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Journal of Thai Traditional & Alternative Medicine Vol. 6 No. 2 May-August (Supplement) 2008 Ò˘

PO-7

Free radical scavenging activity of extracts from the medicinal plants

selected from the Thai Lanna Recipes for diabetes treatment

1,2 1,3 1,2
Jiradej Manosroi , MZ Zaruwa , Arunya Manosroi
1 2
Faculty of Pharmacy, Chiang Mai University; Natural Products Research and Development Center (NPRDC), Institute of Science
and Technology Research and Development (IST), Chiang Mai University, 50200, Thailand;
3
Adamawa State University, Mubi, Nigeria
e-mail: pmpti006@chiangmai.ac.th

Rationale: The plants used in this research were selected from the Thai Lanna Medicinal Plant Recipe Database
for diabetes treatment. This study has investigated free radical scavenging activities of the plants in order to explain
the mechanism of their antidiabetic activities.

Objective: To determine free radical scavenging activity of extracts from the medicinal plants selected from the
Thai Lanna recipes for diabetes treatment.

Method: Aqueous and methanol extracts of the 5 selected plants namely, Dioecrescis erythroclada (Kurz) Tirveng
(DE), Capsicum frutescens L. (CF), Zingiber officinale Roscoe (ZO), Sapindus rarak DC (SR) and Zingiber
montanum (J. Koenig) Link ex A. Dietr. (ZM) from the Thai Lanna medicinal plant recipes were prepared. The
extracts were tested for free radical scavenging activity by the DPPH assay. The average scavenging activity (IC )
50
at 50% concentration of the extract were calculated. The experiments were performed in triplicates.

Results: For aqueous extract, ZO showed about 2 times higher scavenging activity than that of vitamin C, while
DE and ZM gave a slight activity. The extracts of SR and CF showed poor activity and were lower than the
standards (vitamin C and vitamin E). The methanolic extractions from DE, ZO and ZM indicated activity slightly
higher than that of vitamin E, whereas CF and SR gave low activities.

Conclusion: This study has demonstrated the potential of the 3 Thai Lanna medicnal plants, which were DE, ZO

and ZM for further development of pharmaceutical applications.