Isoprenoids are a class of secondary metabolites that are widely distributed in Nature. This thesis describes the synthesis and feeding of isotopically labelled enriched substrates to elucidate features of a new mevalonate independent pathway to isoprenoids. Chapter 2 describes studies with a whole plant system, Mentha citrata, which produces the monoterpene linalyl acetate, and a bacterium Escherichia coli which produces ubiquinone-8. Feeding experiments with stable isotopically enriched compounds demonstrate that the terpene unit of linalyl acetate is biosynthesised via the mevalonate independent pathway, hicorporation of deuterium from [6,6-(^2)H(_2)]-glucose, [(^2)H(_3)]-alanine and [(^13)C(^2)H(_3)]-alanine into luialyl acetate show that the conversion to isopentenyl pyrophosphate does not proceed via a series of dehydrations. Feeding experiments with putative intermediates bearing deuterium into E. coli show that none of the intermediates are incorporated. This suggests that E. coli lacks a kinase to activate exogenously administered substrates fed as the free alcohols. Chapter 3 outlines biosynthesis studies on a meroterpene rosnecatone produced by the fungus R. necatrix. Intact incorporation of (^13)C from the feeding of [l,2-(^13)C(_2)]-acetate shows that the terpenoid moiety is produced via the mevalonic acid pathway and the non-terpenoid unit is polyketide derived. Incorporation of deuterium from [6,6-(^2)H(_2)]-glucose fully describes the pentaketide that delivers the non-terpenoid fragment. The effect on the metabolite production of changing the growth conditions of R. necatrix is investigated. Changing from a static culture to a submerged cultures causes an increased rate of growth, an upregulation of the production of cytochalasan E and a cessation of rosnecatone production. Screening of rosnecatone against two Human cancer cell lines shows IC(_50) values of 4.48µM and 5.78µM.

Synthèse d’inhibiteurs potentiels non phosphorylés de la désoxyxylulose phosphate réductoisomérase et étude de la voie de biosynthèse des unités isopréniques chez Acanthamoeba polyphaga. De nombreux microorganismes pathogènes utilisent la voie du méthylérythritol phosphate (MEP) pour la synthèse des unités isopréniques (IPP et DMAPP). Absente chez l’homme, cette voie constitue une cible de choix pour lutter contre ces microorganismes. La fosmidomycine est un des meilleurs inhibiteurs connus à ce jour de la désoxyxylulose phosphate réductoisomérase (DXR), deuxième enzyme de cette voie. Afin d’améliorer d’une part la biodisponibilité de ce type d’inhibiteur et d’autre part de lutter contre le phénomène de résistance à cet antibiotique, nous avons synthétisé des analogues de la fosmidomycine où le groupement phosphonate est remplacé par un groupement tétrazole ou par un groupement squaryle. Les molécules synthétisées ont été testées sur la DXR d’ Escherichia coli et n’ont pas révélé d’activité inhibitrice significative.Par ailleurs, nous avons montré, par des expériences d’incorporation de glucose marqué au 13C, que l’amibe Acanthamoeba polyphaga, utilise la voie du mévalonate pour synthétiser les unités isopréniques nécessaires à la synthèse de ses stérols / Synthesis of potential non-phosphonate inhibitors of the deoxyxylulose phosphate reductoisomerase and study of the biosynthetic pathway for isoprenoids units synthesis using by Acanthamoeba polyphagaMany pathogenic microorganisms synthesize their isoprenoid units (IPP and DMAPP) via the methylerythritol phosphate pathway (MEP pathway). Absent in man, all enzymes of this metabolic route are potential targets for the design of new antimicrobials. This pathway is present in pathogenic bacteria, but absent in mammals. Hence, the development of small-molecule inhibitors for the MEP enzymes constitutes a novel approach for the design of new antimicrobials. Fosmidomycin is the most efficient inhibitor of the the deoxyxylulose phosphate reductoisomerase (DXR), the second enzyme of the MEP pathway. In an attempt to improve the pharmacological properties and the bioavailability of this antibiotic, we synthesized analogues of the fosmidomycin by replacing the phosphonate group by tetrazole or squaryl moieties. These synthesized compounds were tested on the DXR isolated from Escherichia coli.Otherwise, we showed by achieving incorporation experiments with 13C labeled glucose that the amoeba Acanthamoeba polyphaga utilize the mevalonate pathway to synthesize its sterols.

