Nateglinide is a new quick action/short duration (QRSD) type of oral blood glucose regulator, and nateglinide immediate release tablets are used for patients with mild diabetes under the trade name of Fastic® tablets. In this study, we attempted to determine if it was possible to control both post-prandial blood glucose level (PBG) and fasting blood glucose level (FBG) for moderate or severe diabetes through controlled release of nateglinide. Enteric coated granules were selected for the administration form for controlled release of nateglinide, and three types of enteric coated granules were prepared having dissolution pH values of 5.5, 6.5 and 7.2. The three types of enteric coated granules were each administered separately or the enteric coated granules having an dissolution pH of 6.5 were administered simultaneous to administration of nateglinide immediate release tablets to normal beagle dogs just before feeding followed by measurement of plasma nateglinide concentration, plasma insulin concentration and blood glucose level. In the case of administering enteric coated granules alone (nateglinide: 9 mg/kg), the absorption of nateglinide was confirmed to tend to be delayed as the dissolution pH increased. In the case of an dissolution pH of 5.5, decreases in both PBG and FBG were observed. In the case of dissolution pH values of 6.5 and 7.2, only decrease in FBG was observed. In case of nateglinide immediate release tablets (nateglinide: 9 mg/kg), only decrease in PBG was observed. Decreases in both PBG and FBG were observed in the case of simultaneous administration of dissolution pH 6.5 enteric coated granules and nateglinide immediate release tablets just before feeding (nateglinide: 90 mg/head+60 mg/head). A correlation was observed between plasma nateglinide concentrations and blood glucose levels. On the other hand, there were no correlations observed between changes in plasma insulin concentrations and blood glucose levels. In case of nateglinide immediate release tablets (nateglinide: 150 mg/head), Decreases in both PBG and FBG were observed. However, the nateglinide controlled release formulation is more useful than the nateglinide immediate release tablets from the view point of avoidance of side effect, or of easy control of both PBG and FBG. On the basis of these results, the design of a controlled release formulation that contains nateglinide was suggested to enable control of both PBG and FBG for moderate and severe diabetes patients.
A new chemometric determination by high-performance liquid chromatography (HPLC) with photodiode array (PDA) detection was implemented for the simultaneous determination of naproxen sodium and pseudoephedrine hydrochloride in tablets. Three chemometric calibration techniques, classical least squares (CLS), principle component regression (PCR) and partial least squares (PLS) were applied to the peak area at multiwavelength PDA detector responses. The combinations of HPLC with chemometric calibration techniques were called HPLC-CLS, HPLC-PCR and HPLC-PLS. For comparison purposes the HPLC method called the classic HPLC method was used to confirm the results obtained from combined HPLC-chemometric calibration techniques. A good chromatographic separation between two drugs with losartan potassium as an internal standard was achieved using a Waters Symmetry® C18 Column 5 μm 4.6±250 mm and a mobile phase containing 0.2 M acetate buffer and acetonitrile (v/v, 40 : 60). The multiwavelength PDA detection was measured at five different wavelengths. The chromatograms were recorded as a training set in the mobile phase. Three HPLC-chemometric calibrations and the classic-HPLC method were used to test the synthetic mixtures of naproxen sodium and pseudoephedrine hydrochloride in the presence of the internal standard. The HPLC-chemometric approaches were applied to real samples containing drugs of interest. The experimental results obtained from HPLC-chemometric calibrations were compared with those obtained by a classic HPLC method.
The mechanism of binding of anti-inflammatory drug, nimesulide (NIM) with bovine serum albumin (BSA) was investigated by fluorescence, absorption, circular dichroism (CD) and lifetime measurements under simulative physiological conditions. The analysis of fluorescence data indicated the presence of both dynamic and static quenching mechanism in the binding. Various binding parameters have been evaluated. The CD spectral data revealed the decrease in α-helical content of BSA from 70.9% (in free BSA) to 42.03% (in bound form) thereby indicating the conformational change in BSA upon binding. The binding of NIM to BSA was also confirmed by absorption spectra. Based on the Förster's theory of non-radiation energy transfer, the binding average distance, r between the donor (BSA) and acceptor (NIM) was found to be 2.17 nm. The association constants of NIM-BSA decreased in presence of the common ions and other drugs thereby indicating the availability of higher concentration of free drug (NIM) in plasma.
