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We derive the metallicity (traced by the O/H abundance) of the Narrow LineRegion ( NLR) of 108 Seyfert galaxies as well as radial metallicity gradientsalong their galaxy disks and of these of a matched control sample of no activegalaxies. In view of that, observational data from the SDSS-IV MaNGA survey andstrong emission-line calibrations taken from the literature were considered.The metallicity obtained for the NLRs %each Active Galactic Nucleus (AGN) wascompared to the value derived from the extrapolation of the radial oxygenabundance gradient, obtained from \ion{H}{ii} region estimates along the galaxydisk, to the central part of the host galaxies. We find that, for most of theobjects ($\sim 80\,\%$), the NLR metallicity is lower than the extrapolatedvalue, with the average difference ($<D>$) between these estimates ranging from0.16 to 0.30 dex. We suggest that $<D>$ is due to the accretion of metal-poorgas to the AGN that feeds the nuclear supermassive black hole (SMBH), which isdrawn from a reservoir molecular and/or neutral hydrogen around the SMBH.Additionally, we look for correlations between $D$ and the electron density($N_{\rm e}$), [\ion{O}{iii}]$\lambda$5007 and H$\alpha$ luminosities,extinction coefficient ($A_{V})$ of the NLRs, as well as the stellar mass($M_{*}$) of the host galaxies. Evidences of an inverse correlation between the$D$ and the parameters $N_{\rm e}$, $M_{*}$ and $A_{\rm v}$ were found.

Gas phase metallicity determinations in nearby AGNs with SDSS-IV MaNGA: evidence of metal poor accretion