## 1 Introduction  
Due to their biological and chemical variations, algae have drawn attention as a source of bioactive compounds whose concentration depends on the season, growth conditions, location, and environmental changes [1]. The algae are more frequently represented by three groups (green (_Chlorophyta_), brown (_Phaeoplytta_), and red (_Rhodophyta_)). They contain specific bioactive compounds (e.g., brown algae contain specific polyphenols called phlorotannins [2], red algae have been the main producers of halogenated compounds [3]. Green algae have been the least represented in the literature). Hexadecatrienoic acid is a possible chemotaxonomic marker of the species belonging to the genus _Codium_[4; 5] along with clerosterol [6; 7; 8]. These species also contain long chain fatty acids with palmitic acid as the main saturated fatty acid (SFA) and oleic acid as the most common monounsaturated fatty acid (MUFA) [9]. \(\alpha\)-Linolenic acid (C18:3\(\omega\)3) was the most abundant polyunsaturated fatty acid (PUFA) found in green algae [4]. The investigation of green algae showed that their \(\omega\)6/\(\omega\)3 ratio was very preferable for including them in diets with potential beneficial effect for human health [10]. During the growth and adaptation to abiotic stress, algae produce different volatile organic compounds (VOCs) which serve for the communication and interaction with the surrounding environment. Their concentration and composition depend on the environmental conditions, species, and geographical origin, as well as drying process and method used for their extraction [11]. [PERSON] et al. [12] reviewed about 295 volatile compounds isolated from 31 species of marine macroalgae. Our research group have also been investigating algae VOCs by different isolation techniques. Hydrocarbons were the most common volatile compounds found in algae, followed by alcohols, terpen, ketones, and aldehydes. Volatile oils, as well as the extracts, from brown and red algae, were tested for the inhibition of several bacteria growths [13; 14]. Hydrocarbons were found to be dominant in the volatile oil of _Codium fragile_[15], while long-chain aliphatic alcohols were the major compounds in _Codium tometosum_[16]. In general, the presence of dimethyl sulfide in the algae contributes to the distinct algae flavor [17]. Different studies report that bioactive secondary metabolites isolated from various green macroalgal species exhibit potential for being used as anti-inflammatory, antioxidant [18], antimicrobial [19] or antigenotoxic [20] molecules. However, the species belonging to the genus _Codium_ have been the least investigated for their biological activity among all _Chlorophyceae_. _C. fragile_ has drawn the most attention due to its invasive nature and potential of being utilized for biomedical applications. [PERSON] et al. [21] reported its potential with pro-mineralogenic activity and osteogenic properties. Clerosterol possess great bioactivity potential including the inhibition of human melanoma cell growth [22]. Isolated clerosterol and its derivatives from _Codium arabicum_ exhibited cytotoxic activity [23]. _Codium_ species were tested for antibacterial activity against pathogenic bacteria. Methanol extracts of _C. dichotomous_, _C. fragile_, _C. Bursa_, and _C. tometosum_ showed significant inhibitory activity against _Staphylococcus aureus_, while _C. bursa_ did not inhibit the growth of tested bacteria. Antibacterial activity was influenced by the algal reproductive state and seasonality [24]. Ethanol extracts of _C. bursa_ were used against _Escherichia coli_ and _Staphylococcus simulans_. All the algal extracts showed important antibacterial activity against investigated bacteria [18]. In general, available data on the phytochemical composition and bioactivity of marine macroalgae from the Adriatic sea are limited. Consequently, the focus of this study was on macroalga _Codium bursa_ (Olivi) [PERSON] collected from the Adriatic Sea.