The Jouyban–Acree model has been used to predict the solubility of paracetamol in water–ethanol–propylene glycol binary and ternary mixtures based on model constants computed using a minimum number of solubility data of the solute in water–ethanol, water–propylene glycol and ethanol–propylene glycol binary mixtures. Three data points from each binary solvent system and solubilities in neat solvents were used to calculate the binary interaction parameters of the model. Then the solubility at other binary solvent compositions as well as in a number of ternary solvents were predicted, and the mean percentage deviation (±S.D.) of predicted values from experimental solubilities was 7.4(±6.1)%.
Study was carried out to develop two simple, fast, accurate and sensitive spectrophotometric methods (A and B) for the determination of citalopram hydrobromide in commercial tablet formulations. In method A, UV spectrophotometer determined the contents of citalopram hydrobromide in tablets at 240 nm in methanol solvent. The linear range was 5—40 μg ml−1 with molar absorptivity 1.4×104 l mol−1 cm−1. While the method B based on the reaction of citalopram base as n-electron donor with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone as π-acceptors to give highly colored complex species that absorb maximally at 590 nm. Beer's law was obeyed in the concentration limit of 10—250 μg ml−1 with molar absorptivity 3.3×103 l mol−1 cm−1 for citalopram hydrobromide. The limits of detection and limit of quantification was calculated and found to be 5.2 μg ml−1 and 17.4 μg ml−1 respectively. The proposed methods were found to be rapid, accurate, precise and sensitive for the determination of citalopram hydrobromide in commercial tablet formulations with out interferences from common additives encountered.
From the roots of Scutellaria amabilis HARA, eleven new flavonoids, 5,7,2′-trihydroxy-8-methoxyflavone 7-O-β-D-glucopyranoside, 5,7,2′-trihydroxy-8-methoxyflavone 2′-O-β-D-glucopyranoside, 5,7-dihydroxy-8,2′-dimethoxyflavone 7-O-β-D-glucopyranoside, 5,7,2′-trihydroxyflavone 2′-O-β-D-glucopyranoside, 5,7,2′,5′-tetrahydroxyflavone 7-O-β-D-glucuronopyranoside, (2S)-5,7,2′,5′-tetrahydroxyflavanone, (2S)-5,7,2′,5′-tetrahydroxyflavanone 7-O-β-D-glucopyranoside, (2S)-5,7,2′,5′-tetrahydroxyflavanone 7-O-β-D-glucuronopyranoside, (2S)-7,2′-dihydroxy-5-methoxyflavanone 7-O-β-D-glucuronopyranoside, (I-2S)-I-5,II-5,I-7,II-7,I-2′,II-2′,II-5′-heptahydroxy-[I-6,II-6′]-flavanonylflavone and (I-2S)-I-5,II-5,I-7,II-7,I-2′,II-2′,I-5′,II-5′-octahydroxy-[I-6,II-6′]-flavanonylflavone, were isolated, together with ten known flavonoids, wogonin (5,7-dihydroxy-8-methoxyflavone), 5,7-dihydroxy-8,2′-dimethoxyflavone, (2S)-5,7,2′-trihydroxyflavanone, scutevulin (5,7,2′-trihydroxy-8-methoxyflavone), 5,7,4′-trihydroxy-8-methoxyflavone, alpinetin ((2S)-7-hydroxy-5-methoxyflavanone), 5,7,2′-trihydroxyflavone, 5,7,2′,5′-tetrahydroxyflavone, (2S)-7,2′-dihydroxy-5-methoxyflavanone and 5,7-dihydroxy-8,2′-dimethoxyflavone 7-O-β-D-glucuronopyranoside. The structures were determined on the basis of chemical and spectral data.
A method for sample preparation and analysis by high-performance liquid chromatography with UV detection (HPLC-UV) was developed for analysis of psoralen, bergapten and 5-[3-(4,5-dihydro-5,5-dimethyl-4-oxo-2-furanyl)-butoxy]-7H-furo[3-2-g]benzopyran-7-one in capsules and tablets employed in Brazil for certain illnesses. The linearity, accuracy, the inter- and intra-day precision of the procedure were evaluated. Analytical curves for furanocoumarins were linear in the range of 1.0—50.0 μg/ml. The recoveries of the furanocoumarins in the products analyzed were 97.3—99.5%, and the percent coefficient of variation for the quantitative analysis of the furanocoumarins in the analyses was under 5%. For inter-equipment study gas chromatography (GC) was employed.
Two new prenylated xanthones, afzeliixanthones A (1) and B (2), together with three known xanthones (3—5) and two phytosterols, β-sitosterol and stigmasterol, were isolated from the CH2Cl2/MeOH (1 : 1) extract of the stem bark of Garcinia afzelii ENGL. collected in the South West Province of Cameroon. Structures were mainly established using one and two-dimensional NMR and mass spectroscopies. The antioxidant activities of the crude extracts as well as the new compounds (1) and (2) were evaluated.
