Improved LC methods for the determination of diosmin and/or hesperidin in plant extracts and pharmaceutical formulations

Pedoclimatic Conditions Influence the Morphological, Phytochemical and Biological Features of Mentha pulegium L

In this study, Mentha pulegium leaves and flowers harvested in three different Sicilian areas were investigated from a micromorphological, phytochemical and biological point of view. Light and scanning electron microscopy showed the presence of spherocrystalline masses of diosmin both in the leaf epidermal cells and in thin flower petals. Two different chemotypes were identified (I, kaempferide/rosmarinic acid; II, jaceidin isomer A). Phytochemical screening identified plant from collection site II as the richest in total phenolics (16.74 g GAE/100 g DE) and that from collection site I as the richest in flavonoids (46.56 g RE/100 g DE). Seventy-seven metabolites were identified both in flower and leaf extracts. Plant from site II showed the best antioxidant (0.90-83.72 µg/mL) and anti-inflammatory (27.44-196.31 µg/mL) activity expressed as half-maximal inhibitory concentration (IC₅₀) evaluated by DPPH, TEAC, FRAP, ORAC, BSA denaturation and protease inhibition assays. These data were also corroborated by in vitro cell-based assays on lymphocytes and erythrocytes. Moreover, plant of site II showed the best antiangiogenic properties (IC₅₀ 33.43-33.60 µg/mL) in vivo on a chick chorioallantoic membrane. In conclusion, pedoclimatic conditions influence the chemotype and the biological activity of M. pulegium, with chemotype I showing the most promising biological properties.

Quantitative Determination of Diosmin in Tablets by Infrared and Raman Spectroscopy

Diosmin is widely used in the treatment of chronic venous diseases and hemorrhoids. Based on Raman and infrared reflection spectra of powdered tablets in the mid- and near-infrared regions and results of reference high-performance liquid chromatographic analysis, partial least squares models that enable fast and reliable quantification of the studied active ingredient in tablets, without the need for extraction, were elaborated. Eight commercial preparations containing diosmin in the 66-92% (w/w) range were analyzed. In order to assess and compare the quality of the developed chemometric models, the relative standard errors of prediction for calibration and validation sets were calculated. We found these errors to be in the 1.0-2.4% range for the three spectroscopic techniques used. Diosmin content in the analyzed preparations was obtained with recoveries in the 99.5-100.5% range.

Citrus flavonoids as potential therapeutic agents: A review

The plants Rutaceae family are known to have contributed a lot toward food and medicine. The most important metabolites of the family are flavonoids. A systematic review was conducted to collect chemical and pharmacological information of flavonoids isolated from family Rutaceae till 2018. A plethora of flavonoids have been isolated and studied systematically for various bioactivities, including anticancer, antibacterial, antiviral, analgesic, antioxidant, antidiabetic, antiinflammatory, in bronchitis, ulcers, and so on. The important groups of flavonoids isolated are naringin, poncirin, rhoifolin, marmesin, hesperidin, tangeretin, nobiletin, glychalcone, glyflavanone, lemairone, acacetin 3,6-di-C-glucoside, vicenin-2, lucenin-2 4'-methyl ether, narirutin 4'-O-glucoside, apigenin 8-C-neohesperidoside, phloretin 3',5'-di-C-glucoside, rutin, rhamnetin, dihydrokaempferol, dihydrokaempferol 3-O-rhamnoside (engeletin) and kaempferol, excavaside A and B, myricetin 3-O-β-D-rutinoside, myricetin 3,3'-di-α-l-rhamnopyranoside, myricetin 3'-α-l-rhamnopyranoside, and others. The flavonoids isolated from the citrus family need to be considered from a nutraceutical, therapeutic, and pharmaceutical point of view for future medicine.

A Sustainable Reversed-Phase HPTLC Method for the Quantitative Estimation of Hesperidin in Traditional and Ultrasound-Assisted Extracts of Different Varieties of Citrus Fruit Peels and Commercial Tablets

