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

Simultaneous quantification of 4-hydroxytamoxifen and hesperidin in liposomal formulations: Development and validation of a RP-HPLC method

Breast cancer treatment options are diverse, with tamoxifen commonly used as a selective estrogen receptor modulator (SERM) for hormone receptor-positive breast cancer. However, tamoxifen can have adverse systemic effects. Local transdermal therapy offers a potential solution by delivering the drug directly to the breast and minimizing systemic exposure. Hesperidin, a flavonoid, exerts synergistic effects when combined with anticancer agents. This combination therapy may be a more effective approach to breast cancer management. Analytical methods have been developed to quantify 4-Hydroxytamoxifen (4-HT) and hesperidin separately; however, no method currently exists for their simultaneous quantification in pharmaceutical formulations. This study aimed to develop and validate a reverse-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous quantification of 4-HT and hesperidin in liposomal formulations. A Design of Experiments (DoE) approach was employed using a Box-Behnken design (BBD) to optimize the RP-HPLC method. BBD allowed for a reduction in the number of required tests by creating a statistical model to estimate the significance of various factors and interactions. The methanol concentration, flow rate, and injection volume were considered as independent variables for optimization. A mobile phase (90:10 ratio of methanol: 0.1% v/v orthophosphoric acid) with a flow rate of 0.4 mL/min, and an injection volume of 10 μL was selected as optimized chromatographic condition. 4-HT showed a retention time (Rt) of 5.05 min and hesperidin showed an Rt of 7.11 min using an optimized analytical method and was detected at 275 nm. The developed RP-HPLC method was validated according to the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines, confirming its accuracy, precision, linearity, selectivity, and robustness. The validated method was then successfully applied to determine the entrapment efficiency and permeation of 4-HT and hesperidin into loaded liposomes. This study fills a gap in the literature by providing a simple and reliable RP-HPLC method for the simultaneous quantification of 4-HT and hesperidin in liposomal formulations.

The New Insight into the Effects of Different Fixing Technology on Flavor and Bioactivities of Orange Dark Tea

Peach leaf orange dark tea (ODT) is a fruity tea made by removing the pulp from peach leaf orange and placing dry Qingzhuan tea into the husk, followed by fixing them together and drying. Since the quality of traditional outdoor sunlight fixing (SL) is affected by weather instability, this study explored the feasibility of two new fixing methods, including hot air fixing (HA) and steam fixing (ST). Results showed that fixing method had a great impact on ODT shape, aroma, and taste. Compared with SL and ST, HA endowed ODT with higher fruit aroma, mellow taste, better coordination, and higher sensory evaluation score. Physical-chemical composition analysis showed that SL-fixed orange peel was higher than HA- or ST-fixed peel in the content of polyphenols, flavonoids, soluble protein, hesperidin and limonin, while HA has a higher content of volatile substances and contains more alcohols, aldehydes and ketones, and acid and esters than ST and SL. Activity analysis showed that HA was superior to ST or SL in comprehensive antioxidant activity and inhibitory activity against α-glucosidase. Comprehensive results demonstrated that HA has better performance in improving ODT quality and can replace the traditional SL method in production.

Identification and Comparison of Constituents of Aurantii Fructus and Aurantii Fructus Immaturus by UFLC-DAD-Triple TOF-MS/MS

Although Aurantii Fructus (AF) and Aurantii Fructus Immaturus (AFI) are both the fruits of the same rutaceae plant at different stages of growth, they exert similar yet distinct clinical effects. The chemical composition is crucial for quality control as well as therapeutic application. To address this concern, it is significant to evaluate the similarities and differences of the constituents in both AF and AFI. The extract of AF and AFI were comprehensively analyzed by ultra fast liquid chromatography-photodiode array detector-triple-time of flight-tandem mass spectrometry (UFLC-DAD-Triple TOF-MS/MS). Among the 40 compounds detected, 19 metabolites were detected in both the AF and AFI; whereas 13 compounds were only detected in AF and five constituents were exclusively detected in AFI. In particular, even in AFI, three compounds were only identified in AFI (Citrus aurantium' L. and its cultivar). Among the 18 compounds confirmed by standard database, 13 compounds were reported in AF and AFI for the first time. Furthermore, the distinction was also revealed by the content of naringin, hesperidin, neohesperidin, and synephrine. The study directly contributed to the similarities and differences of AF and AFI. Herein, similarities and the differences in chemical profiles of AF and AFI could explain the current clinical applications.

