Jarkko Rautio - Academia.edu (original) (raw)

Papers by Jarkko Rautio

Research paper thumbnail of Development of Sesamol Carbamate-L-Phenylalanine Prodrug Targeting L-Type Amino Acid Transporter1 (LAT1) as a Potential Antiproliferative Agent against Melanoma

International Journal of Molecular Sciences

Sesamol is a compound reported to have anti-melanogenesis and anti-melanoma actions. Sesamol, how... more Sesamol is a compound reported to have anti-melanogenesis and anti-melanoma actions. Sesamol, however, has low intracellular drug concentration and fast excretion, which can limit its benefits in the clinic. To overcome this drawback and increase intracellular delivery of sesamol into the target melanoma, research has focused on L-type amino acid transporter 1 (LAT1)-mediated prodrug delivery into melanoma cells. The sesamol prodrug was designed by conjugating sesamol with L-phenylalanine at the para position with a carbamate bond. LAT1 targeting was evaluated vis-à-vis a competitive [14C]-leucine uptake inhibition. The sesamol prodrug has a higher [14C]-leucine uptake inhibition than sesamol in human LAT1-transfected HEK293 cells. Moreover, the sesamol prodrug was taken up by LAT1-mediated transport into SK-MEL-2 cells more effectively than sesamol. The sesamol prodrug underwent complete hydrolysis, releasing the active sesamol at 72 h, which significantly exerted its cytotoxicity ...

Research paper thumbnail of vitro p-glycoprotein inhibition assays for assessment of clinical drug interaction potential of new drug candidates: a recommendation for probe substrates. Drug Metab Dispos. 2006;34(5):786–792. submit your manuscript | www.dovepress.com Dovepress Dovepre

Because modulation of P-glycoprotein (Pgp) through inhibition or induction can lead to drug-drug ... more Because modulation of P-glycoprotein (Pgp) through inhibition or induction can lead to drug-drug interactions by altering intestinal, central nervous system, renal, or biliary efflux, it is anticipated that information regarding the potential interaction of drug candidates with Pgp will be a future regulatory expectation. Therefore, to be able to utilize in vitro Pgp inhibition findings to guide clinical drug interaction studies, the utility of five probe substrates (calcein-AM, colchicine, digoxin, prazosin, and vinblastine) was evaluated by inhibiting their Pgp-mediated transport across multidrug resis-tance-1-transfected Madin-Darby canine kidney cell type II mono-layers with 20 diverse drugs having various degrees of Pgp inter-action (e.g., efflux ratio, ATPase, and calcein-AM inhibition). Overall, the rank order of inhibition was generally similar with IC50 values typically within 3- to 5-fold of each other. However, several notable differences in the IC50 values were observed....

Research paper thumbnail of Potenciais Pró-Fármacos do Ácido Flufenâmico

Research paper thumbnail of Anti-bacterial activity of inorganic nanomaterials and their antimicrobial peptide conjugates against resistant and non-resistant pathogens

International Journal of Pharmaceutics, 2020

Our report represents a comprehensive review on the antibacterial activity of inorganic nanomater... more Our report represents a comprehensive review on the antibacterial activity of inorganic nanomaterials and antimicrobial peptides, and how concomitant use of the two can effectively tackle a range of bacterial infections which is a rapidly escalating issues in public health care worldwide. We believe this is of particular current interest with regard to "antimicrobial resistance" being declared one of the top-10 global health threats in 2019 by the WHO. In this group of authors, we have teamed up within the NordForsk-funded university hub Nordic POP (Patient Oriented Products), which we wish to showcase with this contribution. We are currenlty carrying out joint research supported by this network within the topic of the review, so we view this a valuable contribution also within the dissemination of Nordic POP activities.

Research paper thumbnail of Secondary carbamate linker can facilitate the sustained release of dopamine from brain-targeted prodrug

Bioorganic & Medicinal Chemistry Letters, 2018

To achieve the sustained release of dopamine in the brain for the symptomatic treatment of Parkin... more To achieve the sustained release of dopamine in the brain for the symptomatic treatment of Parkinson's disease, dopamine was conjugated to L-tyrosine, an L-type amino acid transporter 1 (LAT1)-targeting vector, using a secondary carbamate linker. The resulting prodrug, dopa-CBT, inhibited the uptake of the LAT1 substrate [ 14 C]-L-leucine in LAT1-expressing MCF-7 cells with an IC 50 value of 28 µM, which was 3.5-times lower than that of the gold standard for dopamine replacement therapy, L-dopa (IC 50 ca. 100 µM). Despite its high affinity for LAT1, dopa-CBT was transported via LAT1 into MCF-7 cells 850-times more slowly (V max < 3 pmol/min/mg) than Ldopa (V max 2.6 nmol/min/mg), most likely due to its large size compared to L-dopa. However, dopa-CBT was significantly more stable in 10% rat liver homogenate than L-dopa, releasing dopamine and L-tyrosine, an endogenous dopamine precursor, slowly, which indicates that it may serve as a dual carrier of dopamine across the blood-brain barrier selectively expressing LAT1.