(+)-18-Crown-6 tetracarboxylic acid (18C6H4) has been used as a chiral selector for D/L-amino acids in HPLC, where L-isomer is usually eluted prior to D-isomer, except for the case of serine. To clarify why serine exhibits the reverse order for the elusion, the chiral interactions of D- and L-serines with (+)-18C6H4 were investigated by the X-ray single crystal analyses, together with the case of D- and L-glutamic acids, which exhibit the usual elution order in HPLC. The backbone structures (amino, Cα-H and carboxyl groups) of these four amino acids showed the nearly same interaction with (+)-18C6H4 despite their different chirality. In contrast, the hydroxyl group of L-serine side chain formed a hydrogen bond with the carboxyl group of (+)-18C6H4, whereas such a interaction was not formed for the side chain of D-serine and D- and L-glutamic acids. Thus, it was shown that the exception of D/L-serine from the first elution rule of L-isomer in HPLC is due to the presence and absence of a hydrogen bond formation of its side chain OH group.
A series of symmetrical 1,5-diamidoanthraquinone derivatives with potentially bioreducible groups has been synthesized and their cytostatic activity against the panel of various cancer cell lines in vitro has been studied. Preliminary structure–activity relationships were established. The results indicated that compounds 5 and 18 exhibited significant potent cytotoxicity at 1.24—1.75 μM for Hepa G2 cell line; compounds 5, 16, and 18 exhibited cytotoxicity at 0.14—1.82 μM for 2.2.15 cell line as determined by XTT colorimetric assay. Two structurally related compounds, mitoxantrone and adriamycin, were tested in parallel as positive controls. In addition, it was found that compounds 5 and 18 were a more potent and specific human hepatoma cell line than mitoxantrone and showed comparable activity to adriamycin. Among them, compound 18 was the most potent for 2.2.15 cells. We have demonstrated that the anthraquinone moiety is essential for activity and that less sterically hindered substituents contribute to enhanced in vitro efficacy. Implications for amidoanthraquinone cytotoxicity as potential anticancer agents are discussed. We further delineate the nature of the pharmacophore for this class of compounds, which provides a rational basis for the structure–activity relationships.
A monolithic osmotic pump tablet (MOPT) of Traditional Chinese Medicine Compound Recipe (TCMCR) was successfully prepared and active components of Jingzhiguanxin prescription which has been widely used in China and Japan was selected as model drug. Analysis methods of maker compound in vitro of danshensu, paeoniflorin and safflor yellow A were built, and different methods were compared by f2 factors. The results showed that there were fine correlation among them. Finally UV method of safflor yellew A was chosen to determine the release of the drugs, which was fast, convenient, met the need of determination and could represent other methods. During the research, single factor influence selection was studied emphatically. It showed that there were significant influence between different varieties and quantity of osmotic promoting agents, different kind of retardants, different varieties and quantity of PEG (polyethylene glycol) and membrane weight. However, no significant influence existed between different quantity of retardants and SDS, different membrane orifices and methods of dissolution. Based on the single factor influence selection, an optimal formulation was decided, and three maker compounds of Jingzhiguanxin MOPT could isochronous release and at the same time they had good zero order release characteristics to 8 h. Paeoniflorin release in vivo was estimated by deconvolution, the results shown that there were a good in-vitro in-vivo correlation (r=0.9571).
A new series of radioiodinated analogues of 1-[2-(3,4-dimethoxyphenyl)ethyl]-4-(3-phenylpropyl)piperazine (SA4503) was synthesized and evaluated as a potential brain sigma-1 receptor imaging ligands by single photon emission computed tomography (SPECT). Iodinated analogues of SA4503 (4a—c) were prepared from piperazine in a high yield. The in vitro competition binding studies using [3H] DTG (sigma-1, 2), [3H] (+)-pentazocine (sigma-1), and [3H] DTG in the presence of carbetapentane (sigma-2) as sigma receptor selective radioligands were revealed that iodinated analogues 4a—c possess high affinities to sigma receptors (IC50: 4a=7.1, 4b=31.0, and 4c=77.3 nM). In particular, the affinity of 4a, bearing iodine at ortho position on the phenyl ring, was 4.4 times greater than SA4503, and 3 times greater than that of haloperidol. The meta-iodo analogue 4b was the same to SA4503, the lead compound. The radioiodinated derivatives, [125I] 4a, 4b were synthesized no-carrier-added from the corresponding tributyltin precursors by the iododestannylation reaction with high yields. The binding of [125I] 4a, 4b have been characterized in the rat brain membranes. These compounds were indicated single population binding to sigma receptor with high affinity (4a: Kd=1.86±0.34 nM, Bmax=205±28.9 fmol/mg protein, 4b: Kd=3.30±0.51 nM, Bmax=231.5±13.8 fmol/mg protein). In vitro blocking studies were confirmed that the high specificity of 4a, 4b. These results suggest that radioiodinated 4a and 4b are promising sigma receptors imaging ligand for pursuing further in vivo studies.
