Apoptosis induction effect of Apocynum venetum polyphenol on human U87 glioma cells via NF-κB pathway.

Aim: Apocynum venetum polyphenol (AVP) was used in in vitro glioma cells culture to prove the growth inhibitory effect of AVP on human U87 glioma cells via NF-κB pathway. Materials & methods: The MTT assay, DAPI morphology, quantitative PCR and western blot experiments were used for determination in vitro. Results & conclusion: AVP can also induce U87 cancer cells apoptosis illustrated by DAPI morphology. AVP could enhance the mRNA and protein expression of IκB-α, TNF-α, TRAIL, caspase-3 and caspase-9 in U87 cancer cells and reduce those of NF-κBp65, cIAP-1, cIAP-2, TGF-ß2, CyclinD1, VEGF and IL-8. After ammonium pyrrolidine dithiocarbamate (PDTC) treatment, the NF-κBp65 expression was reduced in U87 cells, and AVP could raise these effects. The results of HPLC indicate that AVP mainly contains six constituents. The growth inhibitory effects of AVP on U87 glioma cells are predominantly from these natural active constituents.

Meroterpenoids and Isocoumarinoids from a Myrothecium Fungus Associated with Apocynum Venetum.

Four new meroterpenoids 1⁻4 and four new isocoumarinoids 5⁻8, along with five known isocoumarinoids (9⁻13), were isolated from the fungus Myrothecium sp. OUCMDZ-2784 associated with the salt-resistant medicinal plant, Apocynum venetum (Apocynaceae). Their structures were elucidated by means of spectroscopic analysis, X-ray crystallography, ECD spectra and quantum chemical calculations. Compounds 1⁻5, 7, 9 and 10 showed weak α-glucosidase inhibition with the IC50 values of 0.50, 0.66, 0.058, 0.20, 0.32, 0.036, 0.026 and 0.37 mM, respectively.

Quality Evaluation of Apocyni Veneti Folium from Different Habitats and Commercial Herbs Based on Simultaneous Determination of Multiple Bioactive Constituents Combined with Multivariate Statistical Analysis.

Apocyni Veneti Folium (AVF) is a kind of staple traditional Chinese medicine with vast clinical consumption because of its positive effects. However, due to the habitats and adulterants, its quality is uneven. To control the quality of this medicinal herb, in this study, the quality of AVF was evaluated based on simultaneous determination of multiple bioactive constituents combined with multivariate statistical analysis. A reliable method based on ultra-fast liquid chromatography tandem triple quadrupole mass spectrometry (UFLC-QTRAP-MS/MS) was developed for the simultaneous determination of a total of 43 constituents, including 15 flavonoids, 6 organic acids, 13 amino acids, and 9 nucleosides in 41 Luobumaye samples from different habitats and commercial herbs. Furthermore, according to the contents of these 43 constituents, principal component analysis (PCA) was employed to classify and distinguish between AVF and its adulterants, leaves of Poacynum hendersonii (PHF), and gray relational analysis (GRA) was performed to evaluate the quality of the samples. The proposed method was successfully applied to the comprehensive quality evaluation of AVF, and all results demonstrated that the quality of AVF was higher than the PHF. This study will provide comprehensive information necessary for the quality control of AVF.

Apocynum leaf extract inhibits the progress of atherosclerosis in rats via the AMPK/mTOR pathway.

