**7.5 Lyngbyabellins**

This specific peptide was isolated from *Lyngbya majuscula* from south pacific and Caribbean and bear suitable structural resemblances to hectochlorin and dolabellin. Structural of lyngbyabellin A was determined using 2D NMR techniques and its absolute stereochemistry was determined by the chiral HPLC analysis. Lyngbyabellin A exhibited IC50 value of 0.03 μg/mL and 0.50 μg/mL against KB cells (human nasopharyngeal carcinoma cell line) and LoVo cells (human colon adenocarcinoma cells). It also disrupt the microfilament network in fibroblastic A10 cells at 0.01–5.0 μg/mL [64]. At higher concentrations of Lyngbyabellin A many cells became binucleate, an observation which inhibits cytokinesis. Lyngbyabellin B was found to be less toxic than lyngbyabellin A with IC 50 value of 0.10 μg/mL. It produces the same effects as hectochlorin on PtK2 cells, increase in number of binucleate cells were observed, when 10 M of the agent was treated with the cells. This finding proposed that actin is the main cellular target of the lyngbyabellins.
