Clinical effects of Cariprazine and their relationship with polymorphisms of dopamine and serotonin receptors: preliminary results from a prospective study on schizophrenia and bipolar disorder

Introduction

Cariprazine (CAR) is a D2, D3, 5HT1A receptor partial agonist and a 5HT2A, 5HT2B antagonist, used to treat Schizophrenia and Bipolar disorder. Interindividual variability in therapeutic and side effects of antipsychotics is difficult to predict, due to non-genetic and genetic factors. Single nucleotide polymorphisms (SNPs) are the main source of genetic variability, the ones in dopamine and serotonin receptors to which CAR binds are indeed likely to determine response to treatment.

Objectives

The aim of the study is to define a relationship between CAR clinical efficacy and SNPs in dopamine and serotonin receptors genes of patients affected by schizophrenia and bipolar disorder.

Methods

We recruited 16 patients starting a monotherapy with CAR, evaluated at baseline and after 2, 4 and 8 weeks through BPRS rating scale. We selected a panel of SNPs in DR2, DR3, 5HT1A and 5HT2A receptors, with a frequency higher that 10% in Caucasians and functionally characterized. Cut-off for response to treatment was a 50% reduction of BPRS score. Statistical analysis was performed with one-way ANOVA followed by the test for linear trend between columns.

Results

All subjects achieved response after 8 weeks of treatment, but 6 patients after 4 weeks. Early responders have a genetic profile associated with increased dopamine and serotonin receptor expression and/or binding affinity for their specific ligands. The association don’t reach statistical significance, probably due to low number of patients.

Conclusions

Preliminary results suggest that an array of dopamine and serotonin receptors SNPs could predict time to respond to CAR in schizophrenia and bipolar disorder.

Disclosure

The study is founded by Recordati AG, that commercialize the drug under study (Cariprazine) in Switzerland. Funding covers the costs for genetic analysis and other procedures of the study, no financial compensation is planned for investigators/authors.

The gordian knot of overlapping symptoms between dissociative identity disorder and borderline personality disorder, the need for a clear cut: A case report

Introduction

One of the central debates in the psychiatric community is the difficulty in distinguishing Dissociative Identity Disorder (DID) from Borderline Personality Disorder (BPD). The fact that core symptoms of these pathologies such as emotional dysregulation, alterations in sense of Self, amnesia, depersonalization, self harm, hearing voices, difficulties in maintaining relationships, are symptoms that feature in both disorders can lead physicians to a misdiagnosis, thus depriving patients with DID of adequate treatment.

Objectives

To report a complex clinical case of a DID patient initially misdiagnosed as BPD.

Methods

Clinical case report.

Results

A 45-year-old Caucasian woman with a history of childhood intrafamilial sexual abuse and domestic violence, substance use disorder, autolesionistic and suicidal behaviour with an active diagnosis of BPD presented to our ambulatory mental health care service. A more thorough examination revealed a history of emotional and affect dysregulation, depersonalization, amnesia, intrusive traumatic memories and nightmares with affective, cognitive, and sensorimotor aspects, persistent negative Self-perception. Auditory verbal hallucinations were also present described as inner space with commentary and derogatory nature with one of them being a child voice. The diagnosis of tertiary structural dissociation and DID was finally made when three Apparently Normal Personalities emerged with several Emotional Personalities, authorising for cautious partial pharmacological washout and initiation of three phase-orientated treatment approach.

Conclusions

DID is more common than is assumed and the overlap of core symptoms with other disorders can lead to a misdiagnosis. A careful clinical interview and evaluation of symptoms is mandatory to a correct DID diagnosis with a consequent appropriate therapy.

Disclosure

No significant relationships.

25c-nbome: Case report and literature review

Introduction

Novel psychoactive drugs (NPS) have rapidly increase in the last years in the drug market as a recreational use. A new group of toxic phenethylamine derivates named NBOMe of 2 C class present have emerged recently, are frequently bought using the internet and have similar effects to other hallucinogenic drugs; however, they may pose larger risks, due to the limited knowledge about them, their relatively low price and availability via the internet. The purpose of this report is to review the clinical evidence for the potential of abuse of NBOMe compounds. We propose a case report and literature review.

Method

We conducted a systematic review of the literature with the principal database (PubMed, Enbase, PsychInfo) and we present a case report.

Results

The effects of 25C-NBOMe is characterized by hallucination, violent agitation, rhabdomyolysis and kydney injury.

Discussion and conclusion

Effects from 25C-NBOMe in our case report were similar to previous individual case reports in literature. The clinical features were also similar to effects from other analogues in the class (25I-NBOMe, 25B-NBOMe). In our case, violent agitation (signs of serotonergic stimulation), rhabdomyolysis and kidney injury were observed. Further research is warranted to replicate our clinical and qualitative observations and, in general, quantitative studies in large samples followed up over time are needed. Methodological limitations, clinical implications and suggestions for future research directions are considered.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Fenethylline (Captagon) abuse: Case report and literature review

Introduction

Novel psychoactive drugs (NPS) has rapidly increase in the last years in the drug market as a recreational use. Fenethylline is a theophylline, an amphetamine-like drug, having stimulant effects similar to those of other amphetamine-type derivatives. Fenethylline was used as medicament for hyperactivity disorders in children, narcolepsy and depression, but it has also been used as a drug of abuse under the common name of ‘captagon’. The purpose of this report is to review the clinical evidence for the potential of abuse of fenethylline. We propose a case report and literature review.

Method

We conducted a systematic review of the literature with the principal database (PubMed, Enbase, PsychInfo) and we present a case report.

Results

The effects of fenethylline is characterized by euphoria, derealization, autopsychic and somatopsychic depersonalization, hallucination, agitation and decrease of pain perception.

