Laurencia Filiformis: Phytochemical Profiling by Conventional and HPLC-NMR Approaches

Abstract

Chemical investigation of the southern Australian marine alga Laurencia filiformis forma heteroclada resulted in the isolation of two new compounds, cycloisoallolaurinterol (16) and isoallolaurinterol (23), along with the previously reported sesquiterpenes filiformin (1), filiforminol (2), allolaurinterol (3) and bromolaurenisol (10). All structures were secured by detailed spectroscopic analysis since no previous 2D NMR studies had been described for compounds 1, 2 and 10. As a result of this study, the first single X-ray diffraction study for 1 was secured. The investigation of the chemical conversion of allolaurinterol (3) to filiformin (1) was monitored by on-flow HPLC-NMR, which also resulted in the identification of 23. We propose that both compounds 16 and 23 are formed as artefacts from allolaurinterol (3). HPLC-NMR was used to profile the crude extract of a marine organism, as well as for monitoring on-line compound chemical conversions. Both on-flow and stop-flow HPLC-NMR were successfully applied in the chemical profiling and compound chemical conversion studies of L. filiformis forma heteroclada. Compounds 2 and 3 displayed antimicrobial activities.

A Historical Overview of Natural Products in Drug Discovery

“…A number of recent publications have been reported in utilizing this approach [103,104,141,142]. The technique and use of HPLC-NMR in natural products identification/characterization is well documented in the literature but applications of its uses have predominately dealt only with the chemical profiling of plants [145,146,147].…”

Application of HPLC-NMR in the Identification of Plocamenone and Isoplocamenone from the Marine Red Alga Plocamium angustum

“…The application of HPLC-NMR has been demonstrated as being able to offer valuable insight into the structure class and the range of secondary metabolites present in a crude extract. This has been successfully demonstrated in a number of chemical profiling studies conducted within our research group both on marine and terrestrial extracts and also in monitoring chemical interconversions [1,2,3,4,5]. HPLC-NMR is advantageous in that it has the ability to separate components in situ and is a non-destructive technique.…”

Natural Products of Marine Macroalgae from South Eastern Australia, with Emphasis on the Port Phillip Bay and Heads Regions of Victoria

“…Biosynthesis of these compounds has been postulated and discussed [145]. Compounds 386, 390, 393 and 397 showed cytotoxicity toward P388 cancer cells with IC 50 values ranging from >34-43 µM when tested at a concentration of 1 mg/mL, although it should be noted that compounds 390 and 397 were unstable and degraded during the course of the assays [146]. Compounds 387 and 390 were assayed for their anti-cancer activity and whilst compound 390 exhibited strong cytotoxicity against the cancer cell line NSCLC-N6 (IC 50 26.5 µM), compound 387 was found to possess only weak cytotoxicity [147].…”