Assessment of multiple solvents for extraction and direct GC-MS determination of the phytochemical inventory of sansevieria extrafoliar nectar droplets

Abstract

Considerable effort has been devoted to analytical determinations of sugar and amino acid constituents of plant nectars, with the primary aim of understanding their ecological roles, yet few studies have reported more exhaustive organic compound inventories of plant nectars or extrafoliar nectars. This work evaluated the efficacy of four solvents (ethyl acetate, dichloromethane, toluene and hexane) to extract the greatest number of organic compound classes and unique compounds from extrafoliar nectar drops produced by Sansevieria spp. Aggregation of the results from each solvent revealed that 240 unique compounds were extracted in total, with 42.5% of those detected in multiple extracts. Aliphatic hydrocarbons dominated in all but the ethyl acetate extracts, with 44 unique aliphatic hydrocarbons detected in dichloromethane (DCM) extracts, followed by 41, 19 and 8 in hexane, toluene and ethyl acetate extracts, respectively. Hexane extracted the most unique compounds (79), followed by DCM (73), ethyl acetate (56) and toluene (32). Integrated total ion chromatographic peak areas of extracted compound classes were positively correlated with numbers of unique compounds detected within those classes. In addition to demonstrating that multi-solvent extraction with direct GC-MS detection is a suitable analytical approach for determining secondary nectar constituents, to the best of our knowledge, this study also represents: (i) the first attempt to inventory the secondary phytochemical constituents of Sansevieria spp. extrafoliar nectar secretions and (ii) the largest organic solvent extractable compound inventory reported for any plant matrix to date.