Discussion and conclusion

The primary drug market for fenethyline (as captagon) has traditionally been countries located on the Arabian Peninsula but also North Africa since 2013. To our knowledge, there is no report on the recreational use of fenethylline in literature. The clinical features of fenethylline intoxication were also similar to effects from other amphetamine-like drugs. In our case report, dissociative symptoms are the core of fenethylline intoxication. Further research is warranted to replicate our clinical and qualitative observations and, in general, quantitative studies in large samples followed-up over time are needed. Methodological limitations, clinical implications and suggestions for future research directions are considered [1,2].

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Misuse of pregabalin: Case series and literature review

Introduction

Pregabalin is widely used in neurology, psychiatry and primary healthcare, and recently in literature different studies explain the possible misuse [1,2]. Pregabalin has shown greater potency in preclinical models of epilepsy, pain and anxiety, and may have potential in the treatment of cocaine addiction [3]. The purpose of this report is to review the clinical evidence for the potential of abuse and misuse of pregabalin. We propose ten different cases and literature review.

Method

Ten inpatients with misuse of pregabalin were assessed with: the SCID-P, Anamnestic Folio, HAM-A and DAST. We conducted a systematic review of the literature (PubMed, Embase, PsychInfo), using the terms “pregabalin”, “misuse”.

Results

All our patients present: cocaine, alcohol and/heroin positive in drugs urine screening at admission; a significant high level of total anxiety at the HAM-A Tot (P < .001), and especially at the item 7 (P < .001); the misuse of pregabalin is made for sniffing; the predominant symptoms assessed were euphoria, psychomotor activation and sedation.

Discussion and conclusion

Schifano F et al., [1,2] suggest that pregabalin should carefully prescribe in patients with a possible previous history of drug abuse. Our result identifies a particular population the misuse pregabalin that are abuser of cocaine, alcohol and/or heroin. Further research is warranted to replicate our clinical and qualitative observations and, in general, quantitative studies in large samples followed up over time are needed. Methodological limitations, clinical implications and suggestions for future research directions are considered.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Serotonin syndrome with SSRIs augmentation of amisulpride: Two case report and literature review

Introduction

Serotonin syndrome is a potential adverse reaction to drugs increasing serotoninergic activity in the nervous system, some of them being frequently prescribed, such as antidepressant drugs. The association of myoclonus, diarrhea, confusion, hypomania, agitation, hyperreflexia, shivering, in-coordination, fever and diaphoresis, when patients are treated with serotoninergic agents, could constitute a “serotonin syndrome”. The purpose of this report is to review the clinical evidence of serotonin syndrome with SSRIs augmentation of amisulpride. We propose two case report and literature review.

Method

We conducted a systematic review of the literature with the principal database (PubMed, Enbase, PsychInfo) and we present two case report [1,2].

Results

We describe two different case report with SSRIs augmentation of amisulpride.

Discussion and conclusion

To our knowledge this is no report about the emergence of serotonin syndrome due to the use of SSRIs augmentation of amisulpride. Serotonin syndrome symptoms include high body temperature, agitation, increased reflexes, tremor, sweating, fever, dilated pupils, and diarrhea. Further research is warranted to replicate our clinical and qualitative observations and, in general, quantitative studies in large samples followed up over time are needed. Methodological limitations, clinical implications and suggestions for future research directions are considered.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Paramethoxymethamphetamine (Mitsubishi turbo) abuse: Case report and literature review

Introduction

Paramethoxymethamphetamine and paramethoxyamphetamine (PMMA and PMA) are two so-called designer amphetamines, which appear from time to time on the illegal narcotics market in many countries. They are frequently sold as ecstasy or amphetamine, often mixed with amphetamine or methamphetamine [1, 2]. Paramethoxyamphetamine (PMA) is a hallucinogenic synthetic substituted amphetamine with capable of development of dependence [3]. The purpose of this report is to review the clinical evidence for the potential of abuse of paramethoxyamphetamine. We propouse a case report and literature review.

Method

We conducted a systematic review of the literature with the principal database (PubMed, Enbase, PsychInfo) and we present a case report.

Results

The effects of paramethoxyamphetamine is characterized at the beginning with symptoms like euphoria, derealizzation, psychomotor activation, feeling in tune with surroundings and in love for friends, who come to visual and auditory illusions and hallucinations, paranoid delusion, and violent agitation.

Discussion and conclusion

The use of these recreational drugs is especially common among young people participating in rave parties. Occasionally paramethoxymethamphetamine (PMMA) or paramethoxyamphetamine (PMA) are found in street drugs offered as ecstasy. Further research is warranted to replicate our clinical and qualitative observations and, in general, quantitative studies in large samples followed up over time are needed. Methodological limitations, clinical implications and suggestions for future research directions are considered.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

[Melle4]Cyclosporin, a Novel Natural Cyclosporin with anti-HIV Activity: Structural Elucidation, Biosynthesis and Biological Properties

From fermentations of Tolypocladium niveum supplemented with D-threonine, a novel natural cyclosporin, [Melle4]cyclosporin, was isolated. Its structural elucidation is based on amino acid analysis and spectroscopic data; the amino acid sequence was deduced from two-dimensional NMR investigations applied to the iso-derivative of [Melle4]cyclosporin which, in contrast to the natural product, is present as one homogenous conformation in solution. We show that one of the four N-methyl-L-leucine units of cyclosporin A, namely that in position 4, is replaced by N-methyl-L-isoleucine. The putative mechanism by which D-threonine induces in vivo biosynthesis of [Melle4]cyclosporin is discussed. In vitro biosynthesis of [Melle4]cyclosporin was achieved using the previously described enzymatic system [Lawen and Traber (1993) J Biol Chem268: 20452–20465], thereby demonstrating the high affinity of cyclosporin synthetase for isoleucine in position 4.