Apocynum leaf extract is an extract of the dried leaves of Apocynum venetum (a member of the Apocynaceae family) that has many effects on the cardiovascular system. The aim of the present study was to evaluate the protective effects of apocynum leaf extract on the atherosclerosis in rats induced by high-fat diet combined with vitamin D3 intraperitoneal injection. The atherosclerosis in rats were induced with a high-fat diet and an intraperitoneal injection of VD3 once daily for three contiguous days at a total injection dose of 70 U/kg. At the end of the 18th week, serum total cholesterol (TC) and triglyceride (TG) contents were measured. Hydroxyproline content in the aorta were measured by the alkali hydrolysis method. The hematoxylin-eosin (HE) and immunohistochemical staining were applied to evaluate the morphological changes and the collagen I and α-smooth muscle actin expression. The protein expression and the mRNA level of AMPK and mTOR were detected by western blot analysis and reverse transcript PCR. After treatment with apocynum leaf extract, the serum total cholesterol and triglyceride concentration of the atherosclerotic rats were significantly decreased, both the Collagen I expression and the hydroxyproline content in the aorta were significantly reduced, and the α-SMA, a smooth muscle-specific marker, expression were also lower than the untreated atherosclerotic rats. Western blot analyses showed that the apocynum can marked increase the p-AMPK but decrease the mTOR protein expression. The apocynum leaf extract also exhibited higher AMPK and lower mTOR mRNA expression of the aorta in the atherosclerotic rats. We believe that the apocynum leaf extract can effectively reduce blood lipid levels in rats with atherosclerosis, delay atherosclerotic progression by inhibiting excessive collagen synthesis and inhibiting smooth muscle cell over-proliferation. The underlying mechanism may be related to the AMPK/mTOR signaling pathway activity. Our results contribute towards validation of the traditional use of apocynum leaf extract in the treatment of atherosclerosis.

Extraction, Preconcentration and Isolation of Flavonoids from Apocynum venetum L. Leaves Using Ionic Liquid-Based Ultrasonic-Assisted Extraction Coupled with an Aqueous Biphasic System.

BACKGROUND: Ionic liquids (ILs) are considered as green solvents, and widely applied for the extraction of various compounds. METHODS: The present research focuses on the extraction of flavonoids from Apocynum venetum L. leaves by ultrasound-assisted extraction (UAE). Several major influencing factors were optimized. Then, an aqueous biphasic system (ABS) was applied for further isolation of flavonoids. RESULTS: The flavonoids were mainly distributed in the top phase, while impurities were extracted to the bottom phase. The parameters influencing the extraction, namely type and concentration of salt, temperature, and pH, were studied in detail. Under optimized conditions (72.43% IL extract, 28.57% (NH4)2SO4, 25 °C temperature, pH 4.5), the preconcentration factor and extraction efficiency were found to be 3.78% and 93.35%, respectively. CONCLUSIONS: This simple and efficient methodology is expected to see great use in the extraction and isolation of pharmaceutically active components from medicinal plant resources.

Screening and analysis of metabolites in rat urine after oral administration of Apocynum venetum L. extracts using HPLC-TOF-MS.

HPLC with diode array detection and ESI-TOF-MS was used for the study of the constituents in Apocynum venetum L. extracts and the metabolites in rat urine after oral administration of A. venetum L. extracts. A formula database of the known constituents in A. venetum L. was established, and 21 constituents were rapidly identified by accurately matching their molecular masses with the formulae of the compounds in the database. Furthermore, 34 metabolites were detected and elucidated in the rat urine. The scientific and plausible biotransformation pathways of the flavonoid components in A. venetum L. were also proposed together with the presentation of clues for potential mechanisms of bioactivity. This specific and sensitive HPLC-ESI-TOF-MS method can be used to identify the chemical components in the extracts of A. venetum L. and their metabolites in rat urine. This method can also be used to reveal the possible metabolic mechanisms of action of the extract components in vivo.

[Analytical studies on flavonoids constituents in Apocynum venetom leaves by UPLC-Q-TOF-MS].

OBJECTIVE: To establish an ultra-performance liquid chromatography quadrupole-time-of-flight mass spectrometric (UPLC-Q-TOF-MS) method for analyzing the flavonoids constituents in Apocynum venetom leaves. METHODS: The analysis was performed on an Alltima C18 analytical column with a gradient solvent system of acetonitrile-1.0% acetic acid at the flow rate of 0.8 mL/min. The detection wavelength was at 254 nm and the column temperature was at 30 degrees C. Identification and detection were collected under the negative electrospray ion mode using Q-TOF-MS. RESULTS: 11 flavonoids constituents being separated and identified, six of them were detected simultaneously. The results showed that the six detected flavonoids constituents had good linearity between concentrations and peak area (r > 0.9996), and the average recoveries of the method were between 94.3% - 103.3%. CONCLUSION: The method is accurate, reproducible, and can be used for the quality control of Apocynum venetom leaves.

