Comprehensive analysis of the pharmacological potentials of Marrubium vulgare (white horehound): a recent overview of phytochemistry and biological activities

Abstract

Marrubium vulgare L. (M. vulgare) is a medicinal plant widely employed in traditional medicine for the management of respiratory, gastrointestinal, cardiovascular, and inflammatory disorders. Owing to its broad ethnopharmacological applications and rich phytochemical composition, the plant has attracted increasing scientific attention. This review summarizes current knowledge regarding the phytochemistry, traditional uses, and biological activities of M. vulgare, with particular emphasis on marrubiin, its major bioactive diterpene. Available studies indicate that M. vulgare contains a diverse range of secondary metabolites, including diterpenoids, flavonoids, phenolic acids, tannins, and volatile constituents, many of which contribute to its pharmacological properties. Experimental investigations have reported antioxidant, anti-inflammatory, antimicrobial, antidiabetic, hepatoprotective, gastroprotective, cardioprotective, neuroprotective, and antiproliferative/cytotoxic activities. Among these constituents, marrubiin is one of the most extensively investigated compounds and may contribute to several of the reported biological effects. Collectively, the available preclinical evidence provides pharmacological support for several traditional uses of M. vulgare and identifies the plant as a source of compounds worthy of further investigation. However, most evidence is derived from in vitro and animal studies, while clinical data remain scarce. Considerable variability in extract composition and experimental protocols, together with limited information regarding pharmacokinetics, long-term safety, standardization, and mechanism-specific validation, currently restricts clinical interpretation. Further studies using chemically standardized preparations, rigorous mechanistic approaches, comprehensive toxicological assessment, and, where justified, well-designed clinical trials are required to establish the therapeutic relevance of M. vulgare and its major constituents.