Determination of colchicine content in Colchicum hierosolymitanum and Colchicum tunicatum under cultivation

Corms of Colchicum hierosolymitanum and Colchicum tunicatum were collected, identified and planted under field condition. We report here and for the first time the presence of colchicine in an appreciable amount in both species. The effect of different NPK fertilizer levels on colchicine content of the two Colchicum species at different growth stages were evaluated by HPLC. Results indicated that increasing NPK fertilizer levels significantly improve colchicine content in different plant parts and stages. The highest colchicine content observed in corms was at maturity stage 0.766 mg/g and 0.688 mg/g dry weight with C. hierosolimitanum and C. tunicatum, respectively.     

Relative efficiency calibration of Ge(Li) detector in low energy region

The relative gamma-ray intensities in the energy region between 122 and 411 keV in the decay of¹⁵²Eu were measured by using a Ge(Li) detector. Its efficiency calibration was carried out with the radioactive sources of²⁴¹Am,⁵⁷Co,²⁰³Hg,¹³⁷Cs,¹³³Ba,⁷⁵Se,¹⁶⁹Yb and¹⁹²Ir.     

Three new cholinesterase-inhibiting cis-clerodane diterpenoids from Otostegia limbata

Three new tricyclic cis-clerodane type diterpenoids trivially named as limbatolide A (1), limbatolide B (2) and limbatolide C (3) have been isolated from the roots of Otostegia limbata along with two known compounds; oleanic acid and beta-sitosterol. The structure elucidation of the new compounds was based primarily on two-dimensional (2D) NMR techniques. Compounds 1-3 displayed inhibitory potential in a concentration-dependent manner against acetylcholinesterase (AChE; EC 3.1.1.7) and butyrylcholinesterase (BChE; EC 3.1.1.8) enzymes, respectively.     

Structure determination of bioactive galloyl derivatives by NMR spectroscopy

The investigation of the chemical constituents of Symplocos racemosa Roxb led to the isolation of two new glycosides, symcomoside A (1) and symcomoside B (2), together with one known glycoside, tortoside C (3), which is reported for the first time from this plant. The structures of the new compounds were determined by 1D and 2D homonuclear and heteronuclear NMR spectroscopy, from chemical evidence and by comparison with published data for closely related compounds. Symcomoside B (2) showed potent inhibitory activity against alpha-glucosidase in a concentration-dependent fashion with an IC50 value of 0.733 +/- 0.033 mM whereas symcomoside A (1) showed very weak inhibitory activity against alpha-glucosidase (9.90% in 0.70 mM).     

Radiochemical analysis of toxic elements in biological materials

A radiochemical method for simultaneous determination of toxic elements (Hg, Cd and Sb) in biological materials has been developed. The procedure involves the irradiation of samples with thermal neutrons and quantitative one-step separation in 0.1M 4-(5-nonyl)pyridine/benzene from 2.0M hydrochloric acid followed by gamma-ray spectrometry. The procedure is applied for the analysis and to the studies of distribution of these elements in IAEA-RMs, human serum and hair samples. Results obtained are found to be in good agreement with those reported in the literature.     

Activity concentrations of 210Po in the soft parts of cockle (Anadara granosa)at Kuala Selangor, Malaysia

Polonium-210 has been measured in the soft parts of Anadara granosa purchased at Kuala Selangor, West Coast of Malaysia in August 2001, April 2002 and September 2002. It is shown that ²¹⁰Po is non-uniformly distributed within cockles of various sizes (i.e., 2.5, 3.0, 3.5 and 4.0 cm of shell length) and the concentration of ²¹⁰Po in the soft parts of cockle was significantly different (p<0.05) due to sampling date. The highest value was observed in the smallest cockle with a shell length of 2.5 cm (411.6±26.16 Bq/g dry wt.). It is clear that there is an allometric relationship between ²¹⁰Po activity concentration and individual cockle weight. This may reflect on the differences of metabolic rate and growth age of cockles. The mean activity concentration of ²¹⁰Po measured in Kuala Selangor filtered water were 1.75±0.17, 0.79±0.08 and 1.13±0.20 Bq/kg for August 2001, April 2002 and September 2002, respectively. The yield concentration factors for ²¹⁰Po in the soft parts of cockles varies from 27.3^. 10³ to 106.9^. 10³. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of 5-Substituted 1,3-Dimethylpyrazolo[4,3-<Emphasis Type="Italic">e</Emphasis>][1,2,4]triazines

