There are disclosed novel compounds of formula (I) wherein R1, R12, L, X and Y are as defined in the specification, and pharmaceutically acceptable salts thereof; together with processes for their preparation, compositions containing them and their use in therapy. The compounds are inhibitors of the enzyme MPO and are thereby particularly useful in the treatment or prophylaxis of neuroinflammatory disorders, cardiovascular disorders and respiratory disorders.本發明係揭示新穎式(I)化合物其中R1,R12,L,X及Y均如本專利說明書中之定義,及其藥學上可接受之鹽;以及其製法,含有彼等之組合物,及其在治療上之用途。該化合物為酵素MPO之抑制劑,且於是特別可用於治療或預防神經炎性病症、心血管病症及呼吸病症。