Bioprospecting Endophytic Bacteria in <I>Curcuma zedoaria</I> for In Vitro Antioxidant and Anti-inflammatory Potentials

Endophytic bacterial strains in medicinal plants have many valuable pharmacological effects similar to the host plant. This study was conducted to screen endophytic bacteria in Curcuma zedoaria that are capable of producing polyphenols, flavonoids, antioxidants and anti-inflammatories in vitro. Root, rhizome and leaf samples of Curcuma zedoaria were used as raw materials to isolate endophytic bacteria. 2,2-Diphenyl-1-picryl-hydrazyl free radical neutralization, 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) free radical neutralization, total antioxidant capacity, and ferric reducing-antioxidant power were used to evaluate antioxidant activity. Nitric oxide formation inhibition, red blood cell membrane protection, inhibition of bovine serum albumin and egg white albumin denaturation were used to evaluate anti-inflammatory activity. Research results show that, bacterial strains CZ-R5, CZ-Rh4, CZ-Rh7 and CZ-L11 were able to produce polyphenols, flavonoids, antioxidants and anti-inflammatories in vitro more effectively than the remaining bacterial strains. The results of 16S rRNA gene sequencing showed that the bacterial strains CZ-R5, CZ-Rh4, CZ-Rh7 and CZ-L11 belong to the Enterobacter and Bacillus genera. Endophytic bacteria in Curcuma zedoaria can become a source of biologically active bacteria to support the treatment of diseases related to oxidative stress and inflammation.