[Evaluation of high-resolution images application for wild medicinal plants macro monitoring: a case of Apocynum].

To investigate the resources of medicinal plant, such as wild Apocynum, supervised classification based on Principal Component Analysis (PCA) and texture feature were used to monitor wild medicinal plants from image captured by ZY-3 and World-view-2 and compare which satellite Image are more appropriate to monitor the wild medicinal plants. The research results shows that: for more complex growth conditions wild medicinal plants Apocynum, high-resolution images Worldview-2 is more suitable for its remote identification, the low-resolution satellite ZY-3 can only recognizes the wild medicinal plants which distributed intensively. If the study target distribution is more intensive and larger scale, and cultivated type medicinal plants, the use of satellite ZY-3 in low resolution remote sensing data to identify the target can be a good choice, it is not necessary to buy high-resolution data, in order to avoid waste of expenditure, for the scattered distribution, the high-resolution satellite imagery data may be indispensable to identify targets.

Apocynum venetum leaf extract attenuates disruption of the blood-brain barrier and upregulation of matrix metalloproteinase-9/-2 in a rat model of cerebral ischemia-reperfusion injury.

We investigated the neuroprotective effects of Apocynum venetum leaf extract (AVLE) on a rat model of cerebral ischemia-reperfusion injury and explored the underlying mechanisms. Rats were randomly divided into five groups: sham, ischemia-reperfusion, AVLE125, AVLE250, and AVLE500. Cerebral ischemia was induced by 1.5 h of occlusion of the middle cerebral artery. Cerebral infarct area was measured by tetrazolium staining at 24 and 72 h after reperfusion, and neurological function was evaluated at 24, 48 and 72 h after reperfusion. Pathological changes on the ultrastructure of the blood-brain barrier (BBB) were observed by transmission electron microscopy. BBB permeability was assessed by detecting leakage of Evan's blue (EB) dye in brain tissue. The expression and activities of matrix metalloproteinase (MMP)-9/-2 were measured by western blot analyses and gelatin zymography at 24 h after reperfusion. AVLE (500 mg/kg/day) significantly reduced cerebral infarct area, improved recovery of neurological function, relieved morphological damage to the BBB, reduced water content and EB leakage in the brain, and downregulated the expression and activities of MMP-9/-2. These findings suggest that AVLE protects against cerebral ischemia-reperfusion-induced injury by alleviating BBB disruption. This action may be due to its inhibitory effects on the expression and activities of MMP-9/-2.

ILs-based microwave-assisted extraction coupled with aqueous two-phase for the extraction of useful compounds from Chinese medicine.

Ionic liquids-based microwave-assisted extraction (ILs-MAE) of medicinal or useful compounds from plants was investigated as an alternative to conventional organic solvent extractions. The extraction and the preconcentration of aqueous two-phase (ATP) systems have been integrated. Various operating parameters were systematically considered by single-factor and L(9) (3(4)) orthogonal array experiments. 1-Butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) has been selected to extract Apocynum venetum. The extract was then converted to the top phase by [bmim][BF(4)]/NaH(2)PO(4) system which was suitable for the preconcentration. Reversed phase high performance liquid chromatography (RP-HPLC) with ultraviolet detection was employed for the analysis of hyperin and isoquercitrin in Apocynum venetum. The optimal experiment approach could provide higher detection limit of hyperin and isoquercitrin which were 3.82 µg L(-1) and 3.00 µg L(-1) in Apocynum venetum. The recoveries of hyperin and isoquercitrin were 97.29% (RSD = 1.02%) and 99.40% (RSD = 1.13%), respectively, from aqueous samples of Apocynum venetum by the proposed method. Moreover, the extraction mechanism of ILs-MAE and the microstructures and chemical structures of the herb before and after extraction were also investigated. The method exhibited potential applicability with other complicated samples.

