Aqueous extract of Hibiscus sabdariffa calyces offers neuroprotection against unpredictable chronic mild stress-induced neurobehavioral disorders and biochemical perturbations in male Swiss mice

Introduction

Hibiscus sabdariffa (commonly known as roselle or Chinese rose tea) is widely known for its soothing effects, particularly during prolonged stress. In Traditional Chinese Medicine (TCM), it is valued for its therapeutic benefits, including antihypertensive, anti-inflammatory, and hepatoprotective effects. This study explores the neuroprotective potential of the aqueous extract of H. sabdariffa calyces (AEHS) in mitigating stress-induced neurobehavioral and biochemical changes in mice subjected to unpredictable chronic mild stress (UCMS).

Methods

Thirty male Swiss mice were randomly assigned to five groups (n = 6) and treated orally. Groups 1 (control) and 2 (UCMS-control) received distilled water, whereas group 3–5 received AEHS at doses of 50, 100, and 200 mg/kg, respectively. Group 2–5 were subjected to unpredictable chronic mild stress (UCMS) daily for 21 days. The neurobehavioral assessments including locomotor activity, memory, anxiety and depressive-like behaviors conducted on days 20 and 21. On day 22, blood glucose and serum corticosterone levels were analyzed alongside oxidative stress biomarkers, nitrites, pro-inflammatory cytokines (tumor necrosis factor-alpha and interleukin-6), and serotonin levels in the prefrontal cortex, amygdala, and hippocampus. The brain-derived neurotrophic factor (BDNF), nuclear factor kappa B (NF-κB), cyclic adenosine monophosphate (cAMP)-response element binding protein (CREB), and nuclear factor erythroid 2-related factor 2 (Nrf2) were evaluated. The enzymatic activities of acetylcholinesterase (AChE) and glutamic acid decarboxylase (GAD) as well as the histomorphological changes in the brain regions were also assessed.

Results

AEHS effectively modulated UCMS-induced neurobehavioral disorders, along with elevated blood glucose and plasma corticosterone levels. The extract mitigated UCMS-induced increases in malondialdehyde (MDA), nitrites, pro-inflammatory cytokines, NF-κB, and AChE. Additionally, AEHS restored the diminished levels of glutathione, catalase, superoxide dismutase, CREB, BDNF, Nrf2, serotonin, and GAD activity within the brain regions. Furthermore, AEHS ameliorated UCMS-induced histomorphological alterations in the brain.

Discussion/Conclusion

This study demonstrated that AEHS confers neuroprotection against chronic stress-induced neurobehavioral disorders, biochemical and histomorphological alterations by enhancing antioxidant defenses and modulating key signaling pathways, including BDNF, CREB, Nrf2 and NF-κB. These findings underscore the potential therapeutic applications of AEHS in mitigating chronic stress-related psychiatric disturbances within the framework of TCM.