Impact of harvesting time and geographical region on total phenolics, flavonoids and antioxidant activity of olive (Olea ferruginea Royle) leaves, district Zhob

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Research Paper 01/10/2019
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Impact of harvesting time and geographical region on total phenolics, flavonoids and antioxidant activity of olive (Olea ferruginea Royle) leaves, district Zhob

Ayeesha Masood, Abdul Kabir Khan Achakzai, Rasool Baksh Tareen, Misbah Manzoor, Shaista Anjum, Tariq Ismail, Asad Ullah
Int. J. Biosci.15( 4), 350-358, October 2019.
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Abstract

Study area of district Zhob is well known for its naturally occurring population of Olea ferruginea .There was emerging need to unveil status of pharmaceutically active compounds in leaves of this locally used abundant species. Present study was conducted to evaluate influence of some geological parameters and harvesting time on concentration of few secondary metabolites and antioxidant activity of leaves extracted in different solvents.Sites selection was made by dividing the area with dense population of olives in north and south facing slopes. During 2017, leaves were collected from three altitudes at each slope 600 feet apart during four harvesting stages (vegetative, green fruiting, purple fruiting and black dried fruiting stage) Leaves were shade dried and extracted in three solvents (i.e. acetone, water and 80% ethanol) for quantification of total phenolic contents (TPC), total flavonoid content (TFC) and antioxidant activity (AA) on UV-VIS spectrophotometer by following standard protocols. TPC was significantly high at southern slopes (total mean value 23.73 mg/g) and AA at northern slope (with total mean 41.78%) respectively. Altitude had no significant impact on secondary metabolites and antioxidant activity except for DPPH radical scavenging activity that decreased at the mid altitude (38.19%).TPC, TFC and AA were significantly higher at black (27.99mg/g), green (27.11mg/g) and purple fruiting stage (42.44%) respectively. Solvents also had significant effects on TPC that showed high levels in acetone extracts (23.65mg/g) whereas TFC (42.49mg/g) and AA (42.46%) were higher in leaves extracted in 80% ethanol. Study aids to choose suitable location, harvesting time and extraction solvent to obtain maximum polyphenols and enhance antioxidant activity of Olea ferruginea leaves.

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