Herbal Bioactives Targeting Rho GTPases: A Multi-Targeted Strategy for Mitigating Neuroinflammation in Alzheimer's and Parkinson's Diseases.

Neuroinflammation plays an essential role in the pathogenesis of several associated brain diseases, including neurodegenerative disorders (Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS)), and traumatic brain injury (TBI). In these diseases, persistent microglial and astrocyte aggregates, elevated proinflammatory cytokines, and oxidative stress drive neuronal injury and cognitive disability. Rho GTPases, in particular the Rho family members Ras homolog family member A (RhoA), Ras-related C3 botulinum toxin substrate 1 (Rac1), and cell division control protein 42 homolog (CDC42), regulate neuroinflammation, cytoskeletal dynamics, immune responses, and the maintenance of BBB integrity. These proteins are involved in many neuropathological diseases due to dysregulation, making them interesting therapeutic targets. Bioactives used in herbal care have attracted interest for their ability to influence neuroinflammation and even their anti-neurodegenerative activity. Studies show that flavonoids, alkaloids, polyphenols, and other botanical compounds alter Rho GTPase activity, which, in turn, leads to decreased inflammation. This review critically summarizes current evidence regarding phytochemical regulation of Rho GTPase signaling in neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD), with particular emphasis on the underlying molecular mechanisms, context-dependent signaling responses, and current translational challenges. Furthermore, existing knowledge gaps and future research priorities are discussed to facilitate the development of mechanism-based therapeutic strategies targeting Rho GTPases.