Microwave Assisted Extraction of Papaya Leaves and Investigation on Antioxidant Activity

Microwave assisted extraction (MAE) has gained lot of attention due to its advantages such as less solvent consumption, short time period, higher extraction efficiency, therefore serves as better alternative for conventional extraction methods of plant materials. Plant phenolic compounds are important constituents responsible for reducing the oxidative stress that induces tissue damage which is the one of the major causative factors associated with the chronic disease. Papaya plant is a medicinal plant which became popular for the treatment of dengue fever due to its property. Considering the current medicinal importance of the papaya plant, the present study was aimed at microwave assisted extraction of phenolic content from papaya leaf using ethanol, water as solvent and investigate their antioxidant potential.

In order to compare the extraction efficiency of phenolic compounds, conventional extraction and microwave assisted extraction method was used to prepare the extracts. Then extracts were subjected to preliminary phytochemical analysis followed by the estimation of total phenolic content by using Folin-Ciocalteu method. Antioxidant activity was investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay.

The alcoholic and aqueous extracts of papaya leaf showed the presence of steroids, alkaloids, saponins, carbohydrates, phenolic compounds by preliminary phytochemical analysis. FTIR spectrum of both aqueous and ethanolic extract showed characteristic peak at 3314.62 cm-1, 1635 cm-1 which provide evidence for presence of phenolic compounds. The total phenolic content of the alcoholic and aqueous leaf extracts from MAE was found to be 43.58mg and 80.58 mg/g papaya leaf powder of the Gallic acid equivalent (GAE), respectively. Aqueous solvent was found to be suitable for extraction of phenolic content from papaya leaf and Microwave assisted extracts showed higher phenolic content and therefore potential antioxidant activity. Therefore, papaya leaf is a good candidate to be used as a natural antioxidant for the treatment of various diseases.