Browsing Faculty of Science by Author "Majinda, R.R."
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Mazimba, O.; Masesane, I.B.; Majinda, R.R. (Elsevier Science Ltd, http://www.elsevier.com/locate/tetlet, NaN, 2011)[more][less]
Abstract: An efficient total synthesis of flavans from the reactions of salicylaldehyde and acetophenone derivatives is reported. The synthesis involves preparation of chalcones through an aldol reaction followed by reduction of both the double bond and the ketone using NaBH4 and an acetic acid mediated cyclization. Methoxy groups on the aromatic rings did not affect significantly the yields of the procedure. URI: http://hdl.handle.net/10311/1027 Files in this item: 1
Mazimba_TL_2011.pdf (204.0Kb) -
Mazimba, O.; Majinda, R.R.; Modibedi, C.; Masesane, I.B.; Cencicˇ, A.; Chingwaru, W. (Elsevier Science Ltd, http://www.elsevier.com/locate/bmc, NaN, 2011)[more][less]
Abstract: The investigation of Tylosema esculentum (Morama) husks, cotyledons, and tuber yielded griffonilide 2, compound 1, griffonin 3, gallic acid 4, protocatechuic acid 5, b-sitosterol 6, behenic acid 7, oleic acid 8, sucrose 9, 2-O-ethyl-a-D-glucopyranoside 10, kaempferol 11 and kaempferol-3-O-b-D-glucopyranoside 12. The structures of the isolates were determined by NMR, HR-TOF EIMS, IR and UV–vis spectroscopy, and by comparison with literature data. The husk EtOAc and n-butanol extracts demonstrated >90% DPPH radical scavenging activity at concentrations of 25, 50 and 250 lg/mL. Furthermore the husk extracts showed higher total phenolic content (233 mg GAE/g). The extractives exhibited minimum inhibitory quantities of 50–100 lg or no activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Candida albicans. The tuber extracts were inactive against Caco-2 and Hela cell lines, while the husk extracts showed low activity against Caco-2 and Vero cell line with IC50 values >400 lg/mL. The GC–MS analysis showed the beans and tuber non-polar (n-hexane) extracts major constituents as fatty acids. URI: http://hdl.handle.net/10311/1029 Files in this item: 1
Mazimba_BMC_2011.pdf (698.8Kb) -
Mazimba, O.; Majinda, R.R.; Masesane, I.B. (Elsevier Science Ltd, http://www.elsevier.com/locate/tetlet, NaN, 2009)[more][less]
Abstract: A 1,2-hydride shift in the phosphoric acid-promoted cyclodimerization of styrene oxide and its chloro derivatives under solvent-free conditions leading to 2,4-disubstituted 1,3-dioxolanes is described. Methoxy substituents on the aromatic ring of the styrene oxide prevent the 1,2-hydride shift reaction leading to substituted 1,4-dioxanes. A possible mechanism for the formation of the 1,3-dioxolanes is proposed. URI: http://hdl.handle.net/10311/1026 Files in this item: 1
Masesane_TL_2009.pdf (246.5Kb)
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