HPLC-DAD phenolic profile,cytotoxic and anti-kinetoplastidae activity of Melissa officinalis

Context Melissa officinalis subsp. inodora Bornm. (Lamiaceae) has been used since ancient times in folk medicine against various diseases, but it has not been investigated against protozoa.

Objective To evaluate the activities of M. officinalis against Leishmania braziliensis, Leishmania infantum and Trypanosoma cruzi as well as its cytotoxicity in fibroblast cell line.

Materials and methods The fresh leaves were chopped into 1?cm² pieces, washed and macerated with 99.9% of ethanol for 72?h at room temperature. Antiparasitic activity of M. officinalis was accessed by direct counting of cells after serial dilution, while the cytotoxicity of M. officinalis was evaluated in fibroblast cell line (NCTC929) by measuring the reduction of resazurin. The test duration was 24?h. High-performance liquid chromatography (HPLC) was used to characterise the extract.

Results The extract at concentrations of 250 and 125?μg/mL inhibited 80.39 and 54.27% of promastigote (LC_50? value?=_?105.78?μg/mL) form of L. infantum, 80.59 and 68.61% of L. brasiliensis (LC₅₀ value _?=_?110.69?μg/mL) and against epimastigote (LC₅₀ value _?=_?245.23?μg/mL) forms of T. cruzi with an inhibition of 54.45 and 22.26%, respectively, was observed. The maximum toxicity was noted at 500?μg/mL with 95.41% (LC_50? value?=_?141.01?μg/mL). The HPLC analysis identified caffeic acid and rutin as the major compounds.

Discussion The inhibition of the parasites is considered clinically relevant (<?500?μg/mL). Rutin and caffeic acids may be responsible for the antiprotozoal effect of the extract.

Conclusion The ethanol extract of M. officinalis can be considered a potential alternative source of natural products with antileishmania and antitrypanosoma activities.