Biological activities and chemical content of Sung Yod rice bran oil extracted by expression and soxhlet extraction methods.

Background: Sung Yod rice is a red-violet pigmented rice and grown in the southern part of Thailand. Its rice bran oil has attracted the attention of scientists who have described anti-oxidant properties of some ingredients in Sung Yod rice bran oil. Normally, extraction methods of commercial product from rice bran oil are by expression or soxhlet extraction with hexane. Thus, biological activities of Sung Yod rice bran oil related to health and chemical content of rice bran oil from the two methods should be studied. Objective: The objectives of this research were to investigate for biological activities and chemical content of Sung Yod rice bran oil obtained from expression or soxhlet extraction method. Material and Method: Biological activities such as cytotoxic, anti-inflammatory and antioxidant activities were investigated. Sulphorhodamine (SRB) assay was used to test cytotoxic activity against four human cancer cell lines: lung (COR-L23), cervical (HeLa), prostate (PC-3) and breast (MCF-7) and normal human lung cells (MRC-5). The inhibitory effect on lipopolysaccharide (LPS) induced nitric oxide (NO) production in RAW 264.7 cell lines was used for the determination of antiinflammatory effect. DPPH, TEAC and FRAP assay were carried out for antioxidant activity. Total phenolic compound was determined by Folin-Ciocalteu reagent. γ-oryzanol and vitamin E content were determined by HPLC. Sung Yod rice bran oil was produced by expression method (EX) or by soxhlet extraction method using hexane (SXH). Results: The percentage of yield of Sung Yod rice bran oil by EX and SXH were 2.16 and 15.23 %w/w, respectively. Only EX showed the selective cytotoxicity against prostate cancer cells (PC-3), (IC50 = 52.06+1.60 μg/ml). It also exhibited high inhibitory effects on NO production (IC50 = 30.09 μg/ml). In contrast, SXH had no anti-inflammatory effect and cytotoxic activity against any of the cancer cells. EX showed higher antioxidant activity determined using DPPH compared to SXH. It also showed higher amount of γ-oryzanol and vitamin E than that of SXH (3.09+1.04 and 1.35+1.56 mg % w/w of extracts, respectively). Yet, SXH exhibited higher antioxidant power determined by FRAP assay and higher total phenolic content compared with EX. Conclusion: Sung Yod rice bran oil, produced by expression method, had better benefit for health regarding cytotoxicity against prostate cancer cells (PC-3), anti-inflammatory effect and antioxidant (using DPPH) than that produced by soxhlet method extracted with hexane. Keywords: Sung Yod rice bran, Cytotoxicity against cancer cells, Anti-inflammatory, Antioxidant, Gamma oryzanol, Total phenolic content