Products of the isoprenoid biosynthetic pathway are involved in diverse biological functions. For example, the isoprenoid diphosphate, farnesyl diphosphate (FPP), is used for synthesis of squalene, a precursor of cholesterol. In addition, FPP and geranylgeranyl diphosphate (GGPP) are used for protein prenylation, which is a post-translational modification of certain proteins required for their proper membrane localization and function. Enzymes within the isoprenoid biosynthetic pathway have been inhibited successfully by drugs that are now used clinically, including statins and nitrogenous bisphosphonates (NBPs). Statins and NBPs are inhibitors of isoprenoid biosynthetic enzymes, due to their structural resemblance to substrates within the pathway. The bisphosphonate core resembles the diphosphate portion of isoprenoid diphosphate intermediates within the isoprenoid biosynthetic pathway. It is hypothesized that distinct isoprenoid biosynthetic enzymes can be inhibited by bisphosphonates in a manner dependent upon the overall bisphosphonate structure. Along with our collaborators, we have developed novel bisphosphonate inhibitors of multiple isoprenoid biosynthetic enzymes. Potent in vitro inhibitors of squalene synthase (SQS) were identified and evaluated in HepG2 liver cells. A lead inhibitor of squalene synthase was combined with a statin and a nitrogenous bisphosphonate, and focus was placed on these combinations as potential novel mechanisms to reduce cholesterol synthesis while minimizing impairment of non-sterol synthesis. Specifically, it was found that the lead SQS inhibitor prevents lovastatin-mediated impairment of protein farnesylation but not geranylgeranylation. Also, the lead SQS inhibitor prevented both zoledronate-induced impairment of protein farnesylation and geranylgeranylation. Novel bisphosphonates were also identified as inhibitors of geranylgeranyl diphosphate synthase (GGDPS) and protein prenylation in K562 leukemia cells. A novel cellular consequence of GGPP depletion was also established. In PC3 cells, zoledronate and digeranyl bisphosphonate (DGBP; a lead inhibitor of GGDPS) were determined to induce autophagy as measured by accumulation of the autophagic marker LC3-II. GGPP depletion was implicated as the cause of autophagic induction in this system. Specifically, results suggest that impairment of proteins geranylgeranylated by geranylgeranyl transferase II is responsible for the induction of autophagy. Mycobacterium isoprenoid biosynthetic enzymes were also evaluated as inhibitory targets for bisphosphonates. Novel inhibitors of Mycobacteria tuberculosis omega-E,Z-FPP synthase and decaprenyl diphosphate synthase were identified. A lead inhibitor of decaprenyl diphosphate synthase was also evaluated in Mycobacterium smegmatis, which was utilized as a surrogate model. The lead inhibitor was found to have no effect on M. smegmatis growth; however it enhanced growth inhibition mediated by ethambutol. This effect was prevented by addition of exogenous decaprenyl diphosphate, suggesting that the growth inhibition was due to decaprenyl diphosphate depletion. Decaprenyl diphosphate was also found to prevent the growth inhibitory effect of SQ109, a novel anti-mycobacterial drug in clinical development with an unknown mechanism of action.

