No abstract

Baccharis genus Asteraceae is widely used in traditional treatment against fever, headache, hepatobiliary disorders, skin ulcers, diabetes, and rheumatism, as well as an antispasmodic and diuretic. Its phytochemistry mainly shows the presence of flavonoids and terpenoids such as monoterpenes, sesquiterpenes, diterpenes, and triterpenes. Some of them have been evaluated for biological activities presenting allelopathic, antimicrobial, cytotoxic, and anti-inflammatory properties. In this paper, our research group reported the isolation, characterization, and antifungal evaluation of several molecules isolated from the dichloromethane extract from Baccharis prunifolia, Baccharis trinervis, and Baccharis zumbadorensis against the phytopathogen fungus Botrytis cinerea. The isolated compounds have not previously been tested against Botrytis, revealing an important source of antifungals in the genus Baccharis. Six known flavones were isolated from B. prunifolia. The dichloromethane extracts of B. trinervis and B. zumbadorensis were subjected to a bio-guided isolation, obtaining three known flavones, an α-hydroxidihydrochalcone mixture, one labdane, one triterpene, and two norbisabolenes from the most active fractions. The compounds 4′-methoxy-α-hydroxydihydrochalcone (7A), 3β,15-dihydroxylabdan-7-en-17-al (8), and 13-nor-11,12-dihydroxybisabol-2-enone (11) are novel. The most active compounds were the Salvigenin (5) and 1,2-dihydrosenedigital-2-one (10) with an IC50 of 13.5 and 3.1 μg/mL, respectively.

Clovane and isocaryolane derivatives have been proven to show several levels of activity against the phytopathogenic fungus Botrytis cinerea. Both classes of sesquiterpenes are reminiscent of biosynthetic intermediates of botrydial, a virulence factor of B. cinerea. Further development of both classes of antifungal agent requires exploration of the structure–activity relationships for the antifungal effects on B. cinerea and phytotoxic effects on a model crop. In this paper, we report on the preparation of a series of alkoxy-clovane and -isocaryolane derivatives, some of them described here for the first time (2b, 2d, 2f–2h, and 4c–4e); the evaluation of their antifungal properties against B. cinerea, and their phytotoxic activites on the germination of seeds and the growth of radicles and shoots of Lactuca sativa (lettuce). Both classes of compound show a correlation of antifungal activity with the nature of side chains, with the best activity against B. cinerea for 2d, 2h, 4c and 4d. In general terms, while 2-alkoxyclovan-9-ols (2a–2e) exert a general phytotoxic effect, this is not the case for 2-arylalkoxyclovan-9-ols (2f–2i) and 8-alkoxyisocaryolan-9-ols (4a–4d), where stimulating effects would make them suitable candidates for application to plants.