Phytomedicine Plus (Aug 2022)
Phytochemistry, structural diversity, biological activities and pharmacokinetics of iridoids isolated from various genera of the family Scrophulariaceae Juss.
Abstract
Background: Iridoids are naturally occurring oxygenated monoterpenes with wide range of pharmacological activities. Scrophulariaceae Juss. is a family of flowering plants with 74 genera and 1533 species well known as rich sources of iridoids. Purpose: The aim of this review is to describe the phytochemistry and structural diversity of iridoids isolated from various genera of the family. Also, their reported activities and pharmacokinetics are highlighted to provide an overall overview of iridoids in Scrophulariaceae as a fundament for further studies on this important class of compounds. Methods: A literature survey was performed by searching for relevant information through different scientific databases as SciFinder, ScienceDirect, PubMed, Google Scholar and The World Flora Online. Results: More than 190 scientific works of literature were consulted from 1980 to 2022. Nearly 250 compounds belonging to iridoid glycosides, seco-iridoids glycosides and non-glycosidic iridoids are reported herein from 102 species. They are isolated from polar alcoholic or aqueous alcoholic extracts of the plant. These compounds exhibit anti-inflammatory, antiprotozoal, neuroprotective, cardioprotective, antioxidant and anticancer activities. Pharmacokinetic studies reported differences in their behaviour due to structural variations. However, most of these iridoids showed low oral bioavailability. Conclusions: The collected data indicates that more than 70% of iridoids of the family were isolated and identified from Scrophularia, Verbascum and Buddleja genera. Moreover, glycosides of C9 iridoids are the major class representing more than 80% of the total iridoids and third of the identified compounds show activity against inflammation. Further future investigations are recommended regarding the molecular mechanism of action of iridoids, their structure activity relationship, effective doses, toxicity and clinical effects, in order to promote the use of iridoids from Scrophulariaceae as source of new therapeutic medications.
