Bryophytes, phylogenetically placed between algae and pteridophytes, are divided
into three classes, mosses, liverworts, and hornworts. The traditional system of
medicine throughout the world has been utilizing this group of plants to treat various ailments.
One of the outstanding features of these spore-forming plants is their chemistry,
especially that of the liverworts. Liverworts and other bryophytes have yielded a rich array
of secondary metabolites. Many of these compounds are characterized by unprecedented
structures, and some have not been found in any other plants, fungi, or marine organisms.
Among the bryophytes, the chemical constituents of liverworts and their biological activity
have been studied in the most detail. In this review, we demonstrate the chemistry of
the liverworts, mosses, and hornworts, and also neuroprotective activity of dimeric herbertane-
type sesquiterpenoids, mastigophorenes and secoaromadendrane-type sesquiterpenoids, marchantin-type
cyclic bisbibenzyls with muscle-relaxant activity, or ent-longipinane-type sesquiterpenoids with acetylcholinesterase
inhibitory activity, among others.