Turbinaria ornata (Turner) J. Agardh, 1848

Chakraborty, Kajal & Dhara, Shubhajit, 2022, Spirornatas A-C from brown alga Turbinaria ornata: Anti-hypertensive spiroketals attenuate angiotensin-I converting enzyme, Phytochemistry (113024) 195, pp. 1-10 : 5

2.3. Bioactive potentials of the spiroketals isolated from T. ornata

Spirornata A showed noticeably greater ACE-I inhibitory property (IC 50 4.55 μM) compared to those exhibited by spirornata B (IC 50 4.72 μM) and C (IC 50 4.86 μM), as well as comparable activity with the standard ACE-I inhibitor, captopril (IC 50 4.29 μM) ( Table 2 ). The electronegative groups in the oxodecahydrospiro [furo-3,4-c] pyran-7, 2 ʹ - pyranyl framework along with the esterified side chain in spirornata A could evidently form hydrogen bonding interfaces with the aminoacyl residues in the active site of ACE-I, and might form co-ordinate bond with the binding site Zn 2+ ion. Conspicuously greater number of electronegative centers in spirornata A might lead to its greater antihypertensive activity. Also, free radical quenching activities (IC 50DPPH 1.14 and IC 50ABTS 1.28 mM) exhibited by spirornata A were greater when compared to those exhibited by other analogues (IC 50 1.25–1.71 mM) and commercially available standard (IC 50 1.46–1.69 mM). Previoius reports of antioxidant activities of spiroketals ( Zhuravleva et al., 2014) also corroborated the antioxidant activities of currently isolated spiroketals.