A new bioactive eremophilanolide, 1α-tigloyloxy-8βH,10βH-eremophil-7(11)-en-8α,12-olide (1), was isolated from Senecio poepigii and its structure was elucidated by spectral analysis. 1α-Angeloyloxy-8β-methoxy-10βH-eremophil-7(11)-en-8α,12-olide (2) was also isolated. Antifungal and insect antifeedant properties were evaluated.

Phytopathogens are responsible for great losses in agriculture. In particular, Fusarium, Alternaria and Botrytis are fungal diseases that affect crops worldwide. In the search for eco-friendly solutions to pest control, plants and their chemo-biodiversity are promising sources of biopesticides for integrated pest management. The aim of the present study is to report the evaluation of sixteen plant species from the Canary Islands Archipelago against the phytopathogenic fungi Botrytis cinerea, Fusarium oxysporum, and Alternaria alternata. The plants were selected on the basis of their traditional uses in medicine and/or pest control, as well as on scientific studies reporting their uses in crop protection. Their growth inhibition (% I), in an in vitro test-assay on mycelium, was used to identify six ethanolic plant extracts displaying activity (% I > 30% at 1 mg/mL) against at least one of the assayed fungi. The most effective plant extracts were further fractionated by liquid–liquid partition, using solvents of increasing polarity. This procedure led to an improvement of the bioactivity against the phytopathogens, even affecting the hexane fraction from S. canariensis and achieving an 83.93% of growth inhibition at 0.5 mg/mL on B. cinerea. These findings identified five plant-derived extracts as potential candidates for the future development of new biofungicides, which could be applied in integrated pest management.

Botanical biopesticides have emerged as sustainable and eco-friendly alternatives to synthetic pesticides, whose indiscriminate use leads to several drawbacks to human and environmental health. To the best of our knowledge, there have been no reports on M. pubescens’ bioactivity on phytopathogens affecting crops as a potential fungicide or antifeedant. This has encouraged us to investigate the potential of the roots of this plant as a source of biopesticides. The present study reports on the evaluation of the roots extract from Magonia pubescens A. St.-Hill., a species from the Cerrado (Brazilian savannah), on the phytopathogenic fungi Botrytis cinerea, Fusarium oxysporum, and Alternaria alternata. In addition, its insect antifeedant effect was assayed against Chrysodeixis chalcites. Thus, an in vitro test-assay was used to determine the fungicide potential (percentage growth inhibition, % GI) of the ethanolic extract of this plant species, whereas a leaf-disk bioassay on the 5th instar larvae of C. chalcites was performed to evaluate its insecticidal potential. The ethanolic extract was further fractionated by liquid–liquid partition using solvents of increasing polarity. The hexane/dichloromethane fraction exhibited a moderated potency and was similar to the ethanolic extract on the three assayed fungi (around % GI 30 at 1 mg/mL), whereas the n-butanol fraction showed a slight improvement of the fungicide effect against B. cinerea (% GI 39.18 at 1 mg/mL). Moreover, the ethanolic extract exhibited a strong antifeedant activity, with a refusal rate (FR) higher than 90% in both choice and non-choice assays against C. chalcites, while the ethyl acetate and n-butanol fractions behaved as appetite suppressors. These results highlight M. pubescens as a promising source of biopesticides and deserve further investigations to optimize extraction procedures.