Chemical Profiling and In Vitro Bioactivities of Extracts from the Red Alga Jania rubens Collected from the Lebanese Coast

Jania rubens (J. rubens), a Mediterranean red seaweed, is rich in bioactive compounds with potential medicinal applications. This study investigates the therapeutic potential of Lebanese J. rubens through in vitro evaluation of its anti-diabetic, anti-coagulant, anti-inflammatory and anti-hemolytic activities. Various extracts were prepared and characterized using GC-MS and HPLC. Biological activities were assessed through α-amylase inhibition assays, effects on prothrombin time and partial thromboplastin time, anti-inflammatory activity and anti-hemolytic activity. Significant α-amylase inhibition was observed with dichloromethane/methanol and lipid extracts, comparable to acarbose. All types of extracts prolonged PT and PTT, with the lipid extract showing the strongest effect at higher concentrations. Additionally, dichloromethane/methanol extracts exhibited potent anti-hemolytic activity. Moreover, all extracts showed strong anti-inflammatory activity, achieving levels of inhibition of heat-induced BSA denaturation comparable to diclofenac. Characterization revealed 11 amino acids in the protein extracts, and significant fatty acids in the lipid profile. The crude extracts contained diverse compounds, including flavonoids, aldehydes, diterpenoids, terpenoids, fatty acids, and sterol esters, which may contribute to the observed biological activities. These results highlight J. rubens as a potential reservoir of bioactive compounds with promising in vitro activities related to diabetes, thrombotic disorders, inflammation, and oxidative stress. Further research is needed to isolate the active compounds, validate their efficacy in vivo, assess safety, and elucidate the underlying mechanisms.