D-Cysteine is the D-isomer of cysteine and a powerful inhibitor of Escherichia coli growth. D-cysteine is mediated by D-amino acid oxidase to produce H2S and is a neuroprotectant against cerebellar ataxias. D-Cysteine could inhibit the growth and cariogenic virulence of dual-species biofilms formed by S. mutans and S. sanguinis[1][2][3].
[1]. Seki T. Availability of D-cysteine as a protectant for cerebellar neurons. Nihon Yakurigaku Zasshi. 2019;154(3):133-137. [2]. Soutourina J, et al. Role of D-cysteine desulfhydrase in the adaptation of Escherichia coli to D-cysteine. J Biol Chem. 2001 Nov 2;276(44):40864-72. [3]. Guo X1, et al. Effect of D-cysteine on dual-species biofilms of Streptococcus mutans and Streptococcus sanguinis. Sci Rep. 2019 Apr 30;9(1):6689.