In a long series of cyclosporins obtained by in vitro and in vivo biosynthesis, [Melle4]cyclosporin represents the first example that is devoid of immunosuppressive efficacy while retaining strong binding to cyclophilin. It exerts potent in vitro anti-HIV-1 activity.

Towards a redefinition of dissociative spectrum dimensions inside Capgras and misidentification syndromes in bipolar disorder: Case series and literature review

Introduction

Misidentification phenomena and Capgras Syndrome (CS) occur in different psychiatric (psychotic or major affective illnesses) and neurological (traumatic brain injury, epilepsy, neurosyphilis, etc.) disorders [1,2]. The aim of this report is to redefine dissociative spectrum dimensions inside CS and misidentification syndromes in patients with Bipolar Disorder (BD).

Method

Five inpatients were assessed with the SCID-P, SCID-DER, DSS, HRSD, YMRS, a neurological and general medicine review, a first-level brain imaging examination (CT and/or MRI). We conducted a systematic literature review (PubMed, Embase, PsychInfo) using the key terms “Capgras Syndrome” and “Misidentificaition”.

Results

All patients were diagnosed with type-I BD and had concomitant CS that presented with misidentification phenomena in the context of psychotic mixed state. They reported high scores for autopsychic and affective depersonalization symptoms as well as high SCI-DER (mean = 24.4) and DSS (mean = 13) total scores.

Discussion and conclusion

To our knowledge in literature, there are not studies that evaluated dissociative spectrum symptoms in CS in BD. This condition of identity and self fragmentation could be the key to shedding light on the interconnection between affective and non-affective psychotic disorders from schizophrenia to BD, and may underscore the possible validity of the concept of the unitary psychosis proposed by Griesinger [3–5]. Further research is warranted to replicate our clinical and qualitative observations and, in general, quantitative studies in large samples followed up over time are needed. Methodological limitations are considered.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Psychotic mixed state in bipolar I disorder due to neurosyphilis: Case report and literature review

Introduction

The presence of mixed features in bipolar disorder (BD) has been associated with a worse clinical course and high rates of comorbidities including anxiety, personality, alcohol and substance use disorders and head trauma or other neurological problems [1]. A recent study reports the connection of neurosyphilis and mania [2]. The aim of our study is to evaluate an inpatient with a psychotic mixed state due to a medical condition (neurosyphilis).

Method

An inpatient with psychotic mixed state in BD was assessed with: SCID-P, HRSD, YMRS, and a complete internistical examination, blood test exams, urinanalysis, electrocardiogram and ecocardiogram, as well as a first level brain imagin (CT and/or MRI). We conducted a systematic review of the literature (PubMed, Embase, PsychInfo), using the terms “bipolar disorder”, “neurosyphilis” AND “mixed state”.

Results

A comprehensive diagnostic and laboratory screening was unremarkable except for a positive venereal disease research laboratory (VDRL). Treatment for syphilis was started and we used olanzapine to control the psychiatric symptoms.

Discussion and conclusion

The estimated annual incidence of non-HIV STIs (sexually transmitted infections) has increased by nearly 50% during the period 1995–2008 [3]. Our case report underly, like Barbosa et al., the need to evaluate neurosyphilis as a potential cause of behavioural and psychiatric symptoms that simulate a psychotic mixed state of bipolar disorder. Olanzapine control and improve the psychiatric symptomatology in neurosyphilis. Methodological limitations, clinical implications and suggestions for future research directions are considered.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Quetiapine XR reduce impulsivity and dissociation in a sample of alcoholic patients

Introduction

Alcohol dependence (AD) is a major public health problem. Currently, three drugs for the treatment of AD have been approved: acamprosate, disulfiram and oral naltrexone. Quetiapine XR is an atypical antipsychotic has been shown to be a promising medication for the treatment of alcoholism [1,2]. The aim of our study is evaluate quetiapine efficacy on impulsivity in a sample of alcoholic patients.

Method

A sample of alcoholic patients (n = 40) was assessed at the entrance and 2 months with: SCID-P, Brief-Temps, BIS-11, GSR, BPRS, SCI-DER, and CGI. The medium dosage of quetiapine is 300 mg.

Results

Using the last observation carried forward, the mean total BIS score decreased from 60.8 at baseline to 40.2 at the final visit (P = .03). More pronounced improvement was observed in motor impulsiveness (P < .03) and attentional impulsiveness (P < .05) compared with non-planning impulsiveness (P = .09). We observed an improvement in SCI-DER total score (P = .02), in particular in derealization (P = .03) and autopsychic depersonalization (P = .04). A mean weight gain of 4.8 kg was observed. There is not significant different related to the different affective temperament.

Discussion and conclusion

Analyses revealed a significant effect of Quetiapine XR in improving impulsivity and dissociation, in particular motor and attentional impulsiveness, derealization and autopsychic depersonalization. Moreover, an improvement of dissociative symptoms is probably connected with the blockade of postsynaptic 5-HT1A receptors [3]. Methodological limitations, clinical implications and suggestions for future research directions are considered.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Suicidal plan and dissociation

Introduction

The social and economic impact of mood disorders and suicide is extremely high. In depression, suicide is included among the cognitive disturbances, together with guilt, paranoid and obsessive-compulsive symptoms, depersonalization/derealization and agitation [1,2]. The aim of this report is to study a sample of depressed patients with bipolar disorder or major depressive disorder, to evaluate the level of impulsivity and dissociation in a context of a suicidal plan.

Method

Twenty inpatients with suicidal plan were assessed with: the SCID-P for Axis I diagnosis, SCI-DER, DSS, HRSD, HAS, YMRS, GSR. We conducted a systematic literature review (PubMed, Embase, PsychInfo) using the key terms “depression”, “suicide”, “suicidal plan”, “depersonalization”, “derealization” AND “dissociation”.

