title: Optimization protocol for the extraction of antioxidant components from Origanum vulgare leaves using response surface methodology.
abstract: In the present work, the response surface methodology (RSM) based on a central composite rotatable design (CCRD), was used to determine optimum conditions for the extraction of antioxidant compounds from Origanum vulgare leaves. Four process variables were evaluated at three levels (31 experimental designs): methanol (70%, 80%, and 90%), the solute:solvent ratio (1:5, 1:12.5, 1:20), the extraction time (4, 10, 16 h), and the solute particle size (20, 65, 110 micron). Using RSM, a quadratic polynomial equation was obtained by multiple regression analysis for predicting optimization of the extraction protocol. Analysis of variance (ANOVA) was applied and the significant effect of the factors and their interactions were tested at 95% confidence interval. The antioxidant extract (AE) yield was significantly influenced by solvent composition, solute to solvent ratio, and time. The maximum AE was obtained at methanol (70%), liquid solid ratio (20), time (16 h), and particle size (20 micron). Predicted values thus obtained were closer to the experimental value indicating suitability of the model. Run 25 (methanol:water 70:30; solute:solvent 1:20; extraction time 16 h and solute particle size 20) showed highest TP contents (18.75 mg/g of dry material, measured as gallic acid equivalents) and DPPH radical scavenging activity (IC50 5.04 μg/mL). Results of the present study indicated good correlation between TP contents and DPPH radical scavenging activity. Results of the study indicated that phenolic compounds are powerful scavengers of free radical as demonstrated by a good correlation between TP contents and DPPH radical scavenging activity.
authors.affiliation: Institute of Chemistry, Government College University, Faisalabad 38000, Pakistan.
authors.forename: Mudasir
authors.initials: M
authors.lastname: Majeed
authors.affiliation: Institute of Chemistry, Government College University, Faisalabad 38000, Pakistan.
authors.forename: Abdullah I
authors.initials: AI
authors.lastname: Hussain
authors.affiliation: Institute of Chemistry, Government College University, Faisalabad 38000, Pakistan.
authors.forename: Shahzad A S
authors.initials: SA
authors.lastname: Chatha
authors.affiliation: Institute of Chemistry, Government College University, Faisalabad 38000, Pakistan.
authors.forename: Muhammad K K
authors.initials: MK
authors.lastname: Khosa
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China; University of Chinese Academy of Sciences, 10049 Beijing, PR China.
authors.forename: Ghulam Mustafa
authors.initials: GM
authors.lastname: Kamal
authors.affiliation: King Fahad Medical Research Center, King Abdalaziz University, Jeddah, Saudi Arabia.
authors.forename: Mohammad A
authors.initials: MA
authors.lastname: Kamal
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China; University of Chinese Academy of Sciences, 10049 Beijing, PR China.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, PR China; University of Chinese Academy of Sciences, 10049 Beijing, PR China.
authors.forename: Maili
authors.initials: M
authors.lastname: Liu
keywords: Antioxidant compounds; Central composite rotatable design; DPPH free radical scavenging activity; Optimization; Response surface methodology; Total phenolics