Summary.  A novel method for the synthesis of a new series of 5-substituted 1,3-dimethyl pyrazolo[4,3-e][1,2,4]triazines is described. The new synthetic strategy is based on the classical Bischler 1,2,4-benzotriazine synthesis. This approach involves the preparation of 5-hydrazinopyrazole from 5-chloro-1,3-dimethyl-4-nitropyrazole followed by acylation and nitro group reduction to form the corresponding 4-amino-3-(acylhydrazino)pyrazoles. Intramolecular oxidative cyclization of the latter derivatives, using polyphosphoric acid, produced the respective target pyrazolotriazines.     

Synthesis of 5-Substituted 1,3-Dimethylpyrazolo[4,3-e][1,2,4]triazines

A novel method for the synthesis of a new series of 5-substituted 1,3-dimethyl pyrazolo[4,3-e][1,2,4]triazines is described. The new synthetic strategy is based on the classical Bischler 1,2,4-benzotriazine synthesis. This approach involves the preparation of 5-hydrazinopyrazole from 5-chloro-1,3-dimethyl-4-nitropyrazole followed by acylation and nitro group reduction to form the corresponding 4-amino-3-(acylhydrazino)pyrazoles. Intramolecular oxidative cyclization of the latter derivatives, using polyphosphoric acid, produced the respective target pyrazolotriazines.     

Isotope shift studies in the spectra of Gadolinium in UV region and term shifts of high even levels of Gd I

Isotope shift Δσ(¹⁵⁶Gd?¹⁶⁰Gd) is reported in 70 spectral lines of neutral gadolinium atom (Gd I) in the 3290- 3920 Å region providing isotope shift data in UV lines of Gd I spectrum for the first time. The measurements were carried out on a photoelectric recording Fabry-Perot Spectrometer using highly enriched isotopic samples of gadolinium. Term isotope shifts ΔT(¹⁵⁶Gd?¹⁶⁰Gd) have been evaluated for 48 high lying even parity energy levels of Gd I using this data; new ΔT values have been obtained for 24 levels. Electronic configurations 4f⁷5d6s6p, 4ff⁷5df²6p and 4f⁸5d6s assigned earlier to these even levels have been either confirmed or configuration mixing pointed out in some of these levels. Probable assignment of 4f⁸5d6s configuration to 8 even levels between 32 930 and 35 500 cm^-1 have been confirmed.     

Synthesis and anti-HIV-1 activity of novel 10-thiaisoalloxazines,a structural analog of C-5 and/or C-6 substituted pyrimidine acyclonucleoside

A series of novel 10-thiaisoalloxazine derivatives bearing an alkoxymethyl or benzyloxymethyl moiety at the N-1 position has been synthesized through the bromination of 1-substituted-5-hydroxyuracils and subsequent condensation with aminobenzenethiol in a one-pot reaction. Contrary to the previous report, the formation of intermediary 5,6-diethoxy-5-hydroxy-5,6-dihydrouracil seems to be not the necessary factor for the formation of the thiaisoalloxazines, since the reaction proceeds in tetrahydrofuran (THF) or acetonitrile far more smoothly than in ethanol. The anti-human immunodeficiency virus (HIV)-1 activity of the resulted thiaisoalloxazine derivatives was evaluated in lymphocyte cells based on the inhibitory activity against the viral-induced cytopathic activity. Among the derivatives, compounds 6, 7, and 8 bearing an alkoxymethyl moiety at the N-1 position exhibited modest inhibitory activity towards the cytotopathic effect of HIV-1.