{"title":"Stability study of Nepeta cataria iridoids analyzed by LC/MS.","authors":"Anthony Lockhart, James Edward Simon, Qingli Wu","doi":"10.1002/pca.3410","DOIUrl":null,"url":null,"abstract":"<p><strong>Introduction: </strong>Catnip (Nepeta cataria, L.) has well-documented applications in arthropod repellency because of its bioactive iridoids. Long-term stability of nepetalactones and other iridoids in N. cataria are needed to develop as effective pest repellents.</p><p><strong>Objectives: </strong>The present work intends to measure iridoid concentration over time in biomass, plant extracts, and extract solution while identifying degradative byproducts under different storage conditions.</p><p><strong>Methodology: </strong>Samples of desiccated biomass, ethanol extract, and extract in ethanol solution were stored in ambient light or darkness. Through UHPLC-QTOF/MS or UHPLC-QQQ/MS, the concentration of Z,E-nepetalactone, E,Z-nepetalactone, nepetalic acid, and dihydronepetalactone were examined over 2 years and statistically analyzed for determination of best storage practices. Degradation kinetics were applied to each analyte using graphical estimation. With targeted formula searching, degradative byproducts were identified and quantified.</p><p><strong>Results: </strong>Light exposure caused significant decreases in E,Z-nepetalactone concentration in all sample types, while having no effect on Z,E-nepetalactone as it decayed more rapidly. Extract samples lost nepetalactone content faster than biomass or extract solution. Dihydronepetalactone levels were low, but never declined over 2 years. Nepetalic acid increased over some periods, depending on sample type, indicating a relationship between the acid and nepetalactone. Four degradative byproducts-nepetonic acid, dehydronepetalactone, an anhydride, and an ethanolic ester-were identified, with variable responses to light exposure.</p><p><strong>Conclusions: </strong>Protecting catnip products from light is necessary to preserve nepetalactones, and a discernable difference in nepetalactone isomer stability was discovered. Identifying Nepeta chemotypes rich in dihydronepetalactone may provide more resilient botanicals as starting materials for processing.</p>","PeriodicalId":20095,"journal":{"name":"Phytochemical Analysis","volume":" ","pages":"1674-1687"},"PeriodicalIF":3.0000,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Phytochemical Analysis","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1002/pca.3410","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/8/4 0:00:00","PubModel":"Epub","JCR":"Q2","JCRName":"BIOCHEMICAL RESEARCH METHODS","Score":null,"Total":0}
引用次数: 0
Abstract
Introduction: Catnip (Nepeta cataria, L.) has well-documented applications in arthropod repellency because of its bioactive iridoids. Long-term stability of nepetalactones and other iridoids in N. cataria are needed to develop as effective pest repellents.
Objectives: The present work intends to measure iridoid concentration over time in biomass, plant extracts, and extract solution while identifying degradative byproducts under different storage conditions.
Methodology: Samples of desiccated biomass, ethanol extract, and extract in ethanol solution were stored in ambient light or darkness. Through UHPLC-QTOF/MS or UHPLC-QQQ/MS, the concentration of Z,E-nepetalactone, E,Z-nepetalactone, nepetalic acid, and dihydronepetalactone were examined over 2 years and statistically analyzed for determination of best storage practices. Degradation kinetics were applied to each analyte using graphical estimation. With targeted formula searching, degradative byproducts were identified and quantified.
Results: Light exposure caused significant decreases in E,Z-nepetalactone concentration in all sample types, while having no effect on Z,E-nepetalactone as it decayed more rapidly. Extract samples lost nepetalactone content faster than biomass or extract solution. Dihydronepetalactone levels were low, but never declined over 2 years. Nepetalic acid increased over some periods, depending on sample type, indicating a relationship between the acid and nepetalactone. Four degradative byproducts-nepetonic acid, dehydronepetalactone, an anhydride, and an ethanolic ester-were identified, with variable responses to light exposure.
Conclusions: Protecting catnip products from light is necessary to preserve nepetalactones, and a discernable difference in nepetalactone isomer stability was discovered. Identifying Nepeta chemotypes rich in dihydronepetalactone may provide more resilient botanicals as starting materials for processing.
期刊介绍：
Phytochemical Analysis is devoted to the publication of original articles concerning the development, improvement, validation and/or extension of application of analytical methodology in the plant sciences. The spectrum of coverage is broad, encompassing methods and techniques relevant to the detection (including bio-screening), extraction, separation, purification, identification and quantification of compounds in plant biochemistry, plant cellular and molecular biology, plant biotechnology, the food sciences, agriculture and horticulture. The Journal publishes papers describing significant novelty in the analysis of whole plants (including algae), plant cells, tissues and organs, plant-derived extracts and plant products (including those which have been partially or completely refined for use in the food, agrochemical, pharmaceutical and related industries). All forms of physical, chemical, biochemical, spectroscopic, radiometric, electrometric, chromatographic, metabolomic and chemometric investigations of plant products (monomeric species as well as polymeric molecules such as nucleic acids, proteins, lipids and carbohydrates) are included within the remit of the Journal. Papers dealing with novel methods relating to areas such as data handling/ data mining in plant sciences will also be welcomed.
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