Variation of total amount of phenolic compounds, radical scavenging activity and volatile com pounds of Liriodendron tulipifera L. and Ginkgo biloba L. leaves extracts during different vegetation periods

Abstract

There is a lack of research focussing on Liriodendron tulipifera L. and Ginkgo biloba  L. introduced in Lithuania. Moreover, extensive comparative phytochemical studies of these two relict plants have not yet been carried out. Therefore the aim of this study was a complex comparative analysis of biologically active compounds of these two plants introduced in Lithuania, using spectrophotometric, chromatographic and mass spectrometric techniques. To the authors' knowledge there is no data published yet on comparative analysis of Liriodendron tulipifera L. and Ginkgo biloba L. introduced in different countries. Volatile compounds, radical scavenging activity, total amount and composition of phenolic compounds and flavonoids accumulated in leaves of these plants during different vegetation periods were determined. Remarkable differences of quantitative and qualitative composition of phenolic compounds have been determined in different vegetation periods in different plants. The highest total amount of phenolic compounds was in Liriodendron tulipifera L. leaves collected at the start of seed ripening vegetation period (12 300 mg RE/100 g). In Ginkgo biloba L. the highest amount of phenolic compounds was determined at the end of leaves growth (5 990 mg RE/100 g). The qualitative and quantitative analysis of phenolic compounds revealed the presence of rutin, chlorogenic and sinapic acids in extracts of Liriodendron tulipifera L. and rutin with chlorogenic acid in extracts of Ginkgo biloba L. Composition and amount of volatile compounds were dependent on the plant species and vegetation period. The highest concentration of volatile compounds was found in the leaves of Liriodendron tulipifera L. at the end of flowering.