Phytochemical profile, Antimicrobial Activity, Antioxidant Capacity, and Anti- Cyclooxygenase Activity of Green Kohlrabi plant extract

Abstract

Phytochemical compounds were extracted from Green Kohlrabi (GK) tubers plant using soxhlet apparatus with three different solvents including ethanol, water and ethyl acetate. The ethanolic extract showed higher antimicrobial activity than the other extracts. Gas Chromatography-Mass Spectroscopy (GC-MS) analysis found that the ethanolic extract of GK was a rich source of phytochemicals (approximately 32 compounds). whereas analysis with Atomic Absorption Spectrometry (Flame and flameless mode) exhibited that the concentration of trace elements was 9.34×10^-4 g mL^-1 Cu, 37.5×10^-4 g mL^-1 Zn, 8.3×10^-4 g mL^-1 Pb, 0.081×10^-4 g mL^-1 Cd, 0.053×10^-4 g mL^-1 Cr, 0.007×10^-4 g mL^-1 Ni and 0.014×10^-4 g mL^-1 Mn, respectively. Qualitative analysis revealed the presence of alkaloids, tannins, terpenoids, saponins, glycosides, resins, and flavonoids. Total phenolic content was evaluated in the range of 0.2-1 g mL^-1 and the concentration was equal to 0.969 g mL^-1 indicating the high phenolic acid levels in  GK  ethanolic extract.  The spectrophotometric method was used to measure the radical scavenging activity (Folin-Ciocalteu and 2,2- diphenylpicrylhydrazyl (DPPH)) and compared with a new technique called paper-based analytical device (µPADs) and the results obtained indicate a strong and effective antioxidant DPPH scavenging affects 85.14 %, while the µPADs was used for semi-quantitative analysis. The GK extract could inhibit cyclooxygenase (COX-2) enzyme activity better than an anti-inflammatory drug (Aspirin) in sera of thyroid cancer patients. As a result, our study establishes that GK ethanolic extract might be useful as a natural potent antimicrobial, antioxidant, and anti-inflammatory agent.