Linking phytochemistry to traditional uses and pharmacology of an underexplored genus – Psydrax: a review

The genus Psydrax is one of the ethno-medicinally important genera of the Rubiaceae family which has only received a limited scientific attention, despite coming from a pharmacologically and phytochemically important plant family. The genus has found applications in ethnomedical management of diabetes, stomach disorders, inflammations, cardiovascular diseases, epilepsy, wounds, malaria and fever. To unveil knowledge gaps, stimulate research interest and unravel opportunities for drug discovery from the genus Psydrax, we have carried out an extensive review on its traditional applications, phytochemistry and pharmacology for the first time. Literature on these topics was obtained from Google Scholar, Pubmed and ScienceDirect journal articles published from 1788 to September, 2021. Only articles written in English were reviewed. While several species of Pysdrax used in traditional medicine have not been chemically explored for drug discovery, over a hundred secondary metabolites have so far been identified in few species of the genus, and majority of these chemotaxonomic markers are iridoids. Bioactive extracts and some isolated constituents of Psydrax species have shown various in vitro and in vivo pharmacological properties including anti-hyperglycemia, anti-inflammatory, anticonvulsant and antimicrobial, and thus, support some of the ethnomedical uses of the plants. For an evidence-informed application of the genus, Psydrax, in traditional medicine, more ethnobotanical surveys, elaborate in vivo pharmacological assays, in-depth toxicity and holistic phytochemical studies are required to fully exploit more species of the genus prior to future clinical studies. Following documented traditional uses of Psydrax species, the deliberate cultivation of medicinal plants under this genus is recommended for sustainability in medicinal plant utilization.