Hesperidin (HSP) is a bioactive flavanone glycoside, present abundantly in the variety of citrus fruits. The environmental safety and sustainability of the reported analytical assays of HSP analysis have not been considered in the literature. Hence, a sensitive and sustainable “reversed-phase high-performance thin-layer chromatography (RP-HPTLC)” method has been developed and validated for HSP analysis in traditional (TE) and ultrasound-based (UBE) extracts of four different varieties of citrus fruit peels and its commercial tablet dosage forms. The binary combination of green solvents such as ethanol-water (50:50, v v−1) was used as the mobile phase. The detection of HSP was performed at 287 nm. The sustainable RP-HPTLC method was linear in 20–2000 ng band−1 range. The studied validation parameters, including accuracy, precision, robustness, sensitivity were acceptable for HSP analysis. The content of HSP in TE of four different varieties of citrus fruits including grapefruit peels (Citrus paradisi), mosambi peels (Citrus limetta), lemon peels (Citrus lemon), and orange peels (Citrus sinensis) was detected as 8.26, 6.94, 5.90, and 6.81% w w−1, respectively. The content of HSP in TE of commercial formulations A and B was detected as 5.31 and 5.55% w w−1, respectively. However, the content of HSP in UBE of grapefruit peels, mosambi peels, lemon peels, and orange peels was detected as 11.41, 8.86, 7.98, and 8.64% w w−1, respectively. The content of HSP in UBE of commercial formulations A and B was detected as 6.72 and 6.92% w w−1, respectively. The greenness score of the sustainable RP-HPTLC method was predicted as 0.83 using analytical GREEnness (AGREE) metric approach, indicated the excellent greenness profile of the RP-HPTLC method. UBE procedure for HSP was superior over its TE procedure. These observations and results suggested that the present RP-HPTLC method can be successfully used for the quantitative estimation of HSP in the variety of citrus fruit peels and its commercial formulations. In addition, this method is simple, rapid, precise, accurate, and economical compared to the reported analytical methods of HSP analysis. It is also safe and sustainable method due to the use of ethanol-water solvents systems, as both the solvents are green solvents compared to the solvents used in reported analytical methods of HSP analysis.

Determination of Diosmin in Pharmaceutical Products with Chemically Modified Voltammetric Sensors

In this paper, the electrochemical behavior of two types of sensors based on modified screen-printed electrodes (one screen-printed electrode based on carbon (SPCE) and another screen-printed electrode modified with Prussian Blue (PB/SPCE)) was studied with the aim of sensitive detection of diosmin, an active pharmaceutical compound from the class of flavonoids. The scan electron microscopy technique was used for the morphological characterization of PB/SPCE. The preliminary analysis assessed the electrochemical behavior of SPCE and PB/SPCE in KCl solution and in a double solution of potassium ferrocyanide-potassium chloride. It was shown that the active area of PB/SPCE is superior to the one of SPCE, the greater sensitivity being related with the presence of the electroactive modifier. Similarly, in the case of diosmin detection, the PB/SPCE sensor detect more sensitivity the diosmin due to the electrocatalytic effect of PB. From the study of the influence of reaction rate on the sensor's electrochemical response, it was shown that the detection process is controlled by the adsorption process, the degree of surface coverage with electroactive molecules being higher in the case of PB/SPCE. From the PB/SPCE calibration curve, it wasdetermined that it has high sensitivity and low detection and quantification limit values (limit of detection 5.22 × 10^-8 M). The applicability of the PB/SPCE sensor was confirmed by sensitive analysis of diosmin in pharmaceutical products. The voltammetric method is suitable for the detection and quantification of diosmin in pharmaceutical products. The method is simple, accurate, and quick and can be used in routine analysis in the examination of the quality of pharmaceutical products and other types of samples.

Lagenaria siceraria and it's bioactive constituents in carbonic anhydrase inhibition: A bioactivity guided LC-MS/MS approach

INTRODUCTION

Lagenaria siceraria, is a popular food plant among Indians, contains a large number of phenolic compounds with several medicinal benefits, mentioned in Indian System of Medicine (ISM).

OBJECTIVES

To investigate the carbonic anhydrase inhibitory potential and inhibitory mechanism of the most potent fraction of L. siceraria fruits.

MATERIALS AND METHODS

The extract and fraction of dried fruit of L. siceraria screened for their in vitro carbonic anhydrase II (bCA II) inhibitory activity. The active fraction was purified by using flash chromatography. The bioactive compounds were identified and quantified through liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC-QTOF-MS/MS) and reverse-phase high-performance liquid chromatography (RP-HPLC). Finally, the underlying carbonic anhydrase inhibitory mechanism of the compounds was explained by enzyme kinetics and molecular docking study.

RESULTS

The LC-QTOF-MS based identification of the most active fraction revealed the presence of phenolic compounds. The results of the enzyme inhibition assay revealed that coniferyl alcohol, ferulic acid and p-Coumaric acid inhibited bCA II activity [half maximal inhibitory concentration (IC₅₀ ) value range of 80 to 250 μM) in a dose dependent manner. The kinetics study of enzyme inhibition revealed that p-Coumaric acid binds to the enzyme competitively whereas the non-competitive type of inhibition was observed for ferulic acid and coniferyl alcohol. The molecular docking study explored the interaction mechanism of phenolic compounds at the active site of bCA II.

CONCLUSION

The present research led us to conclude that, the phenolic compounds from L. siceraria serve as major contributors for carbonic anhydrase inhibition, which could play a useful role in the management of oedema, hypertension, obesity and related metabolic disorders.