Distinguishing Six Edible Berries Based on Metabolic Pathway and Bioactivity Correlations by Non-targeted Metabolite Profiling

Berries have been used as valuable sources of polyphenols for human health; however, injudicious uses of berries are widespread without regard to the specific metabolite constituent of each berry. We classified 6 different edible berries (honeyberry, blueberry, mandarin melonberry, mulberry, chokeberry, and Korean black raspberry) based on their metabolite distributions in biosynthetic pathways by non-targeted metabolite profiling and bioactive correlation analysis. Principal component analysis revealed a distinct clustering pattern of metabolites for each berry. Metabolic pathway analysis revealed different biosynthetic routes of secondary metabolites in each berry. Mandarin melonberry contains a relatively higher proportion of genistein, genistein glycoside, and genistein-derived isoflavonoids and prenylflavonoids than the other berries. Various anthocyanin glycosides, synthesized from dihydroquercetin and cyanidin, were more abundant in chokeberry and honeyberry, whereas high levels of flavonoid-and anthocyanins-rutinoside forms were observed in Korean black raspberry. The levels of anthocyanins derived from dihydromyricetin were high in blueberry. The highest anti-oxidant activity was observed in chokeberry and Korean black raspberry, which is positively related to the proportional concentration of flavonoids, phenolics, and anthocyanins. The lowest sugar contents were observed in Korean black raspberry, highest acidity in honeyberry, and lowest acidity in mandarin melonberry, which were specific characteristics among the berries. Taken together, biosynthetic pathway and physicochemical characteristics analyses revealed that the different synthesized routes of flavonoids and anthocyanins and associated bio-activities may be distinct features in each berry and explain their phenotypic diversity at the molecular level.

Simultaneous determination of nine bioactive compounds in Yijin-tang via high-performance liquid chromatography and liquid chromatography-electrospray ionization-mass spectrometry

Background

Yijin-tang (YJ) has been used traditionally for the treatment of cardiovascular conditions, nausea, vomiting, gastroduodenal ulcers, and chronic gastritis. In this study, a simple and sensitive high-performance liquid chromatography (HPLC) method was developed for the quantitation of nine bioactive compounds in YJ: homogentisic acid, liquiritin, naringin, hesperidin, neohesperidin, liquiritigenin, glycyrrhizin, 6-gingerol, and pachymic acid.

Methods

Chromatographic separation of the analytes was achieved on an RS Tech C₁₈ column (4.6 mm × 250 mm, 5 μm) using a mobile phase composed of water containing 0.1% (v/v) trifluoroacetic acid (TFA) and acetonitrile with a gradient elution at a flow rate of 1.0 mL/min.

Results

Calibration curves for all analytes showed good linearity (R² ≥ 0.9995). Lower limits of detection and lower limits of quantification were in the ranges of 0.03–0.17 μg/mL and 0.09–0.43 μg/mL, respectively. Relative standard deviations (RSDs; %) for intra- and interday assays were < 3%. The recovery of components ranged from 98.09% to 103.78%, with RSDs (%) values ranging from 0.10% to 2.59%.

Conclusion

This validated HPLC method was applied to qualitative and quantitative analyses of nine bioactive compounds in YJ and fermented YJ, and may be a useful tool for the quality control of YJ.

DIFFERENTIATION OF AURANTII FRUCTUS IMMATURUS AND FRUCTUS PONICIRI TRIFOLIATAE IMMATURUS BY FLOW-INJECTION WITH ULTRAVIOLET SPECTROSCOPIC DETECTION AND PROTON NUCLEAR MAGNETIC RESONANCE USING PARTIAL LEAST-SQUARES DISCRIMINANT ANALYSIS

Two simple fingerprinting methods, flow-injection coupled to ultraviolet spectroscopy and proton nuclear magnetic resonance, were used for discriminating between Aurantii fructus immaturus and Fructus poniciri trifoliatae immaturus. Both methods were combined with partial least-squares discriminant analysis. In the flow-injection method, four data representations were evaluated: total ultraviolet absorbance chromatograms, averaged ultraviolet spectra, absorbance at 193, 205, 225, and 283 nm, and absorbance at 225 and 283 nm. Prediction rates of 100% were achieved for all data representations by partial least-squares discriminant analysis using leave-one-sample-out cross-validation. The prediction rate for the proton nuclear magnetic resonance data by partial least-squares discriminant analysis with leave-one-sample-out cross-validation was also 100%. A new validation set of data was collected by flow-injection with ultraviolet spectroscopic detection two weeks later and predicted by partial least-squares discriminant analysis models constructed by the initial data representations with no parameter changes. The classification rates were 95% with the total ultraviolet absorbance chromatograms datasets and 100% with the other three datasets. Flow-injection with ultraviolet detection and proton nuclear magnetic resonance are simple, high throughput, and low-cost methods for discrimination studies.

