Chemical variation and analysis of diterpenes from seaweed Dictyota menstrualis under controlled conditions

Abstract

Brown algae are a rich source of valuable compounds. The Dictyota species are resources tapped to obtain diterpenes with important bioactivities, that seem to have potential pharmaceutical applications. The bioprocess engineering of seaweeds to produce these compounds is an emerging area of marine biotechnology and species from the Dictyota genus could represent an attractive model to understand not only physiology but also the production of metabolites. In this study, a system for long-term experiments in the laboratory of algae Dictyota menstrualis using the resource of natural seawater, was developed, as a proposal of a low-cost medium for storing biomass and analyzing diterpenoid profile. Two experiments were proposed and using chemical analysis GC–MS it was possible to monitor 11 important diterpenes over time. In Experiment 1 (E1), qualitative comparisons of crude extracts obtained from field samples, initial analysis (AI) and final analysis (FA) of samples after 180 days in maintenance allowed the detection and stability of the chemical profiles of the diterpenes in these two evaluated times. This highlight that production of hydroxy-type dichotomane (17.5%) and acetyl-type xeniane (24.01%) diterpenes was favored under controlled conditions. In Experiment 2 (E2), the maintenance system was monitored every 30 days for 122 days, with respective comparisons of the chemical profile. Important events like the production of acetylated versions, for example, the acetoxy-type dichotomane with 38% at 122 days. Our results showed that the populations of D. menstrualis collected in different places and dates, with technical replicas, survived under laboratory conditions for a period of 4 to 6 months, reporting for the first time, detection of these metabolites under laboratory conditions. These findings propose this alga as target species for the maintenance of algal biomass, which may represent an interesting sustainable way to obtain diterpenes.