Downregulation of MMP1 expression mediates the anti-aging activity of Citrus sinensis peel extract nanoformulation in UV induced photoaging in mice

Aging of the skin is a complicated bioprocess that is affected by constant exposure to ultraviolet irradiation. The application of herbal-based anti-aging creams is still the best choice for treatment. In the present study, Citrus sinensis L. fruit peels ethanolic extract (CSPE) was formulated into lipid nanoparticles (LNPs) anti-aging cream. Eight different formulations of CSEP-LNPs were prepared and optimized using 2³ full factorial designs. In vivo antiaging effect of the best formula was tested in Swiss albino mice where photo-aging was induced by exposure to UV radiation. HPLC-QToF-MS/MS metabolic profiling of CSPE led to the identification of twenty-nine metabolites. CSPE was standardized to a hesperidin content of 15.53 ± 0.152 mg% using RP-HPLC. It was suggested that the optimized formulation (F7) had (245 nm) particle size, (91.065%) EE, and (91.385%) occlusive effect with a spherical and smooth surface. The visible appearance of UV-induced photoaging in mice was significantly improved after topical application on CSPE-NLC cream for 5 weeks, levels of collagen and SOD were significantly increased in CSPE- NLC group, while levels of PGE2, COX2, JNK, MDA, and elastin was reduced. Finally, The prepared anti-aging CSPE-NLC cream represents a safe, convenient, and promising skincare cosmetic product.

A Green RP-HPTLC-Densitometry Method for the Determination of Diosmin in Pharmaceutical Formulations

Green analytical technologies for the determination of a bioactive compound diosmin (DIOM) in the real samples of pharmaceutical formulations and biological fluids are scarce in literature. Therefore, the present investigation was carried out to develop a novel, rapid, simple, and economical green “reversed phase high-performance thin-layer chromatography (RP-HPTLC)” method for the determination of DIOM in commercial tablets and in-house developed spray-dried microparticles (MPs). The quantification of DIOM was conducted via “RP-18 silica gel 60 F254S HPTLC plates”. The binary combination of green solvents, i.e., ethanol:water (5.5:4.5 v/v) was proposed as a green mobile phase. The analysis of DIOM was conducted in absorbance/reflectance mode of densitometry at λmax = 348 nm. The densitograms of DIOM from the commercial tablets and in-house developed spray-dried MPs were verified by recording their single band at Rf = 0.80 ± 0.02 compared to standard DIOM. Green RP-HPTLC method was observed as linear in the range of 100–700 ng/band with R2 = 0.9995. The proposed method was found as “accurate, precise, robust, and sensitive” for the determination of DIOM in the real samples of commercial tablets and in-house developed spray-dried MPs. The % content of DIOM in the real samples of commercial tablets and in-house developed spray-dried MPs was obtained as 99.06 and 101.30%, respectively. The recorded results of this research suggested that the green RP-HPTLC method can be effectively used for the routine analysis of DIOM in pharmaceutical products.

In-silico Designing, ADMET Analysis, Synthesis and Biological Evaluation of Novel Derivatives of Diosmin Against Urease Protein and Helicobacter pylori Bacterium

BACKGROUND

Designing drug candidates against the urease enzyme, which has been found responsible for many pathological disorders in human beings as well as in animals, was done by insilico means.

METHODS

Studies were carried out on a designed library of diosmin derivatives with the help of Schrodinger's maestro package of molecular docking software against a crystallographic complex of plant enzyme Jack bean urease (PDB ID: 3LA4). Best twelve derivatives of diosmin were selected for synthesis by considering their interaction energy along with docking score and were further investigated for antioxidant, urease inhibitory and Anti-H. pylori activity by in- vitro method along with ADMET analysis.

RESULTS

In-vitro results of series concluded compounds D2a, D2d and D7 (IC50 12.6 ± 0.002, 14.14 ± 0.001 and 15.64 ± 0.012 µM respectively in urease inhibition and 5.195 ± 0.036, 5.39 ± 0.020 and 5.64± 0.005 µM in antioxidant behavior against DPPH) were found to be significantly potent with excellent docking score -11.721, -10.795, -10.188 and binding energy -62.674, -63.352, -56.267 kJ/ mol as compared to standard drugs thiourea and acetohydroxamic acid (-3.459, -3.049 and -21.156 kJ/mol and - 17.454 kJ/mol) whereas compounds D2b, D5b, D5d and D6 were found moderate in urease inhibitory activity.

CONCLUSION

Selected candidates from the outcome of in-vitro urease inhibitory were further examined for anti- H. pylori activity by a well diffusion method against H. pylori bacterium (DSM 4867). Compound D2a showed good anti-H. Pylori activity with a zone of inhibition 10.00 ± 0.00 mm and MIC value 500µg/mL as compared to standard drug acetohydroxamic acid having a zone of inhibition 9.00 ± 0.50mm and MIC 1000µg/mL. In- silico studies played an important role in designing the potent ligands against urease protein as well as in explaining the binding pattern of designed and synthesized ligand within the active pocket of jack bean urease protein. ADMET studies were also carried out to check the drug similarity of designed compounds by the means of quikprop module of molecular docking software. Hence, the present investigation studies will provide a new vision for the discovery of potent agents against H. pylori and urease associated diseases.

