Phytochemical Profile and Antibacterial Activity of Solid Residues from Hydrodistillation of Cymbopogon nardus from Burkina Faso

Hydrodistillation of aromatic plants is an extraction process that provides essential oils and also generates unexploited solid and liquid residues. The present study focussed on knowledge on the phytochemical profile and antibacterial potential of the solid residue resulting from the hydrodistillation of Cymbopogon nardus (CN) from Burkina Faso, with the aim of its valorization. Ethanolic extract was prepared for phytochemical screening using Thin Layer Chromatography, and the total phenolic and flavonoid contents were determined using the Folin-Ciocalteu and aluminum chloride (AlCl3) methods, respectively. Antioxidant activity was also evaluated by 2,2- diphenylpicrylhydrazil (DPPH), 2,2' - azino - bis (3 - ethylbenzothiazoline - 6 sulphonic acid (ABTS) and 2, 4, 6 - tri [2 - pyridyl] - s - triazine (TPTZ) methods.The antibacterial potential was evaluated in vitro on six (06) bacterial strains.

A diversity of phytochemical compounds, including flavonoids, tannins, triterpenes, and coumarins, were identified in the ethanolic extract of the residue from the hydrodistillation of Cymbopogon. The total phenolic and flavonoid contents were 42.69±6.88 mg GAE/g and 47.82±3.42 mg QE/g of dry ethanolic extract, respectively. For the antioxidant activity, the IC50 were 0.027 ± 0.006 mg/mL and 0.35 ± 0.02 mg/mL for DPPH and ABTS methods respectively. The FRAP method showed 263.01 ± 22.62 mg TE/ g of dry extract.

The extract exhibited antibacterial activity (diameter ≥8) against S. aureus, S. typhimurium, E. coli, and S. saprophyticus strains. These results indicate that the hydrodistillation residue of Cymbopogon nardus contains bioactive molecules and could be used as an agent to combat bacterial contamination in food.