In this study, endophytic bacteria belonging to the Bacillus genus were isolated from in vitro bulblets of Leucojum aestivum and their ability to produce Amaryllidaceae alkaloids was studied. Proton Nuclear Magnetic Resonance (1H NMR)-based metabolomics combined with multivariate data analysis was chosen to compare the metabolism of this plant (in vivo bulbs, in vitro bulblets) with those of the endophytic bacteria community. Primary metabolites were quantified by quantitative 1H NMR (qNMR) method. The results showed that tyrosine, one precursor of the Amaryllidaceae alkaloid biosynthesis pathway, was higher in endophytic extract compared to plant extract. In total, 22 compounds were identified including five molecules common to plant and endophyte extracts (tyrosine, isoleucine, valine, fatty acids and tyramine). In addition, endophytic extracts were analyzed using Liquid Chromatography-Mass Spectrometry (LC-MS) and Gas Chromatography-Mass Spectrometry (GC-MS) for the identification of compounds in very low concentrations. Five Amaryllidaceae alkaloids were detected in the extracts of endophytic bacteria. Lycorine, previously detected by 1H NMR, was confirmed with LC-MS analysis. Tazettine, pseudolycorine, acetylpseudolycorine, 1,2-dihydro-chlidanthine were also identified by LC-MS using the positive ionization mode or by GC-MS. In addition, 11 primary metabolites were identified in the endophytic extracts such as tyramine, which was obtained by decarboxylation of tyrosine. Thus, Bacillus sp. isolated from L. aestivum bulblets synthesized some primary and specialized metabolites in common with the L.aestivum plant. These endophytic bacteria are an interesting new approach for producing the Amaryllidaceae alkaloid such as lycorine.
The phytochemical profiles of extracts from closed, semi-opened and opened leaf buds and the summer leaves of Ginkgo biloba were studied. The extraction and purification of bilobalide and ginkgolides, using andrographolide as an internal standard, were optimised. The terpene trilactone concentrations increased with bud development, from 1.07 mg/g dry wt in closed buds to a maximum of 3.75 mg/g dry wt in summer leaves. The major terpene trilactone was bilobalide at all developmental stages. The concentration of flavonol aglycones in hydrolysed extracts was also analysed. The flavonol glycoside concentration increased from the closed bud stage (0.21 ± 0.01% dry wt) to the summer leaf stage (1.15 ± 0.01% dry wt). A linear correlation was observed between the terpene trilactone and flavonoid content during gingko leaf development.