Synthesis of small combinatorial libraries of natural products: identification and quantification of new long-chain 3-methyl-2-alkanones from the root essential oil of Inula helenium L. (Asteraceae).

摘要: Introduction Recently, a potent anti-staphylococcal activity of Inula helenium L. (Asteraceae) root essential oil was reported. Also, bioassay guided fractionation the pointed to eudesmane sesquiterpene lactones and series unidentified constituents as main carriers observed activity. Objective To identify nine new (long-chain 3-methyl-2-alkanones) from fraction this with low minimum inhibitory concentration value (0.8 µg/mL) by employing synthetic methodology that leads formation small combinatorial library these compounds. Methods The identity inferred mass spectral fragmentation patterns GC retention data. A 3-methyl-2-alkanones (C11–C19 homologous series) synthesised in three steps starting methyl acetoacetate corresponding alkyl halides. The also screened for vitro anti-microbial activity. Results Gas chromatographic analyses I. samples spiked compounds corroborated tentative identifications long-chain 3-methyl-2-alkanones. availability made it possible construct GC/FID calibration curves determine their content plant material: 0.08 − 24.2 mg/100 g dry roots. Conclusion The approach enabled first unequivocal identification secondary metabolites, and, also, allowed determination not only single compound biological properties, but those group structurally related compounds. Copyright © 2013 John Wiley & Sons, Ltd.