Dear Colleagues,

Biologically active marine derived compounds have been shown to represent an interesting source of novel compounds that are protein kinase inhibitors (PKI). Protein kinases (PK) are validated targets for drug discovery, particularly in cancer. Thus far, a number of potent natural product PKI’s and PK modulators have been isolated including secondary metabolites from marine organisms and these have been useful as pharmacological tools and lead structures to develop novel PKI’s.

Despite their original biological functions, marine compounds often have non-optimal properties when evaluated in vivo such as inappropriate pharmacokinetic properties, or structural complexity that makes them difficult for scale-up synthesis. Therefore, significant medicinal chemistry is often required in order to optimize these compounds for drug discovery purposes. Despite these challenges, a large pool of marine organisms is available to search for novel compounds that could act as novel PKI’s.

Staurosporine, a nonspecific and thus toxic PKI inhibits many of the 518 human PK with high potency and this represents an early and well-known natural product derived PKI. The use of Staurosporine has led to a wealth of ligand-PK structures, providing significant structure-based design opportunities towards more specific PKI’s. The marine-sponge derived Hymenialdisines were discovered as potent inhibitors of PK involved in inflammation, thus blocking interleukin-2/TNF-alpha cytokine production. Subsequently, Hymenialdisine-derived indoloazepine derivatives were optimized leading to selective CHK1 and CHK2 inhibitors. The marine sponge-derived bis-indole alkaloide Fascaplysin, was reported to be a selective CDK4/cyclin D1 ligand. Furthermore, the macrolid lactone Bryostatin-1 produced by Bryozoa, marine invertebrate animals was characterized as a potent modulator of Protein Kinase C. These examples illustrate the importance of marine-derived PKI’s, and no-doubt more novel compounds will be discovered from the oceans in the future.

This Special Issue of Marine Drugs will focus on the exciting area of marine-derived compounds which may allow for novel approaches in PKI drug discovery.

Prof. Dr. Christian Peifer
Guest Editor

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• protein kinase inhibitors (PKI)
• small molecule PKI (smPKI)
• marine sponge metabolites
• potency and selectivity
• Staurosporine bisindole alkaloids
• bryostatin-1
• hymenialdisine
• fascaplysin
• anti-cancer activity
• antibiotic activity