Research paper thumbnail of Prodrugs

Encyclopedia of Molecular Pharmacology, 2021

Research paper thumbnail of Molecular characteristics supporting l-Type amino acid transporter 1 (LAT1)-mediated translocation

Bioorganic Chemistry, 2021

l-Type amino acid transporter 1 (LAT1) is an interesting protein due to its peculiar expression p... more l-Type amino acid transporter 1 (LAT1) is an interesting protein due to its peculiar expression profile. It can be utilized not only as a carrier for improved or targeted drug delivery, e.g., into the brain but also as a target protein by which amino acid supply can be restricted, e.g., from the cancer cells. The recognition and binding processes of LAT1-ligands, such as amino acids and clinically used small molecules, including l-dopa, gabapentin, and melphalan, are today well-known. Binding to LAT1 is crucial, particularly when designing the LAT1-inhibitors. However, it will not guarantee effective translocation across the cell membrane via LAT1, which is a definite requirement for LAT1-substrates, such as drugs that elicit their pharmacological effects inside the cells. Therefore, in the present study, the accumulation of known LAT1-utilizing compounds into the selected LAT1-expressing cancer cells (MCF-7) was explored experimentally over a time period. The differences found among the transport efficiency and affinity of the studied compounds for LAT1 were subsequently explained by docking the ligands into the human LAT1 model (based on the recent cryo-electron microscopy structure). Thus, the findings of this study clarify the favorable structural requirements of the size, shape, and polarity of the ligands that support the translocation and effective transport across the cell membrane via LAT1. This knowledge can be applied in future drug design to attain improved or targeted drug delivery and hence, successful LAT1-utilizing drugs with increased therapeutic effects.

Research paper thumbnail of Addressing the Biochemical Foundations of a Glucose-Based Trojan Horse-Strategy to Boron Neutron Capture Therapy: From Chemical Synthesis to In Vitro Assessment

Research paper thumbnail of Prodrug Approach for Posterior Eye Drug Delivery: Synthesis of Novel Ganciclovir Prodrugs and in Vitro Screening with Cassette Dosing

Because of poor ocular drug bioavailability, intravitreal injection has become the gold standard ... more Because of poor ocular drug bioavailability, intravitreal injection has become the gold standard for drug delivery to the posterior eye. Prodrug approach can be used for optimizing the biopharmaceutical properties of intravitreal drugs. The preclinical screening of prodrugs' properties, such as hydrolysis and bioconversion, should be conducted in a resource-efficient way for an extensive set of synthesized compounds with validated methods. Our objective was to explore cassette dosing in in vitro prodrug hydrolysis and bioconversion studies in buffer, vitreous and retinal pigment epithelium (RPE) homogenate for rapid medium-throughput screening. Moreover, our aim was to correlate prodrug structure with the hydrolytic behavior. We synthesized 18 novel ganciclovir prodrugs and first studied their hydrolysis in aqueous buffer and porcine vitreous in vitro with cassette dosing for 35 h. A method for vitreous homogenate pH equilibration to a physiological level by using buffer and incubation under 5% carbon dioxide was validated. The hydrolysis of the prodrugs was evaluated in porcine RPE homogenate in vitro with cassette dosing, and five prodrugs were assayed individually to examine their bioconversion into ganciclovir in RPE after 2 h. Lastly, the prodrugs' binding to melanin was studied in vitro. The prodrugs showed a wide spectrum of hydrolysis rates, ranging from a few percentages to 100% in the vitreous and RPE; in general, hydrolysis in RPE was faster than in vitreous. Prodrugs with long carbon chains and disubstitution showed lability in the tissue homogenates, whereas prodrugs with branched carbon chains and aromatic groups were stable. All five prodrugs chosen for the bioconversion study in RPE were hydrolyzed into ganciclovir and their hydrolytic behavior matched results from the cassette mix experiment, supporting the cassette mix approach for hydrolysis and bioconversion studies. None of the prodrugs bound highly to melanin (<50% bound). In conclusion, cassette dosing proved useful for rapid screening of prodrug hydrolysis and bioconversion properties. Analyzing several compounds simultaneously can complicate the analytics, thus choosing the compounds of the cassette mix should be done carefully to avoid mutual interference of the compounds with the results. The methodology and results of the work are applicable in ocular drug research and prodrug design.

Research paper thumbnail of Discovery of polar spirocyclic orally bioavailable urea inhibitors of soluble epoxide hydrolase

Bioorganic chemistry, 2018

Spirocyclic 1-oxa-9-azaspiro[5.5]undecan-4-amine scaffold was explored as a basis for the design ... more Spirocyclic 1-oxa-9-azaspiro[5.5]undecan-4-amine scaffold was explored as a basis for the design of potential inhibitors of soluble epoxide hydrolase (sEH). Synthesis and testing of the initial SAR-probing library followed by biochemical testing against sEH allowed nominating a racemic lead compound (±)-22. The latter showed remarkable (> 0.5 mM) solubility in aqueous phosphate buffer solution, unusually low (for sEH inhibitors) lipophilicity as confirmed by experimentally determined logD of 0.99, and an excellent oral bioavailability in mice (as well as other pharmacokinetic characteristics). Individual enantiomer profiling revealed that the inhibitory potency primarily resided with the dextrorotatory eutomer (+)-22 (IC 4.99 ± 0.18 nM). For the latter, a crystal structure of its complex with a C-terminal domain of sEH was obtained and resolved. These data fully validate (+)-22 as a new non-racemic advanced lead compound for further development as a potential therapeutic agent fo...

