Constituents From Brazilian Propolis Against Edwardsiella ictaluri and Flavobacterium covae, Two Bacteria Affecting Channel Catfish (Ictalurus punctatus).

Edwardsiella ictaluri and Flavobacterium covae are two bacteria species that cause diseases in farm-raised channel catfish (Ictalurus punctatus) that cause heavy economic damage to the aquaculture industry, particularly to the channel catfish farming. In search for environmentally benign antibacterial compounds active against E. ictaluri and F. covae, we investigated the constituents isolated from Brazilian red, brown and green propolis. We have also synthetically modified active constituents to see if lipophilicity plays a role in enhancing antibacterial activities. Vestitol, neovestitol and methylvestitol were found to be the active constituents with minimum inhibitory concentration (MIC) relative to drug control florfenicol (RDCF) values (MIC-RDCF) of 7.6, 7.6 and 7.9 mg/L, respectively, against F. covae. The activity against E. ictaluri was not significant.

Larvicidal Activity of Constituents from the Main Brazilian Propolis Types: Green, Red, and Brown against Aedes aegypti.

In search of environmentally benign and mammalian-friendly mosquito-mitigating compounds, we conducted an investigation into the constituents isolated from Brazilian red, brown, and green propolis. Additionally, we synthetically modified active constituents to explore the role of lipophilicity in enhancing their larvicidal activity. Honeybees collect plant resins from their habitats, mix them with saliva, and utilize them to seal their beehives. The constituents present in propolis exhibit a unique composition specific to the geographical location and the fauna of the region. As part of the plant's natural defense mechanism, propolis compounds demonstrate antibacterial, insecticidal, and phytotoxic properties. Given that several insecticides target the enzyme acetylcholinesterase, we conducted in silico studies to examine the interactions between propolis compounds and acetylcholinesterase through molecular docking. In this study, we present the mosquito larvicidal activities of propolis constituents.

Khellin and Visnagin, Furanochromones from Ammi visnaga (L.) Lam., as Potential Bioherbicides.

Plants constitute a source of novel phytotoxic compounds to be explored in searching for effective and environmentally safe herbicides. From a previous screening of plant extracts for their phytotoxicity, a dichloromethane extract of Ammi visnaga (L.) Lam. was selected for further study. Phytotoxicity-guided fractionation of this extract yielded two furanochromones, khellin and visnagin, for which herbicidal activity had not been described before. Khellin and visnagin were phytotoxic to model species lettuce (Lactuca sativa) and duckweed (Lemna paucicostata), with IC50 values ranging from 110 to 175 µM. These compounds also inhibited the growth and germination of a diverse group of weeds at 0.5 and 1 mM. These weeds included five grasses [ryegrass (Lolium multiflorum), barnyardgrass (Echinocloa crus-galli), crabgrass (Digitaria sanguinalis), foxtail (Setaria italica), and millet (Panicum sp.)] and two broadleaf species [morningglory (Ipomea sp.) and velvetleaf (Abutilon theophrasti)]. During greenhouse studies visnagin was the most active and showed significant contact postemergence herbicidal activity on velvetleaf and crabgrass at 2 kg active ingredient (ai) ha-1. Moreover, its effect at 4 kg ai ha-1 was comparable to the bioherbicide pelargonic acid at the same rate. The mode of action of khellin and visnagin was not a light-dependent process. Both compounds caused membrane destabilization, photosynthetic efficiency reduction, inhibition of cell division, and cell death. These results support the potential of visnagin and, possibly, khellin as bioherbicides or lead molecules for the development of new herbicides.