Ilimaquinone is a bioactive marine natural product belonging to the class of sesquiterpenequinones. It was first isolated in 1979 from the sponge Hippospongia metachromia.[1] Since then, it has also been identified in other marine sponges, including Dactylospongia elegans and Halichondria species.[2] The compound features a 4,9-friedodrimane skeleton that is linked via a methyl bridge to a 2,5-disubstituted benzoquinone moiety and contains four stereogenic centers in total.
Ilimaquinone has attracted interest in natural products and drug discovery research, owing to its diverse biological activities, which include antiproliferative,[3]antiviral,[4] and herbicidal[5] effects. The originally reported structure of ilimaquinone contained an incorrect stereochemical assignment, which was revised in 1987 by Capon and colleagues through spectroscopic analysis.[6]
Physicochemical characterization
Ilimaquinone belongs to the class of merosesquiterpene quinones, a subgroup of sesquiterpene quinones. Sesquiterpenes are terpene compounds with a C15 carbon skeleton, composed of three isoprene units.[7] The prefix “mero-” indicates that the molecule is assembled from structurally distinct biosynthetic building blocks.[7] In the case of ilimaquinone, the sesquiterpene core is linked to a methoxy- and hydroxy-substituted 1,4-benzoquinone ring, which places it within the sesquiterpene quinone family.
The chemical reactivity of ilimaquinone is primarily associated with its benzoquinone ring, which operates through two main mechanisms that largely account for the compound’s biological activity. First, the quinone moiety can participate in redox cycling. In biological systems, ilimaquinone can be reduced via single-electron transfer to its semiquinone form, a process mediated by cellular reductants such as NAD(P)H or glutathione.[8] Subsequent reoxidation to the quinone can generate reactive oxygen species (ROS), including peroxide, hydroxyl, or superoxide ions.[8][9] This redox cycling contributes to oxidative stress, which influences cellular signaling pathways and can induce apoptosis.[10]
The second mode of reactivity involves nucleophilic addition at the electrophilic positions of the quinone ring, typically via a Michael addition.[11] Strongly nucleophilic cellular components, particularly free thiol groups in cysteine residues of proteins or in glutathione, can react with ilimaquinone in this way.[10][11] Such covalent modifications may lead to the inactivation of enzymatic functions or interfere with regulatory protein–protein interactions.
In addition, the quinone ring acts as a chromophore: its conjugated π-system is responsible for the characteristic red color of ilimaquinone.[7]
References
↑ Luibrand, Richard T.; Erdman, Timothy R.; Vollmer, John J.; Scheuer, Paul J.; Finer, Janet; Clardy, Jon (January 1979). "Ilimaquinone, a sesquiterpenoid quinone from a marine sponge". Tetrahedron. 35 (5): 609–612. doi:10.1016/0040-4020(79)87004-0.
↑ Goclik, Eva; König, Gabriele M.; Wright, Anthony D.; Kaminsky, Ronald (August 2000). "Pelorol from the Tropical Marine Sponge Dactylospongia elegans". Journal of Natural Products. 63 (8): 1150–1152. Bibcode:2000JNAtP..63.1150G. doi:10.1021/np990502u. PMID10978215.
↑ Capon, Robert J.; MacLeod, John K. (October 1987). "Revision of the absolute stereochemistry of ilimaquinone". The Journal of Organic Chemistry. 52 (22): 5059–5060. doi:10.1021/jo00231a051.
1 2 3 Coates, Robert M. (1976). "Biogenetic-Type Rearrangements of Terpenes". Fortschritte der Chemie Organischer Naturstoffe / Progress in the Chemistry of Organic Natural Products. Vol.33. pp.73–230. doi:10.1007/978-3-7091-3262-3_2. ISBN978-3-7091-3264-7.
1 2 Bolton, Judy L.; Trush, Michael A.; Penning, Trevor M.; Dryhurst, Glenn; Monks, Terrence J. (March 2000). "Role of Quinones in Toxicology". Chemical Research in Toxicology. 13 (3): 135–160. doi:10.1021/tx9902082. PMID10725110.
↑ Kappus, H. (November 1987). "A survey of chemicals inducing lipid peroxidation in biological systems". Chemistry and Physics of Lipids. 45 (2–4): 105–115. doi:10.1016/0009-3084(87)90062-4. PMID3319223.
1 2 van Stuijvenberg, Jana; Proksch, Peter; Fritz, Gerhard (February 2020). "Targeting the DNA damage response (DDR) by natural compounds". Bioorganic & Medicinal Chemistry. 28 (4): 115279. doi:10.1016/j.bmc.2019.115279. PMID31980363.{{cite journal}}: CS1 maint: article number as page number (link)
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