Statins, drugs commonly used to lower serum cholesterol, have been shown to stimulate osteoblast differentiation and bone formation. By inhibiting HMG-CoA reductase (HMGCR) statins deplete the cellular isoprenoid biosynthetic pathway products farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP). Current thought in the field is that statins stimulate bone formation through the depletion of GGPP, since exogenous GGPP prevents the effects of statins on osteoblasts in vitro. We hypothesized that direct inhibition of GGPP synthase (GGPPS) would similarly stimulate osteoblast differentiation. Digeranyl bisphosphonate (DGBP), a specific inhibitor of GGPPS, decreased GGPP levels in MC3T3-E1 pre-osteoblasts and calvarial osteoblasts leading to impaired protein geranylgeranylation. In contrast to our hypothesis, DGBP inhibited the matrix mineralization of MC3T3-E1 cells and the expression of osteoblast differentiation markers in calvarial osteoblasts. The effect on mineralization was not prevented by exogenous GGPP. By inhibiting GGPPS, DGBP led to an accumulation of the GGPPS substrate FPP. We show that FPP and GGPP levels decreased during MC3T3-E1 and calvarial osteoblast differentiation, which correlated with decreased expression of HMGCR and FPP synthase. The decrease in FPP during differentiation was prevented by DGBP treatment. The accumulation of FPP following 24 h DGBP treatment correlated with activation of the glucocorticoid receptor, suggesting a potential mechanism by which DGBP-induced FPP accumulation may inhibit osteoblast differentiation. To further investigate whether FPP inhibits osteoblast differentiation, we utilized the squalene synthase (SQS) inhibitor zaragozic acid (ZGA), which causes a greater accumulation of FPP than can be achieved with GGPPS inhibition. ZGA treatment decreased osteoblast proliferation, gene expression, alkaline phosphatase (ALP) activity, and matrix mineralization of calvarial osteoblasts. Prevention of ZGA-induced FPP accumulation with HMGCR inhibition prevented the effects of ZGA on osteoblast differentiation. Treatment of osteoblasts with exogenous FPP similarly inhibited matrix mineralization. These results suggest that the accumulation of FPP negatively regulates osteoblast differentiation. While we did not find that specific depletion of GGPP stimulates osteoblast differentiation, we obtained evidence that GGPP does negatively regulate the differentiation of these cells. Exogenous GGPP treatment inhibited primary calvarial osteoblast gene expression and matrix mineralization. Interestingly, GGPP pre-treatment increased markers of insulin signaling, despite reduced phosphorylation of the insulin receptor (InsR). Inhibition of osteoblast differentiation by GGPP led to the induction of PPARã and enhanced adipogenesis in osteoblastic cultures, suggesting that GGPP may play a role in the osteoblast versus adipocyte fate decision. Adipogenic differentiation of primary bone marrow stromal cell (BMSC) cultures was prevented by DGBP treatment. Altogether these data present novel roles for the isoprenoids FPP and GGPP in the regulation of osteoblast differentiation and have intriguing implications for the isoprenoid biosynthetic pathway in the regulation of skeletal homeostasis.

Parkinson???s disease (PD) is a progressive neurodegenerative disease characterised pathologically by the selective death of the dopaminergic neurons of the substantia nigra and the appearance of abnormal inclusions in some surviving neurons. A body of evidence from epidemiological, in vitro and in vivo studies suggest that isoprenoids, a lipid family which includes cholesterol, dolichol and ubiquinone, may play a role in PD, although to date the data has been conflicting with little consensus regarding the type or direction of change in isoprenoids in PD. The current study investigated isoprenoids in PD by quantifying a range of isoprenoids in blood sera, brain homogenates and olfactory mucosa derived from PD patients and controls. Further, isoprenoid synthesis pathways were investigated by comparing the activitites and amount of the rate-limiting enzyme for isoprenoid synthesis, HMG CoA reductase, in olfactory mucosal cultures from individuals with sporadic PD and leucine-rich repeat kinase 2 (LRRK2)-PD with those from healthy individuals. Serum levels of total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides and dolichol were unchanged in patients with PD compared with controls. Similarly, total tissue cholesterol was unchanged in degenerating and non-degenerating regions of the PD brain, but tissue dolichol was significantly decreased in the substantia nigra in the PD brain, possibly reflecting a change in the neuron/glia ratio in this brain region. In olfactory mucosa, a significant decrease in cellular cholesterol content was identified in patients with LRRK2-PD compared with patients with sporadic PD or controls. The reduction in cholesterol was similar in two different LRRK2 mutations but was not associated with a change in either the amount or activity of HMG CoA reductase. This study suggests that decreased cholesterol is associated with LRRK2-PD but not with sporadic PD. As cholesterol levels in cells with different LRRK2 mutations were reduced to a similar extent, it is suggested that mutations in this gene result in a loss-of-function of LRRK2 protein. Further it suggests a role for LRRK2 in cholesterol homeostasis independent of HMG-CoA reductase-associated pathways. Recent data has suggested a functional role of LRRK2 in autophagy, a mechanism which may explain the reduction in cholesterol observed in LRRK2-PD.

