Strategies for the synthesis of canonical, non-canonical and analogues of strigolactones, and evaluation of their parasitic weed germination activity

Abstract

Strigolactones (SLs) are natural products with promising applications as agrochemicals to prevent infestation with parasitic weeds due to their ability to trigger seed germination. However, their use is still limited because of the low yields in which they are isolated from natural sources. As such, numerous studies have led to strategies for obtaining them, and various structural analogues, by organic synthesis. These analogues have focused attention on the study of SLs, as some of them are easier to synthesize and possess enhanced properties, such as the level of bioactivity. This review provides an overview of the synthesis of SLs, subsequently focusing on the production of analogues with the canonical structure. The germinating activity of the compounds is also described herein, with positive effects on different species of the problematic genera Striga, Orobanche and Phelipanche having been found. The highly active analogue GR24 is currently the most widely studied in the literature, and relevant structural-activity relationships have been proposed as a result of the study of derivatives functionalized in different positions. Analogues based on other natural SLs such as strigol and orobanchol have also been developed, as have some novel canonical SLs derived from eudesmanolide or guaianolide sesquiterpene lactones. This review aims to provide useful information for the development of bioactive compounds applicable in new generation herbicides, in an attempt to employ similar compounds to those produced naturally in ecosystems that provoke effective herbicide effects at low concentrations.

(4Z)-Lachnophyllum Lactone, a Metabolite with Phytotoxic and Antifungal Activity against Pests Affecting Mediterranean Agriculture: A New Versatile and Easy Scalable Parallel Synthesis

“…The findings augment the repository of natural compounds suitable for application as bioinspired herbicides. The butenolide core, a peculiar feature of natural strigolactones, might also lead to test (4 Z )-lachnophyllum lactone and analogues for a strigolactone-like bioactivity, , thus widening the perspective of possible applications. The amount obtained exceeds the limitation imposed by isolation from natural sources, thereby facilitating the exploration and refinement of bio-formulations.…”

“…1 H NMR (600 MHz, CDCl 3 ): δ 2.33 (t, J = 7.0 Hz, 2H), 1.53 (m, 2H), and 0.97 (t, J = 7.4 Hz, 3H). EI-MS m/z (%): 194 (M + , 100), 165 (31), 65 (28), 41 (71), 39 (39). 27,28 Hepta-1,3-diyn-1-yltrimethylsilane (4).…”

Sesquiterpene Lactones Isolated from Centaurea cineraria L. subsp. cineraria Inhibit the Radicle Growth of Broomrape Weeds

“…It may be noted that germacranolides are a subgroup of sesquiterpene lactones with diverse biological activities of agronomical and pharmacological interest, and from which it is worth highlighting the capacity of some of them to stimulate the germination of specific broomrape species [ 23 , 41 , 42 ]. Furthermore, taking into account that the active compounds contain an α,β-unsaturated lactone ring, they could be used as starting material for the synthesis of new strigolactone analogues following already reported strategies [ 43 ]. Previous reports on the synthesis of derivatives of cnicin would also encourage the study of additional derivatives with improved activities in bioassays with parasitic plants [ 44 , 45 ].…”

Strigolactones: diversity, perception, and hydrolysis

“…Similarly, CYP722C from Lotus japonicus and Gossypium arboreum were implicated in the biosynthesis of strigol-type SLs ( Mori et al 2020a , b ; Wakabayashi et al 2020 ). For more comprehensive review of SLs biosynthesis, we recommend several excellent reviews including Yoneyama and Brewer and Zorrilla et al ( Yoneyama and Brewer 2021 ; Zorrilla et al 2022 ). Future investigations of CYP722C genes from various plants will shed light on the biochemical diversification of canonical SLs and how this large repertoire arose in different plant species.…”