**3. Antimicrobial peptides from ascidians**

Peptides are one of the major structural classes isolated from ascidians, including linear peptides, depsipeptides, and cyclic peptides, with residue numbers spanning from two to forty eight. Most of the active peptides from ascidians have complex cyclic of linear structures rarely found in terrestrial animals. These peptides are found to affect cell behavior with different mechanisms such as apoptosis, affecting the tubulin- microtubule environment and [23] inhibiting angiogenesis.

#### **3.1 Vitilevuamide**

A bicyclic peptide isolated from ascidian *Didemnum cuculiferum* and *Polysyncranton lithostrotum*. It was found that Vitilevuamide show activity against mouse lymphocytic leukemia. Its mechanism of cytotoxicity is due to its inhibition of tubulin polymerization without competitive inhibition of the vinblastine binding site, affects GTP binding to tubulin and also cell cycle arrest in the G2/M phase (**Figure 1**).

#### **3.2 Diazonamides**

A group of macrocytic peptides isolated from the ascidians *Diazona angulate*. Amoung various diazolzmides, Diazolamide A was evaluated for its antitumor activities [24]. It is a tubulin binding agent which blocks the cell cycle in G2/M period. Diazonamides A is a potentially chemotherapeutic agent without significant toxicity on animal models [25].

#### **3.3 Chondromodulin-1 (ChM-1)**

Chondromodulin, a 25kD a glycoprotein isolated from fetal bovine cartilage. Recently, Chondromodulin isolated from the invertebrate ascidian *Ciona savignyl*. It promotes the proliferation of mouse osteoblastic cell and also protects the H2O2 oxidation injury. Chondromodulin also modifies the cell behavior through regulating the cell cycle and cell adhesion [26]. It was found that Chondromodulin acts as a potential antioxidant and antitumor agent [27].

*Antimicrobial Peptides Derived from Ascidians and Associated Cyanobacteria DOI: http://dx.doi.org/10.5772/intechopen.99183*

**Figure 1.** *Image showing* Didemnum cuculiferum.
