Neuroprotection is the preservation of the structure and function of neurons from insults arising from cellular injuries induced by a variety of agents or neurodegenerative diseases (NDs). The various NDs including Alzheimer's, Parkinson's, and Huntington's diseases as well as amyotropic lateral sclerosis affect millions of people around the world with the main risk factor being advancing age. Each of these diseases affects specific neurons and/or regions in the brain and involves characteristic pathological and molecular features. Hence, several in vitro and in vivo study models specific to each disease have been employed to study NDs with the aim of understanding their underlying mechanisms and identifying new therapeutic strategies. Of the most prevalent drug development efforts employed in the past few decades, mechanisms implicated in the accumulation of protein-based deposits, oxidative stress, neuroinflammation, and certain neurotransmitter deficits such as acetylcholine and dopamine have been scrutinized in great detail. In this review, we presented classical examples of plant-derived neuroprotective agents by highlighting their structural class and specific mechanisms of action. Many of these natural products that have shown therapeutic efficacies appear to be working through the above-mentioned key multiple mechanisms of action.

Background:There are ongoing efforts to identify the chemical composition of plants used as food or medicines in other to correlate their components with the numerous claims of their medicinal usefulness in folklore. Objective: This work is aimed at profiling the phytochemical composition of Spondias purpurea using GC-MS, as well as to determine the total phenolic content, total flavonoid content and the antioxidant capacity by DPPH radical scavenging assay. Methods: Whole fruit and stem bark of Spondias purpurea were collected, dried, extracted with methanol and concentrated in vacou before assessing them for their total phenolic content by Folin-Ciocalteu's phenol reagent method; total flavonoid content and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activities. The whole fruit and stem bark extracts were partitioned into n-hexane, dichloromethane, ethyl acetate and aqueous fractions. The n-hexane fraction of the stem bark and whole fruit were analyzed on GC-MS. Results: The stem bark had the highest phenolic content of 29.81± 1.18 GAE mg/g. Similarly, free radical scavenging activities assay showed the stem bark to be most active with IC 50 of 6.20 ± 1.51μg/ml, better than the standard, ascorbic acid with IC 50 of 11.51 ± 0.3μg/ml. The n-hexane partitioned fractions of the fruit and stem bark on GC-MS analysis showed 9 prominent compounds including 9,17-Octadecadienal (5.43%), 3-((4Z,7Z)-Heptadeca-4,7-dien-1-yl) phenol(12%), (Z)-3-(Heptadec-10-en-1-yl) phenol (11.76%), n-Hexadecanoic acid (7.07%) and 13 compounds including 9,17-Octadecadienal (20.51%),trans-13-Octadecenoic acid (12.61%), Pentadecanoic acid (8.3%), n-Hexadecanoic acid(15.24%). Conclusions: This study provides justification for some of the folkloric use of Spondias purpurea.