Dose-dependent renoprotective effect of vanillic acid on methotrexate-induced nephrotoxicity via its anti-apoptosis, antioxidant, and anti-inflammatory properties.

Methotrexate-induced nephrotoxicity is a medical emergency which is associated with a variety of side effects. Vanillic acid (VA), as an antioxidant, removes free radical oxygen to protect cell defense. Therefore, this study investigated VA's beneficial effects on nephrotoxicity induced by methotrexate through its anti-apoptosis, antioxidant, and anti-inflammatory properties. Our study included five groups of male Wistar rats (n = 8): sham, MTX (Methotrexate) group: rats receiving methotrexate (20 mg/kg, intraperitoneally) on Day 2. Moreover, the remaining groups consisted of animals that received vanillic acid (25, 50, and 100 mg/kg, orally for seven days) plus MTX on the 2 nd day. The rats were deeply anesthetized on the eighth day to obtain blood and renal tissue samples. The results showed that MTX can increase blood urea nitrogen and creatinine. However, VA (50 and 100 mg/kg) improved renal function as approved by histological findings. Compared with MTX-treated rats, VA enhanced the contents of total antioxidant capacity (TAC) and reduced renal malondialdehyde (MDA). Moreover, VA reduced mRNA expressions of caspase-3 and Bcl-2-associated x protein (Bax) and caused mRNA overexpression of the renal B-cell lymphoma-2 (Bcl-2), and Nrf-2 (Nuclear factor erythroid 2-related factor 2) compared to the MTX group. Also, VA administration significantly reduced inflammatory agents. Overall, VA protects the kidneys against methotrexate-induced nephrotoxicity via anti-apoptosis, antioxidant, and anti-inflammatory properties. Our results revealed that the most effective dose of VA was 100 mg/kg.