Inflammation is a fundamental protective biological mechanism; however, its chronic progression can lead to severe pathologies. Conventional anti-inflammatory drugs, such as corticosteroids and non-steroidal anti-inflammatory drugs, are often associated with considerable adverse effects. This necessitates the urgent search for novel, safer therapeutic agents, particularly among medicinal plants. Myrtus communis L. is well-recognized for its therapeutic properties, and its leaves have been traditionally utilized in folk medicine for the management of various inflammatory conditions.

The aim of the work was to comparatively evaluate the anti-inflammatory activity and acute toxicity of thick extracts obtained from the leaves of Myrtus communis L., cultivated in natural conditions (in vivo) and those obtained by microclonal propagation (in vitro), given the growing demand for effective and safe natural anti-inflammatory agents.

Materials and methods. Thick extracts of Myrtus communis leaves were obtained using fractional maceration with 70 % ethanol, followed by concentration via a rotary evaporator. Anti-inflammatory activity was assessed on the serotonin-induced edema model in white rats, by measuring the increase in paw volume. Experimental groups received the extracts (100 mg/kg) or ibuprofen (25 mg/kg). Additionally, the influence of the extracts on biochemical markers of inflammation (C-reactive protein, TBARS) and the blood protein profile was studied. Acute toxicity assessment was conducted in accordance with OECD guidelines, starting with a dose of 2000 mg/kg.

Results. The myrtle leaf extracts demonstrated potent anti-exudative activity, reducing paw edema by 33.55 % (in vivo extract) and 35.69 % (in vitro extract), results that are comparable to the effect observed with ibuprofen (42.11 %). The mechanism of action is likely linked to antagonism against serotonin receptors. Furthermore, the extracts significantly reduced the levels of inflammation and oxidative stress markers, concurrently contributing to the restoration of the serum protein profile. The extract obtained through microclonal propagation (in vitro) exhibited slightly superior efficacy, suggesting a potential advantage for this biotechnological approach. Acute toxicity assessment confirmed that both extracts belong to Category 5 of the toxicity classification (LD50 ≥5000 mg/kg for the in vivo thick extract and LD50 2000–5000 mg/kg for the in vitro thick extract), confirming their low acute toxicity.

Conclusions. Concentrated Myrtus communis leaf extracts derived from plants grown under natural conditions and via microclonal propagation demonstrate marked anti-inflammatory and anti-exudative activity. Biotechnological cultivation approaches may offer a promising means of obtaining raw materials with enhanced biological efficacy.