title: A new TLC bioautographic assay for qualitative and quantitative estimation of lipase inhibitors.
abstract: BACKGROUND
  Lipase inhibitory assays based on TLC bioautography have made recent progress; however, an assay with greater substrate specificity and quantitative capabilities would advance the efficacy of this particular bioassay.
  
  
  OBJECTIVE
  To address these limitations, a new TLC bioautographic assay for detecting lipase inhibitors was developed and validated in this study.
  
  
  METHODS
  The new TLC bioautographic assay was based on reaction of lipase with β-naphthyl myristate and the subsequent formation of the purple dye between β-naphthol and Fast Blue B salt (FBB). The relative lipase inhibitory capacity (RLIC) was determined by a TLC densitometry with fluorescence detection, expressed as orlistat equivalents in millimoles on a per sample weight basis. Six pure compounds and three natural extracts were evaluated for their potential lipase inhibitory activities by this TLC bioautographic assay.
  
  
  RESULTS
  The β-naphthyl myristate as the substrate improved the detection sensitivity and specificity significantly. The limit of detection (LOD) of this assay was 0.01 ng for orlistat, the current treatment for obesity. This assay has acceptable accuracy (92.07-105.39%), intra-day and inter-day precisions [relative standard deviation (RSD), 2.64-4.40%], as well as intra-plate and inter-plate precisions (RSD, 1.8-4.9%).
  
  
  CONCLUSIONS
  The developed method is rapid, simple, stable, and specific for screening and estimation of the potential lipase inhibitors.
authors.affiliation: Key Laboratory of Standardisation of Chinese Medicines of Ministry of Education, The Shanghai Key Laboratory for Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
authors.forename: Jihe
authors.initials: J
authors.lastname: Tang
authors.affiliation: Key Laboratory of Standardisation of Chinese Medicines of Ministry of Education, The Shanghai Key Laboratory for Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
authors.forename: Jinge
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Shanghai Edible Fungi Institute, Shanghai Academy of Agricultural Sciences, Shanghai, 201106, China.
authors.forename: Qingjiu
authors.initials: Q
authors.lastname: Tang
authors.affiliation: Key Laboratory of Standardisation of Chinese Medicines of Ministry of Education, The Shanghai Key Laboratory for Compound Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wu
authors.affiliation: Department of Pharmacognosy, School of Pharmacy, Fudan University, Shanghai, 201203, China.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Cheng
mesh_terms: D002855:Chromatography, Thin Layer / Q000295:instrumentation / Q000379:methods*; D003979:Diazonium Compounds / Q000032:analysis / Q000737:chemistry; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D004791:Enzyme Inhibitors / Q000032:analysis* / Q000494:pharmacology; D004867:Equipment Design; D006868:Hydrolysis; D007783:Lactones / Q000032:analysis; D057230:Limit of Detection; D008049:Lipase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009226:Myristates / Q000737:chemistry / Q000378:metabolism; D000077403:Orlistat; D010936:Plant Extracts / Q000032:analysis / Q000494:pharmacology; D015203:Reproducibility of Results
chemical_list: D003979:Diazonium Compounds; D004791:Enzyme Inhibitors; D007783:Lactones; D009226:Myristates; D010936:Plant Extracts; C020747:Fast Blue B; C030017:2-naphthylmyristate; D000077403:Orlistat; D008049:Lipase
keywords: Lipase inhibitor; TLC bioautography; obesity; β-naphthyl myristate