Results

An independent sample T-Test analysis suggested that the patient with high sucidal plan present significant highter score at SCI-DER TOT (P = 0.015), DSS TOT (P = 0.037), BIS-11 motor perseveration factor (P = 0.023) and inversely significant HAS TOT (P = .029).

Discussion and conclusion

It's suggestive that when are lost the boundaries of the self, the clarity of suicidal's purpose reduces the levels of anxiety and suicide appears the only way to achieve the liberation of the suffering of depression. Methodological limitations, clinical implications and suggestions for future research directions are considered.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Cyclosporins: structure-activity relationships for the inhibition of the human MDR1 P-glycoprotein ABC transporter

Cyclic undecapeptide cyclo-[MeBmt(1)-Abu(2)-MeGly(3)-MeLeu(4)-Val(5)-MeLeu(6)-Ala(7)-D-Ala(8)-MeLeu(9)-MeLeu(10)-MeVal(11)], the immunosuppressive and antifungal antibiotic cyclosporin A (CsA), was reported to interfere with the MDR1 P-glycoprotein (Pgp), a transmembranous adenosine 5'-triphosphate binding cassette (ABC) transporter with phospholipid flippase or "hydrophobic vacuum cleaner" properties that mediate multidrug resistance (MDR) of cancer cells. By use of photoaffinity-labeled cyclosporins and membranes from Pgp-expressing cells, it was recently shown that in vitro, Pgp molecules could bind a large cyclosporin domain involving residues 4-9 as well as the side chain of residue 1. Tumor cell MDR can also be reversed by a product more distantly related to cyclosporin with the structure [Thr(2), Leu(5), D-Hiv(8), Leu(10)]-CsA (SDZ 214-103). In a standardized assay that measures Pgp function in vivo (on intact live cells) by the Pgp-mediated efflux of the calcein-AM Pgp substrate and uses human lymphoblastoid MDR-CEM (VBL(100)) cells as highly resistant Pgp-expressing cells, SDZ 214-103 was found to be one of the most active Pgp inhibitors among naturally occurring cyclosporins, with an IC(50) of 1.6 microM in an assay where CsA gives an IC(50) of 3.4 microM. Using the in vivo assay, 60, mostly natural, cyclosporin analogues were analyzed to establish structure-activity relationships (SAR). Our SAR are compatible with the in vitro-defined Pgp binding domain model and further disclose that in vivo Pgp inhibition is favored by larger hydrophobic side chains on cyclosporin residues 1, 4, 6, and 8 and a smaller one on residue 7, although with no effect on the residue 5 side chain; moreover, larger hydrophobic side chains on other residues 2, 3, 10, and 11 (outside the in vitro-defined Pgp binding domain) also favor the eventual inhibition of Pgp function. The N-desmethylation of any of the seven N-methylated amides, as naturally occurring in numerous cyclosporins, regularly leads to a decreased Pgp inhibitory activity (Pgp-InhA), up to its abrogation if it occurs at residues 4 and 9. Nevertheless, despite unfavorable use of [Thr(2)] and [Leu(10)] residues, all [D-Hiv(8)] analogues whose lead is SDZ 214-103 show a large Pgp-InhA. The SAR for Pgp inhibition by cyclosporins are thus very complex. Because CsA and SDZ 214-103 show largely different conformations when free in solution, but remarkably similar ones when bound to the cytosolic cyclophilins, SAR for Pgp inhibition must similarly include requirements for occurrence of suitable conformers for insertion in the cell membrane, sufficient conformational plasticity for gaining access to Pgp binding sites, and an adequate conformer structure there to achieve such binding with a high enough affinity and possibly escape from sequestration on cyclophilins.

New insights into rifamycin B biosynthesis: isolation of proansamycin B and 34a-deoxy-rifamycin W as early macrocyclic intermediates indicating two separated biosynthetic pathways

Proansamycin B, the formerly postulated intermediate of rifamycin B biosynthesis, was isolated from cultures of the Amycolatopsis mediterranei mutant F1/24. The structure was determined using UV, IR, NMR and MS techniques. Biotransformation studies demonstrate that proansamycin B is an intermediate of a shunt pathway, a 8-deoxy variant, of rifamycin B biosynthesis leading to 8-deoxy-rifamycin B as the final product. In addition, 34a-deoxy-rifamycin W, the direct precursor of rifamycin W, could be isolated representing the earliest macrocyclic intermediate obtained so far in the biosynthetic route to rifamycin B. Furthermore, the new rifamycin W-28-desmethyl-28-carboxy and rifamycin W-hemiacetal, intermediates in the transformation sequence of rifamycin W to rifamycin S, were isolated. Application of proton NMR measurements (double resonance and ROESY experiments) on the latter compound indicated that the stereochemistry at the chiral center C-28 is R.

Intermediates of rifamycin polyketide synthase produced by an Amycolatopsis mediterranei mutant with inactivated rifF gene

Rifamycin B biosynthesis in Amycolatopsis mediterranei N/813 was inactivated by introducing a small deletion in the rifF gene situated directly downstream of the rifamycin polyketide synthase (PKS) gene cluster. The corresponding mutant strain produced a series of linear intermediates of rifamycin B biosynthesis that are most probably generated by obstruction of the normal release of the end product of the rifamycin PKS. This result provides evidence that the rifF gene product catalyses the release of the completed linear polyketide from module 10 of the PKS and the intramolecular macrocyclic ring closure by formation of an amide bond, as indicated by sequence similarity of this protein to amide synthases. The chemical structures of the new rifamycin polyketide synthase intermediates released from modules 4 to 10 were determined by spectroscopic methods (UV, IR, NMR and MS) and gave insight into the reaction steps of rifamycin ansa chain biosynthesis and the timing of the formation of the naphthoquinone ring. The intermediates released from modules 6 and 8 were isolated as lactones formed by the terminal carboxyl group; proton NMR double resonance and ROESY(rotated frame nuclear Overhauser enhancement spectroscopy) experiments enabled the deduction of the relative configurations in the linear chain which correspond to the known absolute stereochemistry of rifamycin B.