Diosmin induces caspase-dependent apoptosis in human glioblastoma cells

Diosmin is a flavone glycoside clinically used as the main component of Daflon for the treatment of venous diseases. Several studies demonstrated that this natural compound can induce apoptosis in different tumors. However, isolated diosmin has not been studied regarding its effects on glioblastoma so far. Since glioblastoma is a highly lethal and fast-growing brain tumor, new therapeutic strategies are urgently needed. Herein, we evaluated the role of this flavonoid against glioblastoma cells using in vitro assays. Diosmin significantly reduced the viability of GBM95, GBM02, and U87MG glioblastoma cells, but not of healthy human astrocytes, as verified by MTT assay. Vimentin immunostaining showed that diosmin induced morphological changes in GBM95 and GBM02 cells, making them smaller and more polygonal. Diosmin did not inhibit GBM95 and GBM02 cell proliferation, but it caused DNA fragmentation, as verified by the TUNEL assay, and increased cleaved caspase-3 expression in these cells. In summary, diosmin is able to induce caspase-dependent apoptosis specifically in tumor cells and, therefore, could be considered a promising therapeutic compound against glioblastoma.

Diosmin reduces chronic constriction injury-induced neuropathic pain in mice

Injury or dysfunction of somatosensory system induces a complex syndrome called neuropathic pain, which still needs adequate pharmacological control. The current pharmacological treatments were in part developed from natural compounds. Flavonoids are natural polyphenolic molecules presenting varied biological activities and low toxicity. The flavonoid diosmin is a safe compound with good tolerability and low toxicity. This study evaluated the antinociceptive effect of diosmin in the sciatic nerve chronic constriction injury (CCI)-induced neuropathic pain model. Male Swiss mice were submitted to CCI and 7 days after, diosmin at 1 or 10 mg/kg was administrated intraperitoneally. Mechanical (electronic analgesimeter) and thermal (hot plate) hyperalgesia were evaluated 1-24 h after treatment. The role of the NO/cGMP/PKG/KATP channel signaling pathway in the analgesic effect of diosmin was evaluated using the pretreatment with L-NAME (an inhibitor of NOS), ODQ (an inhibitor of soluble guanylate cyclase), KT5823 (an inhibitor of PKG), or glibenclamide (an ATP-sensitive K+ channels blocker). Single treatment with diosmin inhibited in a dose-dependent manner CCI-induced mechanical and thermal hyperalgesia by activating the NO/cGMP/PKG/KATP channel signaling pathway and inhibiting spinal cord cytokine (Il-1β and Il-33/St2) and glial cells activation (microglia - Iba-1, oligodendrocytes - Olig2) mRNA expression markers. Daily treatment during 7 days with diosmin inhibited CCI-induced mechanical and thermal hyperalgesia by inhibiting spinal cord cytokine (Il-1β, Tnfα, and Il-33/St2) and glial cells activation (astrocytes - Gfap, Iba-1, and Olig2) markers mRNA expression. In conclusion, diosmin inhibits neuropathic spinal cord nociceptive mechanisms suggesting this flavonoid as a potential therapeutic molecule to reduce nerve lesion-induced neuropathic pain.

Polyphenolic content and bactericidal effect of Mexican Citrus limetta and Citrus reticulata

In this study, total phenolics, total flavonoids, hesperidin and ascorbic acid contents in bagasse, juice and seed of mexican sweet lime (Citrus limetta) and mandarine (Citrus reticulata) were determined at two commercial maturity stages (maturation index), as well as their bactericidal effect on Escherichia coli and Staphylococcus aureus. The results showed that bagasses had the highest total phenolics, total flavonoids, and hesperidin content for both, C. limetta, and C. reticulata; highest ascorbic acid contents were found in C. limetta juice (3.36 ± 0.25 mg g^-1 DW) and C. reticulata bagasse (3.83 ± 0.37 mg g^-1 DW). All tested extracts showed bacterial growth inhibition at 50 and 800 µg mL^-1. Bagasse extracts of both fruits showed the highest inhibitions (>90%) on tested bacteria. Total phenolics, total flavonoids, and hesperidin contents, as well as bactericidal effect increased with maturity. Results indicated that both Mexican citric fruits (C. limetta and C. reticulata) were good sources of antioxidant and bactericidal agents.

