Galactosyl Derivative of Nώ-Nitro-L-Arginine: Study of Antiproliferative Activity on Human Thyroid Follicular Carcinoma Cells

The methyl ester prodrug of Nv-nitro-L-arginine (L-NAME) has been reported to exert anticancer effects against several human tumors,
including thyroid carcinoma, by inhibiting nitric oxide synthase (NOS). However, chronic administration of L-NAME has often led to
adverse events causing cardiovascular alterations due to its potential toxic effect. Here we report for the first time the synthesis of the
galactosyl ester prodrug of Nv-nitro-L-arginine, NAGAL, a prodrug capable of inhibiting NOS more efficiently and with fewer adverse
events than its parent drug. For this purpose RO82-W-1, a thyroid cell line derived from human follicular carcinoma, was used. MTT test
results showed that NAGAL affected cell viability to a significantly greater extent than did L-NAME. Moreover, fluorescence activated cell
sorter (FACS) analyses revealed that NAGAL, compared to L-NAME, was able to reduce nitric oxide (NO) production as well as increase
the percentage of apoptotic thyreocytes. Western blot further confirmed the reduction in NOS-II expression by NAGAL. Finally, by using
the LC–MS technique, we found that NAGAL elicited a higher increase inNv-nitro-L-arginine (NA) concentration than did L-NAME. Thus,
this study suggests that NAGAL could be considered a potential therapeutic tool for those pathologies involving an overproduction of
NO, including thyroid carcinoma.