Browsing by Subject "oxidation"
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(2011)River blindness (onchocerciasis) is a human helminth disease that is caused by Onchocerca volvulus filaria. It is endemic in tropical areas in Africa and Latin America. About 37 million people are infected. River blindness manifests in cutaneous and eye symptoms that are caused by the youngest forms (microfilariae). Against river blindness there has been mass drug treatments with ivermectin which has an effect on microfilariae. There is a need for a drug that kills adults or sterilizes females. A vaccine would be even better. Antibiotics are a new treatment because O. volvulus has Wolbachia bacterium as an obligate symbiont. Doxycycline kills at least 60 per cent of adults and sterilizes females. But the course lasts many weeks. A promising compound is emodepside that has a new mechanism of action for an anthelmintic drug. Numerous compounds has been examined to get drugs for filarial diseases. Some of them inhibit enzymes with which filariae evade human immune defence. Others disturb moulting that takes place four times. A good target for a drug is essential for the parasite but absent from mammals. Betulin is a triterpene that is abundant in birch bark. Betulin and many of its derivatives are pharmacologically active compounds that are examined particularly as cancer and HIV drugs. The research group of medicinal chemistry in University of Helsinki has synthesized and examined many derivatives. Some of them are promising for example against Leishmania protozoans, Chlamydia pneumoniae bacterium and alphaviruses. That is why those compounds should be tested against other causes of diseases like filariae. Both Wolbachia and C. pneumoniae have the same lipid biosynthesis pathway that is essential for both. Heterocycloadducts between betulin and nitrogen heterocycle were synthesized whose alcohols were oxidized to carbonyls. In both Leishmania donovani and L. braziliensis examinations the most effective compound was heterocycloadduct of formylbetulin. Although the compounds have not been examined against filariae, in future it would be worth an effort to synthesize derivatives that has nitrogen instead of carbonyls because the compound effective on C. pneumoniae is dioxime.
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(2019)The literature part of the study dealt with frying methods, frying fats and oils, chemical and physical changes of frying fats and oils during the frying and analyse methods of frying fats and oils. The aim of the experimental part was to study changes in rapeseed oil quality during continuous frying process during three different frying periods. Especially the effect of day without production during the frying period was studied. Samples, frying oils, were taken every day during the different frying periods. In period one and two there was one day without production. Oils were stored in storage tanks during that time. In third period, there was production on every day. All samples were inspected for colour, odour, viscosity and clearness by visual methods. Also viscosity by rotation viscometer, smoking point, free fatty acids by titration method, fatty acid content and water content of samples was analysed. Based on sensory evaluation, the quality of oil deteriorated over thedays of use. Colour was darker, viscosity was higher and off-odours were sensed. Instrumental analyses indicate same kind of changes; viscosity and free fatty acid were increased and smoking point and amount of unsaturated fatty acid were decreased while frying time was increasing. In literature, also same changes were mentioned. There was changes in fatty acid content during the frying periods. More fatty acids characteristic to meat was detected in oils at the end of period than in fresh oils. Based on these results, oil quality remained acceptable in everyday use for a typical frying period of one week. Difference between fresh oil and used oils was clear but still acceptable. The amount of free fatty acids, and the level of viscosity and smoking points were under the limits applied in Finland. The day without production deteriorated oils quality substantially Reducing the amount of oil in process and having shorter frying periods or more efficient filtering of oils can help to keep the quality of frying oil better.
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