Hibiscus sabdariffa ameliorates tramadol-induced neurotoxicity via antioxidant, anti-inflammatory, anti-apoptotic, and neurotransmission-regulating mechanisms

Abstract

The misuse and abuse of tramadol, a synthetic opioid analgesic, has become a major public health concern in Africa. Although effective for managing moderate to severe pain, tramadol exposure has been associated with central nervous system toxicity. Hibiscus sabdariffa, commonly consumed as “Zobo,” contains bioactive substances with potent antioxidant and anti-inflammatory properties. Therefore, this study investigated the neuroprotective potential of aqueous H. sabdariffa extract (HSE) against tramadol-induced neurotoxicity in male Swiss mice. Fifty adult male mice were randomly assigned into five groups namely control (normal saline), tramadol (50 mg/kg), and three treatment groups receiving tramadol intraperitoneally plus HSE given through oral route at 50, 100, and 200 mg/kg for 21 days. Neurobehavioral tests assessed motor coordination, cognition, anxiety, and depressive-like behaviors. Brain regions, including the hippocampus, prefrontal cortex, and cerebellum, were analyzed for malondialdehyde, reduced glutathione, catalase, superoxide dismutase, glutathione-S-transferase, nitrite levels, acetylcholinesterase activity, and pro-inflammatory cytokines, including interleukin-6, and tumour necrosis factor-alpha. Histological analysis was performed using Nissl staining, while RT-PCR quantified neurotransmission- and apoptosis-related genes, including GAD2, TH, TP53, BAX, and BCL-2. Molecular docking evaluated interactions of H. sabdariffa phytocompounds with target proteins. Tramadol exposure significantly impaired behavior, increased oxidative stress and inflammation, depleted antioxidant defenses, and induced neuronal damage with altered gene expression. H. sabdariffa extract treatment dose-dependently mitigated these alterations, preserved neuronal architecture, and modulated apoptosis-related genes. Docking computation identified Quercetin-3-O-rutinoside, Baicalin, and Delphinidin-3-O-sambubioside as hit compounds with strong binding affinity to target proteins of the genes evaluated in the RT-PCR. Hibiscus sabdariffa aqueous extract activity suggests robust neuroprotective effects against tramadol-induced neurotoxicity through coordinated antioxidant, anti-inflammatory, anti-apoptotic, and neuromodulatory mechanisms. These findings position H. sabdariffa extract as a promising, accessible therapeutic candidate for managing opioid-induced CNS damage.