No presente estudo avaliou-se a atividade quimiopreventiva do farnesol (FR) e geraniol (GR), isoprenóides presentes em frutas e ervas, quando administrados a ratos Wistar durante as etapas de iniciação e/ou seleção/promoção do modelo de hepatocarcinogênese do \"hepatócito resistente\" (RH). No Protocolo Experimental 1, os animais receberam durante 8 semanas consecutivas, continuamente durante as etapas de iniciação e seleção/promoção, por entubação gástrica e dissolvido em óleo de milho (OM): FR (25 mg/100 g de peso corpóreo [p.c.]; grupo FR) ou GR (25 mg/100 g de p.c.; grupo GR). Além disso, 1 grupo recebeu durante o mesmo período, por entubação gástrica, apenas OM (0,25 mL/100 g de p.c.; grupo OM; controle). Duas semanas após o início dos tratamentos, todos os grupos foram submetidos ao modelo do RH. Esse consistiu na aplicação intraperitoneal de uma dose do agente iniciante dietilnitrosamina (DEN, 20 mg/100 g de p.c.), seguida, 2 semanas após, da aplicação de 4 doses consecutivas de 2-acetilaminofluoreno (2-AAF; 2,5 mg/100 g de p.c.) e de uma hepatectomia parcial (HP) a 70%, acrescida de 2 doses de 2-AAF (2 mg/100 g de p.c.) 2 e 4 dias após a cirurgia. Decorridas 6 semanas após a iniciação com DEN, os animais foram sacrificados administrando-se, entretanto, 2 h. antes desse procedimento 5-bromo-2-desoxiuridina (BrdU) (10 mg/100 g de p.c.). De acordo com a análise macroscópica dos fígados, e em comparação ao grupo OM, verificou-se que o FR inibiu a incidência (p<0,05) e número médio (p<0,05) de lesões pré-neoplásicas (LPN) hepáticas visíveis à macroscopia. No caso do grupo GR, observou-se apenas sugestão de redução da incidência e número médio dessas LPN visíveis à macroscopia. Em relação à análise morfométrica das LPN hepáticas positivas para a enzima glutationa S-transferase forma placentária (GST-P) totais (persistentes + em remodelação), observou-se que em comparação ao grupo OM, o FR reduziu o tamanho (p<0,05) e área do corte ocupada (p<0,05) por essas lesões. O GR, por sua vez, reduziu o tamanho (p<0,05) das LPN GST-P positivas totais, observando-se, também, sugestão de redução pelo isoprenóide da área do corte ocupada pelas mesmas. Em comparação ao grupo OM, o FR e o GR foram capazes de inibir (p<0,05) a proliferação celular nas LPN, enquanto apenas o GR induziu (p<0,05) a apoptose nas mesmas. Além disso, danos no DNA hepático foram menores (p<0,05) nos animais tratados com FR ou GR, em comparação aos tratados com OM (controles). O tratamento com FR, mas não com GR, resultou em inibição (p<0,05) das concentrações plasmáticas de colesterol total. A análise, por \"western blot\", da expressão hepática do receptor nuclear ativado pelo farnesóide X (FXR) não revelou diferenças (p>0,05) entre os diferentes grupos. No Protocolo Experimental 2, os ratos receberam apenas durante 2 semanas consecutivas na fase de iniciação, e por entubação gástrica, FR (25 mg/100 g p.c.; grupo FRi), GR (25 mg/100 g p.c.; grupo GRi) ou OM (0,25 mL/00 g p.c.; grupo OMi, controle), sendo então submetidos ao modelo do RH, conforme descrito para o Protocolo Experimental 1. O sacrifício dos animais ocorreu 6 semanas após iniciação com DEN. De acordo com a análise macroscópica dos fígados, não foram constatadas diferenças entre os diferentes grupos (p>0,05) quanto à incidência de LPN hepáticas visíveis à macroscopia. Em comparação ao grupo OMi (controle), observou-se nos grupos FRi e GRi sugestão de maior número de LPN hepáticas visíveis à macroscopia. Também em comparação ao grupo OMi (controle), observou-se no grupo GRi menor (p<0,05) número de LPN hepáticas GST-P positivas totais (persistentes + em remodelação), e no grupo FRi sugestão de menor número dessas LPN GST-P positivas totais. Além disso, foram observadas nos grupos FRi e GRi, em comparação ao grupo OMi, LPN hepáticas GST-P positivas totais (persistentes + em remodelação) maiores (p<0,05), bem como sugestão de maior área do corte ocupada por essas LPN GST-P positivas. Não