Abstract
Marine Cyanobacteria (blue-green algae) have been shown to possess an enormous potential to produce structurally diverse natural products that exhibit a broad spectrum of potent biological activities, including cytotoxic, antifungal, antiparasitic, antiviral, and antibacterial activities. Here, we report the isolation and structure determination of palstimolide A, a complex polyhydroxy macrolide with a 40-membered ring that was isolated from a tropical marine cyanobacterium collected at Palmyra Atoll. NMR-guided fractionation in combination with MS2-based molecular networking and isolation via HPLC yielded 0.7 mg of the pure compound. The small quantity isolated along with the presence of significant signal degeneracy in both the 1H and 13C-NMR spectra complicated the structure elucidation of palstimolide A. Various NMR experiments and solvent systems were employed, including the LR-HSQMBC experiment that allows the detection of long-range 1H–13C correlation data across 4-, 5-, and even 6-bonds. This expanded NMR data set enabled the elucidation of the palstimolide’s planar structure, which is characterized by several 1,5-disposed hydroxy groups as well as a tert-butyl group. The compound showed potent antimalarial activity with an IC50 of 223 nM as well as interesting anti-leishmanial activity with an IC50 of 4.67 µM.
Highlights
Marine cyanobacteria are extraordinarily rich in biologically active and structurally diverse natural products (NPs), often times deriving from hybrid nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) biosynthetic pathways [1,2,3]
Optical rotations were measured on a JASCO P-2000 polarimeter (JASCO Corporation, Tokyo, Japan), UV/Vis data were obtained using a Beckman DU800 spectrophotometer (Beckman Coulter, Brea, CA, USA), and IR spectra were recorded on a Nicolet 100 FT-IR spectrometer (Nicolet, Madison, WI, USA)
NMR data were obtained on a Bruker AVANCE III 600 MHz NMR with a 1.7 mm dual tune TCI cryoprobe (Bruker, Billerica, MA, USA) and the 1D TOCSY experiments were performed on a JEOL ECZ 500 NMR spectrometer equipped with a 3 mm inverse probe (H3X) (JEOL Ltd., Tokyo, Japan)
Summary
Marine cyanobacteria are extraordinarily rich in biologically active and structurally diverse natural products (NPs), often times deriving from hybrid nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) biosynthetic pathways [1,2,3]. Those cyanobacterial NPs with an exclusive PKS origin are often cyclized to form macrolides, a class of compounds that generally possesses important biomedical properties [4,5]. Molecules 2020, 25, that possess biological activities with potential applications in medicine These carbon-chain compounds show a high diversity in their skeleton architectures along with complex spatial are known to produce aofvariety of structurally diverse macrolides thatbastimolide possess biological configurations
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
