Development and Application of a Novel SPE-Method for Bioassay-Guided Fractionation of Marine Extracts

Abstract

The biological diversity of marine habitats is a unique source of chemical compounds with potential use as pharmaceuticals, cosmetics and dietary supplements. However, biological screening and chemical analysis of marine extracts pose specific technical constraints and require adequate sample preparation. Here we report an improved method on Solid Phase Extraction (SPE) to fractionate organic extracts containing high concentration of salt that hampers the recovery of secondary metabolites. The procedure uses a water suspension to load the extracts on a poly(styrene-divynylbenzene)-based support and a stepwise organic solvent elution to effectively desalt and fractionate the organic components. The novel protocol has been tested on MeOH-soluble material from three model organisms (Reniera sarai, Dendrilla membranosa and Amphidinium carterae) and was validated on a small panel of 47 marine samples, including sponges and protists, within discovery programs for identification of immuno-stimulatory and anti-infective natural products.

Anti-Fouling Effects of Saponin-Containing Crude Extracts from Tropical Indo-Pacific Sea Cucumbers

“…Solid Phase Extraction (SPE) chromatography: The BuOH fraction which contained the saponins was further fractionated by SPE chromatography [99]. Therefore, the SPE column (SUPELCLEAN LC 18 , 60 mL/10 g; Supleco Park, USA) was desalted/washed with 60 mL MeOH and preconditioned with 120 mL distilled water.…”

“…The peak integration of saponins in the final fractions has been assessed (Table S4), and these fractions have been used for AF assay. [99,100]). Sample set 1 and 2 refers to the samples that were tested for anti-fouling (AF) activity in this study.…”

“…(a-e) indicate significance levels according to post hoc test. Figure S2: LC/MS spectra of the crude [99,100]). Sample set 1 and 2 refers to the samples that were tested for anti-fouling (AF) activity in this study.…”

The Missing Piece in Biosynthesis of Amphidinols: First Evidence of Glycolate as a Starter Unit in New Polyketides from Amphidinium carterae

“…In our ongoing search for novel marine bioactive molecules [2], we recently focused our attention on microorganisms from the Mediterranean region. In particular, from Lake Fusaro, near Naples (Italy), we isolated a dinoflagellate strain, which was taxonomically identified as Amphidinium carterae .…”

Creating and screening natural product libraries

“…Importantly, prefractionated natural product samples typically show improved screening performance (oen observed as a higher condence in observed hit rates), enhanced biological activity due to the concentration of active components present as only minor metabolites, sequestration of common nuisance compound classes, as well as streamlined downstream processes for dereplication and the isolation of bioactive components. 21,27,29,40 Similar to the development of large natural product extract libraries, techniques to generate subsequent fraction libraries should balance the retention of maximal chemical diversity with throughput and cost relative to the amount of extract used, number of fractions produced, solvent scheme, drying, weighing, long-term storage, and formatting for HTS (Fig. 2).…”