Comparative Antioxidant and Antimicrobial Activities of Phenolic Compounds Extracted from Five Hypericum Species

Mumtaz Ali¹, Mohammad Arfan², Habib Ahmad³, Khair Zaman², Farhatullah Khan⁴ and Ryszard Amarowicz⁵*

¹Department of Chemistry, University of Malakand, Chakdara, Dir, Pakistan
²Institute of Chemical Sciences University of Peshawar, Peshawar-25120, Pakistan                                                        
³Department of Botany, Hazara University, Mansehra, Pakistan                                                                                       
⁴Department of Biological Sciences, Quaid-e-Azam University, Islamabad, Pakistan                                                              
⁵Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences, Tuwima 10, 10-747 Olsztyn, Poland

Article history:
Received: October 25, 2009
Accepted: April 6, 2010

Key words:
Hypericum monogynum, H. oblongifolium, H. perforatum, H. choisianum, H. dyeri, phenolic compounds, antioxidant activity, antimicrobial activities

Summary:
Phenolic compounds were extracted from five Hypericum species (H. perforatum, H. oblongifolium, H. monogynum, H. choisianum and H. dyeri Redher) using ethanol. The crude extract (called fraction 1) was then fractionated using re-extraction to water (fraction 2), ethyl acetate (fraction 3), and acetone (fraction 4). The final residue was marked as fraction 5. The content of total phenolics in the fractions ranged from 21 mg of gallic acid equivalents per g (fraction 5 of H. dyeri) to 100 mg of gallic acid equivalents per g (fraction 5 of H. choisianum). Phenolic compounds present in the fractions showed antioxidant and antiradical properties investigated using DPPH radical scavenging activity, molybdate method, and reducing power. The strongest antiradical properties were noted for fraction 3 of H. choisianum (EC50=11.2 mg/mL), whereas the weakest was for fraction 5 of H. dyeri (EC50=139.2 mg/mL). Fractions 1 and 5 of H. dyeri showed good antibacterial activity against Escherichia coli, while fractions 3–5 of H. perforatum were active against Staphylococcus aureus and Pseudomonas aeruginosa. Fractions 1–4 of H. perforatum were found most active against Helminthosporium maydis as determined by antifungal screening.

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