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Journal of Thai Traditional & Alternative Medicine Vol. 12 No. 1 January-April 2014 71

Abstract
Free-Radical Scavenging Activities of Essential Oils and Aqueous Extracts from Thai
Herbs
†
Prapai Wongsinkongman*, Jaree Bansiddhi*, Somchai Sanluangin*, Tanawat Tongchin , Panasda
‡
Israngkoon Na Ayudhaya , Noppamas Soonthornchareonnont §
*Medicinal Plant Research Institute, Department of Medical Sciences, Nonthaburi 11000.
†
Regional Medical Sciences Center 2 Phitsanulok, Department of Medical Sciences, Phitsanulok 65000.
‡
National Institute of Health, Department of Medical Sciences, Nonthaburi 11000.
§
Faculty of Pharmacy, Mahidol University, Bangkok 10400.
Corresponding author: prapai.w@dmsc.mail.go.th
The essential oils obtained by hydrodistillation and the aqueous extracts using freeze-
drying apparatus from 12 types (9 families) of fresh Thai herbs were tested for free-radical
scavenging activities using 2,2-diphenyl-1-picryhydrazyl (DPPH) assay. It was found that 3 types
of essential oils from betel, monthadaeng and cajuput leaves exhibited potent free-radical
scavenging activities with IC 50 at 0.04, 0.23, and 3.24 μμ μμ μl/ml, respectively. The physico-chemical
properties of these oils were studied using identification (color test, thin-layer chromatography,
gas chromatography-mass spectrometry, miscibility in 85% ethanol, relative density, and refrac-
tive index). For the aqueous extracts, it was shown that guava and cajuput leaves exhibited the
best free-radical scavenging activities with IC 50 at 3.72 and 4.17 μμ μμ μg/ml, respectively, while those
from cajuput and guava leaves possessed the anti-HIV-1 activity with IC 90 at 15 and 30 μμ μμ μg/ml,
respectively. The results of this study will be useful for further development as herbal products.

Keywords: free-radical scavenging activity, anti-HIV-1 activity, essential oils, herbal aqueous
extract