title: High-throughput micro plate assays for screening flavonoid content and DPPH-scavenging activity in sorghum bran and flour.
abstract: BACKGROUND
  Sorghum possesses phenolic compounds that are health-promoting constituents of the grain. There are approximately 40 000 sorghum accessions, many of which have not been evaluated for the grain's health-promoting potential. Conventional methods for measuring total phenolic content, flavonoid content and 2,2-diphenyl-1-picrylhydrazyl (DPPH)-scavenging capacity are time-consuming and labour-intensive, resulting in low overall throughput. The objective of this study was to develop a high-throughput screening assay for large sorghum sample sets to determine flavonoid and phenolic content and to modify existing DPPH and total phenolic assays.
  
  
  RESULTS
  The 96-well assays exhibited a correlation of > 0.9 with the conventional assays. The 96-well assays allowed for up to 64 samples to be run per day compared with 20-24 samples (depending on the test) for the conventional methods. The 96-well assays had excellent accuracy (97.65-106.16% recovery), precision (1.06-8.28% coefficient of variation (CV)) and reproducibility (1.32-2.13% CV inter-day and 1.36-2.09% CV intra-day).
  
  
  CONCLUSIONS
  The high-throughput 96-well plate method proved to be as robust and reproducible as the conventional method for determining total phenolic content, flavonoid content and DPPH-scavenging capacity in either sorghum bran or flour.
authors.affiliation: USDA-ARS, Center for Grain and Animal Health Research, Manhattan, KS 66502, USA. tom.herald@ars.usda.gov
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Herald
authors.forename: Priyadarshini
authors.initials: P
authors.lastname: Gadgil
authors.forename: Michael
authors.initials: M
authors.lastname: Tilley
mesh_terms: D018556:Crops, Agricultural / Q000737:chemistry; D004043:Dietary Fiber / Q000032:analysis; D055808:Drug Discovery; D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry; D005503:Food Additives / Q000032:analysis / Q000737:chemistry; D005511:Food Handling; D005527:Food, Fortified; D016166:Free Radical Scavengers / Q000032:analysis* / Q000737:chemistry; D055951:Functional Food / Q000032:analysis; D057166:High-Throughput Screening Assays; D010636:Phenols / Q000032:analysis / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D015203:Reproducibility of Results; D012639:Seeds / Q000737:chemistry*; D045868:Sorghum / Q000737:chemistry*; D013045:Species Specificity
chemical_list: D004043:Dietary Fiber; D005419:Flavonoids; D005503:Food Additives; D016166:Free Radical Scavengers; D010636:Phenols; D010936:Plant Extracts