The effects of different extraction solvents of varying polarities on polyphenols of Orthosiphon stamineus and evaluation of the free radical-scavenging activity

G. A. Akowuah, Z. Ismail, I. Norhayati, A. Sadikun

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235 Citations (Scopus)


Leaf powder of Orthosiphon stamineus was extracted with the following solvents; distilled water, 50% aqueous methanol, methanol, 70% aqueous acetone and chloroform, at 2, 4 and 8 h, respectively, on a water bath at 40°C. The extracts were subjected to qualitative and quantitative HPLC analyses of the polyphenols, the most dominant chemical constituents in the leaf. Chloroform extraction from 4 to 8 h at 40°C gave the highest amount of sinensetin and eupatorin. The extraction with 70% aqueous acetone extracts at 4 and 8 h gave a high yield of 3′-hydroxy-5,6,7,4′-tetramethoxyflavone. The yield of rosmarinic acid was high in 50% methanol extracts at 2, 4 and 8 h of extraction. The extracts were screened for free radical-scavenging potential, using a 1,1-diphenyl-2-picrylhydrazyl in vitro model system. The extracts exhibited significant radical-scavenging activity and the acetone extracts showed the highest activity.

Original languageEnglish
Pages (from-to)311-317
Number of pages7
JournalFood Chemistry
Issue number2
Publication statusPublished - Nov 2005
Externally publishedYes


  • HPLC
  • Lipophilic flavones
  • Orthosiphon stamineus
  • Rosmarinic acid

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