Alkaloids are a wide family of basic N-containing natural products, whose research has revealed bioactive compounds of pharmacological interest. Studies on these compounds have focused more attention on those produced by plants, although other types of organisms have also been proven to synthesize bioactive alkaloids, such as animals, marine organisms, bacteria, and fungi. This review covers the findings of the last 20 years (2002–2022) related to the isolation, structures, and biological activities of the alkaloids produced by mushrooms, a fungal subgroup, and their potential to develop drugs and agrochemicals. In some cases, the synthesis of the reviewed compounds and structure−activity relationship studies have been described.

Strigolactones (SLs) are a prime example of allelochemicals, promoting parasitic plant germination and certain hyphal branching factors associated to the growth of symbiotic arbuscular mycorrhizal fungi (AMF). However, the study of SLs is complex, and various issues have yet to be studied in depth. This review intends to provide an overview of the works that have been conducted on the identification, isolation, and evaluation of the allelopathic activity of natural canonical and non-canonical SLs on parasitic weeds and AMF growth. These topics were related with their application in agriculture through trap crops, suicidal germination or intercropping strategies. The high applicability of SLs in agriculture, for example, as preventing herbicides for parasitic weed control, has increased the interest for these compounds and the number of research articles published. This review updates and discusses the last findings in this field, with special emphasis in the results published since 2015, using tables and graphs to summarize and discuss that information. The promising results and conclusions obtained from the bioassays herein presented provide a good reason to encourage and support further research works on these natural products, which must also consider the disadvantages or current limitations that SLs present.

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.

Alternaria alternata is one of the most devastating phytopathogenic fungi. This microorganism causes black spots in many fruits and vegetables worldwide, generating significant post-harvest losses. In this study, an A. alternata strain, isolated from infected pears (Pyrus communis) harvested in Italy, was characterized by focusing on its pathogenicity mechanisms and competitive exclusion in the presence of another pathogen, Botrytis cinerea. In in vitro assays, the fungus produces strong enzymatic activities such as amylase, xylanase, and cellulase, potentially involved during the infection. Moreover, it secretes four different toxins purified and identified as altertoxin I, alteichin, alternariol, and alternariol 4-methyl ether. Only alteichin generated necrotic lesions on host-variety pears, while all the compounds showed moderate to slight necrotic activity on non-host pears and other non-host fruit (lemon, Citrus limon), indicating they are non-host toxins. Interestingly, A. alternata has shown competitive exclusion to the competitor fungus Botrytis cinerea when co-inoculated in host and non-host pear fruits, inhibiting its growth by 70 and 65%, respectively, a result not observed in a preliminary characterization in a dual culture assay. Alteichin and alternariol 4-methyl ether tested against B. cinerea had the best inhibition activity, suggesting that the synergism of these toxins and enzymatic activities of A. alternata are probably involved in the competitive exclusion dynamics in host and non-host pear fruits.

Aminophenoxazinones are degradation products resulting from the metabolism of different plant species, which comprise a family of natural products well known for their pharmacological activities. This review provides an overview of the pharmacological properties and applications proved by these compounds and their structural derivatives during 2000–2021. The bibliography was selected according to our purpose from the references obtained in a SciFinder database search for the Phx-3 structure (the base molecule of the aminophenoxazinones). Compounds Phx-1 and Phx-3 are among the most studied, especially as anticancer drugs for the treatment of gastric and colon cancer, glioblastoma and melanoma, among others types of relevant cancers. The main information available in the literature about their mechanisms is also described. Similarly, antibacterial, antifungal, antiviral and antiparasitic activities are presented, including species related directly or indirectly to significant diseases. Therefore, we present diverse compounds based on aminophenoxazinones with high potential as drugs, considering their levels of activity and few adverse effects.