Supercritical carbon dioxide extraction of Triognella foenum graecum Linn seeds: Determination of bioactive compounds and pharmacological analysis

Abstract

Objective: To investigate the effect of temperature and pressure on supercritical CO2 extraction of Triognella foenum graecum Linn seeds, to determine the optimal condition which leads to highest percentage of the accumulative yield and revealing the chemical composition of supercritical CO2 extract. Methods: Temperatures in the range of 40–60 °C and pressures in the range of 10–25 MPa were used. FTIR and GC–MS analysis were used to detect the bioactive compounds present in the extract. The broth dilution method and slope method were used to evaluate the anti-microbial and anti-tuberculosis activities and the in vitro anti-malarial assay was carried out according to the micro assay protocol of Rieckmann and his co-workers. Results: The temperature was more affected than the pressure on the extraction performance and the highest yield of the extract (3.111%) was attained at 60 °C and 10 MPa. FTIR and GC–MS showed that the chemical composition of the extract included conjugated linoleic acid methyl ester as the major active principle (with concentration of 72.28%), followed by saturated fatty acid methyl esters (16.03%), steroids (8.09%) and organic siloxane compound (3.61%). The extract showed moderate anti-bacterial activity with MIC values 100, 250, 125 μg/mL towards Escherichia coli, Staphylococcus aureus and Streptococcus pyogenus respectively. It exhibited high inhibition effect towards the fungi Candida albican with MFC value (250 μg/mL). The extract had low anti-tuberculosis activity with MIC value (100 μg/mL) and comparable MIC value (0.29 μg/mL) towards Plasmodium flaciparum. Conclusions: Supercritical CO2 extraction as alternate and green technology is performed successfully to extract the bioactive compounds from the seeds of T. foenum graecum Linn and it is concluded that this extract can be used as an alternate source of synthetic anti-biotic drugs. Keywords: Anti-bacterial, Anti-fungal, Anti-malarial, Anti-tuberculosis, Sc–CO2 extraction, Triognella foenum graecum Linn