Chulalongkorn Medical Journal


Background : The inhibition of calcium oxalate monohydrate (COM) growth andaggregation can prevent the kidney stone formation. Black-purple rice (Oryzasativa), including Riceberry rice, contains high amount of antioxidantsubstances, such as anthocyanin, gamma - oryzanol and alpha-tocophorol.A previous study revealed that the high antioxidant content substances canprevent the formation of CaOx crystal.Objective : To prove the high antioxidant activity of unpolished Riceberry rice extractcan inhibit the growth and aggregation of CaOx crystal, especially COM.Methods : Unpolished Riceberry rice (UBR) grain was extracted by ethanol.The monomeric anthocyanin content of the extract was assessed by pHdifferential method. The total phenolic compound was determined by FollinCiocalteu reagent assay. The antioxidant activity assays were carried outby 1,1 diphenyl-2-picryl-hydrazyl radical scavenging activity assay andferric reducing antioxidant power assay. The extracts were then incubatedwith the CaOx crystal, the number and the aggregation of CaOx crystalwere then counted.Results : The results revealed that UBR extract contained high amount ofanthocyanin content and possessed antioxidant activities. The co-incubationof the extracts and CaOx crystal could inhibit the growth of COM withdose-dependent pattern. Moreover, the aggregation of the CaOx crystalwas significant reduced in the incubation with higher concentration of UBRextract.Conclusion : This study indicated that UBR extract performed antioxidant activity, andcould inhibit calcium oxalate crystal growth and aggregation. These resultsshowed the high therapeutic potential of the UBR extract on the formationof kidney stone.


Faculty of Medicine, Chulalongkorn University



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