Sesquiterpene Lactones as Allelochemicals

Abstract

Six new sesquiterpene lactones, annuolide H (3), helivypolides F, H-J (4, 11-13), and helieudesmanolide A (6), together with known compounds, were isolated from polar bioactive fractions of Helianthus annuus cv. SH-222 and Stella fresh leaf water extracts. Spectroscopic analysis of the new data for 1,2-anhydroniveusin A and 1-methoxy-4,5-dihydroniveusin A corrects some previous assignments. The compounds were tested using the etiolated wheat coleoptile bioassay, and the most active compounds were assayed in standard target species (STS) (Lepidium sativum, Allium cepa, Lactucasativa, Lycopersicon esculentum, and Triticum aestivum) from 5 x 10(-4) to 10(-5) M. The most phytotoxic compounds were helivypolide F and 15-hydroxy-3-dehydrodeoxyfruticin, both of which have a carbonyl group at C-3 conjugated with two double bonds.

Differential metabolic and biological profiles of Lychnophora ericoides mart. (Asteraceae) from different localities in the Brazilian "campos rupestres"

“…[9][10][11][13][14][15][16] Furthermore, they are among the major secondary metabolites previously isolated from L. ericoides. 5,7 Since the Ibiraci population is the only one among the plants studied that occupies the border between two different types of forests ("cerrado" and semi-deciduous forest), this suggests a possible relationship between its higher cytotoxic activity and an amplification of its secondary metabolite biosynthesis, especially of STL, in agreement with the proposal that plants under environmental pressure could synthesise and store more defensive secondary metabolites.…”

“…12 There is some evidence for an ecological role for STL in plants, like their effectiveness as insect antifeedants, due to their bitter taste and cytotoxicity [13][14][15] and potential allelopathic activities. 16 As mentioned above, the Lychnophora genus is endemic to the Brazilian "cerrado", where high exposure to UV light, an alternation between long periods of drought and rain and periodic burnings are regional characteristics. Coevolution of these plants with such peculiar environmental characteristics, as well as endemic herbivores and local flora, certainly led to the establishment of protection mechanisms against the deleterious effects of these and other stressful environmental conditions, for instance by the accumulation of cytotoxic compounds and UV protective pigments, such as STL and flavonoids, respectively.…”

Síntese e avaliação da atividade fitotóxica de derivados da α-Santonina

“…Mais de 7000 estruturas já foram descritas, incluindo, germacranolídeos, eudesmanolídeos, pseudoguainolídeos e guaianolídeos. 5 Essas lactonas apresentam amplo espectro de atividades biológicas, incluindo atividades fitotóxica, inseticida e fungicida. 1 Como exemplos de lactonas sesquiterpênicas que apresentam atividade fitotóxica podemse citar os guaianolídeos 1, 2 e 3 provenientes de folhas de girassol (Figura 1).…”

Efeito fitotóxico do óleo volátil de Cleome guianensis Aubl. sobre o crescimento inicial de Senna occidentalis L.

“…N o s g r á f i c o s , o s r e s u l t a d o s s ã o representados em porcentagem em relação ao controle, sendo que o zero representa o controle, valores positivos representam estímulo e valores negativos representam inibição (Macias et al, 2006).…”