Research paper thumbnail of Prodrugs – Recent approvals and a glimpse of the pipeline

European Journal of Pharmaceutical Sciences, 2017

&NA; Prodrugs offer a versatile strategy to overcome flaws of viable drug candidates or clini... more &NA; Prodrugs offer a versatile strategy to overcome flaws of viable drug candidates or clinically approved drugs. However, the strategic importance of prodrugs in the pharmaceutical industry has often been challenged, and prodrugs are often considered as the last option after lead optimization and when the selected drug candidate has faced significant pharmaceutical and pharmacokinetic limitations. Based on recent success in marketed drugs, prodrug strategy should clearly be considered already in early stages of lead optimization. During the past five years or so, prodrugs have accounted for about 10% of all small molecular weight drugs that have come to the market. In 2015 alone, the FDA approved seven prodrugs, which gives a prodrug prevalence of over 20% among the small molecules or over 15% among the total amount of the FDA approved drugs that year. A great number of various prodrugs are also undergoing late stage clinical trials. The pharmaceutical industry will therefore continue to depend on prodrugs for the foreseeable future. In this review, we will present the state of the art in the design of the prodrugs launched by the FDA since 2015. We will also provide an overview of some interesting late stage clinical prodrug candidates. We hope this review will demonstrate potential of prodrug strategies and facilitates the use of prodrugs in drug discovery projects. Graphical abstract Figure. No caption available.

Research paper thumbnail of Novel prodrugs of metformin

Research paper thumbnail of Prodrugs Designed to Target Transporters for Oral Drug Delivery

Methods and Principles in Medicinal Chemistry, 2011

Page 1. 6 Prodrugs Designed to Target Transporters for Oral Drug Delivery Mark S. Warren and Jark... more Page 1. 6 Prodrugs Designed to Target Transporters for Oral Drug Delivery Mark S. Warren and Jarkko Rautio 6.1 Introduction In drug discovery, many drug candidates show effective therapeutic promise but are dropped prior ...

Research paper thumbnail of Prodrug Strategies in Drug Design

Methods and Principles in Medicinal Chemistry, 2011

Research paper thumbnail of Evaluation of novel imidazotetrazine analogues designed to overcome temozolomide resistance and glioblastoma regrowth

Molecular Cancer Therapeutics, 2014

Research paper thumbnail of Design, Synthesis and Brain Uptake of LAT1-Targeted Amino Acid Prodrugs of Dopamine

Pharmaceutical Research, 2013

Drug delivery to the brain is impeded by the blood-brain barrier (BBB). Here, we attempted to enh... more Drug delivery to the brain is impeded by the blood-brain barrier (BBB). Here, we attempted to enhance the brain uptake of cationic dopamine by utilizing the large amino acid transporter 1 (LAT1) at the BBB by prodrug approach. Three amino acid prodrugs of dopamine were synthesized and their prodrug properties were examined in vitro. Their LAT1-binding and BBB-permeation were studied using the in situ rat brain perfusion technique. The brain uptake after intravenous administration and the dopamine-releasing ability in the rat striatum after intraperitoneal administration were also determined for the most promising prodrug. All prodrugs underwent adequate cleavage in rat tissue homogenates. The prodrug with phenylalanine derivative as the promoiety had both higher affinity for LAT1 and better brain uptake properties than those with an alkyl amino acid - mimicking promoiety. The phenylalanine prodrug was taken up into the brain after intravenous injection but after intraperitoneal injection the prodrug did not elevate striatal dopamine concentrations above those achieved by corresponding L-dopa treatment. These results indicate that attachment of phenylalanine to a cationic drug via an amide bond from the meta-position of its aromatic ring could be highly applicable in prodrug design for LAT1-mediated CNS-delivery of not only anionic but also cationic polar drugs.