Benzo[c]phenanthridine alkaloids such as oxynitidine, oxysanguinarine, oxyavicine and phenolic oxyfagaronine were synthesized from easily available starting benzonitriles 5 and toluamides 6 using a lithiated toluamide-benzonitrile cycloaddition reaction. The coupling reaction provided 3-arylisoquinolinones that were transformed to the benzo[c]phenanthridones. This method is highly efficient and could be useful for preparing diverse substituted aromatic benzo[c]phenanthridine compounds on a multi gram scale.
Enhancement of skin permeability of salicylate from non-aqueous vehicle by ion-pair formation with either alkylamines or benzylamine as model cationic ions was examined in excised guinea pig dorsal skin. Solubility of salicylate in isopropyl myristate (IPM) was increased by the addition of either alkylamines or benzylamine as counter ions. The increase was more significant in the presence of amines with longer alkyl chains. Flux of salicylate increased in the presence of these amines due to the increase in the solubility. Maximum flux was observed in the presence of n-hexylamine, which induced an 11-fold increase due to 137-fold increase in solubility. Flux and permeability coefficients of salicylate in the presence of n-butylamine, n-hexylamine, iso-octylamine and benzylamine as counter ions in IPM were larger than those of the non-ionic form of salicylic acid. Flux of 3-methylsalicylate (3-CH3 substituent) and that of 5-hydroxysalicylate (5-OH substituent) were smaller than that of salicylate in the presence of n-hexylamine. After partition to the skin surface, the ion-pair is suggested to dissociate and permeate separately according to the study using lidocaine as the counter ion. Flux of salicylate increased in the presence of benzylamine as the counter ion by the addition of 15% ethanol and 15% ethanol plus 1% l-menthol due to further improvement in the solubility as well as an increase in the permeability coefficient.
Stereocontrolled syntheses of model compounds related to a major antigenic epitope against antibupleurum 2IIc/PG-1-IgG from antiulcer pectic polysaccharide are described. A trisaccharide derivative (13) was prepared as a precursor and a novel and simple approach for the rational design of a glycocluster and glycodendrimer was developed, through the syntheses of the fluorescence-labeled glycocluster (2) and glycodendrimer (3).
High-performance liquid chromatography (HPLC) with UV detection for the simultaneous determination of the free form of p-hydroxymethamphetamine (p-OHMA) and its metabolite, glucuronide (p-OHMAG) was accomplished for the first time. We achieved this by employing 1) an ion pair reagent for retention of sample to a solid-phase extraction (SPE) cartridge, Sep-Pak® Light C18 and 2) a simple two-step stepwise elution technique for subsequent ion pair RP-HPLC. The proposed method was optimized for resolution of p-OHMAG, p-OHMA and MA. The method was successfully applied to urine samples collected from MA abusers.
Mycelia of Antrodia cinnamomea were extracted with chloroform and hot water. A neutral polysaccharide named ACN2a separated from the water extract was purified using 10% CCl3COOH, and repeated column chromatography on HW-65 and DE-52 cellulose. Its structure was determined by chemical and spectroscopic analyses. ACN2a was composed of Gal, Glc, Fuc, Man and GalN (in the ratio 1 : 0.24 : 0.07 : 0.026 : faint), in which an α-D-(1→6)-Gal linkage accounted for 73% of all linkages. The ratio of branch points was about 16% of the total residual numbers, and branches were attached to C-2 of galactosyl residues of the main chain. ACN2a had an average molecular weight of 12.9×105 Daltons, [α]D25=+115° (c=0.44, H2O); [η]=0.0417dl·g−1, Cp=0.2663 cal/(g·°C). The hepatoprotective effect of ACN2a was evaluated using a mouse model of hepatic injury that was induced by Propionibacterium acnes (P. acnes) and lipopolysaccharide (LPS). The administration of ACN2a (0.4, 0.8 g/kg/d, p.o.), significantly prevented increases in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzyme activities in mice treated with P. acnes–LPS, indicating hepatoprotective activity in vivo.