Induction of rapid IL-1 beta mRNA degradation in THP-1 cells mediated through the AU-rich region in the 3'UTR by a radicicol analogue

A radicicol analogue (analogue A) was found to inhibit interleukin 1 beta (IL-1 beta) and tumour necrosis factor alpha (TNF-alpha) secretion from THP-1 cells. If added to cells activated by interferon gamma and lipopolysaccharide, radicicol analogue A not only inhibited the secretion of IL-1 beta but also induced an extremely rapid degradation of IL-1 beta, IL-6 and TNF-alpha mRNA to undetectable levels within 5-8 h. This degradation is independent of translation and of the signal inducing transcription. The common feature of these genes is the inclusion of one or more copies of the mRNA-instability sequence, AUUUA, in the 3' untranslated region. Indeed, no destabilizing effect of radicicol analogue A could be observed on mRNA derived from the expression of an IL-1 beta construct lacking the AUUUA motifs of the 3'UTR. The effect of radicicol analogue A on protein/mRNA interaction and on post-translational modifications of cytoplasmic proteins is described. This class of compound constitutes a valuable tool for the further elucidation of the mechanism of mRNA degradation of cytokines and proto-oncogenes.

Microbial biotransformation products of cyclosporin A

In order to mimic the human metabolic pathway of cyclosporin A (CyA) a total of 28 bacterial and 72 fungal strains was screened for their ability to transform CyA. Among 3 bacteria and 11 fungi, which produced the main human metabolite OL-17 [eta HyMeBmt1]CyA, Actinoplanes sp. (ATCC 53771) achieved the best transformation rate (5.4%). Furthermore, the two N-demethylated minor products [Leu4]CyA (3.2%) and [Leu9]CyA (4.7%) were isolated, both known as minor natural metabolites and the first one also as a human biotransformation product. Microbial conversion of CyA using the actinomycete Sebekia benihana (NRRL 11111) yielded [gamma HyMeLeu4]CyA (35%), [gamma HyLeu4]CyA (4.5%) and [gamma HyMeLeu4, gamma HyMeLeu6]CyA (8.6%). The structures of these derivatives correspond with those of the human metabolic pathway. The related compounds [Nva2]CyA (CyG) and [D-MeSer3]CyA were similarly converted to the corresponding 4-gamma-hydroxylated analogues. None of the biotransformation products showed a better immunosuppressive effect than CyA, although in various cases the cyclophilin binding affinity was comparable to that of CyA.

Biosynthesis of the unusual amino acid (4R)-4-[(E)-2-butenyl]-4-methyl-L-threonine of cyclosporin A: enzymatic analysis of the reaction sequence including identification of the methylation precursor in a polyketide pathway

3(R)-Hydroxy-4(R)-methyl-6(E)-octenoic acid, the C9-backbone of the unusual amino acid (4R)-4-[(E)-2-butenyl]-4-methyl-L-threonine (Bmt), is biosynthesized as a coenzyme A thioester from acetyl-CoA, malonyl-CoA, NADPH, and S-adenosylmethionine via a polyketide pathway. Here we present detailed enzymatic studies about the basic assembly process. After attachment of the activated building units to Bmt polyketide synthase the intermediates remained enzyme-bound throughout the cycle. Premature cutoff of biosynthesis led to the release of the intermediates from the enzyme, either as coenzyme A thioesters or, in the case of reactive C8-intermediates, as lactones. Enzyme-bound 3-oxo-4-hexenoic acid, the condensation product of the second elongation cycle, could be identified as the exclusive substrate for the introduction of the methyl group. Part of the biosynthesis including the first elongation cycle, the second condensation reaction, and the methylation step was shown to follow a processive mechanism. All activated intermediates of this processive part could be introduced into the correct pathway at the respective steps, whereas 2-methyl-3-oxo-4-hexenoyl-CoA and all following methylated intermediates were not able to enter the cycle any more. Obviously, the region of Bmt polyketide synthase responsible for this latter part of the biosynthetic pathway is inaccessible for externally supplied coenzyme A thioesters. Butyryl-CoA was recognized by Bmt polyketide synthase with an efficiency comparable to that of crotonyl-CoA and processed to 3-hydroxy-4-methyloctanoyl-CoA, the saturated analog of the natural basic assembly product, indicating a relaxed specificity of Bmt polyketide synthase with respect to the starter unit.

Reversal of multidrug resistance by novel cyclosporin A analogues and the cyclopeptolide SDZ 214-103 biosynthesized in vitro

It was shown that cyclopeptolide SDZ 214-103 (10 microM) is more active in rhodamine-123 accumulation in actinomycin-D-resistant human lymphoma cells CCRF/ACTD400 than cyclosporin A (10 microM), but equipotent in the doxorubicin-resistant Friend erythroleukemia cell line F4-6/ADR. In F4-6/ADR cells, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay showed comparable cytotoxic effects of doxorubicin at various concentrations in the presence of SDZ 214-103 and cyclosporin A. For the other novel cyclosporin A analogues minor multidrug-resistance-modulating potency was demonstrated. At equipotent modulating doses of verapamil (10 microM) and cyclosporin A (10 microM) in the MTT assay regarding doxorubicin cytotoxicity, cyclosporin A was efficient in the rhodamine-123-uptake assay while verapamil was not active when identical incubation times were used.

