to be stable for both hesperetin and naringenin through three freeze-thaw cycles and at room temperature for 24 h (error < or = 3.6%).

Antiallergic Activity of Hesperidin Is Activated by Intestinal Microflora

When hesperidin isolated from pericarpium of Citrus unshiu (family Rutaceae) was incubated with human intestinal microflora, its main metabolite was hesperetin, which was a main metabolite in urine of orally hesperidin-administered rats. The antiallergic activity of hesperidin and its metabolite hesperetin were investigated. Hesperidin did not inhibit the histamine release from RBL-2H3 cells induced by IgE. However, its metabolite hesperetin potently inhibited the histamine release from RBL-2H3 cells induced by IgE and the PCA reaction. The inhibitory activity of hesperetin was found to be comparable with azelastine, a commercially available antiallergic drug, and to potently inhibit prostaglandin E2 production in lipopolysaccharide-stimulated RAW 264.7 cells. Hesperetin weakly inhibits cyclooxygenase 2 enzyme activities. These results suggest that hesperidin may be a prodrug, which is metabolized to hesperetin by intestinal bacteria.

[Studies on chemical constitutents in roots of Jasminum sambac]

OBJECTIVE

To isolate and identify the chemical constitutents in roots of Jasminum sambac.

METHOD

The compounds were isolated by means of chromatography and the structures were identified on the basis of physical and spectral data.

RESULT

Dotriacontanoic acid, dotriacontanol, oleanolic acid, daucosterol and hesperidin were elucidated.

CONCLUSION

All compounds were found in this plant for the first time.

Polyacylated neohesperidosides from Geranium caespitosum: bacterial multidrug resistance pump inhibitors

Bioassay-directed fractionation for Staphylococcus aureus multidrug resistance efflux pump inhibitors resulted in isolation of novel acylated neohesperidosides from Geranium caespitosum. The more highly acylated compounds had no direct activity against S. aureus, but potentiated activity of the antibiotics berberine, rhein, ciprofloxacin and norfloxacin. Cellular concentrations of berberine were greatly increased in the presence of active esters.

[Prediction of eluotropic sequence of solutes in countercurrent chromatography]

According to the retention equation of countercurrent chromatography (CCC), the eluotropic sequence of solutes depends mainly on the order of their partition coefficients between the two immiscible liquid phases. The varying tendencies of partition coefficients of some compounds in aqueous or non-aqueous solvent systems by calculating the phase equilibria with universal quasichemical functional group activity coefficient (UNIFAC) (Dortmund) model are predicted. These compounds included saturated and unsaturated fatty acids ethyl esters, N-2,4-dinitrophenylamino alcohols, p-nitrophenyl glucosides and so on, with simple structures and much differences in polarity. It has been found that the predicted tendencies of partition coefficients of the analogues were consistent with the experimental ones reported in literature, and the best results were obtained for saturated fatty acid ethyl esters in hexane-acetonitrile (1:1 in volume ratio) solvent system. The establishment of a method for prediction will be helpful for the selection of non-electrolyte solvent systems in CCC.

[Studies on chemical constituents from the flower of Citrus aurantium]

The chemical constituents from the flower of Citrus aurantium were studied. 11 compounds were isolated and identified including neohesperidin(I), synephrin(II), 5,8-epidioxyergosta-6,22-dien-3 beta-ol(III), adenosine(IV), asparagine(V), tyrosine(VI), valine(VII), isoleucine(VIII), alanine(IX),beta-sitosterol(X) and beta-daucosterol(XI).