Plant Growth Inhibitors Isolated from the Liverwort, Plagiochila ovalifolia

Abstract

In the course of our investigation on the terpenoids displaying plant growth-inhibiting properties from the liverworts (Hepaticae), four sesquiterpenoids were isolated from a leafy liverwort, Plagiochila ovalifolia Mitt, and their structures were identified as (+)-ovalifoliene [I], (+)-ovalifolienalone [2] (+)-ovalifolienal [3], and (+)-plagiochiline A [4] The ent-2,3-seeo-alloaromadendranes [1] [2] [5] and [4] almost completely inhibited the growth of the rice seedlings at the concentrations of 25, 250, 50 and 50ppm, respectively. The details of their growth-inhibitory effects are shown in Table 1 and 2. Furthermore, the reaction products [5]∼[9] derived from (+)-ovalifoliene [l] were also tested for the biological activity (see Table 1 and 2) in order to study relationship between the biological activity and the chemical structure. The results suggest that the inhibitory activity is due to the acetyl hemiacetal moeity. α-Methylene--lactone C [9]} revealed almost similar inhibitory activity to the natural inhibitors [1 ] [3], and [4] The ketone [2] and the γ-lactone [8], however, promoted the growth of the root at the low concentration. © 1981, The Chemical Society of Japan. All rights reserved.