Kinetic and thermodynamic characteristic of Aspergillus awamori EM66 levansucrase.

This study is a new trial aimed to solve levansucrase high cost and levan associated problems during the purification process. Also, kinetic and thermodynamic study was done to compare between the partial pure (PP) and purified forms (PF). Within this context, Aspergillus awamori EM66 levansucrase was produced constitutively (5.44 U.mL-1) using rice straw as the sole medium component. The enzyme was partially purified and was eluted as single protein after two purification steps. Its molecular weight was determined to be 44.5 KDa. The optimum temperature recorded 40 °C for both enzyme forms. While, the purification process lowering the enzyme pH from 5.2 to 4.0. The NaCl concentrations (0.5-3.0 M) pointed to the halophilic nature of the enzyme. The PP form retained about 76% of its original activity after 1 h at 55 °C while the other retained about 57% after 45 min. at the same temperature. The kinetic parameters Km and Vmax concluded that the PF was more efficient than the PP. The thermodynamic parameters such as Ea, Ed, T1/2, D-value, also, ∆G*, ∆H* and ∆ S* for activation recorded that the PP had higher stability than the PF.

Computer-aided identification of novel anticancer compounds with a possible dual HER1/HER2 inhibition mechanism.

HER1 and HER2 are frequently overexpressed in human tumors where they drive cellular proliferation. For this reason they are considered important targets in anticancer therapy with dual HER1/HER2 inhibitors being recently approved and marketed. In this paper we report the identification of a series of compounds with anticancer activity by a combined virtual screening approach on the kinase domains of HER1 and HER2. 6 hit compounds that present a sub- or low-micromolar activity in two cell-based assays, were initially identified and a subsequent design cycle led to the synthesis of a compound with nanomolar activity in the cell-based assays.

Synthesis and antioxidant activity of new pyridines containing gallate moieties.

Pyridines containing the galloyl moiety have been prepared utilizing 4-acetyl pyrogallol. In addition, fused pyridines were synthesized from the obtained pyridines via further chemical transformations. The results indicated that compound 4a showed stronger DPPH scavenging activity than the other compounds, and the scavenging effect decreased in the following order 4a > t-BHQ > 2a > 2b > 3a > 3b > 4b. Accordingly, other antioxidant assays were conducted for 4a. The results suggested that compound 4a could be a good antioxidant candidate. The absence of mortality of rats receiving 5000 mg/kg body weight of 4a as single oral dose may indicate that it could be a safe antioxidant and may be used for further studies.

Synthesis, biological and medicinal significance of S-glycosido-thieno[2,3-d]-pyrimidines as new anti-inflammatory and analgesic agents.

Several 2-thioglycosides were prepared. Glycosylation of 2-thioxo-thieno[2,3-d]-pyrimidines 5a,b with 1-bromo-2,3,5-tri-O-acetyl-alpha-d-arabinofuranosyle 7, 2,3,4,6-tetra-O-acetyl-alpha-d-glucopyranosyl and galacto-pyranosyl bromide 8a,b gave the protected beta-d-nuclosides 10a,b and 13a-d in high yields, which were transformed to deacetylated derivatives 14a,b and 15a-d. The structures of the compounds were elucidated by spectral and elemental analysis. Anti-inflammatory and Analgesic activities screening of the new compounds (at a dose of 100 mg/kg body weight) utilizing in vivo acute carrageenan-induced paw oedema standard method exhibited that the deacetylated derivatives 14a,b and 15a-d possess highly promising activities.

Voltammetric determination of parthenolide in spiked human plasma and urine.

The voltammetric behaviour of parthenolide, a biologically active sesquiterpene lactone, was studied using direct current (DCt), alternating current and differential-pulse polarography (DPP). Parthenolide developed well-defined cathodic waves over the whole pH range in Britton-Robinson buffers. At pH 10 the diffusion current constant was 3.54 +/- 0.08 (+/- standard deviation; n = 8). The current vs concentration plots were rectilinear over the range 4-36 and 1-28 micrograms/mL in the DCt and DPP modes, respectively, with a minimum detectability of 0.06 microgram/mL (about 1 x 10(-7) M) using the latter technique. The waves were characterised as being diffusion controlled, although adsorption phenomenon played a limited role in the electrode process. The described analytical method was applied to the determination of parthenolide in spiked human urine and plasma; the percentage recoveries were 95.72 +/- 0.22 and 94.0 +/- 0.13 (+/- standard deviation; n = 9), respectively.

