Citric acid and enzyme‐assisted modification of flavonoids from celery ( Apium graveolens ) extract and their anti‐inflammatory activity in HMC‐1.2 cells

Apium graveolens (celery) of the family Apiaceae contains bioactive compounds including luteolin and apigenin. The purpose of this study was to increase the extraction yield of apigenin and luteolin in celery extract using green technology and to evaluate their biological activities. The results showed that CA and β-glucosidase-assisted celery extraction transformed apiin in the celery to apigenin with an increase in luteolin concentration. The CA and β-glucosidase-treated celery extract (CAGE) improved the anti-inflammatory properties of celery extract by inhibiting the expression and production of inflammatory cytokines (IL-6, IL-8, IL-31, and TNF-α) in IL-33-stimulated mast cells (HMC-1.2 cells). Their mechanism of action was tied to the inhibition of ERK, JNK, IKKα, IκBα, and NF-κB activation by CAGE in the stimulated cells. In conclusion, CA and enzyme treatment can be considered as a useful biotechnology tool for the improvement of bioactive compounds in celery and hence improve on their bioactivity. Practical applications Apium graveolens commonly called celery is an edible agricultural product cultivated throughout the world and known as a “superfood.” Celery contains bioactive compounds including apigenin and luteolin that contribute to their described biological activities. However, extracting celery using normal extraction procedures such as hot water and ethanol methods yields only a small amount of apigenin and luteolin. In the present study, we introduced an eco-friendly method using citric and β-glucosidase to obtain apigenin and luteolin-rich celery extract with improved anti-inflammatory activities. The present work will spark studies on the conversion of less biologically active compounds in functional food materials to more active compounds using CA and β-glucosidase, and the development of functional food with specifically enriched bioactive substances at the industrial levels.