In vitro biosynthesis of ring-extended cyclosporins

Cyclosporin synthetase, a multifunctional polypeptide, catalyses the biosynthesis of the set of natural cyclosporins. We report that this enzyme is also capable of introducing a beta-alanine into position 7 or 8 of the ring instead of the alpha-alanines present at these positions in cyclosporin A. This leads to 34-membered rings in contrast to the 33-membered ring of the cyclo-undecapeptide cyclosporin A. Both [beta Ala7]CyA and [beta Ala8]CyA show immunosuppressive activity. The cyclosporin synthetase-related enzyme peptolide SDZ 214-103 synthetase, on the other hand, does not incorporate either beta-alanine into position 7 or beta-hydroxy acids into position 8, confirming the previously described higher substrate specificity of this enzyme compared with cyclosporin synthetase [Lawen and Traber (1993) J. Biol. Chem. 268, 20452-20465].

Biosynthesis of the unusual amino acid (4R)-4-[(E)-2-butenyl]-4-methyl-L-threonine of cyclosporin A. Identification of 3(R)-hydroxy-4(R)-methyl-6(E)-octenoic acid as a key intermediate by enzymatic in vitro synthesis and by in vivo labeling techniques

The biosynthesis of (4R)-4-[(E)-2-butenyl]-4-methyl-L-threonine (abbreviation: Bmt, systematic name: 2(S)-amino-3(R)-hydroxy-4(R)-methyl-6(E)-octenoic acid) is proposed to involve two principal phases: the formation of a polyketide backbone and a subsequent transformation process to the final product. Here we report on the identification of 3(R)-hydroxy-4(R)-methyl-6(E)-octenoic acid as the end product of the first phase. The primary indication of 3(R)-hydroxy-4(R)-methyl-6(E)-octenoic acid as the key intermediate in the proposed biosynthetic route came from in vivo labeling studies with [1-13C,18O2]acetate, demonstrating retention of 18O in the 3-hydroxy group. Final identification of this intermediate in in vitro polyketide assays with enriched enzyme fractions of Tolypocladium niveum was achieved after development of highly sensitive and specific detection methods and by use of synthetic reference substances. Two additional methylated in vitro products could be detected and characterized as 4(R)-methyl-(E,E)-2,6-octadienoic acid and 4(R)-methyl-6(E)-octenoic acid by liquid chromatography-mass spectrometry analysis and comparison with synthetic reference samples. Their relevance for Bmt biosynthesis is discussed. Bmt polyketide synthase shows optimal activity at substrate concentrations of 200 microM acetyl-CoA, 150 microM malonyl-CoA, and 200 microM S-adenosylmethionine, around pH 7 and at 35 degrees C. Interestingly the Bmt backbone is released from the enzyme as a coenzyme A thioester, suggesting that subsequent transformation to Bmt takes place upon this activated intermediate.

Substrate specificities of cyclosporin synthetase and peptolide SDZ 214-103 synthetase. Comparison of the substrate specificities of the related multifunctional polypeptides

The recently discovered multifunctional polypeptide cyclosporin synthetase is capable of synthesizing the cyclic undecapeptide cyclosporin A in a batch reaction. Substrates are the unmethylated constitutive amino acids of cyclosporin A. Exchange of one or more of these by various amino acids gives a picture of the substrate specificity of the enzyme in vitro, which is different from the known picture obtained by in vivo studies. The uncommon amino acid butenylmethylthreonine in position 1 of the cyclosporin ring can be exchanged by an unexpected large spectrum of different amino acids, showing a great flexibility of this site. Position 2, on the other hand, which shows the greatest variability in vivo, has an only slightly lower specificity in vitro. Position 3 has a very high degree of specificity; positions 4, 6, 7, 9, and 10 have marginally less. The variability of positions 5 and 11 is moderate, whereas position 8 shows only low substrate specificity in vitro. In general, most sites of SDZ 214-103 synthetase appear to be more specific than those of cyclosporin synthetase. Site 11 has nearly identical substrate specificity compared with that of cyclosporin synthetase. The D-2-hydroxy acid position (position 8) can be occupied by a large spectrum of substrates varying from D-lactic acid to D-2-hydroxyisocaproic acid. Within the limits of the present data, the addition of further functional groups to the D-2-hydroxy acid moiety are apparently not tolerated by the enzyme.

In vitro biosynthesis of [Thr2,Leu5,D-Hiv8,Leu10]-cyclosporin, a cyclosporin-related peptolide, with immunosuppressive activity by a multienzyme polypeptide

A new cyclic peptolide (SDZ 214-103), which is produced by the fungus Cylindrotrichumoligospermum (Corda) BONORDEN (Dreyfuss, M. M., Schreier, M. H., Tscherter, H., and Wenger, R. (June 15, 1988) European Patent Application 0 296 123 A2) and is closely related to cyclosporin A (CyA), has as the main structural difference D-2-hydroxyisovaleric acid in ester linkage at position 8 instead of D-alanine in the cyclosporins. This peptolide exerts similar biological activities to CyA. We were able to prepare an enzyme fraction of crude extracts of the mycelium, which is capable of synthesizing the peptolide with consumption of the constitutive amino acids, D-2-hydroxyisovaleric acid, ATP, and S-adenosyl-L-methionine. The in vitro product co-chromatographs with authentic peptolide on thin layer chromatography and high performance liquid chromatography and shows similar immunosuppressive activity in vitro. The enzyme does not synthesize CyA, whereas cyclosporin synthetase does not synthesize the peptolide. Peptolide synthetase has a high molecular weight (in the same range as cyclosporin synthetase) and also does not appear to be glycosylated. The enzyme cross-reacts with antibodies directed specifically against cyclosporin synthetase.