Trypsin treatment is frequently used during chromosome preparation for removal of cellular contaminants, and ethidium bromide (EB) staining of bands is often used to facilitate high-resolution observations by optical microscopy. However, conventional optical microscopy is unable to visualize potential aberrations of chromosome structures caused by these physicochemical treatments. In this article, we use atomic force microscopy (AFM) in the tapping mode to obtain and analyze high-resolution images of chromosome surface structure damage associated with trypsinization and EB treatment. According to our results, the trypsin-based digestion effects became more severe as incubations increased across a range from 10 to 40 s; a digestion time of 10 to 20 s appeared to be most suitable for observation by AFM. In terms of chromosomal damage induced by EB treatment, addition of EB into the media of cultured human blood cells induced chromosomal breakage in a dose-dependent fashion, and the results indicate centromeric region damnifyed severer than arms. Together, these results indicate that EB staining and the standard chromosomal preparative techniques of trypsinization can induce chromosomal damage that may affect the observed results.
The methanol-eluted fraction of the methanolic extract from the tubers of Gymnadenia conopsea was found to show radical scavenging activities for DPPH and super oxide anion (·O2−) radicals. Three new glucosyloxybenzyl 2-isobutylmalates, gymnosides VIII, IX, and X, were isolated from this natural medicine together with 58 known constituents. The stereostructures of gymnosides were elucidated on the basis of chemical and physicochemical evidence. In addition, the phenanthrene and dihydrostilbene constituents showed radical scavenging activities and suggested the following structural requirements on radical scavenging activities; a) phenanthrenes: 1) dihydrogenation at the 9,10-positions enhances the activities, 2) the 1 or 3-p-hydroxybenzyl group enhances the activities; b) dihydrostilbenes: 1) methylation of the 3′-position reduces the activities, 2) the 2- and/or 6-p-hydroxybenzyl groups enhance the activities.
A novel intragastric floating drug delivery system (FDDS) has been prepared by pulsed plasma-irradiation on the double-compressed tablet of 5-Fluorouracil (5-FU) as a core material with outer layer composed of a 68/17/15 weight ratio of Povidone (PVP), Eudragit RL (E-RL) and NaHCO3. The plasma heat flux caused the thermal decomposition of NaHCO3 to generate carbon dioxide and the resultant gases were trapped in bulk phase of outer layer, so that the tablets turned to have a lower density than the gastric contents and remained buoyant in simulated gastric fluid for a prolonged period of time. In addition, the release of 5-FU from the tablet is sustained by occurrence of plasma-induced crosslink reaction on the outer layer of tablet and the release rate of 5-FU can be well controlled by plasma operational conditions.
The antiviral drug acyclovir (Ac, 1) was treated with triplet excited ketones, which have been generated in thermal decomposition of 3-(hydroxymethyl)-3,4,4-trimethyl-1,2-dioxetane (HTMD), in the dark. Three major oxidation products were detected by means of spectroscopic measurements. The products were (2-hydroxyethoxy) methyl spiroiminodihydantoin (2), (2-hydroxyethoxy) methyl (amino)-2-imino-1,2-dihydroimidazole-5-one (3), and 2,2-diamino-4-[(2-hydroxyethoxy) methyl) amino)-5-[2H]-oxazolone (4). Equal amounts of type I and type II photooxidation products were found, as could be established by comparison with predominant type I (riboflavin) and type II (rose bengal) photosensitizers. The concentration and time profiles for the HTMD-induced oxidation of Ac were also determined. The participation of singlet oxygen in HTMD-induced oxidation was confirmed by the substantial D2O effect in the formation of spiroiminodihydantoin (2).
A two-step binding assay for globotriaosylceramide (Gb3) content was developed by histidine-tagging strategy, which is a well-established method for the purification of recombinant proteins. The complete binding of the recombinant His-tagged Shiga toxin 1B subunit (1B-His) (1 μg/ml) to the standard Gb3 adsorbed on a multi-well H type plate was observed within 30 min at 37 °C; and its binding could be visualized by the following applications of HisProbe-HRP (8 μg/ml) and tetramethylbenzidine (TMB) peroxidase substrate. The 1B-His binding assay was linear over the range of 1 to 100 ng of Gb3 per well. The binding of 1B-His was specific to Gb3 separated from HeLa cells, and no major cross-reactivity of other glycolipids in Folch's lower fractions extracted from HeLa cells was detected. The glycolipids in Folch's lower fractions from HeLa cells, human fibroblasts and mouse heart were suitable for this assay, but the further purification was needed for glycolipids from human plasma, thus sample preparation is critical factor for the reliable determination of Gb3 content. The 1B-His binding to Gb3 was inhibited by the addition of galactose, but not mannose. This 1B-His binding assay will be useful not only for the determination of Gb3 content, but also for screening for the compounds which inhibit the toxin-binding to Gb3. The strategy of our present method may be applicable for other binding assay, such as Cholera toxin B-subunit for ganglioside GM1.
