Effect of Methyl Jasmonate on the Terpene Trilactones, Flavonoids, and Phenolic Acids in Ginkgo biloba L. Leaves: Relevance to Leaf Senescence

Marcin Horbowicz,Justyna Góraj-Koniarska,Junichi Ueda,Marian Saniewski,Wiesław Wiczkowski,Kensuke Miyamoto

doi:10.3390/molecules26154682

Abstract

The present study compared the effects of natural senescence and methyl jasmonate (JA-Me) treatment on the levels of terpene trilactones (TTLs; ginkgolides and bilobalide), phenolic acids, and flavonoids in the primary organs of Ginkgo biloba leaves, leaf blades, and petioles. Levels of the major TTLs, ginkgolides B and C, were significantly higher in the leaf blades of naturally senesced yellow leaves harvested on 20 October compared with green leaves harvested on 9 September. In petioles, a similar effect was found, although the levels of these compounds were almost half as high. These facts indicate the importance of the senescence process on TTL accumulation. Some flavonoids and phenolic acids also showed changes in content related to maturation or senescence. Generally, the application of JA-Me slightly but substantially increased the levels of TTLs in leaf blades irrespective of the difference in its application side on the leaves. Of the flavonoids analyzed, levels of quercetin, rutin, quercetin-4-glucoside, apigenin, and luteolin were dependent on the JA-Me application site, whereas levels of (+) catechin and (−) epicatechin were not. Application of JA-Me increased ferulic acid and p-coumaric acid esters in the petiole but decreased the levels of these compounds in the leaf blade. The content of p-coumaric acid glycosides and caffeic acid esters was only slightly modified by JA-Me. In general, JA-Me application affected leaf senescence by modifying the accumulation of ginkogolides, flavonoids, and phenolic acids. These effects were also found to be different in leaf blades and petioles. Based on JA-Me- and aging-related metabolic changes in endogenous levels of the secondary metabolites in G. biloba leaves, we discussed the results of study in the context of basic research and possible practical application.

Highlights

IntroductionGinkgo biloba (L.) is the only surviving member of the Ginkgoaceae family, one of the most ancient living gymnosperms, and is planted worldwide as an ornamental tree for its resistance to urban conditions [1]
The green leaves of G. biloba collected on 9 September and naturally senesced yellow leaves collected on 20 October were found to contain specific terpene trilactones, called ginkgolides A, B, C, and J and bilobalide
There were clear differences in the contents of trilactones in the leaf blades and petioles between green leaves harvested on the day the experiment was set up (Figure 1, marked as 1) and naturally senesced yellow leaves harvested on 20 October (Figure 1, marked as 2)

Summary

Introduction

Ginkgo biloba (L.) is the only surviving member of the Ginkgoaceae family, one of the most ancient living gymnosperms, and is planted worldwide as an ornamental tree for its resistance to urban conditions [1]. G. biloba is one of the most commercialized medicinal plants, as extracts from the leaves contain ingredients that improve memory, increase blood circulation, and benefit those suffering from Alzheimer’s disease [2,3,4]. The leaf contains multiple compounds, such as terpene trilactones, flavonoids, and phenolic acids, and the biological effect of G. biloba extracts has been thought to be a synergistic action of these compounds. Ginkgolides and bilobalide are unique components found only in G. biloba and are thought to contribute to its neuroprotective and vasotropic effects [5,6,7]

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Conclusion