Qualitative and nutraceutical aspects of lemon fruits grown on the mountainsides of the Mount Etna: A first step for a protected designation of origin or protected geographical indication application of the brand name 'Limone dell'Etna'

The cultivation of lemon (Citrus limon (L.) Burm f.) has occurred for centuries at the mountainsides of the Mount Etna the largest active volcano in Europe (Sicily, Italy). The peculiar geographical, soil and climatic conditions that characterize this area have recently prompted citrus growers to launch the brand name 'Limone dell'Etna' for the lemon fruits produced in that area. The present research focused on evaluating the quality and nutraceutical properties of the 'Limone dell'Etna' fruit juice ('Primofiore', 'Bianchetto', and 'Verdello' blooming) to enhance the value of a product that, due to its peculiar qualities, could be awarded with one of the European certified labels protecting the lemon geographical origin. Qualitative parameters, health-promoting components (such as ascorbic acid, flavonoids, and hydroxycinnamic acids) and the in-vitro total antioxidant capacity (ORAC, FCR) of fruit juice of two different varieties ('Femminello zagara bianca' and 'Monachello') were determined at fruit maturity. The results showed that the Bianchetto and Verdello lemon fruit exhibited higher levels of ascorbic acid than those recorded for the Primofiore production. The amount of flavonoids in Verdello fruits of both cultivars was the highest, as was reflected in the highest antioxidant activity. Thus, the 'Limone dell'Etna' production, with particular reference to the Verdello fruit, must be considered as a new, valuable and original source of natural antioxidants to be valorized and even exploited in the processing industry.

Unzipped carbon nanotubes: analytical and binding applications of semisynthetic phlebotropic flavonoid, diosmin

Present study describes the utility of unzipped carbon nanotubes as electrochemical sensing platform for the determination of diosmin in pharmaceutical formulations and for the investigation of its binding to human serum albumin.

Quantitative estimation of hesperidin by HPTLC in different varieties of citrus peels

OBJECTIVE

To develop a simple, selective, sensitive and accurate high-performance thin layer chromatography (HPTLC) method to determine the quantity of hesperidin in different varieties of citrus fruits.

METHODS

The method was carried out in aluminum-backed silica gel 60 F254 plates with ethyl acetate-methanol-water 15:3:2 (%, v/v) as mobile phase.

RESULTS

A compact band was obtained for hesperidin at Rf value of (0.40±0.04). The calibration plot was linear in the range of 100-800 ng/spot of hesperidin and the correlation coefficient of 0.998 6 was indicative of good linear dependence of peak area on concentration. Limit of detection (8.87 ng/spot), limit of quantification (23.21 ng/spot), accuracy (less than 2%) and recovery (ranging from 98.55-99.38) were found satisfactory.

CONCLUSIONS

The method developed can be used for routine analysis of hesperidin in crude drug as well as in herbal and pharmaceutical dosage form containing citrus fruits as an ingredient.

Development and Validation of UV Spectrophotometric Method for Simultaneous Estimation of Hesperidin and Diosmin in the Pharmaceutical Dosage Form

A simple, rapid, precise and highly selective spectrophotometric method was developed for simultaneous estimation of Hesperidin and Diosmin in tablet dosage form. This method, involves the measurement of absorbances of Hesperidin and Diosmin at the wavelengths of 285 nm (λmax of Hesperidin) and 268 nm (λmax, of Diosmin). The UV spectra’s of Hesperidin and Diosmin prepared in different solvents water, methanol, and acetonitrile and 0.2 N sodium hydroxide were recorded. These two drugs showed good absorbances when dissolved in 0.2 N NaOH. Hence 0.2 N NaOH was selected as the solvent for the method. Two wavelengths 285 and 268 nm were selected which are λmax of two drugs Hesperidin and Diosmin, respectively. Different concentrations of Hesperidin (5–50 μg/mL) and Diosmin (2–24 μg/mL) and a mixture of Hesperidin and Diosmin were prepared, scanned and absorbances were noted at the two wavelengths were fixed for the study. The method showed good reproducibility and recovery with % RSD less than 2. The LOD of Hesperidin and Diosmin was found to be 0.139 μg/mL and 0.048 μg/ml and LOQ of Hesperidin and Diosmin was found to be 0.42 μg/mL and 0.147 μg/mL, respectively. Thus the proposed method was found to be rapid, specific, precise, accurate and cost effective quality control tool for the routine analysis of Hesperidin and Diosmin in bulk and combined dosage form.

Suppression of plasminogen activators and the MMP-2/-9 pathway by a Zanthoxylum avicennae extract to inhibit the HA22T human hepatocellular carcinoma cell migration and invasion effects in vitro and in vivo via phosphatase 2A activation

This study shows that the ECM degradation-associated pathway, including uPA and tPA and the downstream MMP-2/-9 protein, was significantly suppressed in HA22T cells treated with a Zanthoxylum avicennae extract (YBBE). The endogenous inhibitors, including TIMP-1/-2 and PAI-1, were enhanced in HA22T cells by the YBBE treatment. The expression of MMP-2/-9 and TIMP-1/-2 was respectively assessed by using RT-PCR and a zymography assay. The mRNA levels and enzymatic activity of MMP-2/-9 were down-regulated by the YBBE treatment in a dose-dependent manner, while the TIMP-1/-2 levels were conversely markedly increased. The PP2A siRNA or PP2A inhibitor totally reversed the YBBE effects, confirming the essential role of PP2A in YBBE inhibiting the HA22T cell migration and invasion effects. Xenografted animal experiments on nude mice demonstrated similiar results to the in vitro system. Both the in vitro and in vivo models clearly demonstrate that YBBE inhibited the highly metastatic HA22T liver cancer cell migration and invasion effects through PP2A activation.