Highly selective and sensitive determination of free and total amino acids in Apocynum venetum L. (Luobuma tea) by a developed HPLC-FLD method coupled with pre-column fluorescent labelling.

Amino acids (AA) are important chemical constituents of tea leaves remarkably influencing the quality of tea. In this study, free AA and total AA in Apocynum venetum L. (Luobuma tea) were estimated by HPLC equipped with fluorescent detector using 2-[2-(7H-dibenzo[a,g]carbazol-7-yl)-ethoxy] ethyl chloroformate (DBCEEC) as a fluorescent labelling reagent. Different parameters for derivatization and separation were optimized. AA were rapidly derivatized within 3 min at room temperature with DBCEEC. In conjunction with a gradient elution, a baseline resolution of 20 analytes was achieved on a reversed-phase Hypersil BDS C18 column. LC separation for the derivatized AA showed good reproducibility. Twenty AA were detected and showed significant linear responses with correlation coefficients (>0.9992). This developed method offered the low detection limit of 2.88-23.4 fmol.

Protective effects of flavonoid extract from Apocynum venetum leaves against corticosterone-induced neurotoxicity in PC12 cells.

Depression is a major psychiatric disorder affecting nearly 21% of the world population and imposes a substantial health burden on society. Although significant progress has been made in depression research, the common molecular mechanism of antidepressants is still far from clearly understood. The neuroprotective effect of antidepressants has been proposed as a possible mechanism. Although Apocynum venetum (AV) L. (Apocynaceae) was previously shown to produce an antidepressant-like effect in the tail suspension test, the mechanisms underlying such antidepressant-like effect are yet to be understood. In this work, we studied the neuroprotective effect of AV leaf flavonoid extract in corticosterone-induced neurotoxicity, using PC12 cells as a suitable in vitro model of depression. Cell viability was quantitated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The release amount of lactic dehydrogenase (LDH) and intracellular Ca(2+) concentration were measured using kit, cell period change was tested by flow cytometry, and transcript abundances of brain-derived neurotrophic factor (BDNF) and microtubule-associated protein 4 (MAP4) were determined by real-time RT-PCR. The results showed that AV extract (25, 50, and 100 µg/ml) increased the A490 nm values, but decreased LDH release and Ca(2+) concentration, suppressed the apoptosis of PC12 cells and up-regulated BDNF and MAP4 transcript abundances compared with the corresponding corticosterone-treated group. These results suggest that the AV extract could generate a neuroprotective effect on corticosterone-induced neurotoxicity in PC12 cells, pointing to a possible action pathway by decreasing the Ca(2+) concentration and up-regulating BDNF and MAP4 genes.

One-step separation of three flavonoids from Poacynum hendersonii by high-speed counter-current chromatography.

INTRODUCTION: Owing to them having the same traditional name, the leaves of Apoacynum venetum and Poacynum hendersonii are used indiscriminately in some areas of China. Although a series of studies have been conducted on Apoacynum venetum, there are only a few studies on Poacynum hendersonii. OBJECTIVE: To develop an efficient method for the preparative isolation and purification of flavonoids from the leaves of Poacynum hendersonii by high-speed counter-current chromatography (HSCCC). METHODOLOGY: Powdered Poacynum hendersonii lead was extracted three times with 75% ethanol at 60 °C for 3 h. The distribution constant (K(D) ) was measured to select an optimal two-phase solvent system for HSCCC separation. The purities of the target compounds were tested using HPLC and their structures were identified by ¹H-NMR and ¹³C-NMR. RESULTS: Using a two-phase solvent system composed of n-butanol-petroleum ether-0.5% acetic acid (5:3:5, v/v), three main flavonoids, i.e. isoquercitrin, quercetin-3-O-sophoroside and quercetin-3-O-(6''-O-malonyl)-ß-D-glucoside, were separated from 240 mg crude sample in a one-step separation by using HSCCC method. After further purification with a Sepdex-LH20 column, 5.7 mg isoquercitrin (LC purity 98.72%), 4.9 mg quercetin-3-O-sophoroside (LC purity 99.06%) and 7.4 mg quercetin-3-O-(6''-O-malonyl)-ß-D-glucoside (LC purity 99.31%) were obtained, respectively. CONCLUSION: The optimised high-speed counter-current chromatography method is fast, simple and efficient for the preparative separation of flavonoids from the leave of Poacynum hendersonii.