Motions of an α-cyclodextrin (α-CD) molecule on a dodecyl chain adopting the all-trans conformation were investigated in the presence of water by molecular dynamics simulations with CVFF force fields, where the trimethylammonium group of dodecyltrimethylammonium bromide (DTAB) is protruded outside the secondary hydroxyl rim of α-CD (the secondary-in structure). The α-CD molecule shuttled rapidly on the chain without decomplexation. This rapid motion is consistent with the NMR data. The plane formed by 6 O4 atoms of α-CD is most populated between the C6 and C7 atoms of DTAB. This structure is very close to that estimated by NMR. The α-CD molecule underwent a restricted rotation in a range of 60° with regard to the plane of the dodecyl chain: this plane at the most population is middle between the two diagonal lines of the normal hexagon formed by 6 O4 atoms of α-CD. The published NMR data were reanalyzed in terms of the rotation angle, and a slightly better structure was obtained. The distortion of the α-CD cavity from the normal hexagon was decreased upon complex formation with DTAB. The deviation of the center of α-CD from the center of the dodecyl chain predicted by molecular dynamics simulations is consistent with the NMR data. The secondary-in structure is energetically more stable than the primary-in structure, as calculated by molecular mechanics with CVFF and Amber force fields. This result is consistent with the NMR data. Molecular dynamics simulations were also carried out for the primary-in structure. Some of the results are close to those of the secondary-in structure.
One new and eight known ceanothane- and lupane-type triterpenes were isolated from the root bark of Ziziphus cambodiana PIERRE (Rhamnaceae). Based on spectral analyses, the structure of the new compound was elucidated as 3-O-(4-hydroxy-3-methoxybenzoyl)ceanothic acid (3-O-vanillylceanothic acid) (1), while the known compounds were identified as lupeol (2), betulinaldehyde (3), betulinic acid (4), 2-O-E-p-coumaroyl alphitolic acid (5), alphitolic acid (6), zizyberanalic acid (7), zizyberenalic acid (8) and ceanothic acid (9). Compounds 1, 5 and 8 exhibited significant in vitro antiplasmodial activity against the parasite Plasmodium falciparum, with inhibitory concentration (IC50) values of 3.7, 0.9 and 3.0 μg/ml, respectively. Compounds 1 and 3—8 showed antimycobacterial activity against Mycobacterium tuberculosis with respective MIC values of 25, 25, 25, 12.5, 50, 50 and 100 μg/ml.
Hyosgerin, a new optically active coumarinolignan, has been isolated and characterized along with three other coumarinolignans, venkatasin, cleomiscosin A and cleomiscosin B, from the seeds of Hyoscyamus niger L. The structure was determined on the basis of spectroscopic analysis and chemical conversion. The optical properties and absolute stereochemistry of these coumarinolignans have also been studied and discussed.
A new triterpene and two new natural dibenzocyclooctadiene lignans were isolated from the stems of Schisandra propinqua. In addition, three known lignans, octadecanoic acid, 2,3-dihydroxypropyl ester and β-sitosterol were isolated. The structures of the new triterpene and new natural products were elucidated base on spectral analysis, including 1D and 2D NMR experiments. The isolates were tested for their cytotoxic effects against several tumor cell lines by MTT assay.
From the aerial parts of Scoparia dulcis L. (Scrophulariaceae) grown in Vietnam, four scopadulane-type diterpenoids (4—7), of which 7 is new and was given the trivial name scopadulcic acid C, together with nine known compounds were isolated. Their structures were elucidated by spectroscopic analyses. The absolute configurations of 4—7 were ascertained by applying the modified Mosher's method to iso-dulcinol (6). The isolation of the lignans nirtetralin and niranthin for the first time from S. dulcis is also of chemotaxonomic interest. The cytotoxic activity in KB cells, inhibitory effect on LPS/IFNγ-induced NO production, inhibition of multidrug resistance (MDR), and antibacterial and antifungal activities of the scopadulane-type diterpenoids 4—7 were examined in this study.