foram observadas diferenças (p>0,05) entre os diferentes grupos quanto à concentração hepática de DNA. No Protocolo Experimental 3, os ratos receberam inicialmente uma dose de DEN (20 mg/100 g de p.c.). Duas semanas após, os animais passaram a receber por entubação gástrica, durante 6 semanas consecutivas em período compreendendo a etapa de seleção/promoção: FR (25 mg/100 g p.c.; grupo FRs/p), GR (25 mg/100 g p.c.; grupo GRs/p) ou OM (0,25 mL/100 g p.c.; grupo Oms/p; controle). Nesse experimento, as administrações de 2-AAF e a realização da HP ocorreram 4 semanas após a iniciação com DEN. O sacrifício dos animais ocorreu após 8 semanas da iniciação com DEN. Em comparação ao grupo OMs/p (controle), observou-se nos grupos FRs/p e GRs/p sugestão de menor número médio de LPN hepáticas visíveis à macroscopia. Não foram constatadas diferenças (p>O,05) entre os diferentes grupos quanto à incidência de LPN hepáticas visíveis à macroscopia; quanto ao número, tamanho e área do corte ocupada por LPN hepáticas GST-P positivas totais (persistentes + em remodelação); e quanto à concentração hepática de DNA. De acordo com os resultados do estudo, considerou-se pronunciada a atividade quimiopreventiva do FR quando administrado a ratos Wistar continuamente durante as etapas de iniciação e seleção/promoção do modelo de hepatocarcinogênese do RH (Protocolo Experimenta! 1). Nessas mesmas condições, considerou-se moderada a atividade quimiopreventiva do GR. Inibições da proliferação celular e de danos no DNA parecem estar envolvidas com as ações anticarcinogênicas do FR e GR, enquanto que a indução da apoptose parece ser mecanismo de ação específico do GR. Além disso, as ações protetoras do FR e GR não parecem envolver alterações na expressão do receptor nuclear FXR. Finalmente, quando administrados especificamente durante a etapa de iniciação (Protocolo Experimental 2) ou de seleção/promoção (Protocolo Experimental 3), ambos os isoprenóides não foram capazes de apresentar atividades quimiopreventivas efetivas. Dessa forma, em ratos Wistar submetidos ao modelo do RH, é necessária a administração contínua de FR ou GR durante as etapas de iniciação e seleção/promoção para a ocorrência de atividades quimiopreventivas. / In the present study, the chemopreventive activity of farnesol (FR) and geraniol (GR), isoprenoids present in fruits and herbs, was evaluated when administered to Wistar rats during the initiation and/or selection/promotion phases of the \"resistant hepatocyte\" (RH) model of hepatocarcinogenesis. In Experimental Protocol 1, animals received during 8 consecutive weeks, continuously during the initiation and selection/promotion phases, by gavage and dissolved in corn oil (CO): FR (25 mg/100g9 body weight [b.w.]; FR group) or GR (25 mg/100 g de b.w.; GR group). Moreover, 1 group received during the same period, by gavage, only CO (0,25 mL/100 g de b.w.; CO group; controls). Two weeks after the beginning of the treatments, all groups were submitted to the RH model. Initiation was obtained by administration of a single intraperitoneal dose of diethylnitrosamine (DEN; 20 mg/100 g b.w.) followed, 2 weeks after, by the administration of 4 consecutive doses of 2-acetylaminofluorene (2-AAF; .2.5 mg/100 b.w.) and by a partial (70%) hepatectomy (PH). Finally, 2 and 4 days after PH, 2 additional 2-AAF doses (2 mg/100 g b.w.) were administered. Six weeks after initiation with DEN, the animals were anesthetized and sacrificed by exsanguination. Two hours before sacrifice, the rats received 5-bromo-2\'-deoxyuridine (10 mg/100 g b.w.). According to the macroscopic examination of the livers, and compared to CO group, FR inhibited the incidence (P<0.05) and mean number (P<0.05) of visible hepatic preneoplastic lesions (PNL). Regarding GR group, only a suggestion of inhibition of visible PNL incidence and mean number was observed. Morphometrical analysis of total (persitent and remodeling) glutathione S-transferase (GST-P) positive