Research paper thumbnail of Novel Cyclic Phosphate Prodrug Approach for Cytochrome P450-activated Drugs Containing an Alcohol Functionality

Pharmaceutical Research, 2007

Purpose. A cyclic phosphate prodrug of a descriptive molecule containing an alcohol functionality... more Purpose. A cyclic phosphate prodrug of a descriptive molecule containing an alcohol functionality was designed, synthesized and characterized in vitro as a cytochrome P450 (CYP)-selective prodrug. Materials and Methods. To achieve efficient CYP-oxidation and prodrug bioconversion, 1,3-cyclic propyl ester of phosphate was designed to have a C4-aryl substituent and synthesized using phosphorus(III) chemistry. The two-step bioconversion of the cyclic phosphate prodrug was evaluated in vitro using human liver microsomes and recombinant CYP enzymes. Results. This cyclic phosphate prodrug underwent initial CYP-catalyzed oxidation and was mainly catalyzed by the CYP3A4 form. The hydroxylated product was slowly converted to a ring-opened intermediate, which subsequently transformed by b-elimination reaction to a free phosphate. The free phosphate was further dephosphorylated by microsomal phosphatases, releasing the parent molecule with a free hydroxyl group. The cyclic phosphate was reasonably stable in buffer solutions at the pH range 1.0j9.0. Conclusions. Since CYP enzymes reside predominantly in the liver and secondarily in the small intestine, the results indicate that cyclic phosphate prodrugs represent a very feasible liver-or intestinaltargeted drug delivery strategy for drug molecules containing an alcohol functionality. This may potentially improve the efficacy and the safety profile of the alcoholic parent drugs.

Research paper thumbnail of Large Amino Acid Transporter 1 (LAT1) Prodrugs of Valproic Acid: New Prodrug Design Ideas for Central Nervous System Delivery

Molecular Pharmaceutics, 2011

Central nervous system (CNS) drug delivery is a major challenge in drug development because the b... more Central nervous system (CNS) drug delivery is a major challenge in drug development because the blood-brain barrier (BBB) efficiently restricts the entry of drug molecules into the CNS at sufficient amounts. The brain uptake of poorly penetrating drugs could be improved by utilizing the transporters at the BBB with a prodrug approach. In this study, we designed four phenylalanine derivatives of valproic acid and studied their ability to utilize a large amino acid transporter 1 (LAT1) in CNS delivery with an aim to show that the meta-substituted phenylalanine prodrugs bind to LAT1 with a higher affinity compared with the affinity of the para-substituted derivatives. All of the prodrugs crossed the BBB carrier mediatedly via LAT1 in in situ rat brain perfusion. For the first time, we introduced a novel meta-substituted phenylalanine analogue promoiety which improved the LAT1 affinity 10-fold and more importantly the rat brain uptake of the prodrug 2-fold compared with those of the para-substituted derivatives. Therefore, we have characterized a new prodrug design idea for CNS drug delivery utilizing a transporter-mediated prodrug approach.

Research paper thumbnail of Design, Synthesis, and Evaluation of Novel Cyclic Phosphates of 5-Aminosalicylic Acid as Cytochrome P450-Activated Prodrugs

Molecular Pharmaceutics, 2013

Four novel cyclic phosphates of the anti-inflammatory agent 5-aminosalicylic acid (5-ASA) were de... more Four novel cyclic phosphates of the anti-inflammatory agent 5-aminosalicylic acid (5-ASA) were designed and synthesized as cytochrome P450 (CYP)-activated prodrugs. These prodrugs can be used for targeting into gut wall, since these types of cyclic phosphates are known to be activated mainly by CYP3A forms, which are expressed not only in the liver but also in the small intestine and to a lesser extent in the colon. The present study shows that aromatic ring activating substituents, like chlorine, are definitely needed to obtain the desired enzymatic cleavage of the cyclic phosphate prodrugs of 5-ASA. However, the position of the activating substituent has also a strong impact on the chemical stability, and therefore, an appropriate balance between the rates of prodrug bioactivation and chemical stability needs to be taken into consideration in future studies on cyclic phosphate prodrugs of 5-ASA.

Research paper thumbnail of Synthesis and antileishmanial activity of novel buparvaquone oxime derivatives

Bioorganic & Medicinal Chemistry, 2004

In order to optimize the antileishmanial activity of piperazinyl-linked 5-(5-nitrofuran-2-yl)-1,3... more In order to optimize the antileishmanial activity of piperazinyl-linked 5-(5-nitrofuran-2-yl)-1,3,4-thiadiazoles, we synthesized a series of 5-(5-nitrofuran-2-y1)-1,3,4-thiadiazoles with piperazinyl-linked benzamidine substituent as scaffold found in pentamidine related antiprotozoals. The structure of target compounds was confirmed by IR, 1 H NMR, 13 C NMR and Mass spectral data. All compounds were tested for in vitro activity against the promastigote and amastigote forms of Leishmania major. From the results, we found that the substitution on amidine nitrogen has profound role in the biological activity of these compounds. The 5-nitrofuran-2-yl-1,3,4-thiadiazoles having n-propyl, n-butyl and benzyl side chain on benzamidine (as in compounds 2d, 2e and 2g, respectively) showed very good activity in both forms of promastigote and amastigote. The most active compound was N-propyl-4-(4-(5-(5-nitrofuran-2-yl)-1,3,4-thiadiazol-2-yl)piperazin-1-yl) benzamidine hydrochloride (2d) with IC 50 value of 0.08 mM in promastigote model. This compound showed a very low level of toxicity against macrophages (CC 50 ¼ 785 mM), with the highest selectivity index (SI ¼ 78.5) among the tested compounds.