Lyophilized phytosomal nanocarriers as platforms for enhanced diosmin delivery: optimization and ex vivo permeation

Diosmin (DSN) is an outstanding phlebotonic flavonoid with a tolerable potential for the treatment of colon and hepatocellular carcinoma. Being highly insoluble, DSN bioavailability suffers from high inter-subject variation due to variable degrees of permeation. This work endeavored to develop novel DSN loaded phytosomes in order to improve drug dissolution and intestinal permeability. Three preparation methods (solvent evaporation, salting out, and lyophilization) were compared. Nanocarrier optimization encompassed different soybean phospholipid (SPC) types, different solvents, and different DSN:SPC molar ratios (1:1, 1:2, and 1:4). In vitro appraisal encompassed differential scanning calorimetry, infrared spectroscopy, particle size, zeta potential, polydispersity index, transmission electron microscopy, drug content, and in vitro stability. Comparative dissolution studies were performed under sink versus non-sink conditions. Ex vivo intestinal permeation studies were performed on rats utilizing noneverted sac technique and high-performance liquid chromatography analysis. The results revealed lyophilization as the optimum preparation technique using SPC and solvent mixture (Dimethyl sulphoxide:t-butylalchol) in a 1:2 ratio. Complex formation was contended by differential scanning calorimetry and infrared data. Optimal lyophilized phytosomal nanocarriers (LPNs) exhibited the lowest particle size (316 nm), adequate zeta-potential (-27 mV), and good in vitro stability. Well formed, discrete vesicles were revealed by transmission electron microscopy, drug content, and in vitro stability. Comparative dissolution studies were performed. LPNs demonstrated significant enhancement in DSN dissolution compared to crude drug, physical mixture, and generic and brand DSN products. Permeation studies revealed 80% DSN permeated from LPNs via oxygenated rat intestine compared to non-detectable amounts from suspension. In this study, LPNs (99% drug loading) could be successfully tailored for DSN with improved dissolution and permeation characteristics, which is promising for lowering the influence of exogenous factors and increasing drug delivery.

Lyophilized phytosomal nanocarriers as platforms for enhanced diosmin delivery: optimization and ex vivo permeation

Diosmin (DSN) is an outstanding phlebotonic flavonoid with a tolerable potential for the treatment of colon and hepatocellular carcinoma. Being highly insoluble, DSN bioavailability suffers from high inter-subject variation due to variable degrees of permeation. This work endeavored to develop novel DSN loaded phytosomes in order to improve drug dissolution and intestinal permeability. Three preparation methods (solvent evaporation, salting out, and lyophilization) were compared. Nanocarrier optimization encompassed different soybean phospholipid (SPC) types, different solvents, and different DSN:SPC molar ratios (1:1, 1:2, and 1:4). In vitro appraisal encompassed differential scanning calorimetry, infrared spectroscopy, particle size, zeta potential, polydispersity index, transmission electron microscopy, drug content, and in vitro stability. Comparative dissolution studies were performed under sink versus non-sink conditions. Ex vivo intestinal permeation studies were performed on rats utilizing noneverted sac technique and high-performance liquid chromatography analysis. The results revealed lyophilization as the optimum preparation technique using SPC and solvent mixture (Dimethyl sulphoxide:t-butylalchol) in a 1:2 ratio. Complex formation was contended by differential scanning calorimetry and infrared data. Optimal lyophilized phytosomal nanocarriers (LPNs) exhibited the lowest particle size (316 nm), adequate zeta-potential (-27 mV), and good in vitro stability. Well formed, discrete vesicles were revealed by transmission electron microscopy, drug content, and in vitro stability. Comparative dissolution studies were performed. LPNs demonstrated significant enhancement in DSN dissolution compared to crude drug, physical mixture, and generic and brand DSN products. Permeation studies revealed 80% DSN permeated from LPNs via oxygenated rat intestine compared to non-detectable amounts from suspension. In this study, LPNs (99% drug loading) could be successfully tailored for DSN with improved dissolution and permeation characteristics, which is promising for lowering the influence of exogenous factors and increasing drug delivery.

Diosmin – Isolation Techniques, Determination in Plant Material and Pharmaceutical Formulations, and Clinical Use

Diosmin is a naturally occurring flavone glycoside used in the treatment of venous diseases. In this review, we present the clinical aspects of the use of diosmin preparations in venous stasis, hemorrheologic disorders and vein wall remodeling. Because of its multiple applications in biology and its many therapeutic activities, research on isolation and identification of diosmin is of high relevance. The aim of this review is to present an overview of techniques of isolation and separation of diosmin in plant material, pharmaceutical formulations such as Daflon®, Diosed® and Dioven® tablets, and biological fluids.