PNL showed that compared to CO group, FR group presented with smaller total GST-P positive PNL (p<0.05) that occupied a smaller area of the liver section (p<0.05). Also compared to CO group, GR group presented with smaller total GST-P positive PNL (p<0.05) and a suggestion of reduction of the liver section area occupied by these LPN was observed. Compared to CO group, FR and GR inhibited (p<0.05) PNL cell proliferation, whereas only GR induced (p<0.05) apoptosis in these PNL. Furthermore, hepatic DNA damage was lower (p<0.05) in FR or GR treated animals, compared to CO treated ones (controls). Animal treatment with FR, but not with GR, inhibited (p<0,05) total plasma cholesterol levels. Farnesoid X activated receptor (FXR) expression analysis by western blot did not reveal differences (p>0,05) between the different groups. In the Experimental Protocol 2, rats received only for 2 consecutive weeks during the initiation phase, and by gavage: FR (25 mg/100 g body weight b.w.; FRi group), GR (25 mg/100 g de b.w.; GRi group) or CO (0,25 mL/100 g de b.w.; COi group; controls) being submitted to the RH model as described for Experimental Protocol 1. Six weeks after initiation with DEN, the animals were sacrificed. According to the macroscopic examination of the livers, no differences (p>0.05) were observed among the different groups regarding the incidence of visible PNL. In FRi and GRi groups a suggestion of higher number of visible PNL was observed, when compared to COi group (controls). Also compared to COi group, GRi group presented with smaller (p<0.05) number of total (persistente + remodeling) GST-P positive PNL, whereas in FRi group a suggestion of smaller number of these visible PNL was observed. Moreover, compared to COi group, FRi and GRi groups presented with total (persistent + remodelling) GST-P positive PNL with greater (p<0,05) size, and a suggestion of greater area of the liver section occupied by these GST -P positive PNL was observed. No differences (p>0.05) among the different groups were observed regarding hepatic DNA concentration. In Experimental Protocol 3, rats were first initiated with DEN (20 mg/100 g de b.w.). After 2 weeks, animals received by gavage for 6 consecutive weeks during the selection/promotion phase: FR (25 mg/100 g body weight b.w.; FRs/p group), GR (25 mg/100 g de b.w.; GRs/p group) or CO (0,25 Ml/100 g de b.w.; COs/p group; controls). In this experiment animals received 2-AAF doses and were submitted to PH 4 weeks after initiation with DEN. Six weeks after initiation with DEN, the animals were sacrificed. Compared to COs/p group (controls), a suggestion of smaller visible PNL mean number was observed in FRs/p e GRs/p groups. No differences (p>0.05) among the different groups were observed regarding visible PNL incidence; regarding number, size and liver section occupied by total (persistent + remodeling) GST-P positive PNL; and regarding hepatic DNA concentration. According to the results of the study, FR chemopreventive activity was considered pronounced when administered to Wistar rats continuously during the initiation and selection/promotion phases of the RH model of hepatocarcinogenesis (Experimental Protocol 1). In these same conditions, GR chemopreventive activity was considered moderate. Cell proliferation and DNA damage inhibition seem to be involved with FR and GR anticarcinogenic actions, whereas apoptosis induction seems to represent a GR specific mechanism. Furthermore, FR and GR protective actions do not seem to involve alterations in FXR expression. Finally, when administered specifically during the initiation (Experimental Protocol 2) or selection/promotion (Experimental Protocol 3) phase, both isoprenoids did not present effective chemopreventive activity. Thus, in Wistar rats submitted to the RH model, FR or GR should be administered continuously during the initiation and selection/promotion phases in order to obtain chemopreventive activities.

