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Pak. J. Bot., 48(2): 621-627, 2016.

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EFFECT OF EXTRACTION SOLVENTS ON POLYPHENOLS AND ANTIOXIDANT ACTIVITY OF MEDICINAL HALOPHYTES

MUHAMMAD QASIM¹, IRFAN AZIZ¹, MUNAWWER RASHEED², BILQUEES GUL^1* AND M. AJMAL KHAN³

Abstract: This study was conducted to determine the most effective solvent for extraction of polyphenols and antioxidant activity of medicinally important coastal halophytes (Thespesia populneoides, Salvadora persica, Ipomoea pes-caprae, Suaeda fruticosa and Pluchea lanceolata) known for high antioxidant potential. Five different solvents (water, 80% methanol, 80% ethanol, acetone and chloroform) were used to quantify polyphenols including total phenolic (TPC), total flavonoid (TFC) and proanthocyanidin contents (PC) and antioxidant capacity using DPPH radical scavenging and Ferric reducing antioxidant power (FRAP) activities. Among solvents of different polarities 80% methanol appeared most effective for polyphenol extraction. Thespesia populneoides had the highest polyphenols (TPC, TFC and PC) followed by Salvadora persica. Highest antioxidant activity was also found in T. populneoides and S. persica using the same solvent (80% methanol) which appeared better than synthetic antioxidants (BHA and BHT). The correlation analyses of each solvent showed strong to weak relationships among all studied parameters with maximum values (r and R²) in methanol followed by ethanol and water. Weaker correlation of acetone and chloroform indicates low capacity of these solvents both for polyphenol extraction and antioxidant activity. Our results reveal that aqueous methanol extracts of coastal halophytes had comparatively higher antioxidant activity than commercial antioxidants which indicate both their prospective efficacy and potential to replace synthetic derivatives from edible and medicinal products.

Key words: Arabian Sea, Coastal plants, DPPH, Economic potential, FRAP, Saline habitats, Salt tolerant plants, Secondary metabolites.

¹Institute of Sustainable Halophyte Utilization, University of Karachi, Karachi-75270, Pakistan

²Centre of Excellence in Marine Biology, University of Karachi, Karachi-75270, Pakistan

³Qatar Shall Chair in Sustainable Development, College of Arts and Sciences, Qatar University, Doha, P.O. Box 2713, Qatar

^*Corresponding author’s email: bilqueesgul@uok.edu.pk; Phone: (9221) 34820253; Fax: (9221) 34820258