Natural products of marine origin have become an attractive area in the search of new anti-cancer agents because of their distinct chemical novelty and the presence of strong bioactive substances. This study was intended to examine pharmacognostic potential of a few marine-derived compounds on cancer cell proliferation in animal experimental models. Marine sponges and algae were extracted crudely and screened phytochemically, and then in vivo assayed in tumor-induced mice models. The information was obtained by the measurement of tumor volume, analysis of survival rates, and histopathological tests. It was found that alkaloids isolated in marine sponges showed a significant decrease of the tumor volume (mean = 45.2 mm 3, SD = 4.8) compared to control (mean = 92.6 mm 3, SD = 6.2), whereas terpenoids isolated in algae increased survival rates and caused strong apoptosis in cancerous tissues. In general, the results indicate that bioactive compounds of marine origin have strong anti-cancer activity, which underlines their significance as new pharmacognostic sources of cancer treatment. The paper highlights the need of marine pharmacognosy in the broadening of natural product-based drug discovery and suggests additional research to achieve efficacy, safety, and mechanistic insights.