Anthocyanin derived from purple sweet potato water extracts ameliorated oxidative stress, inflammation, mechanical allodynia, and cold allodynia among chronic constriction injury-induced neuropathic pain in rats

Abstract

BACKGROUND: Nerve injury leads to multiple events, including oxidative stress, inflammation, and glial cells activation, which all bring about the neuropathic pain condition. Any alternative novel treatment modalities from natural products are thus highly anticipated, given the account that current treatments for neuropathic pain have not generated any satisfactory efficacy. AIM: This study aims to address the pleiotropic effects of water extracts from the purple sweet potato (PSP) (Ipomoea batatas L.) as an antioxidant, anti-inflammatory, and anti-nociceptive agent to alleviate neuropathic pain behavior. METHODS: This is a randomized post-test control group design using chronic constriction injury (CCI) rat models. Thirty-two Wistar rats (34 survived until the end of study period) fulfilling the eligible criteria were randomized into either treatment or control group. Treatment group received water extracts of PSP containing 400 mg/kg of body weight/d of anthocyanin for 28 days. Antioxidant activity was evaluated from malondialdehyde (MDA) levels, anti-inflammatory activity was evaluated from prostaglandin E2 (PGE2) levels. Neuropathic pain was assessed from the animal’s behavioral responses toward mechanical and cold allodynia. RESULTS: The results showed that mean MDA levels of treatment group were significantly lower than control group (0.291 ± 0.046 µmol vs. 0.394 ± 0.057 µmol; p < 0.001). Furthermore, treatment group’s PGE2 levels were also significantly lower than control’s (0.342 ± 0.096 ng/mL vs. 0.431 ± 0.061 ng/mL; p = 0.004). In addition, neuropathic pain behavior comprising mechanical and cold allodynia were significantly milder among treatment group than in the control group during the observation period (p < 0.05). CONCLUSION: PSP water extracts had been shown to ameliorate oxidative stress, as well as exerted anti-inflammatory and anti-nociceptive effects and was able to suppress neuropathic pain behavior in Wistar rats with peripheral nerve injury.