บทคัดย่อ (ABSTRACT)

Bioactivities of organic riceberry broken rice and crude riceberry rice oil

บทคัดย่อ (ABSTRACT)



Introduction: Riceberry broken rice (RBR) and crude riceberry rice oil (CRO) are inevitably generated from organic rice process in Thailand for several tons per year with low value. The aims of this work were to determine gamma-oryzanol content, fatty acid content, antioxidant activities, total phenolic content (TPC), total flavonoid content (TFC), and tyrosinase-stimulating activity of the extracts from RBR and CRO. Materials and Methods: Different organic solvents were used to extract bioactive compounds from RBR and ethanol was used for CRO. Extracts were analyzed for gamma-oryzanol content by high-performance liquid chromatography and fatty acid content by gas chromatography-mass spectrometry. Their bioactivities were tested using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), 2,2’-Azinodi(3-ethyl-benzthiazoline sulfonic (ABTS) assays. TPC and TFC assays were performed, and tyrosinase-stimulating activities were also determined. Results: Gamma-oryzanol content in ethanolic CRO (234 mg/100 g) extract was much higher than that in aqueous RBR extract (52.5 mg/100 g). The four isomers of gamma-oryzanol including 24-methylene campesteryl ferulate (51.3%) > campesteryl ferulate (26.0%) > cycloartanyl ferulate (13.1%) > β-sitosteryl ferulate (9.6%) were found in CRO as well as RBR; however in lesser content. Seven fatty acids in the descending order: 41% oleic acid >30% linoleic acid >19% hexadecanoic acid >8% 10-octadecenoic acid >1% 9-octadecenoic acid > 0.6% pentadecanoic acid >0.4% stearic acid were found in CRO and similarly in RBR. Moreover, RBR extract exhibited antioxidant activities at 6.36 mg Trolox Equivalent Antioxidant Capacity (TEAC)/g (DPPH), 1.33 mg FeSO4 /g (FRAP), 5.82 mg TEAC/g (ABTS) with TPC of 9.94 mg gallic acid equivalent(GAE)/g, and TFC of 67.2 mg catechin equivalent (CE)/g. Interestingly, aqueous RBR extract and ethanolic CRO exhibited 45% and 26% tyrosinase-stimulating activity, respectively. Conclusion: These bioactive compounds and bioactivities in CRO and RBR have a potential to promote hair growth and hair melanogenesis and thus proved useful as cosmetic ingredients in hair product development.