Selective 13C-labelling of cyclosporin A

Cyclosporin A is biosynthetically labelled with 13C by growing an overproducing strain of Tolypocladium inflatum on minimal media containing either [1-13C]-, [2-13C]-, [3-13C]- or [6-13C]glucose as the only carbon source. NMR analysis of the 13C-labelled peptide showed a labelling pattern in which 13C occurs at specific sites. These can be predicted by consideration of the relevant biosynthetic pathways. Quantitation of the site-specific enrichments revealed that the 13C-label incorporation is efficient and selective. Metabolic fluxes through alternative pathways can also be estimated from these results. Isotopically labelled peptides will be a very useful tool for the study of molecular interactions with their receptors.

The NMR structure of cyclosporin A bound to cyclophilin in aqueous solution

Cyclosporin A bound to the presumed receptor protein cyclophilin was studied in aqueous solution at pH 6.0 by nuclear magnetic resonance spectroscopy using uniform 15N- or 13C-labeling of cyclosporin A and heteronuclear spectral editing techniques. Sequence-specific assignments were obtained for all but one of the cyclosporin A proton resonances. With an input of 108 intramolecular NOEs and four vicinal 3JHN alpha coupling constants, the three-dimensional structure of cyclosporin A bound to cyclophilin was calculated with the distance geometry program DISMAN, and the structures resulting from 181 converged calculations were energy refined with the program FANTOM. A group of 120 conformers was selected on the basis of the residual constraint violations and energy criteria to represent the solution structure. The average of the pairwise root-mean-square distances calculated for the backbone atoms of the 120 structures was 0.58 A. The structure represents a novel conformation of cyclosporin A, for which the backbone conformation is significantly different from the previously reported structures in single crystals and in chloroform solution. The structure has all peptide bonds in the trans form, contains no elements of regular secondary structure and no intramolecular hydrogen bonds, and exposes nearly all polar groups to its environment. The root-mean-square distance between the backbone atoms of the crystal structure of cyclosporin A and the mean of the 120 conformers representing the NMR structure of cyclosporin A bound to cyclophilin is 2.5 A.

Isolation of (4R)-4-[(E)-2-butenyl]-4-methyl-L-threonine, the characteristic structural element of cyclosporins, from a blocked mutant of Tolypocladium inflatum

By mutagenic treatment of a strain of Tolypocladium inflatum, a cyclosporin non-producing mutant was obtained which accumulated the characteristic building unit of cyclosporins, (4R)-4-[(E)-2-butenyl]-4-methyl-L-threonine (abbreviation Bmt; systematic name: (2S,3R,4R,6E)-2-amino-3-hydroxy-4-methyl-6-octenoic acid) in free form. The isolation from a culture filtrate was performed by extraction, chromatographic separation and final crystallization from methanol - water. The structure and stereochemistry of this amino acid was determined by chemical transformation and correlation to dihydro-MeBmt, with known chirality [(2S,3R,4R)-3-hydroxy-4-methyl-2-methylamino-octanoic acid], obtained by hydrolysis of dihydrocyclosporin A.

Overcoming multidrug resistance in Chinese hamster ovary cells in vitro by cyclosporin A (Sandimmune) and non-immunosuppressive derivatives

Cyclosporin A (Sandimmune) increased the in vitro susceptibility of 'parental' and 'multidrug-resistant' (MDR) chinese hamster ovary (CHO) cell lines to three anti-tumour drugs: colchicine, daunomycin, and vincristine. Several immunosuppressive or non-immunosuppressive derivatives of cyclosporin (Cs) were compared for their ability to sensitise both parental and MDR cells to chemotherapeutic agents. Although 5-10-fold increases of sensitivity to anti-tumour drugs could be obtained for cells of the parental line with several Cs-derivatives, the largest 'gains' of sensitivity (chemosensitisation) were obtained for the cells of the MDR line and with only some of the Cs derivatives. The MDR cells employed displayed the typical MDR phenotype. However, we found no correlation between the immunosuppressive activity of Cs derivatives and their capacity to reverse MDR and all four possible combinations of these two activities could indeed be shown among the tested Cs derivatives. This study demonstrates for the first time that some immunosuppressive Cs can be devoid of chemosensitising activity.

Cell-free biosynthesis of new cyclosporins

An enzyme preparation, isolated from extracts of the fungus Beauveria nivea (previously designated Tolypocladium inflatum), is able to synthesize cyclosporins (Cy's) in vitro. At suboptimal temperature it was possible to yield about 50 micrograms of CyA per ml. The enzyme also produces several of the naturally occurring congeners of CyA, such as the Cy's B, C, D, G, M, O, Q, U and V and some of the analogues known to be produced by the fungus via precursor directed biosynthesis, like dihydro-CyA, [N-methyl-L-beta-cyclohexylalanine]CyA, [L-allylglycine]CyA and [D-serine]CyA. Furthermore, Cy's not obtainable by the fungus could be prepared by the enzyme system in the presence of the appropriate precursor amino acids; the synthesis of [N-methyl-(+)-2-amino-3-hydroxy-4,4-dimethyloctanoic acid]CyA, [L-norvaline, N-methyl-L-norvaline]CyA, [L-norvaline, N-methyl-L-norvaline]CyA, [L-allo-isoleucine, N-methyl-L-allo-isoleucine]CyA, [L-allo-isoleucine]CyA, [D-2-aminobutyric acid]CyA and [beta-chloro-D-alanine]CyA could be established. The immunosuppressive effects of the new derivatives are discussed.

Cyclosporins--new analogues by precursor directed biosynthesis

Cyclosporin A (ciclosporin), a potent and clinically important immunosuppressive drug (Sandimmun), represents the main component of a group of over 25 closely related, cyclic undecapeptides produced by the fungus Tolypocladium inflatum. By feeding experiments using DL-alpha-allylglycine as precursor, specific incorporation in position 2 was attained leading to [Allylgly2]cyclosporin A. Exogenously supplied L-beta-cyclohexylalanine results in the almost exclusive production of [MeCyclohexylala1]cyclosporin A (replacement of methylbutenyl-methylthreonine-1). D-Alanine in position 8 can be successfully substituted by D-serine. The new [D-Ser8] analogues of the cyclosporins A, C, D and G as well as [Allylgly2]cyclosporin A exhibit high immunosuppressive effects.

