Efficacy of selected natural products as therapeutic agents against cancer

With emerging sophistication in the exploration of ocean environment, a number of marine bioactive products have been identified with promising anticancer activity. Many of these are in active phase I or phase 11 clinical trials or have been terminated because of adverse side effects, mainly hematological in nature. Nonetheless, the information derived has aided enormously in providing leads for laboratory synthesis with modifications in the parent structure affecting compound solubility, absorption, and toxicity, resulting in less severe toxicity while achieving maximum efficacy in smaller doses. We describe herein, a few of the compounds obtained from marine and terrestrial sources [bryostatin I (1), dolastatin 10 (2), auristatin PE (3), and combretastatin A4 (4)] that have been extensively investigated in our laboratory and continue to be investigated for their sensitization effects with other cytotoxic agents in several different site-specific tumors employing murine models or human subjects.