Five metabolites tentatively called GS-1 (1)—5 (5) from Gelasinospora santi-florii, and four tentatively called EQ-4 (6), EQ-6 (7)—8 (9) together with 1—4 from Emericella quadrilineata have been isolated in a screening study on immunomodulatory fungal constituents. Among these nine metabolites, EQ-7 and 8 have been unknown. This time, the structures of GS-4 which has previously been isolated, EQ-7, and -8 have been determined to be (4R,4aS,9aR)-1,9a-dihydronidulalin A (4), (4S,4aR,9aR)-4a-carbomethoxy-1,4,4a,9a-tetrahydro-4,8-dihydroxy-6-methylxanthone (8), and 9-hydroxymicroperfuranone (9), respectively, and the six other metabolites have been identified. On bioassay, a dihydroxanthone, nidulalin A (1), a hexaketide, sordarial (5), and a xanthone, pinselin (7) have displayed significant immunosuppressive activities. The structure–activity relationships of these constituents have also been discussed.
Reduction of a double bond at C-1 of 1,4-dien-3-one steroids 7 and 8 with LiAl2H4 in THF or NaB2H4 in MeOH and H2O gave stereospecifically [1α-2H]-labeled 4-en-3-one steroids 9 and 10, respectively. When the deuterated solvents, MeO2H and 2H2O, were used for the reaction of steroid 8 with NaB2H4, [1α,2ξ-2H2]-labeled compound 10 was produced. This indicates that the reaction proceeds through the initial hydride attack at the C-1α position, followed by ketonization of the 2-en-3-ol intermediate.
Five new triterpenoid saponins, platycoside H [3-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl-2β,3β,16α,23-tetrahydroxyolean-12-en-28-oic acid 28-O-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranoside], platycoside I [3-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl-2β,3β,16α,23-tetrahydroxyolean-12-en-28-oic acid 28-O-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranoside], platycoside J [3-O-β-D-glucopyranosyl-2β,3β,16α,23-tetrahydroxyolean-12-en-28-oic acid 28-O-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranoside], platycoside K [3-O-β-D-glucopyranosyl-(1→3)-β-D-glucopyranosyl-2β,3β,16α,23,24-pentahydroxyolean-12-en-28-oic acid], and platycoside L [3-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl-2β,3β,16α,23,24-pentahydroxyolean-12-en-28 oic acid], and three known triterpenoid saponins, platycoside F, platycoside B, and platycoside C, were isolated from the roots of Platycodon grandiflorum A. DC. Their chemical structures were elucidated on the basis of their spectral data and chemical evidence.
The phase behavior of poly(ethylene glycol) grafted liposomes (PEG-liposomes) was investigated by differential scanning calorimetry (DSC), dynamic light scattering (DLS) and cryo-transmission electron microscopy (cryo-TEM). PEG-liposomes were prepared from mixtures of dipalmitoyl phosphatidylcholine (DPPC) and distearoyl phosphatidylethanolamine with a covalently attached PEG molecular weight of 2000 (DSPE-PEG2000). From the results of DLS measurements, the coexistence of PEG-liposomes and small molecular assemblies were confirmed at mole fractions of DSPE-PEG2000 above about 0.1. Moreover, it was confirmed that small molecular assemblies were disk micelles by cryo-TEM. However, the phase transition enthalpies of PEG-liposomes were hardly changed according to the DSC measurement, though the mole fraction of the PEG lipid increased. From these results, it was suggested that the phase transition enthalpies hardly changed despite mixed micelles being formed because the bilayer structure of the disk micelle maintains high cooperativity between the DPPC molecules.
A sensitive spectrofluorimetric procedure for the determination of paroxetine–HCl in pharmaceutical formulations and human plasma has been described. The native fluorescence of the drug has been studied under different conditions. Maximum fluorescence intensity was obtained in methanol at 340 nm using 290 nm for excitation. Different surfactants showed negative effect on the fluorescence intensity of paroxetine–HCl. Regression analysis of Beer's plot showed good correlation (r=0.9999) between fluorescence intensity and concentration over the range of 0.05—0.40 μg ml−1 with lower limit of detection (LOD) of 0.015 μg ml−1. The drug was successfully determined in its tablets with average % recovery of 98.00±0.99% which was in accordance with those given by a compendial method. The method was also applied to the determination of paroxetine–HCl in spiked human plasma with average recovery of 77.70±1.06%.
Three new saponins, capilliposide A (1), capilliposide B (2) and capilliposide C (3) were isolated from an ethanol extract of Lysimachia capillipes. Their structures were determined by 1D and 2D NMR (1H–1H COSY, HMBC, HMQC, DEPT and TOCSY) techniques, MS, and hydrolysis. Capilliposide B showed significant cytotoxicity against human A-2780 cells.