Selected activities of Citrus maxima Merr. fruits on human endothelial cells: enhancing cell migration and delaying cellular aging

Endothelial injury and damage as well as accumulated reactive oxygen species (ROS) in aging play a significant role in the development of cardiovascular disease (CVD). Recent studies show an association of high citrus fruit intake with a lower risk of CVD and stroke but the mechanisms involved are not fully understood. This study investigated the effects of pummelo (Citrus maxima Merr. var. Tubtim Siam, CM) fruit extract on human umbilical vein endothelial cell (HUVECs) migration and aging. The freeze-dried powder of fruit extract was characterized for antioxidant capacity (FRAP assay) and certain natural antioxidants, including ascorbic acid, gallic acid, hesperidin, and naringin (HPLC). Short-term (48 h) co-cultivation of HUVECs with CM enhanced cell migration as evaluated by a scratch wound assay and Boyden chamber assay. A long-term treatment with CM for 35 days significantly increased HUVEC proliferation capability as indicated by population doubling level (PDL). CM also delayed the onset of aging phenotype shown by senescence-associated β-galactosidase (SA-β-gal) staining. Furthermore, CM was able to attenuate increased ROS levels in aged cells when determined by 2′,7′-dichlorodihydrofluorescein diacetate (DCDHF) while eNOS mRNA expression was increased but the eNOS protein level was not changed. Thus, further in vivo and clinical studies are warranted to support the use of pummelo as a functional fruit for endothelial health and CVD risk reduction.

Development and Validation of Liquid Chromatographic Method for Estimation of Naringin in Nanoformulation

A simple, precise, accurate, rapid, and sensitive reverse phase high performance liquid chromatography (RP-HPLC) method with UV detection has been developed and validated for quantification of naringin (NAR) in novel pharmaceutical formulation. NAR is a polyphenolic flavonoid present in most of the citrus plants having variety of pharmacological activities. Method optimization was carried out by considering the various parameters such as effect of pH and column. The analyte was separated by employing a C₁₈ (250.0 × 4.6 mm, 5 μm) column at ambient temperature in isocratic conditions using phosphate buffer pH 3.5: acetonitrile (75 : 25% v/v) as mobile phase pumped at a flow rate of 1.0 mL/min. UV detection was carried out at 282 nm. The developed method was validated according to ICH guidelines Q2(R1). The method was found to be precise and accurate on statistical evaluation with a linearity range of 0.1 to 20.0 μg/mL for NAR. The intra- and interday precision studies showed good reproducibility with coefficients of variation (CV) less than 1.0%. The mean recovery of NAR was found to be 99.33 ± 0.16%. The proposed method was found to be highly accurate, sensitive, and robust. The proposed liquid chromatographic method was successfully employed for the routine analysis of said compound in developed novel nanopharmaceuticals. The presence of excipients did not show any interference on the determination of NAR, indicating method specificity.

Pummelo protects Doxorubicin-induced cardiac cell death by reducing oxidative stress, modifying glutathione transferase expression, and preventing cellular senescence

Citrus flavonoids have been shown to reduce cardiovascular disease (CVD) risks prominently due to their antioxidant effects. Here we investigated the protective effect of pummelo (Citrus maxima, CM) fruit juice in rat cardiac H9c2 cells against doxorubicin (DOX-) induced cytotoxicity. Four antioxidant compositions (ascorbic acid, hesperidin, naringin, and gallic acid) were determined by HPLC. CM significantly increased cardiac cell survival from DOX toxicity as evaluated by MTT assay. Reduction of cellular oxidative stress was monitored by the formation of DCF fluorescent product and total glutathione (GSH) levels. The changes in glutathione-S-transferase (GST) activity and expression were determined by enzyme activity assay and Western blot analysis, respectively. Influence of CM on senescence-associated β-galactosidase activity (SA-β-gal) was also determined. The mechanisms of cytoprotection involved reduction of intracellular oxidative stress, maintaining GSH availability, and enhanced GST enzyme activity and expression. DOX-induced cellular senescence was also attenuated by long-term CM treatment. Thus, CM fruit juice can be promoted as functional fruit to protect cells from oxidative cell death, enhance the phase II GSTP enzyme activity, and decrease senescence phenotype population induced by cardiotoxic agent such as DOX.