Research paper thumbnail of Development of Sesamol Carbamate-L-Phenylalanine Prodrug Targeting L-Type Amino Acid Transporter1 (LAT1) as a Potential Antiproliferative Agent against Melanoma

International Journal of Molecular Sciences

Sesamol is a compound reported to have anti-melanogenesis and anti-melanoma actions. Sesamol, how... more Sesamol is a compound reported to have anti-melanogenesis and anti-melanoma actions. Sesamol, however, has low intracellular drug concentration and fast excretion, which can limit its benefits in the clinic. To overcome this drawback and increase intracellular delivery of sesamol into the target melanoma, research has focused on L-type amino acid transporter 1 (LAT1)-mediated prodrug delivery into melanoma cells. The sesamol prodrug was designed by conjugating sesamol with L-phenylalanine at the para position with a carbamate bond. LAT1 targeting was evaluated vis-à-vis a competitive [14C]-leucine uptake inhibition. The sesamol prodrug has a higher [14C]-leucine uptake inhibition than sesamol in human LAT1-transfected HEK293 cells. Moreover, the sesamol prodrug was taken up by LAT1-mediated transport into SK-MEL-2 cells more effectively than sesamol. The sesamol prodrug underwent complete hydrolysis, releasing the active sesamol at 72 h, which significantly exerted its cytotoxicity ...

Research paper thumbnail of vitro p-glycoprotein inhibition assays for assessment of clinical drug interaction potential of new drug candidates: a recommendation for probe substrates. Drug Metab Dispos. 2006;34(5):786–792. submit your manuscript | www.dovepress.com Dovepress Dovepre

Because modulation of P-glycoprotein (Pgp) through inhibition or induction can lead to drug-drug ... more Because modulation of P-glycoprotein (Pgp) through inhibition or induction can lead to drug-drug interactions by altering intestinal, central nervous system, renal, or biliary efflux, it is anticipated that information regarding the potential interaction of drug candidates with Pgp will be a future regulatory expectation. Therefore, to be able to utilize in vitro Pgp inhibition findings to guide clinical drug interaction studies, the utility of five probe substrates (calcein-AM, colchicine, digoxin, prazosin, and vinblastine) was evaluated by inhibiting their Pgp-mediated transport across multidrug resis-tance-1-transfected Madin-Darby canine kidney cell type II mono-layers with 20 diverse drugs having various degrees of Pgp inter-action (e.g., efflux ratio, ATPase, and calcein-AM inhibition). Overall, the rank order of inhibition was generally similar with IC50 values typically within 3- to 5-fold of each other. However, several notable differences in the IC50 values were observed....

Research paper thumbnail of Potenciais Pró-Fármacos do Ácido Flufenâmico

Research paper thumbnail of Anti-bacterial activity of inorganic nanomaterials and their antimicrobial peptide conjugates against resistant and non-resistant pathogens

International Journal of Pharmaceutics, 2020

Our report represents a comprehensive review on the antibacterial activity of inorganic nanomater... more Our report represents a comprehensive review on the antibacterial activity of inorganic nanomaterials and antimicrobial peptides, and how concomitant use of the two can effectively tackle a range of bacterial infections which is a rapidly escalating issues in public health care worldwide. We believe this is of particular current interest with regard to "antimicrobial resistance" being declared one of the top-10 global health threats in 2019 by the WHO. In this group of authors, we have teamed up within the NordForsk-funded university hub Nordic POP (Patient Oriented Products), which we wish to showcase with this contribution. We are currenlty carrying out joint research supported by this network within the topic of the review, so we view this a valuable contribution also within the dissemination of Nordic POP activities.

Research paper thumbnail of Secondary carbamate linker can facilitate the sustained release of dopamine from brain-targeted prodrug

Bioorganic & Medicinal Chemistry Letters, 2018

To achieve the sustained release of dopamine in the brain for the symptomatic treatment of Parkin... more To achieve the sustained release of dopamine in the brain for the symptomatic treatment of Parkinson's disease, dopamine was conjugated to L-tyrosine, an L-type amino acid transporter 1 (LAT1)-targeting vector, using a secondary carbamate linker. The resulting prodrug, dopa-CBT, inhibited the uptake of the LAT1 substrate [ 14 C]-L-leucine in LAT1-expressing MCF-7 cells with an IC 50 value of 28 µM, which was 3.5-times lower than that of the gold standard for dopamine replacement therapy, L-dopa (IC 50 ca. 100 µM). Despite its high affinity for LAT1, dopa-CBT was transported via LAT1 into MCF-7 cells 850-times more slowly (V max < 3 pmol/min/mg) than Ldopa (V max 2.6 nmol/min/mg), most likely due to its large size compared to L-dopa. However, dopa-CBT was significantly more stable in 10% rat liver homogenate than L-dopa, releasing dopamine and L-tyrosine, an endogenous dopamine precursor, slowly, which indicates that it may serve as a dual carrier of dopamine across the blood-brain barrier selectively expressing LAT1.

