Chemical Composition and Biological Activity of Essential Oil and Extract from the Seeds of Tropaeolum majus L. var. altum

Research background. Plant Tropaeolum majus L. belongs to the family Tropaeolaceae, and contains benzyl glucosinolate. The breakdown product of benzyl glucosinolate, benzyl isothiocyanate (BITC), exhibits various biological activities such as antiproliferative, antibacterial, and antiinflammatory activities. In order to optimize the content of biologically active volatile compounds in plant extract and essential oil, the use of appropriate extraction technique has a crucial role. 
Experimental approach. The current study investigated the effect of two modern extraction methods (microwave-assisted distillation (MAD) and microwave hydrodiffusion and gravity (MHG)) on the chemical composition of volatile components present in essential oil and extract of T. majus L. var. altum seeds. The biological activity of samples (essential oil, extract and pure compounds) was focused on the antiproliferative effect against different cancer cell lines: cervical cancer cell line (HeLa), human colon cancer cell line (HCT116), and human osteosarcoma cell line (U2OS), and the antibacterial activity which was evaluated against growth and adhesion to polystyrene surface of Staphylococcus aureus and Escherichia coli. 
Results and conclusions. Essential oil and extract of T. majus seeds were isolated by two extraction techniques: MAD and MHG. BITC and benzyl cyanide (BCN) present in extract were identified by GC-MS. Essential oil of T. majus showed higher antiproliferative activity (IC50<5 µg/mL) than T. majus extract (IC50<27 µg/mL) against three cancer cell lines: HeLa, HCT116, and U2OS. BITC showed much higher inhibitory effect on all tested cells in contrast to BCN. Essential oil and extract of T. majus showed 
strong antimicrobial activity against S. aureus and E. coli. 
Novelty and scientific contribution. This work represents the first comparative report on the antiproliferative activity of essential oil and extract of T. majus seeds, BITC and BCN against HeLa, HCT116, and U2OS cells as well as their antimicrobial activity against S. aureus and E. coli. This study demonstrated that essential oil of T. majus seeds exhibits stronger antiproliferative and antimicrobial activity than plant extract.