The underexploited biotechnology of overexploited Origanum species: Status, knowledge gaps, prospects and potential

Abstract

The genus Origanum is a group of phytochemically diverse, aromatic species. Distributed mainly in Eurasia and Mediterranean, they are used in traditional medicine, cosmetics and for culinary purposes. They possess antiproliferative, antioxidant, antiviral, antiseptic, anti-inflammatory, anti-hypertensive properties. The major constituents of Origanum spp. are carvacrol and/or thymol together with ?-terpinene, p-cymene, linalool, terpinene-4-ol and sabinene hydrate. Several flavonoids and glycosides are also found. Although the Origanum spp. can either be cultivated or sourced from nature, high demand has necessitated increased production. Overexploitation from natural habitat has threatened these species. Also, due to its poor viability and small-sized seeds, cross-pollination abilities, less productive vegetative propagation, climate-dependent conventional propagation, its genetic improvement has been limited and thus scientific management of available germplasms through biotechnological approach is necessary. For in-vitro propagation, the literature review showed significant differences in culture protocols, genotypes and their success rates. Studies reported cell culture-based production of secondary metabolites or isolation of active compounds in different species of Origanum, which show antiproliferative activity in cancerous cell lines. However, significant knowledge gaps exist. The urgent need is to use advance technologies in enhancing either plant propagation thus the production of source material for active constituents or for genetic improvement of Origanum germplasms for contents, as well as to validate the therapeutic potential of Origanum constituents. This review critically appraises the status of mostly underexploited biotechnological know-how and research on highly valued medicinal herbs, Origanum and throws light on prospects and potential.