Neurodegenerative diseases (NDs) affect millions of people worldwide, and to date Alzheimer's and Parkinson's disease are the most common NDs. The risk of developing NDs increases dra-matically with age, and genetic and environmental factors can be crucial in their progression. The main feature of NDs is the abnormal presence of specific proteins that can lead to neuronal death, proteotoxic stress, and alteration of catabolic systems, which are major players in the processes of neurodegeneration and neuroinflammation. Despite research efforts to date, the therapies cur-rently in use for the treatment of NDs provide marginal therapeutic benefit, so the focus is now being direct toward the search of natural products that could be a valuable aid in combating these diseases, including the natural compound Andrographis paniculata (Ap) and especially its main constituent Andrographolide (Andro). Preclinical studies have shown that the aqueous extract of Ap is capable to modulate neuroinflammatory and neurodegenerative responses, determining a reduction in inflammatory markers and oxidative stress in various NDs. Therefore, in this review we will focus on the molecular mechanisms through which Ap and Andro are able to modulate the processes of neurodegeneration and neuroinflammation that are major causes of neuronal death and cognitive decline.

Here we have chosen to highlight the main natural molecules extracted from camellia sinensis, andrographis paniculata and curcuma longa that may possess antioxidant activities of interest for skin protection. The molecules involved, in the antioxidant process are respectively catechins derivatives, in particular EGCG, andrographolide and its derivatives as well as various curcuminoids. These plants are generally used as beverages for camellia sinensis (tea tree), as dietary supplements or as spices. The molecules they contain are known for their diverse therapeutic activities, including anti-inflammatory, antimicrobial, anti-cancer, antidiabetic and dermatological treatment. Their common antioxidant activities and therapeutic applications are widely documented, but their use in cosmetic is more recent. In this review, we will endeavor to compile the cosmetic uses of these natural molecules of interest, the various structural modulations reported, with the aim of improving their bioavailability as well as establishing their different mechanisms of action.