Mechanistic insights of the anti-ageing dietary plant secondary metabolites vis-à-vis the modern hallmarks of ageing: Implications for developing novel anti-ageing foods

Plant secondary metabolites (PSM) including polyphenols, alkaloids, and terpenes are diverse dietary influencers of human health that are also emerging as potent longevity modulators. However, the mechanistic understanding of the anti-ageing effects of PSM vis-à-vis the modern hallmarks of ageing i.e., cellular senescence, chronic inflammation, gut dysbiosis, telomere attrition, genome instability, proteostasis and autophagy, epigenetic alterations, nutrient sensing pathways, and stem cells dysfunctions, is limited. The present work provides a comprehensive review of the extent and depth of PSM as regulators of ageing within the framework of the modern hallmarks of ageing. Current evidence suggests that PSM can influence all known ageing hallmarks albeit to a varying degree. There is immense scope for identifying novel PSM targeting the hallmarks of ageing especially related to cellular senescence (as senolytics), gut microbiome, and epigenetic mechanisms. In addition, PSM and gut dysbiosis are of particular interest due to their mutual bidirectional interactions and amalgamation that could be useful in developing novel anti-ageing functional foods. Future research on the development of PSM-based anti-ageing therapies is recommended to focus on the integrative assessment of the modern hallmarks of ageing for a more holistic approach.