Alkaloids are a class of secondary metabolites that can be derived from plants, fungi and marine sponges. They are widely known as a continuous source of medicine for the management of chronic disease including cancer, diabetes and neurodegenerative diseases. For example, galanthamine and huperzine A are alkaloid derivatives currently being used for the symptomatic management of neurodegenerative disease. The etiology of neurodegenerative diseases is polygenic and multifactorial including but not limited to inflammation, oxidative stress and protein aggregation. Therefore, natural-product-based alkaloids with polypharmacology modulation properties are potentially useful for further drug development or, to a lesser extent, as nutraceuticals to manage neurodegeneration. This review aims to discuss and summarise recent developments in relation to naturally derived alkaloids for neurodegenerative diseases.

Polymeric nanoparticles are widely used for drug delivery due to their biodegradability property. Among the wide array of polymers, chitosan has received growing interest among researchers. It was widely used as a vehicle in polymeric nanoparticles for drug targeting. This review explored the current research on the antimicrobial activity of chitosan nanoparticles (ChNP) and the impact on the clinical applications. The antimicrobial activities of ChNP were widely reported against bacteria, fungi, yeasts and algae, in both in vivo and in vitro studies. For pharmaceutical applications, ChNP were used as antimicrobial coating for promoting wound healing, preventing infections and combating the rise of infectious disease. Besides, ChNP also exhibited significant inhibitory on foodborne microorganisms, particularly on fruits and vegetables. It is noteworthy that ChNP can be also applied to deliver antimicrobial drugs, which further enhance the efficiency and stability of the antimicrobial agent. The present review addresses the potential antimicrobial applications of ChNP from these few aspects.

Plant-derived terpenes are the prolific source of modern drugs such as taxol, chloroquine and artemisinin, which are widely used to treat cancer and malaria infections. There are research interests in recent years on terpene-derived metabolites (diterpenes, triterpenes and sesquiterpenes), which are believed to serve as excellent cholinesterase inhibitors. As cholinesterase inhibitors are the current treatment for Alzheimer’s disease, terpene-derived metabolites will have the potential to be involved in the future drug development for Alzheimer’s disease. Hence, a bibliographic search was conducted by using the keywords “terpene”, “cholinesterase” and “Alzheimer’s disease”, along with cross-referencing from 2011 to 2020, to provide an overview of natural terpenes with potential anticholinesterase properties. This review focuses on the extraction, chemical structures and anti-cholinesterase mechanisms of terpenes, which support and encourage future research on drug discovery and development in treating Alzheimer’s disease.