Volume 172, 1 April 2015, Pages 423–427
1Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Johannesburg, South Africa.
2Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Johannesburg, South Africa. Electronic address: email@example.com.
Received 29 July 2013, Revised 20 June 2014, Accepted 10 September 2014, Available online 17 September 2014
Pressurised hot water extraction (PHWE) is a “green” technology which can be used for the extraction of essential components in Moringa oleifera leaf extracts. The behaviour of three flavonols (myricetin, quercetin and kaempferol) and total phenolic content (TPC) in Moringa leaf powder were investigated at various temperatures using PHWE. The TPC of extracts from PHWE were investigated using two indicators. These are reducing activity and the radical scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH). Flavonols content in the PHWE extracts were analysed on high performance liquid chromatography with ultra violet (HPLC-UV) detection. The concentration of kaempferol and myricetin started decreasing at 150 °C while that of quercetin remained steady with extraction temperature. Optimum extraction temperature for flavonols and DPPH radical scavenging activity was found to be 100 °C. The TPC increased with temperature until 150 °C and then decreased while the reducing activity increased.
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DPPH; Flavonols; Moringa oleifera; PHWE; Total phenolic content