Research paper thumbnail of Prodrugs

Encyclopedia of Molecular Pharmacology, 2021

Research paper thumbnail of Molecular characteristics supporting l-Type amino acid transporter 1 (LAT1)-mediated translocation

Bioorganic Chemistry, 2021

l-Type amino acid transporter 1 (LAT1) is an interesting protein due to its peculiar expression p... more l-Type amino acid transporter 1 (LAT1) is an interesting protein due to its peculiar expression profile. It can be utilized not only as a carrier for improved or targeted drug delivery, e.g., into the brain but also as a target protein by which amino acid supply can be restricted, e.g., from the cancer cells. The recognition and binding processes of LAT1-ligands, such as amino acids and clinically used small molecules, including l-dopa, gabapentin, and melphalan, are today well-known. Binding to LAT1 is crucial, particularly when designing the LAT1-inhibitors. However, it will not guarantee effective translocation across the cell membrane via LAT1, which is a definite requirement for LAT1-substrates, such as drugs that elicit their pharmacological effects inside the cells. Therefore, in the present study, the accumulation of known LAT1-utilizing compounds into the selected LAT1-expressing cancer cells (MCF-7) was explored experimentally over a time period. The differences found among the transport efficiency and affinity of the studied compounds for LAT1 were subsequently explained by docking the ligands into the human LAT1 model (based on the recent cryo-electron microscopy structure). Thus, the findings of this study clarify the favorable structural requirements of the size, shape, and polarity of the ligands that support the translocation and effective transport across the cell membrane via LAT1. This knowledge can be applied in future drug design to attain improved or targeted drug delivery and hence, successful LAT1-utilizing drugs with increased therapeutic effects.

Research paper thumbnail of Addressing the Biochemical Foundations of a Glucose-Based Trojan Horse-Strategy to Boron Neutron Capture Therapy: From Chemical Synthesis to In Vitro Assessment

Research paper thumbnail of Prodrug Approach for Posterior Eye Drug Delivery: Synthesis of Novel Ganciclovir Prodrugs and in Vitro Screening with Cassette Dosing

Because of poor ocular drug bioavailability, intravitreal injection has become the gold standard ... more Because of poor ocular drug bioavailability, intravitreal injection has become the gold standard for drug delivery to the posterior eye. Prodrug approach can be used for optimizing the biopharmaceutical properties of intravitreal drugs. The preclinical screening of prodrugs' properties, such as hydrolysis and bioconversion, should be conducted in a resource-efficient way for an extensive set of synthesized compounds with validated methods. Our objective was to explore cassette dosing in in vitro prodrug hydrolysis and bioconversion studies in buffer, vitreous and retinal pigment epithelium (RPE) homogenate for rapid medium-throughput screening. Moreover, our aim was to correlate prodrug structure with the hydrolytic behavior. We synthesized 18 novel ganciclovir prodrugs and first studied their hydrolysis in aqueous buffer and porcine vitreous in vitro with cassette dosing for 35 h. A method for vitreous homogenate pH equilibration to a physiological level by using buffer and incubation under 5% carbon dioxide was validated. The hydrolysis of the prodrugs was evaluated in porcine RPE homogenate in vitro with cassette dosing, and five prodrugs were assayed individually to examine their bioconversion into ganciclovir in RPE after 2 h. Lastly, the prodrugs' binding to melanin was studied in vitro. The prodrugs showed a wide spectrum of hydrolysis rates, ranging from a few percentages to 100% in the vitreous and RPE; in general, hydrolysis in RPE was faster than in vitreous. Prodrugs with long carbon chains and disubstitution showed lability in the tissue homogenates, whereas prodrugs with branched carbon chains and aromatic groups were stable. All five prodrugs chosen for the bioconversion study in RPE were hydrolyzed into ganciclovir and their hydrolytic behavior matched results from the cassette mix experiment, supporting the cassette mix approach for hydrolysis and bioconversion studies. None of the prodrugs bound highly to melanin (<50% bound). In conclusion, cassette dosing proved useful for rapid screening of prodrug hydrolysis and bioconversion properties. Analyzing several compounds simultaneously can complicate the analytics, thus choosing the compounds of the cassette mix should be done carefully to avoid mutual interference of the compounds with the results. The methodology and results of the work are applicable in ocular drug research and prodrug design.

Research paper thumbnail of Discovery of polar spirocyclic orally bioavailable urea inhibitors of soluble epoxide hydrolase

Bioorganic chemistry, 2018

Spirocyclic 1-oxa-9-azaspiro[5.5]undecan-4-amine scaffold was explored as a basis for the design ... more Spirocyclic 1-oxa-9-azaspiro[5.5]undecan-4-amine scaffold was explored as a basis for the design of potential inhibitors of soluble epoxide hydrolase (sEH). Synthesis and testing of the initial SAR-probing library followed by biochemical testing against sEH allowed nominating a racemic lead compound (±)-22. The latter showed remarkable (> 0.5 mM) solubility in aqueous phosphate buffer solution, unusually low (for sEH inhibitors) lipophilicity as confirmed by experimentally determined logD of 0.99, and an excellent oral bioavailability in mice (as well as other pharmacokinetic characteristics). Individual enantiomer profiling revealed that the inhibitory potency primarily resided with the dextrorotatory eutomer (+)-22 (IC 4.99 ± 0.18 nM). For the latter, a crystal structure of its complex with a C-terminal domain of sEH was obtained and resolved. These data fully validate (+)-22 as a new non-racemic advanced lead compound for further development as a potential therapeutic agent fo...

