Neuro-nutraceutical role of Indian spices, spice mixes and their bio-actives: An update

Neurodegenerative disorders (NDD), one of the major health care challenges, are exponentially increasing as the elderly segment of the population continues growing in size worldwide. Currently, the role of nutraceuticals, in general and particularly for brain health, has generated immense research interest. Ancient, traditionally used culinary spices have been recognized for their potential health benefits. Abundant evidence clearly suggests that spices do impart considerable biological activity in the central nervous system (CNS). Owing to the multi-mechanistic actions of spices/bioactives, scientific interest is resurgent in characterizing, understanding, and exploring their neuro-nutraceutical role. The current review summarizes experimental evidence on the nutraceutical attributes of a subset of Indian spices. Major molecular mechanisms by which these compounds counteract neuropathology-such as antioxidant activity, anti-inflammatory effects, modulation of signaling pathways (e.g., Nrf2, NF-κB, MAPK), enhancement of synaptic plasticity, and stimulation of neurogenesis are discussed. The neuroprotective efficacy of Spice extract/bioactives as therapeutics is dependent on bioavailability, pharmacokinetics, and delivery challenges that prevent adequate concentrations from reaching the brain. However, the development of several nano-formulations for various spice bioactives has significantly addressed these issues. Further, the data limitations, potential obstacles to be overcome, and current research on metabolic engineering and the nanotechnology of spice bioactives are also presented. Although the randomized controlled trials (RCTs) in humans are limited, and restricted to a few spice bio-actives, abundant evidence in various preclinical models prompts one to hypothesize that Indian spices/bio-actives are quite promising as neuro-nutraceuticals in the management of NDD.