Isolation of Active Substances from the Seeds of the Milk Thistle Plant (Silybum marianum) and Determination of Antioxidant Activity

Opisana je izolacija silimarina, smjese dobro definiranih flavonolignana, iz sjemena biljke sikavice (Silybum marianum). Silimarin je ekstrahiran acetonom iz deoleinizirana sjemena bez zagrijavanja. Iskorištenje je iznosilo Y = 4,1 %. Antioksidacijska aktivnost silimarina određena je na sobnoj temperaturi kolorimetrijski 2,2-difenil-1-pikrilhidrazilom (DPPH) pri λ = 515 nm. Aktivnost je određena na temelju smanjenja apsorbancije, kao rezultat promjene boje DPPH iz purpurne u žutu. Dobiveni rezultati pokazuju da je askorbinska kiselina znatno jači antioksidans od ispitivana silimarina, ali je silimarin znatno jači hvatač radikala DPPH od standarda silibinina.Isolation of silymarin, a mixture of well-defined flavonolignans, from the seeds of milk thistle (Silybum marianum) was achieved. Silymarin was extracted from defatted seed with acetone without heating; the yield was Y=4.1 %. The antioxidant activity of silymarin was determined at ambient temperature by means of a 2,2-diphenyl-1-picrylhydrazyl (DPPH) colorimetry with a detection scheme at λ= 515 nm. The activity was evaluated by the decrease in absorbance as the result of a DPPH radical color change from purple to yellow. The results obtained showed that ascorbic acid was a substantially more powerful antioxidant than silymarin, but silymarin was a significantly stronger quencher of DPPH radical than the standard silibinin

Evaluation of Pyrocondensates as a Polymerization Raw Material

Two pyrocondensate samples were examined in order to evaluate them as polymerization raw materials. The components were identified or undoubtedly characterized by means of mass spectral data taken by GC-MS and by gas chromatography retention data. Quantitative analysis of pyrocondensates and the residues which remained after cationic, thermal or free radical polymerizations was made by high resolution gas chromatography, Pyrocondensates contained mainly alkyl and alkenyl substituted benzenes and fused ring compounds. In one sample bicyclic components, with cyelopentadiene and cyclohexadiene as constitutive bases, were found. As the samples contained a fairly high portion of components able to polymerize, they were found to be of interest for polymerization into resins. Polimerization yields of the whole sample and of a single reactive component depended on the type of polymerization. Cationic polymerization gave the highest and polymerization by peroxides the lowest polymerization yield in the whole sample. Alkenylbenzenes and indenes reacted in the cationic polymerization better than in the other two kinds of polymerization, while bicyeles gave the best yield in the polymerization of thermal type

Investigations of Tll Suspensions

Thallous iodide suspensions were obtained by direct mixing of TlN03 and Na! solutions. The amount of TH was kept constant in the systems, while the concentrations of Na! (in excess), laurylamine nitrate (LAN) or myristylamine nitrate (MAN) were varied. Tyndallometric values were recorded as the function of Na!, LAN, and MAN concentrations respectively, for suspensions aged for various times. Particle sizes of differently aged TH in \u27Suspensions containing Na! and Eu(N03)a in solution were determined. Tyndal.:. lometry and electronmicroscopy showed fast particle growth of TH in suspension. After about 10 minutes the TH particle grew up to 1.3 μ. The zero point of charge, determined by microelectrophoresis, was attained at 0.001-0.005 M Na! and 0.0001-0.0005 M LAN depending on the conditions under which the system had been prepared. The results of radiometrically recorded adsorption- desorption equilibria show a constant increase of the adsorption capacity as the electrolyte concentration increases

Syntheses of the New Indole Derivatives Related to Indomethacin

Syntheses and properties of the new indole derivatives 18-33, being potential antiinflammatoric agents, are described. 1-p-Chlorobenzoyl- 2-methyl-3-(2\u27-methyl-4\u27-nitroimidazol-1\u27-yl)-5-methoxyindole (32) have been found to possess pronounced antiinflammatoric activity and very low ulcerogenity. Attempting preparation of N-benzoylindole derivative 38 via sigmatropic rearrangement of the open chain precursor 35, as a model procedure for the new synthesis of indomethacin, very low yields on the desired cyclic product 38 have inevitably been obtained

