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Local anaesthetics (LAs) are frequently used for diagnostic procedures in equine veterinary practice. The objective of this study was to investigate the physico-chemical stability and bacterial contamination of bupivacaine, lidocaine and mepivacaine used for lameness examinations in horses. The LAs were stored in 12 different groups at different temperatures (−18 °C to 70 °C), light intensities and in common veterinary field conditions for up to 16 months. The pH, presence of bacterial contamination and concentrations of LAs and methylparaben (a preservative present in lidocaine) were determined serially in both new and repeatedly punctured (RP) vials. Mepivacaine remained chemically stable. A 1.9% increase in bupivacaine concentration was evident in one group, whereas a 1.9–3.7% decrease was noted in six groups. Risk factors associated with a change in concentration were light and RP vials. Lidocaine concentration decreased 6.3% in one group and increased 5.3–7.2% in two groups. Risk factors for degradation were heat and RP vials whereas storage in practice vehicles was a risk factor for increased concentrations. Methylparaben decreased 8.3–75.0% in seven groups, and RP vials, heat and storage in practice vehicles were risk factors for degradation. No contamination was present in any of the LAs and pH remained stable. Commercially available solutions of lidocaine, mepivacaine and bupivacaine stored under common veterinary field conditions are extremely stable and sterile for extended periods. The minor changes in concentration documented in this study are unlikely to affect anaesthetic efficacy during equine lameness examinations. When using products containing methylparaben, degradation of the preservative over time is to be expected.

Udgivelsesdato: 1998-Aug, Extracts of the leaves from Vernonia brachycalyx showed in vitro activity against Plasmodium falciparum and promastigotes of Leishmania major. The germacrane dilactone 16,17-dihydrobrachycalyxolide (1) which was previously isolated from the aerial parts of the plant was shown to be the major antiplasmodial principle. An X-ray crystallographic analysis established the absolute configuration and some signals in the NMR spectra were reassigned. 16,17-Dihydrobrachycalyxolide (1) elicited a strong antiplasmodial and antileishmanial activity but also a high toxicity against human lymphocytes.

Udgivelsesdato: 1997-May, Two new isomeric 5-methylcoumarins, 2'-epicycloisobrachycoumarinone epoxide (1) and cycloisobrachycoumarinone epoxide (2), have been isolated from the roots of Vernonia brachycalyx by means of bioactivity-guided fractionation. The structures were elucidated by MS and NMR spectroscopic methods. Compounds 1 and 2 showed in vitro activity against Leishmania major promastigotes and against Plasmodium falciparum schizonts and demonstrated an inhibition on the proliferation of human lymphocytes, which was significantly weaker than the antiparasitic effects.

Udgivelsesdato: 1997-Oct, Two antiprotozoal compounds have been isolated from the roots of Asparagus africanus Lam. (Liliaceae), a new sapogenin, 2 beta, 12 alpha-dihydroxy-(25R)-spirosta-4,7-dien-3-one (1), which was named muzanzagenin, and the lignan (+)-nyasol (2), (Z)-(+)-4,4'-(3-ethenyl-1-propene-1,3-diyl)-bisphenol. The structure of the sapogenin was elucidated by MS and by 1D and 2D NMR methods and established by a single crystal X-ray analysis. (+)-Nyasol potently inhibits the growth of Leishmania major promastigotes, the IC50 being 12 microM, and moderately inhibits Plasmodium falciparum schizonts with the IC50 49 microM. These concentrations only moderately affect the proliferation of human lymphocytes. Muzanzagenin showed a moderate in vitro activity in all three tests, the IC50 against leishmania promastigotes was 70 microM, and against four different malaria schizont strains the IC50 values were 16, 163, 23, and 16 microM, respectively.

Udgivelsesdato: 1994-Apr, A bioassay guided fractionation of an extract of Chinese licorice roots led to the isolation of (E)-1-[2,4-dihydroxy-3-(3-methyl-2-butenyl)phenyl]-3-[4- hydroxy-3-(3-methyl-2-butenyl]phenyl-2-propen-1-one, which in vitro showed potent antileishmanial activity. In addition, the novel chalcone (E)-1-[2,4-dihydroxy-3-(3-methyl-2- butenyl)phenyl]-3-(2,2-dimethyl-8-hydroxy-2H-benzopyran-6-yl)-2-prope n-1-one was isolated from the roots. The latter compound only showed antileishmanial activity at high concentrations.

Seven molecular forms of arsenic were separated by anion- and cation-exchange high-performance liquid chromatography (HPLC) with on-line detection by flame atomic absorption spectrometry (FAAS). The interfacing was established by a vented poly(tetrafluoroethylene) capillary tubing connecting the HPLC column to the nebulizer of the atomic absorption spectrometer. Arsenite, arsenate, monomethylarsonate (MMA) and dimethylarsinate (DMA) were separated from each other and from the co-injected cationic arsenic compounds, arsenobetaine (AsB), arsenocholine (AsC) and the tetramethylarsonium ion (TMAs) on an organic polymeric anion-exchange column with 0.1 mol dm-3 carbonate at pH 10.3 as the mobile phase. The three cationic species were separated from each other and from the co-injected anionic species on a silica based cation-exchange column with pyridine at a pH of 2.65 as the mobile phase. The signal-to-noise ratio of the on-line AAS detector was optimized. This involved the use of the hydrogen-argon-entrained air flame, a slotted tube atom trap in the flame for signal enhancement, electronic noise damping and a high-intensity light source. The detection limits in mu-g cm-3, using 100 mm3 injections of mixtures of arsenic standards into the HPLC system were: arsenite, As(III) 1.1; arsenate, As(V) 1.4; MMA 1.4; DMA 0.7; AsB 0.3; AsC 0.5; and the TMAs 0.4. The HPLC-AAS system was used for the analysis of arsenic species in aqueous extracts of soil samples from a polluted land site. Only arsenate was found in the soil extracts. For comparison, inductively coupled plasma mass spectrometry was also used as an on-line detection technique with the same HPLC systems.