Anti-Ovarian Cancer Conotoxins Identified from Conus Venom

Conotoxins constitute a treasury of drug resources and have attracted widespread attention. In order to explore biological candidates from the marine cone snail, we isolated and identified three novel conopeptides named as Vi14b, Vi002, Vi003, three conotoxin variants named as Mr3d.1, Mr3e.1, Tx3a.1, and three known conotoxins (Vi15a, Mr3.8 and TCP) from crude venoms of Conus virgo, Conus marmoreus and Conus texile. Mr3.8 (I-V, II-VI, III-IV) and Tx3a.1 (I-III, II-VI, IV-V) both showed a novel pattern of disulfide connectivity, different from that previously established for the µ- and ψ-conotoxins. Concerning the effect on voltage-gated sodium channels, Mr3e.1, Mr3.8, Tx3a.1, TCP inhibited Na(v)1.4 or Na(v)1.8 by 21.51~24.32% of currents at semi-activated state (TP2) at 10 μmol/L. Certain anti-ovarian cancer effects on ID-8 cells were exhibited by Tx3a.1, Mr3e.1 and Vi14b with IC(50) values of 24.29 µM, 54.97 µM and 111.6 µM, respectively. This work highlights the role of conotoxin libraries in subsequent drug discovery for ovarian cancer treatment.