Page 71 - journal-8-2-S-Full

Journal of Thai Traditional & Alternative Medicine Vol. 8 No. 2 May-August (Supplement) 2010 ˆı

PP-22

EXAMINATION OF ANTIOXIDANT ACTIVITY AND DEVELOPMENT OF RICE BRAN

OIL AND GAMMA-ORYZANOL MICROEMULSION

1 1 1 1
Suwanna Vorarat , Chittima Managit , Lukkhana Iamthanakul , Wikalda Soparat ,
1,2
Narisa Kamkaen
1
Faculty of Pharmacy, Srinakharinwirot University, Ongkharak, Nakhorn-nayok, 26120
2
Research and Development Institute, Suan Dusit Rajabhat University, Bangkok 10300

Rationale: Rice bran oil (RBO) is the oil extracted from the germ and inner husk of rice. RBO contains a
range of oils, with 18-23% of the unsaturated oil including monounsaturated and polyunsaturated oil. The fatty

acids compositions are linolenic acid (omega-3, omega-6) and oleic acid (omega 9). This natural oil is rich in
essential vitamin E complex; tocotrienols and gamma oryzanol. Gamma oryzanol serves as an important anti-
oxidation effect, protects the skin from Ultra-violet radiation and increase moisture to the skin as well. There-
fore, the idea for application in the cosmetics is both antiwrinkle and moisturizer for the skin.
Objective: To examine the antioxidant activity and formulate rice bran oil and gamma-oryzanol product.
Methodology: The antioxidant activity examinations were performed by using DPPH radical scavenging
assay and Ferric Reducing Antioxidant Potential (FRAP) assay. The phase diagrams of RBO and RBO plus
gamma-oryzanol microemulsion were developed by using the surfactant and co-surfactant. The skin irritation
studies were performed in 12 healthy volunteers in accordance with the guidelines of the Consumer Product

Safety Commission.
Results: The antioxidant activity of RBO and RBO plus gamma-oryzanol microemulsion were evaluated
by DPPH and FRAP assay. The outcome of free radical scavenging properties of gamma-oryzanol was demon-
strated in term of Trolox equivalent antioxidant capacity (TEAC). For DPPH assay, TEAC values were of 0.0015-
0.0206 mmol/g when the concentrations were 0.0625-1.0000 mg/ml. For FRAP assay, TEAC values were of
0.0054-0.0272 mmol/g when the concentrations were 0.0680-1.0910 mg/ml. While the linear correlation between
TEAC and log concentration was determined as R2 = 0.9929 and 0.9975 respectively. The outcomes of free

radical scavenging properties of rice bran oil, for DPPH assay, TEAC values were of 0.0059-0.0214 mmol/g when
the concentrations were 8-40 mg/ml, while FRAP assay could not examine the antioxidant activity because of
the immiscibility between reagent and rice brain oil. Then microemulsion was formulated using rice brain oil
and gamma-oryzanol as an active antioxidant, cremophor and span 80 as a surfactant and absolute ethanol as
a co-surfactant. The safety of the products was observed in term of the skin irritation (edema and erythema).
The developed formulation showed non-irritant to the skin with no erythema or edema in all subjects.
Conclusion: The RBO, in general, showed high antioxidant activities and vitamin E complex particularly
gamma-oryzanol. Relatively, the antioxidant activity both assays showed the highest in gamma-oryzanol. More-
over, there were relative between antioxidant activities and gamma-oryzanol contents in microemulsion. The

RBO plus gamma-oryzanol microemulsion showed higher antioxidant activity than RBO microemulsion. It could
be concluded that gamma-oryzanol contribute to antioxidant activity in RBO plus gamma-oryzanol microemulsion.