[Location and relative quantity of flavonoids in the leaf of Apocynum venetum].

In this study, laser scanning confocal microscopy (LSCM) was used to determine the location and relative quantity of flavonoids in the leaves of Apocynum venetum L. from the top, middle and basal parts of the branch. The leaves of the plants of one, two and three years old, separately, were collected in July. ANOVA and LSD test were employed in the statistical analysis. The results indicated that flavonoids located mainly in xylem conduit of vein, collenchyma, epidermic cells and cuticle. The data of flavonoids contents under statistical analysis showed that difference existed in the leaves of different parts and different ages. This study provided the reliable scientific material about the analysis of the ecological and the exploitation of the leaves of Apocynum venetom L.

[Simultaneous determination of six flavonoids in Apocynum venetum by HPLC].

OBJECTIVE: To develop a high-performance liquid chromatography (HPLC) method for the simultaneous determination of rutin, hyperoside, isoquercetin, astragulin, quercetin, and kaempferol in Apocynum venetum and its extracts. METHOD: The separation was carried out on a Shim pack ODS (4.6 mm x 250 mm, 5 microm) colum eluted with in mobile phases of water containing 0.2% phosphoric acid and acetonitrile containing 0.2% phosphoric acid in acetonitrile gradient mode. The column temperature was 40 degrees C, and the flow rate was 1.0 mL x min(-1). The detection wavelength was set at 360 nm. RESULT: The good seperation of six flavonoids was achieved within 40 min, with the relative standard deviations (RSD) of intra- and inter-day precision < or = 2.0%. Calibration curves of rutin, hyperoside, isoquercetin, astragulin, quercetin, and kaempferol showed good linear relationship (R2 > 0.999 7, n = 6). The average recoveries of the six flavonoids were within 97.30% - 105.8% (RSD 2.6%). Three batches of A. venetum and 2 batches of its extracts were determined. CONCLUSION: The developed method is simple, accurate, and repeatable, and can be readily used as a powerful tool for the quality control of A. venetum and its extracts.

[Preparation and in vitro release characteristics of pulsed-release tablets of Apocynum venetum].

OBJECTIVE: Using Apocynum venetum as a model drug to prepare pulsed-release tablets based on diffusion, swelling, osmotic pressure mechanism and to evaluate the release characteristics. METHOD: The pulsatile release tablets were prepared by film coating methods using HPMC E5 and Eudragit The effect of formulation on pulsatile release of A. venetum was investigated. RESULT: The pulsed-release tablet was prepared by a swelling layer coating which contains HPMC E5 and a controlled-release membrane containning Eudragit. The delayed release time of the tablets was (5.0 +/- 0.5) h. CONCLUSION: The pulsatile release characteristics of A. venetum pulsatile release tablets were confirmed in vitro.

Apocynum venetum leaf extract protects rat cortical neurons from injury induced by oxygen and glucose deprivation in vitro.

This study aimed to investigate the protective effect of Apocynum venetum leaf extract (AVLE) on an in vitro model of ischemia-reperfusion induced by oxygen and glucose deprivation (OGD) and further explored the possible mechanisms underlying protection. Cell injury was assessed by morphological examination using phase-contrast microscopy and quantified by measuring the amount of lactate dehydrogenase (LDH) leakage; cell viability was measured by XTT reduction. Neuronal apoptosis was determined by flow cytometry, and electron microscopy was used to study morphological changes of neurons. Caspase-3, -8, and -9 activation and Bcl-2/Bax protein expression were determined by Western blot analysis. We report that treatment with AVLE (5 and 50 µg/mL) effectively reduced neuronal cell death and relieved cell injury induced by OGD. Moreover, AVLE decreased the percentage of apoptotic neurons, relieved neuronal morphological damage, suppressed overexpression of active caspase-3 and -8 and Bax, and inhibited the reduction of Bcl-2 expression. These findings indicate that AVLE protects against OGD-induced injury by inhibiting apoptosis in rat cortical neurons by down-regulating caspase-3 activation and modulating the Bcl-2/Bax ratio.

