Acetate-Derived Metabolites from the Brown Alga Lobophora variegata

Abstract

Seven new nonadecaketides (1-7), lobophorols A-C, lobophopyranones A and B, and lobophorones A and B, along with the first naturally occurring related metabolites (8-10), were isolated from specimens of Lobophora variegata collected from the Canary Islands. Their structures were determined by extensive spectroscopic methods. In addition, an insight into the biosynthesis of these compounds on the basis of the involvement of type III polyketide synthases is proposed. Lobophorol A (1) showed significant antibacterial activity against Staphylococcus aureus.

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

“…This was suggested to be due to an increase in alkene production during rapid growth of the alga or potentially due to smaller alkene losses in the Southern hemisphere winter [79]. The brown alga Lobophora variegata, commonly found in the Canary Islands, was also shown to yield saturated and unsaturated ketones (225-227) [80]. This particular species of algae has been reported to suffer extremely low levels of microbial infection and has also been studied in an ecological perspective with particular interest in its role in absorbing heavy metal ions [81].…”

“…This particular species of algae has been reported to suffer extremely low levels of microbial infection and has also been studied in an ecological perspective with particular interest in its role in absorbing heavy metal ions [81]. A 2015 study examined the anti-bacterial properties of the compound lobophorone E (227) against both Gram-negative and Gram-positive bacteria, but it was shown to be significantly outperformed by the positive control ciprofloxacin [80].…”

“…These low molecular weight compounds were identified on the basis of GC-MS experiments [100]. Compounds 296 and 297, isolated from the brown alga L. variegata, were shown to exhibit small to moderate inhibition against the Gram-positive bacteria S. aureus [80]. A summary of the phenols/phenolic acids/resorcinols is given in the Supporting Information ( Figure S20).…”

“…In a 2015 study, several polyketides (335-339) were isolated from L. variegata of which only 335 displayed any notable biological activity. When assayed against S. aureus, compound 335 displayed significant growth inhibition, but was relatively ineffective against both E. coli and E. faecalis [80]. A summary of the miscellaneous compounds isolated from brown algae is given in the Supporting Information ( Figure S21).…”

Metabolomic variability of four macroalgal species of the genus Lobophora using diverse approaches

“…Three sulfoquinovosyldiacylglycerols (SQDGs) and later lobophorolide were identified from L. variegate (Cantillo-Ciau et al, 2010;Kubanek et al, 2003). Recently, seven nonadecaketides named lobophorols, lobophopyranones and lobophorones (Gutiérrez-Cepeda et al, 2015) were found in the Atlantic L. variegate while the polyunsaturated lobophorenols A, B and C were described in the tropical L. rosacea (Vieira et al, 2016).…”