Book Reviews

Gmelins Handbuch der anorganischen Chemie. 8. Auflage. Herausgegeben vom Gmelin-Institut in Frankfurt am Main, Verlag Chemie, GMBH, Weinheim/Bergstrasse. System-Nummer 519: Magnetische Werkstoffe (Magnetische und elektrische Eigenschaften), zugleich 2. Erganzugsband zum Eisen Teil D, 1959, XXXVIII, 580 str., 308 sl

Intenzitet habanja kod različito toplinski poboljšanog nodularnog lijeva

In the paper we investigate the relationship between the wear intensity of two nodular cast irons and their heat treatment conditions. Disks tempered by austempering and isothermal procedure were used. The wear test was realized by using Pin and Disk tribometer. Measurement of the disks wear, after the contact for duration of 30 min, was done by the PQ meter. The quantity of the wear products in lubricant is determined by the PQ index. The best wear resistance posses the disk isothermally tempering with 30 minutes holding at 390 °C temperature.U ovom radu je ispitivana zavisnost između intenziteta habanja dva nodularna lijeva kao i uvjeta pri njihovoj toplinskoj obradi. Uzorci za ispitivanje nodularnog lijeva su bili poboljšani klasičnim i izotermalnim postupkom. Ispitivanje intenziteta habanja je realizirano uz pomoć Pin on Disc tribometra. Mjerenje pohabanosti diska, nakon trenja u trajanju od 30 minuta, je obavljeno na PQ metru. Količina čestica nastalih kao produkti habanja, u sredstvu za hlađenje i podmazivanje je određena PQ indexom. Najveću otpornost na habanje posjeduje disk izotermalno temperovan na 390 °C u trajanju od 30 minuta

Chiral 1,4-Benzodiazepines. VIII. Concerning the Rate of WD Exchange and Optical Stability of the Chiral Centre C(3).

Various chiral substituted 1,4-benzodiazepin-2-ones with 3- -acyloxy (general formula I), 3-hydroxy- and 3-alkoxy (general formula II), 3-alkyl (general formula III) and 3-quaternary ammonium (general formula IV) groups as substituents were subjected to C(3)-H-D exchange rate measurements in order to obtain information on the optical stability of the chiral centre and on the mechandsm of racemization. Only type IV compounds (IVa-j) exhibited H/D exchange, but acid catalyzed racemization took place in type I and II compounds, indkating some other mechani. sms in this process. Type III compounds as free bases (IIIa-c), N4-protonated acids, or N4-oxides (III, e; f) underwent no H/D exchange and are optically sfable as well. In cases whe,re deprotonation- reprotonation mechanism of racemization can be excluded two other mechanisms are discussed, i. e. acid-\u27catalyzed ring-chain tautomerism and identity substitution with alkoxide ion

Attempted Diastereoselective Preparation and Chiroptical Properties of (2S)-1-(3-Mercapto-2-Methyl-1-Oxopropyl)-L-Proline (Captopril) and Some Congeners

CD and 13C-NMRstudy of the eonformational properties of (2S)-1-(3-mercapto-2-methyl-1-oxopropyl)-L-proline (captopril, 1), and its congeners 2-5, 8, 9 is reported. 13C-NMRdata (in DMSO-d6) reveal an E/Z (cis/trans) ratio of ea. (15-30) : (70-85) for the N-acetyl-prolines 1, 5, 10, and for N-acetyl-L-proline. CD data indicate practically identical conformations for the ring systems of 8 and 9. Attempted diastereoselective cyclization of the sodium salt of 7 or the free thioacid into 8 and 9 resulted in low chemical yields (-30%) and low diastereoselectivity, favouring formation of the »wrong- diastereomer 9 in small excess (-20%)