Abstract
Biodiversity is key for maintenance of life and source of richness. Nevertheless, concepts such as phenotype expression are also pivotal to understand how chemical diversity varies in a living organism. Sesquiterpene pyridine alkaloids (SPAs) and quinonemethide triterpenes (QMTs) accumulate in root bark of Celastraceae plants. However, despite their known bioactive traits, there is still a lack of evidence regarding their ecological functions. Our present contribution combines analytical tools to study clones and individuals of Maytenus ilicifolia (Celastraceae) kept alive in an ex situ collection and determine whether or not these two major biosynthetic pathways could be switched on simultaneously. The relative concentration of the QMTs maytenin (1) and pristimerin (2), and the SPA aquifoliunin E1 (3) were tracked in raw extracts by HPLC-DAD and 1H-NMR. Hierarchical Clustering Analysis (HCA) was used to group individuals according their ability to accumulate these metabolites. Semi-quantitative analysis showed an extensive occurrence of QMT in most individuals, whereas SPA was only detected in minor abundance in five samples. Contrary to QMTs, SPAs did not accumulate extensively, contradicting the hypothesis of two different biosynthetic pathways operating simultaneously. Moreover, the production of QMT varied significantly among samples of the same ex situ collection, suggesting that the terpene contents in root bark extracts were not dependent on abiotic effects. HCA results showed that QMT occurrence was high regardless of the plant age. This data disproves the hypothesis that QMT biosynthesis was age-dependent. Furthermore, clustering analysis did not group clones nor same-age samples together, which might reinforce the hypothesis over gene regulation of the biosynthesis pathways. Indeed, plants from the ex situ collection produced bioactive compounds in a singular manner, which postulates that rhizosphere environment could offer ecological triggers for phenotypical plasticity.
Highlights
It has been established that biodiversity is a central theme in several political and scientific forums.Over the last decades, the impact that biodiversity has on life maintenance on the planet has furnished several theories, such as the Gaia theory, proposed by Lovelock in the 60s, and the Anthropocene geological era theory, proposed by Crutzen [1,2].Molecules 2019, 24, 1160; doi:10.3390/molecules24061160 www.mdpi.com/journal/moleculesBiodiversity reached the headlines of academic topics building on the principle that it provides richness
The dereplication of bioactive metabolites in M. ilicifolia raw extracts was successful due to combination of a few practical tasks: (1) rigorous spectroscopy and chromatographic data survey of compounds previously investigated in taxonomically-related species and (2) the proper use of analytical tools and detection channels to narrow information down to the target group of compounds
One useful aspect of this paper is as a proof of concept that these two practical tasks can be adopted for rapid selection of botanical vouchers displaying high contents of active terpenes
Summary
It has been established that biodiversity is a central theme in several political and scientific forums.Over the last decades, the impact that biodiversity has on life maintenance on the planet has furnished several theories, such as the Gaia theory, proposed by Lovelock in the 60s, and the Anthropocene geological era theory, proposed by Crutzen [1,2].Molecules 2019, 24, 1160; doi:10.3390/molecules24061160 www.mdpi.com/journal/moleculesBiodiversity reached the headlines of academic topics building on the principle that it provides richness. It has been established that biodiversity is a central theme in several political and scientific forums. In Nature, this intrinsic value of biodiversity extends beyond ecosystem variability, ecological services and genetic heritage and determines both individual viability and community plasticity. The evaluation of biodiversity [3,4,5,6] has culminated in bio-economic development [7] and fostered Brazilian public policies towards conservation of this resource [5]. Recent findings on the Brazilian “Mata Atlântica” rainforest, alongside the efforts of the FAPESP Research Program on Biodiversity Characterization, Conservation, Restoration and Sustainable Use (BIOTA, http://www.biota.org.br/en/) are a handful of successful study cases on how biodiversity data could be used for conservation and sustainable use of Brazilian natural resources
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