Further insights on the structural aspects of PLA(2) inhibition by gamma-hydroxybutenolide-containing natural products: a comparative study on petrosaspongiolides M-R.
Petrosaspongiolides M-R (PM-PR, 1-5) are marine sesterterpenes structurally characterised by a gamma-hydroxybutenolide moiety. They have shown an in vitro and in vivo potent anti-inflammatory activity, mediated by specific inhibition of secretory phospholipase A(2) (sPLA(2) enzymes). The molecular mechanism underlying the sub-micromolar irreversible inhibition of the bee-venom PLA(2) (bvPLA(2)) by PM has been clarified combining mass spectrometry (MS) and molecular modelling approaches. The N-terminal amino group (Ile-1 residue), recently identified as the unique PM covalent binding site on this enzyme, selectively delivers a nucleophilic attack onto the masked aldehyde at C-25 of the pharmacophoric gamma-hydroxybutenolide ring of PM, giving rise to a Schiff base. In the attempt of broadening the knowledge of the mechanism at molecular level of PLA(2) inactivation by this family of compounds, we performed a comparative analysis on petrosaspongiolides M-R, whose results are discussed in this paper. Firstly, the amount of bvPLA(2) enzyme covalently modified after incubation with each of petrosaspongiolides M-R was measured and resulted to be in good agreement with pharmacological in vitro data. Then, a full characterisation of the bvPLA(2) adduct with PR, one of the least active and most structurally different among petrosaspongiolides, by LC-MS, MS(n), and computational methods, confirmed the same inhibition mechanism and covalent binding site already found for PM. Finally, extensive molecular docking studies performed in comparison on the PM-PLA(2) and PR-PLA(2) complexes provided critical insight on how the balance between non-covalent and covalent inhibitor-enzyme interactions may affect the final potency exhibited by the various compounds of the petrosaspongiolide family.
Monti
Maria Chiara
MC
Dipartimento di Scienze Farmaceutiche, Università di Salerno, via Ponte Don Melillo, 84084, Fisciano (SA), Italy.
Casapullo
Agostino
A
Riccio
Raffaele
R
Gomez-Paloma
Luigi
L
D015107:4-Butyrolactone / Q000031:analogs & derivatives; D000818:Animals; D001514:Bee Venoms / Q000201:enzymology*; D001665:Binding Sites; D001688:Biological Products; D002851:Chromatography, High Pressure Liquid; D019295:Computational Biology; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D005663:Furans / Q000737:chemistry* / Q000494:pharmacology; D007166:Immunosuppressive Agents / Q000737:chemistry / Q000494:pharmacology; D013058:Mass Spectrometry; D008958:Models, Molecular; D015394:Molecular Structure; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000494:pharmacology*; D010741:Phospholipases A / Q000037:antagonists & inhibitors* / Q000737:chemistry
D001514:Bee Venoms; D001688:Biological Products; D004791:Enzyme Inhibitors; D005663:Furans; D007166:Immunosuppressive Agents; C118309:petrosaspongiolide m; D009828:Oleanolic Acid; C004511:butenolide; D010741:Phospholipases A; D015107:4-Butyrolactone