Total Phenolics and Antioxidant Activity of Defatted Fresh Taif Rose, Saudi Arabia

Recently, the residues or by-products of agriculture industry take attention for their valuable source of natural antioxidants. Taif rose (Rosa damascena trigintipetala Dieck) is considered one of the most important economic products of Taif, Saudi Arabia. In this study, the antioxidant and total phenolic contents of the defatted flowers of fresh Taif rose were investigated. The antioxidant activity was chemically determined using three methods; 1,1-diphenyl picrylhydrazyl (DPPH.) free radical scavenging activity, phosphomolybdenum method and reducing power activity. The methanol extract showed antiradical activity with SC50=49.44 mg/ml. Different fractions obtained from successive fractionation of the methanol extract with organic solvents of different polarities; chloroform (CHCl3), ethyl acetate (EtOAc) and n-butanol (n-BuOH); showed that, the EtOAc fraction had higher antiradical activity than n-BuOH fraction, and their respective SC50 were 15.62 and 36.29 mg/ml. On the other hand, CHCl3 fraction had a poor antiradical activity (SC50>100 mg/ml). The total phenolics, flavonoids, flavonols and RP-HPLC analysis of the methanol extract and its EtOAc and n-BuOH fractions were determined. The ethyl acetate fraction had the highest contents of phenolics, flavonoids and flavonols that correlated with the antioxidant activity. From this work, it is obvious that the by-product from concrete oil production of Taif rose could be used as a good inexpensive source of antioxidant polyphenolics.