Ecdysteroid metabolism in mammals: The fate of ingested 20-hydroxyecdysone in mice and rats

Phytoecdysteroids are molecules derived from sterol metabolism and found in many plants. They display a wide array of pharmacological effects on mammals (e.g. anabolic, anti-diabetic). Although these effects have been long established, the molecular targets involved remain to be identified. Like endogenous steroid hormones and bile acids, which are biochemically related, ingested or injected phytoecdysteroids undergo a set of reactions in mammals leading to the formation of numerous metabolites, only some of which have been so far identified, and it is presently unknown whether they represent active metabolites or inactivation products. In the large intestine, ecdysteroids undergo efficient 14-dehydroxylation. Other changes (reductions, epimerization, side-chain cleavage) are also observed, but whether these occur in the liver and/or large intestine is not known. The purpose of this study was to investigate the pharmacokinetics of 20-hydroxyecdysone (20E), the most common phytoecdysteroid, when administered to mice and rats, using, when required, tritium-labelled molecules to permit metabolic tracking. Bioavailability, the distribution of radioactivity and the kinetics of formation of metabolites were followed for 24-48 hours after ingestion and qualitative and quantitative analyses of circulating and excreted compounds were performed. In mice, the digestive tract always contains the majority of the ingested 20E. Within 30 min after ingestion, 20E reaches the large intestine, where microorganisms firstly remove the 14-hydroxyl group and reduce the 6-one. Then a very complex set of metabolites (not all of which have yet been identified) appears, which correspond to poststerone derivatives formed in the liver. We have observed that these compounds (like bile acids) undergo an entero-hepatic cycle, involving glucuronide conjugation in the liver and subsequent deconjugation in the intestine. Despite the very short half-life of ecdysteroids in mammals, this entero-hepatic cycle helps to maintain their plasma levels at values which, albeit low (≤0.2 μM), would be sufficient to evoke several pharmacological effects. Similar 20E metabolites were observed in mice and rats; they include in particular 14-deoxy-20E, poststerone and 14-deoxypoststerone and their diverse reduction products; the major products of this metabolism have been unambiguously identified. The major sites of metabolism of exogenous ecdysteroids in mammals are the large intestine and the liver. The entero-hepatic cycle contributes to the metabolism and to maintaining a low, but pharmacologically significant, concentration of ecdysteroids in the blood for ca. 24 h after ingestion. These data, together with parallel in vitro experiments provide a basis for the identification of 20E metabolite(s) possibly involved in the physiological effects associated with ecdysteroids in mammals.

Testing the efficacy and safety of BIO101, for the prevention of respiratory deterioration, in patients with COVID-19 pneumonia (COVA study): a structured summary of a study protocol for a randomised controlled trial

Objectives

As of December, 1^st, 2020, coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2, resulted in more than 1 472 917 deaths worldwide and death toll is still increasing exponentially. Many COVID-19 infected people are asymptomatic or experience moderate symptoms and recover without medical intervention. However, older people and those with comorbid hypertension, diabetes, obesity, or heart disease are at higher risk of mortality. Because current therapeutic options for COVID-19 patients are limited specifically for this elderly population at risk, Biophytis is developing BIO101 (20-hydroxyecdysone, a Mas receptor activator) as a new treatment option for managing patients with SARS-CoV-2 infection at the severe stage.

The angiotensin converting enzyme 2 (ACE2) serves as a receptor for SARS-CoV-2. Interaction between ACE2 and SARS-CoV2 spike protein seems to alter the function of ACE2, a key player in the renin-angiotensin system (RAS). The clinical picture of COVID-19 includes acute respiratory distress syndrome (ARDS), cardiomyopathy, multiorgan dysfunction and shock, all of which might result from an imbalance of the RAS. We propose that RAS balance could be restored in COVID-19 patients through MasR activation downstream of ACE2 activity, with 20-hydroxyecdysone (BIO101) a non-peptidic Mas receptor (MasR) activator. Indeed, MasR activation by 20-hydroxyecdysone harbours anti-inflammatory, anti-thrombotic, and anti-fibrotic properties. BIO101, a 97% pharmaceutical grade 20-hydroxyecdysone could then offer a new therapeutic option by improving the respiratory function and ultimately promoting survival in COVID-19 patients that develop severe forms of this devastating disease. Therefore, the objective of this COVA study is to evaluate the safety and efficacy of BIO101, whose active principle is 20-hydroxyecdysone, in COVID-19 patients with severe pneumonia.