A malária é uma das principais e a mais disseminada das parasitoses humanas. A falta de uma vacina eficaz e o problema da resistência aos fármacos tem contribuído para o adiamento da solução do controle desta infecção. A busca de novos alvos biológicos tem se concentrado, em parte, na compreensão de vias metabólicas. Em P. falciparum, identificamos a biossíntese das duas formas da vitamina K (filoquinona e menaquinona). Na via MEP foram caracterizadas duas importantes enzimas bifuncionais, a farnesil difosfato sintase/geranilgeranil difosfato sintase (FPPS/GGPPS) capaz de formar farnesil difosfato e geranilgeranil difosfato e octaprenil pirofosfato sintase/fitoeno sintase (OPP/PSY) responsável pela biossíntese da cadeia isoprênica que se liga ao anel da via de ubiquinona, como também forma o primeiro caroteno na via de carotenóides. Este projeto tem como objetivo caracterizar o gene MenA da biossíntese de MQ, determinar a localização de FPPS/GGPPS em P. falciparum e investigar a importância de OPP/PSY e de FPPS/GGPPS no ciclo intraeritrocítico de P. falciparum. / Malaria is one of the main widespread human parasites. The lack of an effective vaccine and the problem of drug resistance haves contributed to the delay of the control solution of this infection. The search for new biological targets has focused in part on the understanding of metabolic pathways. In P. falciparum, identified the biosynthesis of the two forms of vitamin K (phylloquinone and menaquinone). In the MEP pathway were characterized two important bifunctional enzyme, farnesyl diphosphate synthase/geranylgeranyl diphosphate synthase (FPPS/GGPPS) able to form farnesyl diphosphate and geranylgeranyl diphosphate and octaprenyl pyrophosphate synthase/phytoene synthase (OPP/PSY) responsible for the biosynthesis of isoprenic side chains attached to the benzoquinone ring of ubiquinones, but also forms the first carotene in the carotenoid pathway. This project aims to characterize the MenA gene from the MQ biosynthesis, determine the localization of FPPS/GGPPS and investigate the importance of OPP/PSY and FPPS/GGPPS in intra-erythrocytic cycle of P. falciparum.

O desenvolvimento de antimaláricos é necessario pois, há linhagens de Plasmodium resistentes às drogas em uso e um alvo importante é a via de isoprenoides. Importantes alvos derivados desta via são: heme O já que, há antimaláricos relacionados ao heme; e a giberilina pois, há inibidores desta que não são prejudiciais ao homem. Inabenfide (INA) e uniconazol-P (UNP) inibem a biossíntese de giberilina em plantas e o crescimento de P. falciparum. Inicialmente, identificamos no parasita genes homólogos para a síntese de heme O e A, cox10 e 15, que codificam as enzimas HOS e HAS. Parasitas transgênicos com HOS e HAS marcados com GFP permitiram identificar a localização de cox10 no núcleo e de cox15 na mitocôndria. Identificamos heme O por marcações metabólicas e espectrometria de massa. Entretanto, não identificamos heme A e giberelina. INA e UNP diminuem a biossíntese de heme O e a parasitemia, observado por oxido-redução e marcação metabólica, o que torna a sintese de heme O um interessante alvo para antimaláricos. / The development of antimalarials is necessary because there are Plasmodium strains resistant to the drugs in use and an important target is the isoprenoid pathway. Targets derived from the isoprenoid pathway are: heme O as there are antimalarial drugs related to heme; And gibberillin, because there are inhibitors which are not harmful to man. Inabenfide (INA) and uniconazole-P (UNP) inhibit biosynthesis of gibberillin in plants and of growth the P. falciparum. Initially, we identified in P. falciparum genes homologous to cox10 and 15 encoding the enzymes (HOS and HAS) for synthesis of heme O and A. We created transgenic parasite lines which had HOS and HAS tagged to GFP. These revealed that the subcellular location of cox10 is in the nucleus and of cox15 in mitochondria. We identified heme O by metabolic labeling and mass spectrometry. However, no heme A or gibberellin was detected. INA and UNP decreased heme O biosynthesis and parasitemia as observed by oxido-reduction and metabolic labeling. Our data point to heme O as an important target for antimalarials.