Mechanism of light-induced reduction of biological redox centers by amino acids. A flash photolysis study of flavin photoreduction by ethylenediaminetetraacetate and nitrilotriacetate

The mechanism of flavin photoreduction by the amino acids, EDTA, and nitrilotriacetate is shown to be due to light-induced charge separation, which is irreversible in the dark. The irreversibility originates from the decarboxylation of the amino acid radical. This fast process changes the redox properties of the radical and makes a further donation of an electron equivalent possible. In the case of EDTA the electron acceptor of the second electron is flavin, which was left unexcited by the flash or is formed by dismutation from the flavosemiquinone, generated in the primary one-electron transfer process. In contrast to this, a mechanism for the flavin photoreduction by nitrilotriacetate is proposed, in which the decarboxylated nitrilotriacetate radical adds to the flavosemiquinone to yield an alkylated flavohydroquinone. The latter decays to free reduced or oxidized flavin, depending on the position of addition at the flavin chromophore. The difference in reaction mechanism between the nitrite anion, EDTA, and nitrilotriacetate is discussed in terms of differences in molecular structure.

Structure and properties of 5-deazaflavin radicals as compared to natural flavosemiquinones

In order to gain more insight into flavin radicals, on which the selection of 1e-, and 2e- -oxireduction modes in flavoproteins depends, we have investigated structure, spectral properties and decay mode of molecular species occurring in the half-reduced 5-deazaflavin "model" system by flash photolysis and pulse radiolysis. (1) Enforced 1e- -reduction of 5-deazaflavin yields the short-lived red-colored 1-HdFl, which is a strong reductant. In the absence of any electron acceptor, this radical decays by 1,5-prototropy (see below) and dismutation, which is rapidly reversed upon illumination. Competing with this photo-comproportionation, irreversible formation of the photo-stable sigma-dimmer (HdFl)2, covalently linked via C(5), is observed, which becomes prevalent under prolonged illumination. (2) Enforced 1e- -abstraction from 1,5-dihydro-5-deazaflavin yields the tautomeric 5-HdFl, which is a mild oxidant and is transparent at lambda 480 nm. Prototropy 5-HdFl in equilibrium or formed from 1-HdFl can be rate-determining in 5-deazaflavin redox reactions. Hence, the radical state in the 5-deazaflavin system does not mediate double 1e- -oxidoreduction as do natural flavosemiquinones. Instead, 5-deazaflavin flavors nucleophilic substrate addition (carbanion transfer) and formation of intermediate sigma-adducts in (photo)reductions even over the extent observed with natural flavin. This confirms the description of 5-deazaflavin as a "flavin-shaped nicotinamide derivative". It explains at the same time the mechanism of 5-deazaflavin acting as a mild and yet potent photosensitizer in 1e- -reductions of biological redox systems. (3) It is shown that replacement of N(5) by CH in the flavin nucleus also leads to the disappearance of the known action-pK in the photoreduction, which confirms the assignment of the latter pK in the natural flavin system to 5-protonation of the excited flavin triplet. From these model studies the following biological conclusions can be confirmed: The tautomer equilibrium of natural flavin semiquinones is diffusion-controlled and regulated thermodynamically: 5-HFl in equilibrium or formed from 1-HFl, while in flavo-proteins the same equilibrium is regulated by regiospecific H-bridges from the apoprotein, which thus decides between 1e- - (stable 5-HFl) and 2e- -reaction (unstable 1-HFl) modes.

A radioimmunoassay to measure cyclosporin A in plasma and serum samples

A radioimmunoassay for the immunosuppressant drug Cyclosporin A has been developed which makes possible the monitoring of the drug by direct measurements in clinical plasma and serum samples. The antisera have been produced in rabbits using the hemisuccinate derivative of a structural analogue of Cyclosporin A as a hapten. The assay has both adequate specificity and sensitivity for Cyclosporin A to be suitable for the routine monitoring of therapy. Some degree of cross-reactivity has been shown to occur with four metabolites which were isolated from urine samples.

Distinction of 2e- and 1e- reduction modes of the flavin chromophore as studied by flash photolysis

Evidence is given for the fact that the excited flavin triplet (3Flox) exhibits competitive 1e- and 2e- transfer chemistry, depending on the nature of the photosubstrate. As an 'external' photo-reductant, the 2e- donor borohydride has been investigated. Borohydride is found to compete effectively with the 'internal' 1e- donors, namely excess starting flavin in the ground state (Flox) and, as primary product, (alkyl)dihydroflavin (RFlredH). It will be shown that some of the flavin radicals, observed by earlier authors in the reaction of 3Flox with CH or C-COO- substrates or in the autophotolytic side-chain cleavage of riboflavin, are due to the dye-dye reaction (I): 3Flox + Flox H+ leads to HFl + Fl+ -H+ leads to 2Flox. (I) In contrast flavin photoreduction by borohydride or hydrocarbon substrates need not involve radicals, but may in fact be a hydride or 'carbanion-plus-proton' addition towards the highly polar and considerably basic (pK = 4.4) acceptor triplet (cf. reaction II) (see text: Formula). The products are much more photoreactive than the starting substrates, which leads to the secondary photocomproportionation (III): 3Flox + R-FlredH leads to HFl + RFl, (R = alkyl or H). (III) This latter reaction is the second source of radicals in the system. This (cf. II) 'photohydrogenation' of flavin is mechanistically related to the biological reduction of flavin by CH substrates.