Sedentary marine organisms such as sponges and corals have adapted to the extreme conditions of the marine environment by synthesizing secondary metabolites with unique structural characteristics that have shown a wide range of biological activities in vitro and in vivo. Furthermore, compounds from the class of steroids, terpenoids and alkaloids with primarily cytotoxic effects were isolated via bioprospecting programmes from octocorals of the genus Eunicella. Even though Eunicella corals from the Mediterranean Sea have been the subject of several studies over the past few decades, those from the Adriatic Sea have not been investigated so far with the aim of isolating natural compounds and their biological evaluation. Therefore, within this doctoral research, chemical characterization of metabolites and biological evaluation of extracts and semi-purified fractions obtained from the coral Eunicella cavolini (Koch, 1887) were carried out for the first time, with the aim of determining the potential of antiproliferative, antioxidant, antimicrobial and anti-inflammatory effects. Preliminary data showed that coral extracts and fractions show a moderate antiproliferative effect on a panel of tumour cells and activity against Gram-positive bacteria. Also, toxic effects were observed in the development of zebrafish (Danio rerio) embryos. Consequently, a pregnane-type steroid was isolated and characterized from fraction F1, whose biological activities were tested for the first time, and a derivative was additionally prepared by modifying the substituent. These compounds showed potential anti-inflammatory activity by inhibiting soy lipoxygenase and albumin denaturation with moderate inhibition of cancer cells growth and selectivity towards colon adenocarcinoma cells. Natural pregnane had a noticeable antibacterial effect (MIC = 62.5 µM on B. subtilis) while both pregnane and its derivative exerted toxic effects on zebrafish development were also observed at low concentrations. On the other hand, the doctoral thesis included the preparation of one of the metabolites that occurs naturally in the coral genus Eunicella, granulatamide B, and a dozen of its structural analogues were prepared by modulating the fatty acid side chain (chain length, saturation, conjugation of double bonds). Granulatamide B and analogues with unsaturated and/or conjugated double bonds were shown to cause moderate inhibition of cancer cells growth, with the analogue with a retinoic acid chain showing antioxidant activity comparable to the control. Additionally, only granulatamide B had antibacterial activity against Gram-positive B. subtilis. Given that the structural analogue of granulatamide B with an α-linolenic chain did not cause abnormal development of zebrafish and had a more selective effect on cancer cell lines, it could represent a molecule of interest for further structural change in order to achieve better biological effects. Finally, this research paves the way for further investigation of the biological potential of the extract, or compounds of the Adriatic coral, E. cavolini with an emphasis on the chemical modification of the structures with the aim of reducing the toxicity of the samples.