A malária é uma das principais e a mais disseminada das parasitoses humanas. A falta de uma vacina eficaz e o problema da resistência aos fármacos tem contribuído para o adiamento da solução do controle desta infecção. A busca de novos alvos biológicos tem se concentrado, em parte, na compreensão de vias metabólicas. Em P. falciparum, identificamos a biossíntese das duas formas da vitamina K (filoquinona e menaquinona). Na via MEP foram caracterizadas duas importantes enzimas bifuncionais, a farnesil difosfato sintase/geranilgeranil difosfato sintase (FPPS/GGPPS) capaz de formar farnesil difosfato e geranilgeranil difosfato e octaprenil pirofosfato sintase/fitoeno sintase (OPP/PSY) responsável pela biossíntese da cadeia isoprênica que se liga ao anel da via de ubiquinona, como também forma o primeiro caroteno na via de carotenóides. Este projeto tem como objetivo caracterizar o gene MenA da biossíntese de MQ, determinar a localização de FPPS/GGPPS em P. falciparum e investigar a importância de OPP/PSY e de FPPS/GGPPS no ciclo intraeritrocítico de P. falciparum. / Malaria is one of the main widespread human parasites. The lack of an effective vaccine and the problem of drug resistance haves contributed to the delay of the control solution of this infection. The search for new biological targets has focused in part on the understanding of metabolic pathways. In P. falciparum, identified the biosynthesis of the two forms of vitamin K (phylloquinone and menaquinone). In the MEP pathway were characterized two important bifunctional enzyme, farnesyl diphosphate synthase/geranylgeranyl diphosphate synthase (FPPS/GGPPS) able to form farnesyl diphosphate and geranylgeranyl diphosphate and octaprenyl pyrophosphate synthase/phytoene synthase (OPP/PSY) responsible for the biosynthesis of isoprenic side chains attached to the benzoquinone ring of ubiquinones, but also forms the first carotene in the carotenoid pathway. This project aims to characterize the MenA gene from the MQ biosynthesis, determine the localization of FPPS/GGPPS and investigate the importance of OPP/PSY and FPPS/GGPPS in intra-erythrocytic cycle of P. falciparum.

Lavenders (Lavandula) are widely grown for their essential oils, which have extensive applications in cosmetics, hygiene products and alternative medicine. The therapeutic and olfactory properties of lavender essential oils are attributed to monoterpenes, a class of low molecular weight (C₁₀) isoprenoids. Oil composition in these plants is primarily determined by plant genotype, but can also be influenced by developmental and environmental factors. In order to define some of the mechanisms that control monoterpene abundance in lavenders, I measured the abundance of quality-defining monoterpenes in several L. angustifolia and L. x intermedia cultivars grown in the Okanagan. Data obtained confirmed that essential oil yield, as well as the abundance of camphor, borneol, linalool, and limonene was species-specific. L. angustifolia cultivars contained high amounts of linalool but yielded little oil, whereas L. x intermedia cultivars were rich in camphor and total oil. Monoterpene abundance changed during flower development, and differed between vegetative and reproductive tissues indicating differential regulation of the biosynthetic pathways, or specialized ecological functions. The abundance of linalool correlated with the transcription of the linalool synthase gene, suggesting that linalool production is in part regulated transcriptionally. However, the degree of correlation between linalool abundance and linalool synthase transcription differed between L. angustifolia and L. x intermedia, suggesting additional, and differing mechanisms that control linalool abundance in these species. In addition, monoterpene abundances were subject to loss during storage and suboptimal detection, two factors that must be considered in future analyses. Results obtained in this study provide insight into the regulation of monoterpene production in lavenders, and build the basis for future research aimed at improving essential oil production in these plants.