High-performance liquid chromatography with photodiode array detection for determination of nobiletin content in the brain and serum of mice administrated the natural compound

We recently demonstrated that nobiletin, a citrus flavonoid, exhibits anti-dementia action in animals. However, no determination methods for the content of nobiletin with beneficial action in the brain of nobiletin-administered animals have been developed, nor has its pharmacokinetics been revealed completely. Here, we established the high-performance liquid chromatography/photodiode array detection method for nobiletin determination using Bond Elut C18 SPE cartridges for extraction, where the calibration curve was linear over 0.025-10 ng, with coefficient of variation of less than 6.76%. This method enabled us to determine pharmacokinetic parameters of nobiletin given intraperitoneally or per os in the brain of mice.

Separation of adrenergic amines in Citrus aurantium L. var. amara by capillary electrochromatography using a novel monolithic stationary phase

This manuscript reports on the use of capillary electrochromatography for the determination of tyramine, (±) synephrine, and (±) octopamine, the major alkaloids in bitter orange peel. A novel methacrylate-based monolithic stationary phase was prepared by UV-photopolymerization in 100 μm id fused-silica capillaries. It facilitated the quantitative assessment of alkaloids with a mobile phase comprising aqueous 10 mM ammonium acetate in ACN and isopropanol. Applied voltage and temperature were 25 kV and 25°C, and samples were injected in electrokinetic mode. The method reported herein revealed adequate sensitivity (LOD ≤0.6 μg/mL), repeatability (σrel ≤4.1%), accuracy (recovery rates between 95.2 and 102.2%), and precision (intra-day variation ≤5.7%, inter-day variation ≤4.1%). The application of the CEC assay on C. aurantium var. amara plant material and dietary supplements, which usually are advertised for slimming properties, indicated that synephrine (0.17-0.82%) is the dominant alkaloid.

Simultaneous determination of flavanones, hydroxycinnamic acids and alkaloids in citrus fruits by HPLC-DAD-ESI/MS

A simple and accurate method has been developed to simultaneously separate and determine 10 bioactive compounds in citrus fruits by high-performance liquid chromatography coupled with diode array detection and electrospray ionisation mass spectrometry (HPLC-DAD-ESI/MS). This HPLC assay was performed on a reversed-phase C18 column with acetonitrile and 0.1% (v/v) aqueous formic acid as mobile phase. DAD has been performed at 273, 283 and 324nm for quantification of the alkaloids, flavanones and hydroxycinnamic acids. MS was also employed to identify the each analyte. Ten analytes (naringin, hesperidin, neohesperidin, ferulic acid, p-coumaric acid, chlorogenic acid, caffeic acid, octopamine, synephrine and tyramine) demonstrated good linearity (r⩾0.9990) in a relatively wide concentration range. The method revealed high average recovery (range, 92.1-97.9%) and good precision with interday and intraday variations with less than 4.71%. The limits of detection (LODs) ranged from 0.02 to 0.11μg/ml, while the limits of quantification (LOQs) were defined in the range of 0.08-0.39μg/ml. The proposed method has been successfully applied to analyse three types of bioactive constituents in eight citrus hybrids pulps and eight citrus hybrids peels, which has been successfully cultivated in China.

Natural bioactive compounds of Citrus limon for food and health

Citrus genus is the most important fruit tree crop in the world and lemon is the third most important Citrus species. Several studies highlighted lemon as an important health-promoting fruit rich in phenolic compounds as well as vitamins, minerals, dietary fiber, essential oils and carotenoids. Lemon fruit has a strong commercial value for the fresh products market and food industry. Moreover, lemon productive networks generate high amounts of wastes and by-products that constitute an important source of bioactive compounds with potential for animal feed, manufactured foods, and health care. This review focuses on the phytochemistry and the analytical aspects of lemon compounds as well as on the importance for food industry and the relevance of Citrus limon for nutrition and health, bringing an overview of what is published on the bioactive compounds of this fruit.