Sustainable use of mangroves as sources of valuable medicinal compounds: Species identification, propagation and secondary metabolite composition

Abstract

Mangroves are able to withstand a number of stress factors, such as high salt concentrations, tidal flooding, strong wind, solar radiation and heat. Their ability to grow under these circumstances is based on morphological and physiological adaptations, among them the high abundance of plant secondary metabolites. We are interested to investigate and exploit their medicinal and biotechnological potential for new bioactive compounds, without collecting material in the countries of origin and in a sustainable way. Therefore, a simple identification system based on molecular marker analysis, and a sustainable greenhouse propagation protocol for the continuous supply of fresh plant material, were established. DNA barcoding of the internal transcribed spacer (ITS) including ITS1, the 5.8S rRNA region and ITS2 as a molecular marker was applied for several mangrove species. The obtained data and GenBank sequences were used for species identification. Three mangrove species are cultivated in our greenhouse and propagated in different ways: Avicennia species produced many propagules in the greenhouse, however, further propagation by cuttings was not successful. Laguncularia racemosa was propagated by cuttings in a fog house whereas Bruguiera cylindrica was difficult to cultivate and propagation was not successful. Finally, the concentration of secondary phenolic compounds, including flavonoids, and the content of major elements were compared among naturally and greenhouse-grown mangroves indicating comparable amounts and composition.