Research paper thumbnail of Prodrugs – Recent approvals and a glimpse of the pipeline

European Journal of Pharmaceutical Sciences, 2017

&NA; Prodrugs offer a versatile strategy to overcome flaws of viable drug candidates or clini... more &NA; Prodrugs offer a versatile strategy to overcome flaws of viable drug candidates or clinically approved drugs. However, the strategic importance of prodrugs in the pharmaceutical industry has often been challenged, and prodrugs are often considered as the last option after lead optimization and when the selected drug candidate has faced significant pharmaceutical and pharmacokinetic limitations. Based on recent success in marketed drugs, prodrug strategy should clearly be considered already in early stages of lead optimization. During the past five years or so, prodrugs have accounted for about 10% of all small molecular weight drugs that have come to the market. In 2015 alone, the FDA approved seven prodrugs, which gives a prodrug prevalence of over 20% among the small molecules or over 15% among the total amount of the FDA approved drugs that year. A great number of various prodrugs are also undergoing late stage clinical trials. The pharmaceutical industry will therefore continue to depend on prodrugs for the foreseeable future. In this review, we will present the state of the art in the design of the prodrugs launched by the FDA since 2015. We will also provide an overview of some interesting late stage clinical prodrug candidates. We hope this review will demonstrate potential of prodrug strategies and facilitates the use of prodrugs in drug discovery projects. Graphical abstract Figure. No caption available.

Research paper thumbnail of Novel prodrugs of metformin

Research paper thumbnail of Prodrugs Designed to Target Transporters for Oral Drug Delivery

Methods and Principles in Medicinal Chemistry, 2011

Page 1. 6 Prodrugs Designed to Target Transporters for Oral Drug Delivery Mark S. Warren and Jark... more Page 1. 6 Prodrugs Designed to Target Transporters for Oral Drug Delivery Mark S. Warren and Jarkko Rautio 6.1 Introduction In drug discovery, many drug candidates show effective therapeutic promise but are dropped prior ...

Research paper thumbnail of Prodrug Strategies in Drug Design

Methods and Principles in Medicinal Chemistry, 2011

Research paper thumbnail of Evaluation of novel imidazotetrazine analogues designed to overcome temozolomide resistance and glioblastoma regrowth

Molecular Cancer Therapeutics, 2014

Research paper thumbnail of Design, Synthesis and Brain Uptake of LAT1-Targeted Amino Acid Prodrugs of Dopamine

Pharmaceutical Research, 2013

Drug delivery to the brain is impeded by the blood-brain barrier (BBB). Here, we attempted to enh... more Drug delivery to the brain is impeded by the blood-brain barrier (BBB). Here, we attempted to enhance the brain uptake of cationic dopamine by utilizing the large amino acid transporter 1 (LAT1) at the BBB by prodrug approach. Three amino acid prodrugs of dopamine were synthesized and their prodrug properties were examined in vitro. Their LAT1-binding and BBB-permeation were studied using the in situ rat brain perfusion technique. The brain uptake after intravenous administration and the dopamine-releasing ability in the rat striatum after intraperitoneal administration were also determined for the most promising prodrug. All prodrugs underwent adequate cleavage in rat tissue homogenates. The prodrug with phenylalanine derivative as the promoiety had both higher affinity for LAT1 and better brain uptake properties than those with an alkyl amino acid - mimicking promoiety. The phenylalanine prodrug was taken up into the brain after intravenous injection but after intraperitoneal injection the prodrug did not elevate striatal dopamine concentrations above those achieved by corresponding L-dopa treatment. These results indicate that attachment of phenylalanine to a cationic drug via an amide bond from the meta-position of its aromatic ring could be highly applicable in prodrug design for LAT1-mediated CNS-delivery of not only anionic but also cationic polar drugs.

