Characterization of Copper Complexes from Copper Salt and Crude Garlic Extracts

Thumbnail Image
Journal Title
Journal ISSN
Volume Title
Two varieties of garlic; Allium sativum var sativum and var ophioscorodon, were studied to ascertain the feasibility of forming copper colloid suspensions with their crude extracts. They were extracted in borax, SDS-borax and urea-borax buffers gravimetrically at a pH of 10. By comparison, the extracts of var ophioscorodon which was a locally grown garlic variety contained significantly higher levels of protein (0.396-0.415 %) and phenols (23.00-29.46 au) than var sativum which ranged between 0.275-0.336 % for protein and 10.88-11.98 au for phenolic content. The buffers used for extraction did not have any apparent effect on differences in protein and phenolic content. The extracts were treated with equimolar cupric-nitrite solution. Uv/vis and IR spectroscopy were used to assess the relevant interaction of garlic extract with Cu (II) ions. Two uv/vis absorption bands observed for garlic extracts and their complexes band I (274-276 nm) and band II (307-365 nm). Band II was diminished upon complexation representing interaction of Cu ions with the garlic extracts. Multiple inflection points along the titration curves and their first derivatives indicated a stepwise formation of copper complexes. IR bands at 991.97-996.23 (C-H def), 1207.05 (C-O-C str), 1384.37-1384.97 (C-O str) and 1724.97 (C=O str) revealed a spectral pattern similar to that observed for the flavonols implicating such compounds in the chelation of Cu in the garlic extracts. In conclusion, garlic buffer extracts formed copper complex suspensions by chelating Cu(II) ions with flavonol-like compounds.
A thesis submitted to the Department of Food Science and Technology, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of Master of Science,