Separation and quantification of the major daucane esters of Ferula hermonis by HPLC.

A simple HPLC method was developed to quantify the major daucane sesquiterpene esters present in herb and roots of Ferula hermonis Boiss. The method utilized a C(18) reversed phase analytical column with isocratic elution for 30 minutes and UV detection at 240 nm. Extracts from two crude plant samples and two commercial products were fingerprinted and quantitatively analyzed.

A weakly antimalarial biflavanone from Rhus retinorrhoea.

The biflavanone (2S,2"S)-7,7"-di-O-methyltetrahydroamentoflavone and five known flavonoids, 7-O-methylnaringenin, 7,3'-O-dimethylquercetin, 7-O-methylapigenin, 7-O-methylluteolin, and eriodictyol were isolated from the leaves of Rhus retinorrhoea Steud, Ex Olive. The biflavanone exhibited moderate antimalarial activity with IC50 0.98 microg/ml against Plasmodium falciparum (W2 Clone) and weak activity against P. falciparum (D6 Clone) with IC50 2.8 microg/ml. Nevertheless, it did not display any cytotoxicity. 7-O-Methylnaringenin showed weak antimicrobial activity against Candida albicans, C. krusei, Staphylococcus aureus, Mycobacterium smegmatis, M. intracellulare, and M. xenopi with MIC approximately 100 microg/ml. Characterization of each compound was based on spectral analysis and comparison with reported data.

Microbial transformation of pyrethrosin.

Microbial transformation of the germacranolide pyrethrosin (1) using Rhizopus nigricans NRRL 1477 has resulted in the isolation of 6 alpha-acetoxy-1 beta,4 alpha-dihydroxy-5,7 alpha H,8 beta H-eudesm-11 beta,13-dihydro-8,12-olide (5), a new eudesmanolide-type metabolite, in addition to the previously reported eudesmanolides: 2, 3, 4, and 6. The structure elucidation of these metabolites was based primarily on 1D and 2D NMR analyses. The isolated metabolites exhibited cytotoxic, antifungal, and antiprotozoal activities.

Microbial hydroxylation and reduction of the diterpene psiadin.

Microbial bioconversion studies conducted on the diterpene psiadin have revealed that it was metabolized by Aspergillus niger (NRRL 2295) to give 2alpha-hydroxydeoxopsiadin, Cunninghamella blakesleeana (ATCC 8688a) to give 11beta-hydroxypsiadin, and Cylindrocephalum aureum (ATCC 12720), Gongronella butleri (ATCC 22822), Kloeckera africana (ATCC 20111), and Kluyveromyces marxianus var. lactis (ATCC 2628) to yield 7alpha-hydroxypsiadin. Their structures have been established on the basis of spectral data. The structure and relative stereochemistry of 7alpha-hydroxypsiadin was confirmed by single-crystal X-ray analysis.

Daucane sesquiterpenes from Ferula hermonis.

The roots of Ferula hermonis Boiss yielded two new daucane esters, 14-(4'-hydroxybenzoyloxy)dauc-4,8-diene (1) and 14-(4'-hydroxy-3'-methoxybenzoyloxy)dauc-4,8-diene (2), together with the four known sesquiterpenes jaeschkeanadiol p-hydroxybenzoate (3), jaeschkeanadiol benzoate (4), jaeschkeanadiol (5), and epoxyjaeschkeanadiol (6). The identities of the isolated compounds were ascertained primarily using NMR and MS data. Compounds 1 and 3 exhibited antimicrobial activity against Staphylococcus aureus with IC(50) 1.5 and 3.5 microg/mL, respectively, and against Methicillin-resistant S. aureus with IC(50) 2.0 and 4.0 microg/mL, respectively.

New eudesmane sesquiterpenes from Plectranthus cylindraceus.

Three new eudesmane sesquiterpenes, plectranthone (1), desacetylplectranthone (2), isodeacetylplectranthone (3), and the three known flavonols pachypodol, casticin, and chrysosplenol D were isolated for the first time from the aerial parts of Plectranthus cylindraceus. Their structures have been established on the basis of spectral data. The structures and relative stereochemistries of 1 and 2 were confirmed by single-crystal X-ray analysis.

Microbial metabolism of artemisitene.

