PubMed · 5088482
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1971-07-10. Seminar on headache.. https://pubmed.ncbi.nlm.nih.gov/5088482/
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The objective of this study was to assess the influence of the peroxidase/coniferyl alcohol (CA) ratio on the dehydrogenation polymer (DHP) synthesis. The soluble and unsoluble fractions of horseradish peroxidase (HRP)-catalyzed CA dehydrogenation mixtures were recovered in various proportions, depending on the polymerization mode (Zutropf ZT/Zulauf ZL) and HRP/CA ratio (1.6-1100purpurogallin U mmol(-1)). The ZL mode yielded 0-57%/initial CA of unsoluble condensed DHPs (thioacidolysis yields <200micromolg(-1)) with a proportion of uncondensed CA end groups increasing with the HRP/CA ratio (7.2-55.5%/total uncondensed CA). Systematically lower polymer yields (0-49%/initial CA) were obtained for the ZT mode. In that mode, a negative correlation was established between the beta-O-4 content (thioacidolysis yields: 222-660micromolg(-1)) and the HRP/CA ratio. In both modes, decreasing the HRP/CA ratio below 18Ummol(-1) favoured an end-wise polymerization process evidenced by the occurrence of tri-, tetra- and pentamers involving at least one beta-O-4 bond. At low ratio, the unsoluble ZT DHP was found to better approximate natural lignins than DHPs previously synthesized with traditional methods. Besides its possible implication in lignin biosynthesis, peroxidase activity is a crucial parameter accounting for the structural variations of in vitro DHPs.
Widdrol (1) was tested against the necrotrophic plant pathogens Botrytis cinerea and Colletotrichum gloeosporioides. While 1 was found to be inactive against C. gloeosporioides, it showed a selective and effective control of B. cinerea, significantly inhibiting the mycelial growth of the fungus at concentrations of 100 ppm and above. In addition, the biotransformation of 1 by both fungi was studied. Incubation with C. gloeosporioides and B. cinerea afforded four and one biotransformation products (2-6), respectively. Biotransformation with C. gloeosporioides was highly regioselective, yielding for the most part oxidation products at C-10: 10-oxowiddrol (2), 10beta-hydroxywiddrol (3), 10alpha-hydroxywiddrol (4), and 14alpha-hydroxywiddrol (5). The structures of all products were determined on the basis of their spectroscopic data, including coupling constants, two-dimensional NMR analysis (heteronuclear multiple quantum coherence, heteronuclear multiple bond correlation, and nuclear Overhauser enhancement spectroscopy), and nuclear Overhauser effect. The biotransformation products were then tested against B. cinerea and found to be inactive. These results shed further light on the structural modifications, which may be necessary to develop selective fungal control agents against B. cinerea.
The photostability of selected benzocycloheptane antihistaminic agents, namely, loratadine (I), pizotifen (II), ketotifen fumarate (III) and cyproheptatidine (IV), was investigated. Both I and II were photolabile while III and IV were photostable. To perform stability studies on the photolabile compounds (I and II), specific stability-indicating high performance liquid chromatographic (HPLC) methods were established. The accuracy, precision and reliability of the developed HPLC methods for the assay of I and II in their pharmaceutical dosage forms were reported. Assay results for both drugs were within R.S.D. values <2%. The stability-indicating power of the developed methods was validated through study of UV-degraded solutions of I and II contained in quartz cells. The photostability of both drugs was studied under UV-irradiation at 254 nm. The photodegradation kinetics of both drugs, studied in different solvents, are also reported. TLC fractionation of photodegraded solutions of both drugs, revealed two fluorescent photodegradates of drug I. The use of UV-absorbers (ascorbic acid and p-aminobenzoic acid (PABA)) enhanced the photostability of both drugs possibly through a spectral-overlay effect.