Search for New Liverwort and Fern Constituents of Biological Interest

Over several hundred new compounds have been isolated from the liverworts and more than 40 new carbon skeletal terpenoids (1,2) and aromatic compounds (3) have been found in this class. The biological activity ascribed to liverworts is due mainly to lipophilic sesqui- and diterpenoids, phenolic compounds and acetogenins which are constituents of oil bodies. Most of liverworts elaborate characteristic odiferous, hot tasting and bitter compounds many of which show allergenic contact dermatitis, cytotoxicity, insecticide, anti-HIV, antimicrobial, antifungal and antiinfluenza, superoxide anion radical release, plant growth regulatory, neurotrophic, NO production inhibitory, muscle relaxing and antiobesity activity.[1 – 3] Several ferns produce pungent, bitter or sweet substances. Thelypteris hispidula and Blechnum fluviatile produce a large amount of polygodial, responsible for their pungency and its related drimanes. Elaphoglossum and Hymenophyllum species elaborate bitter styrene glucosides, and hemiterpene glucosides (4) with phenylacetic acid, respectively. [4 – 6]

Reboulia hemisphaerica elaborates

(1) Plagiochilin A (2) Epi-chandonanthone (3) Riccardin C (4) Hymenoside A

References: [1] Asakawa Y, (1982) Chemical constituents of Hepaticae. In: Progress in the Chemistry of Organic Natural Products. Springer, Vienna. 42: 1 – 278. [2] Asakawa Y, (1995) Chemical Constituents of Bryophytes. ibid. 65: 1 – 618. [3] Asakawa Y, Ludwiczuk A, Nagashima F. (2013) Chemical Constituents of Bryophytes: Bio- and Chemical Diversity, Biological Activity, and Chemosystematics. ibid. 95, 1 – 796. [4] Asakawa Y (2008) Curr. Pharm. Design. 14: 3067 – 3088. [5] Socolsky, C., Asakawa, Y. et al. (2010)J Nat Prod, 73: 901 – 904. [6] Socolsky C, Asakawa Y, et al. (2009)J Nat Prod, 72: 787 – 790.