PP2A mediates diosmin p53 activation to block HA22T cell proliferation and tumor growth in xenografted nude mice through PI3K-Akt-MDM2 signaling suppression

Hepatocellular carcinoma is a common type of cancer with poor prognosis. This study examines the in vitro and in vivo mechanisms of diosmin on human hepato-cellular carcinoma HA22T cell proliferation inhibition. HA22T cells were treated with different diosmin concentrations and analyzed with Western blot analysis, MTT assay, wound healing, flow cytometry, siRNA transfection assays and co-immuno-precipitation assay. The HA22T-implanted xeno-graft nude mice model was applied to confirm the cellular effects. Diosmin showed strong HA22T cell viability inhibition in a dose dependent manner and significantly reduced the cell proliferative proteins as well as inducing cell cycle arrest in the G2/M phase through p53 activation and PI3K-Akt-MDM2 signaling pathway inhibition. However, protein phosphatase 2A (PP2A) siRNA or PP2A inhibitor totally reversed the diosmin effects. The HA22T-implanted nude mice model further confirmed that diosmin inhibited HA22T tumor cell growth and down regulated the PI3K-Akt-MDM2 signaling and cell cycle regulating proteins, as well as activating PP2A and p53 proteins. Our findings indicate that HA22T cell proliferation inhibition and tumor growth suppression by diosmin are mediated through PP2A activation.

Simultaneous determination of flavonoids and phenylethanoids in the flowers of Verbascum densiflorum and V. phlomoides by high-performance liquid chromatography

INTRODUCTION

Mullein (Verbascum) flowers are highly valued herbal drugs used in the treatment of inflammation, asthma, spasmodic coughs and other respiratory tract diseases. Their phenolic constituents are considered to be responsible for the anti-inflammatory and antimicrobial activity of the herb. However, knowledge about the contents of phenolics in flowers is limited and no HPLC method for their analysis is available.

OBJECTIVE

To develop and validate an RP-HPLC-UV method for the simultaneous determination of eight flavonoids and two phenylethanoids in the flowers of Verbascum densiflorum and V. phlomoides.

METHODOLOGY

HPLC separation was accomplished on a C(18) Lichrosphere 100 column (5 microm, 250 mm x 4.6 mm, i.d.) with an acetonitrile gradient elution using aqueous 0.5% (w/v) orthophosphoric acid solution containing 1% (v/v) tetrahydrofurane.

RESULTS

All the calibration curves showed good linear correlation coefficients (r > 0.997) over the wide test ranges. The relative standard deviation of the method was less than 3.4% for intra- and inter-day assays, and the average recoveries were between 93.5 and 101.9%. High sensitivity was demonstrated with detection limits of 0.062-0.083 microg/mL for flavonoid aglycones, 0.156-0.336 microg/mL for flavonoid glycosides and 0.390-0.555 microg/mL for phenylethanoids. The flower samples of V. phlomoides were found to contain high levels of diosmin and tamarixetin 7-rutinoside (2.327-2.392% of dry weight), whereas verbascoside (0.688-0.742% of dry weight) and luteolin 7-glucoside (0.204-0.279% of dry weight) dominated in the V. densiflorum flower.

CONCLUSION

The HPLC method established is appropriate for the quality assurance and the differentiation of V. phlomoides and V. densiflorum samples.

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.

A broad review of commercially important southern African medicinal plants

AIMS OF THE STUDY

Commercially important indigenous medicinal plants of southern Africa are reviewed in the context of fundamental knowledge about their ethnobotany, phylogeny, genetics, taxonomy, biochemistry, chemical variation, reproductive biology and horticulture. The aim is to explore the rapidly increasing number of scientific publications and to investigate the need for further research.

MATERIALS AND METHODS

The Scopus (Elsevier) reference system was used to investigate trends in the number of scientific publications and patents in 38 medicinal plant species. Fifteen species of special commercial interest were chosen for more detailed reviews: Agathosma betulina, Aloe ferox, Artemisia afra, Aspalathus linearis, Cyclopia genistoides, Harpagophytum procumbens, Hoodia gordonii, Hypoxis hemerocallidea, Lippia javanica, Mesembryanthemum tortuosum, Pelargonium sidoides, Siphonochilus aethiopicus, Sutherlandia frutescens, Warburgia salutaris and Xysmalobium undulatum.

RESULTS

In recent years there has been an upsurge in research and development of new medicinal products and new medicinal crops, as is shown by a rapid increase in the number of scientific publications and patents. Despite the fact that an estimated 10% of the plant species of the world is found in southern Africa, only a few have been fully commercialized and basic scientific information is often not available.

CONCLUSIONS

The limited available information indicates that some of the plants display remarkable regional variation in morphological, genetic and chemical characters that should be more thoroughly investigated. Basic biological information is needed to guide the rapidly accelerating commercialization process, especially the selection of superior clones, the development of new cultivars and the standardization of raw materials.

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.

