Potent antibacterial activity of halogenated metabolites from Malaysian red algae, Laurencia majuscula (Rhodomelaceae, Ceramiales)

Abstract

Red algae genus Laurencia (Rhodomelaceae, Ceramiales) are known to produce a wide range of chemically interesting secondary halogenated metabolites. This investigation delves upon extraction, isolation, structural elucidation and antibacterial activity of inherently available secondary metabolites of Laurencia majuscula Harvey collected from two locations in waters of Sabah, Malaysia. Two major halogenated compounds, identified as elatol (1) and iso-obtusol (2) were isolated. Structures of these compounds were determined from their spectroscopic data such as IR, 1H-NMR, 13C-NMR and optical rotation. Antibacterial bioassay against human pathogenic bacteria was conducted using disc diffusion (Kirby-Bauer) method. Elatol (1) inhibited six species of bacteria, with significant antibacterial activities against Staphylococcus epidermis, Klebsiella pneumonia and Salmonella sp. while iso-obtusol (2) exhibited antibacterial activity against four bacterial species with significant activity against K. pneumonia and Salmonella sp. Elatol (1) showed equal and better antibacterial activity compared with tested commercial antibiotics while iso-obtusol (2) only equaled the potency of commercial antibiotics against K. pneumonia and Salmonella sp. Further tests conducted using dilution method showed both compounds as having bacteriostatic mode of action against the tested bacteria.

Biological activity of the red alga Laurencia brandenii

“…Our result is in accordance with the antibacterial activity of Laurencia spp. reported from various geographic regions (DE NYS et al 1996, HELLIO et al 2001, TASKIN et al 2007) against marine, human and fish bacterial pathogens (VAIRAPPAN et al 2001(VAIRAPPAN et al , 2003BANSEMIR et al 2006). Based on the present findings L. brandenii could be utilized as renewable bioresource for the development of potential antimicrobials.…”

Halogenated Organic Molecules of Rhodomelaceae Origin: Chemistry and Biology

“…The potency observed was as good as or better than six standard, commercial available antibiotics (augmentin, latamoxef, ceflaclor, ceftriaxone, kanamycin, and netilmicin). 504 In the same study, iso-obtusol (64) exhibited antibacterial activity against four bacteria with especially noteworthy activities against K. pneumoniae and Salmonella sp. 504 Further experiments demonstrated that both compounds displayed bacteriostatic rather than bactericidal effects.…”

“…504 Further experiments demonstrated that both compounds displayed bacteriostatic rather than bactericidal effects. 504 While brominated diterpene 10-acetoxyangasiol (289) exhibited antibacterial activity against Vibrio cholerae with MIC 100 μg/mL, 194 the bromoditerpene 10-hydroxykahukuene B (341) displayed weak antibacterial activity against Staphylococcus aureus, and this compound as well as the ACG derivative laurenmariallene (433) exhibited weak activity against Escherichia coli. 67 Recently, ACG derivatives 455 and 458−460 were reported to have antistaphylococcal activity against a panel of multidrug and methicillin-resistant S. aureus strains with MICs ranging from 8 to 256 μg/mL.…”

Phytochemical and Biological Properties of Sesquiterpene Constituents From the Marine Red Seaweed Laurencia: A Review

“…Vairappan et al reported significant antibacterial activity for compound 25 against Staphylococcus epidermis, Klebsiella pneumonia and Salmonella sp, whereas, isoobtusol was significantly active against K. pneumonia and Salmonella sp. Further tests indicated that both compounds were bacteriostatic rather than bactericidal [36]. Elatol showed potent antiproliferative activity against promastigote and intracellular amastigote forms of Leishmania amazonensis, with an IC 50 of 4.0 μM and 0.45 μM, respectively [37].…”