Marine Organisms and Terrestrial Lichens of Hawai`i as Sources of Bioactive Compounds

Abstract

Investigations directed toward the discovery of structurally novel and biologically active secondary metabolites from marine organisms and lichens collected around Hawaii for potential pharmaceutical applications led to the isolation of four novel compounds. Two of these showed bioactivity, and two previously reported compounds from sponges collected employing remotely-operated vehicle (ROV) from the mesophotic zone in the `Au`au Channel, Maui, Hawai`i. Their chemical structures were elucidated employing extensive spectroscopic and spectrometric analyses including, one-dimensional (1D) nuclear magnetic resonance (NMR) spectroscopy, two-dimensional (2D) NMR spectroscopy, infrared (IR) spectroscopy, ultraviolet-visible (UV/Vis) spectroscopy, and mass spectrometry (MS). The sponges, identified as Dactylospongia sp. and Hyrtios sp., belong to Family Thorectidae and support previous research that identifies members of this family as producers of bioactive secondary metabolites. The four compounds isolated from these organisms, puupehenol (1), puupehenone (2), 11-O-methylpuupehenol (3), 11-O-methylpuupehenol dimer (4), auauamine (5), and puupehenone peroxydimer (7) belong to the terpenoid structural class. Compounds 1, 2, and 5 exhibited antioxidant and antimicrobial activities, and 5 was observed to have mild, nonselective activity against a variety of cancer cell lines. Additionally, comparative analyses were undertaken to further validate Hawaiiﾒs potential to yield bioactive compounds. Antioxidant analysis of shallow water and mesophotic sponge extracts revealed significant potential for bioactive secondary metabolite production in deep-water organisms. Antioxidant activity comparisons of lichens from Hawaii and Iceland showed a higher average antioxidant activity amongst Hawaiian lichen samples. The overall result supports Hawaiiﾒs viability as a source for novel bioactive compounds.