Bioassay-directed fractionation of the stem bark extract of Erythrina variegata L. has resulted in the isolation of three new isoflavones: 5,4′-dihydroxy-8-(3,3-dimethylallyl)-2″-methoxyisopropylfurano[4,5:6,7]isoflavone (1), 5,7,4′-trihydroxy-6-(3,3-dimethylallyloxiranylmethyl)isoflavone (2), 5,4′-dihydroxy-8-(3,3-dimethylallyl)-2″-hydroxymethyl-2″-methylpyrano[5,6:6,7]isoflavone (3) and a new isoflavanone, 5,4′-dihydroxy-2′-methoxy-8-(3,3-dimethylallyl)-2″,2″-dimethylpyrano[5,6:6,7]isoflavanone (4) together with seven known compounds, euchrenone b10 (5), isoerysenegalensein E (6), wighteone (7), laburnetin (8), lupiwighteone (9), erythrodiol (10), and oleanolic acid (11). The structures were determined on the basis of spectroscopic analyses and chemical evidence. The effect of these compounds on the proliferation of rat osteogenic sarcoma (UMR106) is also reported.
From the bark of Cryptomeria japonica were isolated sugikurojins I (1) and J (2), and an abietane derivative (3) was obtained for the first time as a natural product. These structures were elucidated primarily through extensive NMR experiments. Sugikurojin I (1) has a unique skeleton incorporating an abietane diterpene and a 1,10-secocadinane sesquiterpene. Sugikurojin J (2) is a peroxyester of hydroxyabietane diterpene and isopimarane acid diterpene. Compound 3 was p-quinone acid, which occurred by cleavage between C-7 and C-8 of sugiol; it was deduced to [4′-isopropyl-1(S),3,3-trimethyl-3′,6′-dioxo-bicyclohexyl-1′,4′-dien-2(R)-yl]-acetic acid. Also obtained in this investigation were three known diterpenes (4—6).
Two bisanthraquinones named (+)-epicytoskyrin (1) and (+)-1,1′-bislunatin (2) were produced by the endophytic fungus from a tea plant, which is a species closely related to Diaporthe phaseolorum strain sw-93-13. The chemical structures of the metabolites were elucidated on the basis of the physicochemical properties including the circular dichroism (CD) spectrum.
To explore physicochemical properties of 3-phenyl-5-acyloxymethyl-2H,5H-furan-2-ones derivatives responsible for their antifungal activity, a quantitative structure activity relationship, Hansch approach was applied on sixteen compounds of above mentioned derivatives. Various physicochemical descriptors and reported minimum inhibitory concentration values of different fungal organisms were used as independent variables and dependent variable respectively. The best models for twelve different fungal organisms were first validated by leave-one-out cross validation procedure. Further, bootstrapping method was adopted to assess the robustness of the models. It was revealed that electronic parameters were found to have overall significant correlationship with antifungal activity and these studies provide an insight to design new molecules.
A high-performance liquid chromatograph with mass spectrum detection (HPLC-MS/APCI) method has been established for simultaneous determination of ten major bioactive components of Naodesheng injection including safflor yellow A, puerarin, daidzein, ginsenosides (Rg1, Rg2, Rb1, Rd, Re, Rh1), and notoginsenoside R1. The separations were carried out with a Luna C18 column (5 μm, 150×4.6 mm, Phenomenex, U.S.A.) with a stepwise gradient elution of the mobile phase consisting of water (0.1% of formic acid, v/v)–methanol (0 min, 70 : 30; 8 min, 30 : 70; 20 min, 10 : 90) at a flow-rate of 0.8 ml/min. The proposed method was applied to analyze five various Naodesheng injections and produced data with acceptable linearity, repeatability, precision and accuracy having lower limits of quantitation (LLOQs) of 0.02—0.2 μg. The calibration curves were linear in respective range for all compounds, all of them with coefficients of determination above 0.9900. The intraday precessions were less than 5.0%. The proposed method is accurate, sensitive and simple, a useful alternative for routine analysis in the quality control of Traditional Chinese Medicine.
Polymer-supported dicyanoketene acetal (poly-DCKA-1), synthesized by copolymerization of a DCKA bearing a 4-vinylbenzyl group with ethyleneglycol dimethacrylate, was found to be an excellent recyclable catalyst for the three-component Mannich-type reaction of aldehydes, aromatic amines, and TMS enolate of ethyl isobutyrate in water as the sole solvent.