Antioxidant Activity, Total Phenolic and Flavonoid Contents of Essential Oils of Three Cyperus Species (Cyperaceae)

Aims: To determine the in vitro antioxidant activity, total phenolic and flavonoid contents of essential oils from the rhizomes of Cyperus distans, Cyperus papyrus and Cyperus rotundus collected from different locations.
Study Design: The study was design to investigate the total phenolic and flavonoid contents and antioxidant properties of essential oils from the rhizomes of Cyperus distans, Cyperus papyrus and Cyperus rotundus in order to assess their medicinal values.
Place and Duration of Study: Fresh plant materials of Cyperus distans, Cyperus papyrus and Cyperus rotundus were randomly collected at the flowering stage between October, 2006 and September, 2007 from different locations in KwaZulu-Natal Province, South Africa.
Methodology: The antioxidant potential of the oils of C. distans, C. papyrus and C. rotundus was evaluated by 1,1-diphenylpicryl-hydrazyl (DPPH), hydroxyl radical, nitric oxide, metal chelating and reducing potential methods. The total phenolic and flavonoid contents of the oils were determined by spectrophotometer using Gallic acid and Quercetin equivalents, respectively.
Results: The essential oils of C. distans, C. papyrus and C. rotundus showed no metal chelating activity and poor aptitude to scavenge 1,1-diphenyl-2-picrylhydrazyl radical with inhibitory concentration (IC50) >173 µg/mL, when compared to standard antioxidants; butyl hydroxyl anisole (BHA), butyl hydroxyl toluene (BHT), ascorbic acid (Vitamin C) and α-tocopherol with IC50 ≤10.70 µg/ mL. But, displayed significant antioxidant effects, when tested with other methodologies. The total phenolic content and the concentrations of flavonoid in the oils varied from (0.032 to 0.085) mg (Gallic acid)/100 µL and (0.027 to 0.072) mg (Quercetin)/ 100 µL equivalents, respectively.
Conclusion: The observed difference in antioxidant activities of the essential oils of C. distans, C. papyrus and C. rotundus may be due to climatic, seasonal and geographic conditions, harvest period, distillation technique, plant maturity and the presence of some major components or synergy between compounds present in the essential oils.