Phytochemicals of Liverworts: Biological Activity and Their Application to Cosmetics, Foods and Medicines

Abstract

There are 6000 species of liverworts in the world. Almost all liverworts possess beautiful cellular oil bodies. Many species of liverworts possess characteristic fragrant odors and an intense pungent, sweet, or bitter taste. Generally, liverworts are not damaged by bacteria, fungi, insect larvae and adults, snails, slugs, and other small mammals. Although liverworts possess such bioactive products, their isolation and structural elucidation were neglected for almost a century. Since 1972, we collected more than 800 species of liverworts around the world and chemically analyzed them with respect to their chemistry, pharmacology, and application as sources of cosmetics and human diets, and as medicinal or agricultural agents. The biological activities of liverworts are due to the terpenoids and aromatic compounds which are present in the oil bodies in each species. Several hundred new compounds have been isolated from the essential oils and solvent extracts of liverworts, and more than 60 new carbon skeletal terpenoids and aromatic compounds such as bis-bibenzyls, marchantin A (1) and riccardin A (2), which are very rare natural products, were found. Most of the liverworts studied elaborate characteristic scent, pungent, and bitter tasting compounds, many of which show antimicrobial, antifungal, antiviral, allergenic contact dermatitis, cytotoxic, insecticidal, anti-HIV, superoxide anion radical release, plant growth regulatory, neurotrophic, NO production inhibitory, muscle relaxing, antiobesity, piscicidal, nematocidal activity, and many others. The most characteristic chemical phenomenon of the liverworts is that most of the sesqui- and diterpenoids are enantiomers to those found in higher plants.