Green HPLC Method for Simultaneous Analysis of Three Natural Antioxidants by Analytical Quality by Design

Glutathione, silybin, and curcumin are well-known potential antioxidants that are recommended as adjuvant therapy in cancer treatment.

Based on the principles of Analytical Quality by Design (AQbD) and green analytical chemistry, a simple, robust, and environmentally benign HPLC method for the simultaneous estimation of glutathione, silybin, and curcumin in bulk and formulation was performed.

Elution was achieved by an Agilent Eclipse XDB C18 (150 mm × 4.6 mm id, 3.5 μm) column using a gradient mobile phase composed of ethanol-water pH 6.7 (with 0.1%, v/v orthophosphoric acid) and 1.07 mL/min flow rate with PDA detection at 215 nm. Critical method variables were identified by risk assessment using an Ishikawa diagram, and multivariate optimization of the experimental conditions for the HPLC technique was accomplished by central composite design using design of experiments (DoE) software.

The separation was achieved within 15 min, where the retention time of glutathione, silybin, and curcumin were 3.3, 4.9, and 7.3 min, respectively. The standard curve was linear in the range of 3.75-26.25 µg/mL for glutathione, 62.50-437.50 µg/mL for silybin, and 12.5-87.50 µg/mL for curcumin. The developed method was validated as per ICH guidelines Q2 (R1), and all the parameters are within specified limits.

The proposed method is simple, precise, and robust, which can be employed for routine analysis and also concluded to be a greener approach according to AGREE, Green Analytical Procedure Index, and analytical eco-scale tools.

The chosen antioxidants were evaluated for the very first time simultaneously using the chromatographic technique in bulk and dosage forms employing green solvents. The peak purity of all three compounds was studied using a PDA detector. Wastage was reduced in terms of time, cost, and solvents by employing AQbD elements and tools. Complete application of environmentally sustainable safe solvents were employed.