Determination of trace levels of diosmin in a pharmaceutical preparation by adsorptive stripping voltammetry at a glassy carbon electrode

A systematic study on the electrochemical behavior of diosmin in Britton-Robinson buffer (pH 2.0-10.0) at a glassy carbon electrode (GCE) was made. The oxidation process of the drug was found to be quasi-reversible with an adsorption-controlled step. The adsorption stripping response was evaluated with respect to various experimental conditions, such as the pH of the supporting electrolyte, the accumulation potential and the accumulation time. The observed anodic peak current at +0.73 V vs. Ag/AgCl reference electrode increased linearly over two orders of magnitude from 5.0x10(-8) M to 9.0x10(-6) M. A limit of detection down to 3.5x10(-8) M of diosmin at the GCE was achieved with a mean recovery of 97+/-2.1%. Based on the electrochemical data, an open-circuit accumulation step in a stirred sample solution of BR at pH 3.0 was developed. The proposed method was successfully applied to the determination of the drug in pharmaceutical formulations. The results compared favorably with the data obtained via spectrophotometric and HPLC methods.

Analytical separation and detection methods for flavonoids

Flavonoids receive considerable attention in the literature, specifically because of their biological and physiological importance. This review focuses on separation and detection methods for flavonoids and their application to plants, food, drinks and biological fluids. The topics that will be discussed are sample treatment, column liquid chromatography (LC), but also methods such as gas chromatography (GC), capillary electrophoresis (CE) and thin-layer chromatography (TLC), various detection methods and structural characterization. Because of the increasing interest in structure elucidation of flavonoids, special attention will be devoted to the use of tandem-mass spectrometric (MS/MS) techniques for the characterization of several important sub-classes, and to the potential of combined diode-array UV (DAD UV), tandem-MS and nuclear magnetic resonance (NMR) detection for unambiguous identification. Emphasis will be on recent developments and trends.

Additive or synergetic effects of phenolic compounds on human low density lipoprotein oxidation

The in vitro assessment of the antioxidant capacity of four phenolic compounds; catechin, hesperidin, ferulic acid, and quercetin was evaluated by the examination of their ability to inhibit copper (Cu(2+))-mediated human low density lipoprotein (LDL) oxidation by using the thiobarbituric acid-reactive substances (TBARS) assay. Individually, the enrichment of LDLs with various concentrations of catechin, hesperidin, ferulic acid, and quercetin produced both antioxidant and prooxidant effects depending on enrichment concentrations of the polyphenolic compounds. Catechin and hesperidin had predominantly antioxidant effects (51.1%, 76.9%, respectively) while ferulic acid and quercetin had mostly prooxidant effects (166.4%; 191.8%, respectively) on LDL oxidation. However, when the mixture of the four phenolic compounds was used to enrich the LDLs, significant antioxidant capacity was demonstrated at all enrichment levels with a dose-response. Synergistic effects of the polyphenolic compounds as mixtures in preventing human LDL oxidation may reflect that nutritional advantages are found in the consumption of a variety of fruits and vegetables in preventing LDL oxidation and perhaps a host of cardiovascular diseases.

Microquantitative determination of hesperidin by pulse perturbation of the oscillatory reaction system

A simple and reliable kinetic method for the determination of hesperidin (Hesp) is developed. It is based on potentiometric monitoring of the concentration perturbations of the matrix reaction system which is in a stable non-equilibrium stationary state close to the bifurcation point. The Bray-Liebhafsky oscillatory reaction is used as the matrix system. The response of the matrix to perturbations by different concentrations of Hesp is followed by using a Pt electrode. A linear relationship between maximal potential shift and the logarithm of Hesp concentrations is obtained between 7.5 and 599.4 microg mL-1. The limit of detection is 0.65 microg mL-1. The described procedure has been successfully applied to the determination of Hesp from different sources (capsules, industrial and hand-squeezed orange juice, and white wine).

Simultaneous reversed-phase high-performance liquid chromatographic method for the determination of diosmin, hesperidin and naringin in different citrus fruit juices and pharmaceutical formulations

Diosmin, hesperidin and naringin are flavonoid glycosides that occur naturally in citrus fruits. They exert a variety of pharmacological properties such as anti-inflammatory, antioxidant and free radical scavenging and antiulcer effects and also inhibit selected cytochrome P-450 enzymes resulting in drug interactions. A reversed-phase high-performance liquid chromatographic method has been developed for the simultaneous determination of diosmin, hesperidin and naringin in different citrus fruit juices and pharmaceutical preparations. Diosmin, hesperidin, naringin and the internal standard rhoifolin were separated using tetrahydrofuran/water/acetic acid (21:77:2, v/v/v) as the mobile phase at 34 degrees C, using a C8 reversed-phase column. The method was linear in the 0.25-20.0 microg/ml concentration range for all three flavonoid glycosides (r>0.999). The method has been successfully applied to the determination of all three flavonoid glycosides in several samples of different citrus fruit juices sold in Greece and for the determination of diosmin and hesperidin in pharmaceutical preparations.