Comparative effects of lantadene A and its reduced metabolite on mitochondrial bioenergetics

Lantana (Lantana camara Linn.) is a noxious weed to which certain medicinal properties have been attributed, but its ingestion has been reported to be highly toxic to animals and humans, especially in the liver. The main hepatotoxin in lantana leaves is believed to be the pentacyclic triterpenoid lantadene A (LA), but the precise mechanism by which it induces hepatotoxicity has not yet been established. This work addressed the action of LA and its reduced derivative (RLA) on mitochondrial bioenergetics. At the concentration range tested (5-25 mu M), RLA stimulated state-4 respiration, inhibited state-3 respiration, circumvented oligomycin-inhibited state-3 respiration, dissipated membrane potential and depleted ATP in a concentration-dependent manner. However. LA did not stimulate state-4 respiration, nor did it affect the other mitochondrial parameters to the extent of its reduced derivative. The lantadenes didn`t inhibit the CCCP-uncoupled respiration but increased the ATPase activity of intact coupled mitochondria. The ATPase activity of intact uncoupled or disrupted mitochondria was not affected by the compounds. We propose, therefore, that RLA acts as a mitochondrial uncoupler of oxidative phosphorylation, a property that arises from the biotransformation (reduction) of LA, and LA acts in other mitochondrial membrane components rather than the ATP synthase affecting the mitochondrial bioenergetics. Such effects may account for the well-documented hepatoxicity of lantana. (C) 2010 Elsevier Ltd. All rights reserved.

Comparative effects of lantadene A and its reduced metabolite on mitochondrial bioenergetics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeitos de lantadenos sobre a bioenergética em mitocôndrias isoladas de fígado de rato

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of fipronil on energy metabolism in the perfused rat liver

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Pyrrolizidine alkaloids in Senecio madagascariensis from Australia and Hawaii and assessment of possible livestock poisoning

The alkaloid content of Senecio madagascariensis collected from Australia and Hawaii was examined. Alkaloids were identified from the above ground whole plant (stems, leaves and flowers) by GUMS analysis and included: senecivernine, senecionine, integerrimine, senkirkine, mucronatinine, retrosine, usaramine, otosenine, acetylsenkirkine, desacetyldoronine, florosenine and doronine. Plant material collected from the Hawaiian Islands was found to be identical in pyrrolizidine alkaloid content to that from a single composite collection made from northern New South Wales, Australia. Overall, no appreciable differences in alkaloid content were found between locations, whereas variation among individual plants was evident. The average total pyrrolizidine alkaloid content varied from a low of 217 mu g/g to a high of 1990 mu g/g (dry weight basis) among the locations. Based on comparable alkaloid content and documented pyrrolizidine alkaloidosis cases from Australia, S. madagascariensis may pose a significant risk to livestock grazing heavily infested ranges on the Hawaiian Islands. (c) 2006 Elsevier Ltd. All rights reserved.

Nutritional and biochemical profiling of Leucopaxillus candidus (Bres.) singer wild mushroom

The wild mushroom Leucopaxillus candidus (Bres.) Singer was studied for the first time to obtain information about its chemical composition, nutritional value and bioactivity. Free sugars, fatty acids, tocopherols, organic and phenolic acids were analysed by chromatographic techniques coupled to different detectors. L. candidus methanolic extract was tested regarding antioxidant potential (reducing power, radical scavenging activity and lipid peroxidation inhibition). L. candidus was shown to be an interesting species in terms of nutritional value, with high content in proteins and carbohydrates, but low fat levels, with the prevalence of polyunsaturated fatty acids. Mannitol was the most abundant free sugar and β-tocopherol was the main tocopherol isoform. Other compounds detected were oxalic and fumaric acids, p-hydroxybenzoic and cinnamic acids. The methanolic extract revealed antioxidant activity and did not show hepatoxicity in porcine liver primary cells. The present study provides new information about L. candidus.