Phytotoxicity evaluation of sesquiterpene lactones and diterpenes from species of the Decachaeta , Salvia and Podachaenium genera

Abstract

Decachaeta, Salvia and Podachaenium genera are known for their wide variety of biological activities. Synthetic herbicides have caused a variety of environmental and resistance problems. Natural products represent an important alternative to combat such issues. Sesquiterpene lactones and diterpenes are families of bioactive natural products for which a range of activities have been described. The bioactivities of nine sesquiterpene lactones, eight heliangolides, one guaianolide and twenty two diterpenes isolated from species of the Decachaeta, Salvia and Podachaenium genera were tested by applying a methodical procedure that involves assays of compounds on etiolated wheat coleoptiles (Triticum aestivum), Standard Target Species (STS) and two important weeds (barnyardgrass and brachiaria). The results clearly show that all of the sesquiterpene lactones studied were active on coleoptiles. In addition, six lactones were phytotoxic on both STS and weeds, meaning that these compounds could be used in the development of natural herbicide models.

Recent advances in allelopathy for weed control: from knowledge to applications

“…Recently, a wide range of sesquiterpenes, specifically sesquiterpene lactones, have been tested in standard target species as promising allelochemicals for use as natural herbicides. The compounds 7‐ epi ‐eudesm‐4(15)‐ene‐1β,6β‐diol and (7 R )‐opposit‐4(15)‐ene‐1β,7‐diol showed strong phytotoxic activity, particularly against tomato, whereas incomptin A and 7α‐hydroxy‐3‐desoxyzaluzanin C were active by inhibiting root and shoot length in lettuce and onion …”

“…Furthermore, two of these bioactive compounds, salvixalapadiene and tehuanin G (Fig. ), weakly inhibit germination and root and shoot growth in Lepidium sativum , Solanum lycopersicum , Lactuca sativa and Allium cepa . In addition to the aforementioned diterpenoids, the most widely studied compounds are momilactones (Fig.…”

Structure‐activity relationship studies on naphthoquinone analogs. The search for new herbicides based on natural products

“…In the same way as for the coleoptile bioassay; the herbicide Logran® was used as positive control and buffered nutritive aqueous solution with DMSO (5 μL DMSO solution mL −1 buffer) without any test compound was used as negative control. Evaluated parameters (germination rate, root and shoot length) were recorded using a Fitomed® system for evaluation and statistical analysis of the data was carried out …”

Phytotoxic Diterpenoids from Plants and Microorganisms

“…Compound 131 ( Figure ) was obtained from the aerial parts of Salvia herbacea and 132 ( Figure ) was isolated from the aerial parts of Salvia gesneriflora . L. sativum L. (cress), L. sativa L. (lettuce), Solanum lycopersicon L. (tomato), A. cepa L. (onion), E. crus‐galli L. (barnyard grass) and Urochloa decumbens (brachiaria) were selected as the tested plants.…”

“…Compound 131 (Figure 2) was obtained from the aerial parts of Salvia herbacea and 132 ( Figure 2) was isolated from the aerial parts of Salvia gesneriflora. [32] The ethanol extracts of Viguiera tucumanensis in the preflowering, flowering, and fructification stages showed phytotoxic effects against crop and weed species. Clerod-14-ene-3α,4β,13ξ-triol (133; Figure 3) was obtained from the three extracts.…”