Annonaceous acetogenins: Precursors from the seeds of Annona squamosa

From the less polar fractions of an Annona squamosa (Annonaceae) seeds extract, four new annonaceous acetogenins, dieposabadelin (1), squamocenin (2), lepirenin (3) and dotistenin (4), were isolated, along with sixteen known acetogenins: corepoxylone, diepomuricanins A and B, dieporeticenine, tripoxyrollin, bullatencin, glabrencin B, reticulatains-1, -2, uvariamicins I, II, III, erythrosolamin, annotemoyin-1 and -2, and solamin. Fourteen are reported for the first time in this species.     

Genetic background determines metabolic phenotypes in the mouse

To evaluate the contribution of genetic background to phenotypic variation, we compared a large range of biochemical and metabolic parameters at different ages of four inbred mice strains, C57BL/6J, 129SvPas, C3HeB/FeJ, and Balb/cByJ. Our results demonstrate that important metabolic, hematologic, and biochemical differences exist between these different inbred strains. Most of these differences are gender independent and are maintained or accentuated throughout life. It is therefore imperative that the genetic background is carefully defined in phenotypic studies. Our results also argue that certain backgrounds are more suited to study a given physiologic phenomenon, as distinct mouse strains have a different propensity to develop particular biochemical, hematologic, and metabolic abnormalities. These genetic differences can furthermore be exploited to identify new genes/proteins that contribute to phenotypic abnormalities. The choice of the genetic background in which to generate and analyze genetically engineered mutant mice is important as it is, together with environmental factors, one of the most important contributors to the variability of phenotypic results.     

Labdane diterpenoids from Aframomum sceptrum: NMR study and antiparasitic activities

Two novel labdane diterpenoids, 15ξ-methoxy-labdan-8(17),11(E),13(14)-trien-15,16-olide (1) and 12(S)-hydroxy-15ξ-methoxy-labdan-8(17),13(14)-dien-15,16-olide (2) were isolated from the rhizomes of Aframomum sceptrum K. Schum (Zingiberaceae). Their structures were established on the basis of their spectroscopic data. Stigmast-4-en-6β-ol-3-one and caryophylene oxide were also obtained. In vitro trypanocidal and leishmanicidal activities of labdanes 1 and 2 were evaluated. Compound 2 exhibited activity similar to that of reference drugs against Leishmania donovani.     

Development of a SPE/HPLC/DAD method for the determination of antileishmanial 2-substituted quinolines and metabolites in rat plasma

A SPE/HPLC/DAD method was developed for the in vivo monitoring of three new antileishmanial 2-substituted quinolines under study in our laboratory for the development of an oral treatment. Three phase I metabolites were included in this work for the optimization of the method. Trifunctional tC(18) cartridges (resulting from the reaction of trifunctional silanes with silica surface) were selected among four sorbents tested. Two linear gradients were developed to ensure resolution of metabolites. Recovery of quinolines from rat plasma was comprised between 80.6 and 88.2%. In a drug development perspective, apparent pK(a), lipophilicity and solubility were determined, as well as the extent of plasma protein or albumin binding.     

Systems Genetics of Metabolism: The Use of the BXD Murine Reference Panel for Multiscalar Integration of Traits

Metabolic homeostasis is achieved by complex molecular and cellular networks that differ significantly among individuals and are difficult to model with genetically engineered lines of mice optimized to study single gene function. Here, we systematically acquired metabolic phenotypes by using the EUMODIC EMPReSS protocols across a large panel of isogenic but diverse strains of mice (BXD type) to study the genetic control of metabolism. We generated and analyzed 140 classical phenotypes and deposited these in an open-access web service for systems genetics (www.genenetwork.org). Heritability, influence of sex, and genetic modifiers of traits were examined singly and jointly by using quantitative-trait locus (QTL) and expression QTL-mapping methods. Traits and networks were linked to loci encompassing both known variants and novel candidate genes, including alkaline phosphatase (ALPL), here linked to hypophosphatasia. The assembled and curated phenotypes provide key resources and exemplars that can be used to dissect complex metabolic traits and disorders.     

Annonacin, a lipophilic inhibitor of mitochondrial complex I, induces nigral and striatal neurodegeneration in rats: possible relevance for atypical parkinsonism in Guadeloupe

In Guadeloupe, epidemiological data have linked atypical parkinsonism with fruit and herbal teas from plants of the Annonaceae family, particularly Annona muricata. These plants contain a class of powerful, lipophilic complex I inhibitors, the annonaceous acetogenins. To determine the neurotoxic potential of these substances, we administered annonacin, the major acetogenin of A. muricata, to rats intravenously with Azlet osmotic minipumps (3.8 and 7.6 mg per kg per day for 28 days). Annonacin inhibited complex I in brain homogenates in a concentration-dependent manner, and, when administered systemically, entered the brain parenchyma, where it was detected by matrix-associated laser desorption ionization-time of flight mass spectrometry, and decreased brain ATP levels by 44%. In the absence of evident systemic toxicity, we observed neuropathological abnormalities in the basal ganglia and brainstem nuclei. Stereological cell counts showed significant loss of dopaminergic neurones in the substantia nigra (-31.7%), and cholinergic (-37.9%) and dopamine and cyclic AMP-regulated phosphoprotein (DARPP-32)-immunoreactive GABAergic neurones (-39.3%) in the striatum, accompanied by a significant increase in the number of astrocytes (35.4%) and microglial cells (73.4%). The distribution of the lesions was similar to that in patients with atypical parkinsonism. These data are compatible with the theory that annonaceous acetogenins, such as annonacin, might be implicated in the aetiology of Guadeloupean parkinsonism and support the hypothesis that some forms of parkinsonism might be induced by environmental toxins.     

Chronic systemic complex I inhibition induces a hypokinetic multisystem degeneration in rats

In Parkinson's disease, nigral dopaminergic neurones degenerate, whereas post-synaptic striatal target neurones are spared. In some atypical parkinsonian syndromes, both nigral and striatal neurones degenerate. Reduced activity of complex I of the mitochondrial respiratory chain has been implicated in both conditions, but it remains unclear if this affects the whole organism or only the degenerating brain structures. We therefore investigated the differential vulnerability of various brain structures to generalized complex I inhibition. Male Lewis rats infused with rotenone, a lipophilic complex I inhibitor [2.5 mg/kg/day intraveneously (i.v.) for 28 days], were compared with vehicle-infused controls. They showed reduced locomotor activity and loss of striatal dopaminergic fibres (54%), nigral dopaminergic neurones (28.5%), striatal serotoninergic fibres (34%), striatal DARPP-32-positive projection neurones (26.5%), striatal cholinergic interneurones (22.1%), cholinergic neurones in the pedunculopontine tegmental nucleus (23.7%) and noradrenergic neurones in the locus ceruleus (26.4%). Silver impregnation revealed pronounced degeneration in basal ganglia and brain stem nuclei, whereas the hippocampus, cerebellum and cerebral cortex were less affected. These data suggest that a generalized mitochondrial failure may be implicated in atypical parkinsonian syndromes but do not support the hypothesis that a generalized complex I inhibition results in the rather selective nigral lesion observed in Parkinson's disease.