Studies on the microbial transformation of the sesquiterpene endoperoxide artemisitene have revealed that artemisitene was metabolized by Aspergillus niger (NRRL 599) to yield 11-epi-artemisinin, 9 beta-hydroxydeoxy-11-epi-artemisinin and 9 beta-hydroxy-11-epi-artemisinnin. These metabolites were characterized on the basis of their spectral data.

Artemisinin-derived sesquiterpene lactones as potential antitumour compounds: cytotoxic action against bone marrow and tumour cells.

We determined the in vitro cytotoxic activity of the sesquiterpene lactone endoperoxide artemisinin (1) and some chemically prepared derivatives, which have been found to display cytotoxicity to cloned murine Ehrlich ascites tumour (EAT) cells and human HeLa cells and against murine bone marrow using a clonogenic assay for committed progenitor cells of the granulocyte-monocyte lineage (CFU-GM assay). Comparing artemisinin (1) to deoxyartemisinin (2), the endoperoxide group appeared to play a role in cytotoxicity to CFU-GM cells. Dimers of dihydroartemisinin and dihydrodeoxyartemisinin revealed that the stereochemistry of the ether linkage of the dimers was a more important determinant for this cytotoxic activity. The nonsymmetrical dimer of dihydroartemisinin (3) and the corresponding endoperoxide-lacking dimer of dihydrodeoxyartemisinin (5) were equally cytotoxic to CFU-GM cells. Despite the differences between both systems, it may be stated that most compounds displayed higher cytotoxicity to CFU-GM cells than to EAT cells. Dimers of dihydroartemisinin (3, 4) were selected as potential antitumour compounds and subjected to the National Cancer Institute drug-screening programme consisting of about sixty human cancer cell lines derived from nine different tissues. Both compounds displayed the same specific cytotoxicity pattern. Throughout the screen dimer 3 was more active than 4.

Stereochemistry-dependent cytotoxicity of some artemisinin derivatives.

We determined the cytotoxicity of some artemisinin derivatives against EN2 tumor cells using the MTT assay. Artemisinin (1) was clearly more cytotoxic than deoxyartemisinin (2), which lacks the endoperoxide bridge. Ether-linked dimers of dihydroartemisinin with defined stereochemistry were found to differ in the extent of cytotoxic effect on EN2 cells. The nonsymmetrical dimer (3) was more cytotoxic than the symmetrical dimer (4). The nonsymmetrical dimer of dihydrodeoxyartemisinin (5) lacking the endoperoxide bridges was also effective in the MTT assay, although less cytotoxic than 3 and 4. Similarly, the symmetrical dimer (6) was less effective than 5. Epoxides of artemisitene also showed that stereochemistry was an important factor for cytotoxicity. The results suggested that the endoperoxide bridge was not crucial for cytotoxicity to the tumor cells, but contributed to the cytotoxic effect apparently exerted by the ether linkage of the dimers. Flow cytometry data indicated that the dimers 3 and 4 caused an accumulation of the cells in the G1-phase of the cell cycle. In contrast, artemisinin (1) caused a slight increase of S-phase cells.

Glucose-conjugation of the flavones of Psiadia arabica by Cunninghamella elegans.

Microbial transformation of psiadiarabin and its 6-desmethoxy analogue 5,3' dihydroxy-7,2',4'5'-tetramethoxyflavone by Cunninghamella elegans NRRL 1392 gave the 3'-glucoside conjugates of the two flavones. Structural elucidation of these two new metabolites was achieved using 1D and 2D NMR spectroscopy and CIMS.

Antitumor germacranolides from Anvillea garcinii.

The aerial parts of Anvillea garcinii yielded two new germacranolides, 9 alpha-hydroxy-1 beta, 10 alpha-epoxyparthenolide (4) and parthenolid-9-one (5), in addition to the known 9 alpha-hydroxyparthenolide (1), 9 beta-hydroxyparthenolide (2), and 9 beta-hydroxy-1 beta, 10 alpha-epoxyparthenolide (3). The structures of the new compounds were elucidated from their spectral data (IR, MS, 1H- and 13C-NMR, 1H-1H COSY, and 1H-13C HETCOR) and by chemical derivatization. The hitherto unreported 13C-NMR data and carbon atom assignments of the previously isolated lactones 1, 2, and 3 were given. The in-vitro antitumor and anti-HIV activities were evaluated for the isolated compounds.