Solvent gradient elution for comprehensive separation of constituents with wide range of polarity in Apocynum venetum leaves by high-speed counter-current chromatography.

A novel gradient elution was efficiently utilized for the separation of the chemical components with a wide range of polarity from the mixed extract of the Chinese medicinal herb Apocynum venetum or mixed standards by high-speed counter-current chromatography. Three sets of solvent systems, n-hexane-ethyl acetate-methanol-water (1.5:3.5:2:4.5 v/v/v/v), ethyl acetate-methanol-water (5:2:5 v/v/v) and n-butanol-methanol-water (5:1:5 v/v/v) were used for the one-step elution. The separation was initiated by filling the column with the lower phase of n-hexane-ethyl acetate-methanol-water (1.5:3.5:2:4.5 v/v/v/v) as a stationary phase followed by elution with the upper phase of n-hexane-ethyl acetate-methanol-water (1.5:3.5:2:4.5 v/v/v/v) to separate the hydrophobic compounds (tail to head). Then the mobile phase was switched to the upper phase of ethyl acetate-methanol-water (5:2:5 v/v/v) to elute the moderate hydrophobic compounds, and finally the hydrophilic compounds still retained in the column were fractionated by eluting the column with the upper phase of n-butanol-methanol-water (5:1:5 v/v/v). A total of 13 compounds including adhyperforin, hyperforin, amentoflavone, biapigenin, quercetin, astragalin, trifolin, isoquercetin, hyperside, acetyled hyperside, rutin, chlorogenic acid and quercetin-3-O-ß-D-glucosyl-ß-D-glucopyranoside were successfully separated via the three sets of solvent systems in one-step operation for 90 min.

Comparison of the phenolic content and antioxidant activities of Apocynum venetum L. (Luo-Bu-Ma) and two of its alternative species.

The leaves of Apocynum venetum L. (AV), a native Chinese plant, have been used as folk medicine in China and Japan. This study evaluated the content of the active antioxidant component and antioxidant activities of AV, and its two alternative species, Poacynum pictum (Schrenk) Baill. (PP) and Poacynum hendersonii (Hook.f.) Woodson (PH). The total phenolic and total flavonoid contents were determined. In addition, the quantitative analysis of two major flavonoid compounds (hyperoside and isoquercitrin) was carried out by HPLC. The antioxidant activities were investigated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity method, the reducing power test and the chelating ability of ferrous ions. The highest total phenolic and flavonoid contents were observed in the AV methanolic extract, followed by the PP and PH methanolic extracts. HPLC analysis indicated that isoquercitrin was one of the major components in all three species, however, hyperoside was only detected in AV at high levels. All the antioxidant assays we performed demonstrated that the AV extract was markedly superior to those of the other two species.

[Protective effect of extract of Apocynum venetum on kidneys of streptozotocin-induced diabetic rats].

The aim of this study is to investigate the effects and mechanism of extract of Apocynum venetum (AV) on kidneys of streptozotocin-induced diabetic rats. Diabetes mellitus (DM) was induced in rats by intraperitoneal injection of streptozotocin (STZ). The indexes of the blood glucose, renal function and oxidative stress were observed. The DM rats were administrated with the AV for 8 weeks, the above-mentioned indexes were detected. The blood glucose level, BUN, 24 h urine protein excretion, urine volume, renal index, renal cortex's MDA level in model groups all increased significantly. Renal cortex's SOD and GSH activities decreased significantly compared with the normal control group (P < 0.05). The above-mentioned indexes were significantly improved by the AV treatment (P < 0.05). AV have protective effects on renal function of kidneys of streptozotocin-induced diabetic rats, and maybe via inhibition of the renal oxidative stress.