Research paper thumbnail of Novel Cyclic Phosphate Prodrug Approach for Cytochrome P450-activated Drugs Containing an Alcohol Functionality

Pharmaceutical Research, 2007

Purpose. A cyclic phosphate prodrug of a descriptive molecule containing an alcohol functionality... more Purpose. A cyclic phosphate prodrug of a descriptive molecule containing an alcohol functionality was designed, synthesized and characterized in vitro as a cytochrome P450 (CYP)-selective prodrug. Materials and Methods. To achieve efficient CYP-oxidation and prodrug bioconversion, 1,3-cyclic propyl ester of phosphate was designed to have a C4-aryl substituent and synthesized using phosphorus(III) chemistry. The two-step bioconversion of the cyclic phosphate prodrug was evaluated in vitro using human liver microsomes and recombinant CYP enzymes. Results. This cyclic phosphate prodrug underwent initial CYP-catalyzed oxidation and was mainly catalyzed by the CYP3A4 form. The hydroxylated product was slowly converted to a ring-opened intermediate, which subsequently transformed by b-elimination reaction to a free phosphate. The free phosphate was further dephosphorylated by microsomal phosphatases, releasing the parent molecule with a free hydroxyl group. The cyclic phosphate was reasonably stable in buffer solutions at the pH range 1.0j9.0. Conclusions. Since CYP enzymes reside predominantly in the liver and secondarily in the small intestine, the results indicate that cyclic phosphate prodrugs represent a very feasible liver-or intestinaltargeted drug delivery strategy for drug molecules containing an alcohol functionality. This may potentially improve the efficacy and the safety profile of the alcoholic parent drugs.

Research paper thumbnail of Large Amino Acid Transporter 1 (LAT1) Prodrugs of Valproic Acid: New Prodrug Design Ideas for Central Nervous System Delivery

Molecular Pharmaceutics, 2011

Central nervous system (CNS) drug delivery is a major challenge in drug development because the b... more Central nervous system (CNS) drug delivery is a major challenge in drug development because the blood-brain barrier (BBB) efficiently restricts the entry of drug molecules into the CNS at sufficient amounts. The brain uptake of poorly penetrating drugs could be improved by utilizing the transporters at the BBB with a prodrug approach. In this study, we designed four phenylalanine derivatives of valproic acid and studied their ability to utilize a large amino acid transporter 1 (LAT1) in CNS delivery with an aim to show that the meta-substituted phenylalanine prodrugs bind to LAT1 with a higher affinity compared with the affinity of the para-substituted derivatives. All of the prodrugs crossed the BBB carrier mediatedly via LAT1 in in situ rat brain perfusion. For the first time, we introduced a novel meta-substituted phenylalanine analogue promoiety which improved the LAT1 affinity 10-fold and more importantly the rat brain uptake of the prodrug 2-fold compared with those of the para-substituted derivatives. Therefore, we have characterized a new prodrug design idea for CNS drug delivery utilizing a transporter-mediated prodrug approach.

Research paper thumbnail of Design, Synthesis, and Evaluation of Novel Cyclic Phosphates of 5-Aminosalicylic Acid as Cytochrome P450-Activated Prodrugs

Molecular Pharmaceutics, 2013

Four novel cyclic phosphates of the anti-inflammatory agent 5-aminosalicylic acid (5-ASA) were de... more Four novel cyclic phosphates of the anti-inflammatory agent 5-aminosalicylic acid (5-ASA) were designed and synthesized as cytochrome P450 (CYP)-activated prodrugs. These prodrugs can be used for targeting into gut wall, since these types of cyclic phosphates are known to be activated mainly by CYP3A forms, which are expressed not only in the liver but also in the small intestine and to a lesser extent in the colon. The present study shows that aromatic ring activating substituents, like chlorine, are definitely needed to obtain the desired enzymatic cleavage of the cyclic phosphate prodrugs of 5-ASA. However, the position of the activating substituent has also a strong impact on the chemical stability, and therefore, an appropriate balance between the rates of prodrug bioactivation and chemical stability needs to be taken into consideration in future studies on cyclic phosphate prodrugs of 5-ASA.

Research paper thumbnail of Synthesis and antileishmanial activity of novel buparvaquone oxime derivatives

Bioorganic & Medicinal Chemistry, 2004

In order to optimize the antileishmanial activity of piperazinyl-linked 5-(5-nitrofuran-2-yl)-1,3... more In order to optimize the antileishmanial activity of piperazinyl-linked 5-(5-nitrofuran-2-yl)-1,3,4-thiadiazoles, we synthesized a series of 5-(5-nitrofuran-2-y1)-1,3,4-thiadiazoles with piperazinyl-linked benzamidine substituent as scaffold found in pentamidine related antiprotozoals. The structure of target compounds was confirmed by IR, 1 H NMR, 13 C NMR and Mass spectral data. All compounds were tested for in vitro activity against the promastigote and amastigote forms of Leishmania major. From the results, we found that the substitution on amidine nitrogen has profound role in the biological activity of these compounds. The 5-nitrofuran-2-yl-1,3,4-thiadiazoles having n-propyl, n-butyl and benzyl side chain on benzamidine (as in compounds 2d, 2e and 2g, respectively) showed very good activity in both forms of promastigote and amastigote. The most active compound was N-propyl-4-(4-(5-(5-nitrofuran-2-yl)-1,3,4-thiadiazol-2-yl)piperazin-1-yl) benzamidine hydrochloride (2d) with IC 50 value of 0.08 mM in promastigote model. This compound showed a very low level of toxicity against macrophages (CC 50 ¼ 785 mM), with the highest selectivity index (SI ¼ 78.5) among the tested compounds.