Trial design

Randomized, double-blind, placebo-controlled, multi-centre, group sequential and adaptive which will be conducted in 2 parts.

Part 1:

Ascertain the safety and tolerability of BIO101 and obtain preliminary indication of the activity of BIO101, in preventing respiratory deterioration in the target population

Part 2:

Re-assessment of the sample size needed for the confirmatory part 2 and confirmation of the effect of BIO101 observed in part 1 in the target population.

The study is designed as group sequential to allow an efficient run-through, from obtaining an early indication of activity to a final confirmation. And adaptive – to allow accumulation of early data and adapt sample size in part 2 in order to inform the final design of the confirmatory part of the trial.

Participants

Inclusion criteria

Age: 45 and above

A confirmed diagnosis of COVID-19 infection, within the last 14 days, prior to randomization, as determined by PCR or other approved commercial or public health assay, in a specimen as specified by the test used.

Hospitalized, in observation or planned to be hospitalized due to COVID-19 infection symptoms with anticipated hospitalization duration ≥3 days

With evidence of pneumonia based on all of the following:

Clinical findings on a physical examination

Respiratory symptoms developed within the past 7 days

With evidence of respiratory decompensation that started not more than 4 days before start of study medication and present at screening, meeting one of the following criteria, as assessed by healthcare staff:

Tachypnea: ≥25 breaths per minute

Arterial oxygen saturation ≤92%

A special note should be made if there is suspicion of COVID-19-related myocarditis or pericarditis, as the presence of these is a stratification criterion

Without a significant deterioration in liver function tests:

ALT and AST ≤ 5x upper limit of normal (ULN)

Gamma-glutamyl transferase (GGT) ≤ 5x ULN

Total bilirubin ≤ 5×ULN

Willing to participate and able to sign an informed consent form (ICF). Or, when relevant, a legally authorized representative (LAR) might sign the ICF on behalf of the study participant

Female participants should be: at least 5 years post-menopausal (i.e., persistent amenorrhea 5 years in the absence of an alternative medical cause) or surgically sterile; OR

Have a negative urine pregnancy test at screening

Be willing to use a contraceptive method as outlined in inclusion criterion 9 from screening to 30 days after last dose.

Male participants who are sexually active with a female partner must agree to the use of an effective method of birth control throughout the study and until 3 months after the last administration of the investigational product.

(Note: medically acceptable methods of contraception that may be used by the participant and/or partner include combined oral contraceptive, contraceptive vaginal ring, contraceptive injection, intrauterine device, etonogestrel implant, each supplemented with a condom, as well as sterilization and vasectomy).10.

Female participants who are lactating must agree not to breastfeed during the study and up to 14 days after the intervention.

11.

Male participants must agree not to donate sperm for the purpose of reproduction throughout the study and until 3 months after the last administration of the investigational product.

12.

For France only: Being affiliated with a European Social Security.

Exclusion criteria

Not needing or not willing to remain in a healthcare facility during the study

Moribund condition (death likely in days) or not expected to survive for >7 days – due to other and non-COVID-19 related conditions

Participant on invasive mechanical ventilation via an endotracheal tube, or extracorporeal membrane oxygenation (ECMO), or high-flow Oxygen (delivery of oxygen at a flow of ≥16 L/min.).

Participant is not able to take medications by mouth (as capsules or as a powder, mixed in water).

Disallowed concomitant medication: Consumption of any herbal products containing 20-hydroxyecdysone and derived from Leuzea carthamoides; Cyanotis vaga or Cyanotis arachnoidea is not allowed (e.g. performance enhancing agents).

Any known hypersensitivity to any of the ingredients, or excipients of the study medication, BIO101.

Renal disease requiring dialysis, or known renal insufficiency (eGFR≤30 mL/min/1.73 m2, based on Cockcroft & Gault formula).

In France only:

Non-affiliation to compulsory French social security scheme (beneficiary or right-holder).

Being under tutelage or legal guardianship.

Participants will be recruited from approximately 30 clinical centres in Belgium, France, the UK, USA and Brazil. Maximum patients’ participation in the study will last 28 days. Follow-up of participants discharged from hospital will be performed through post-intervention phone calls at 14 (± 2) and 60 (± 4) days.

Intervention and comparator

Two treatment arms will be tested in this study: interventional arm 350 mg b.i.d. of BIO101 (AP 20-hydroxyecdysone) and placebo comparator arm 350 mg b.i.d of placebo. Administration of daily dose is the same throughout the whole treatment period. Participants will receive the study medication while hospitalized for up to 28 days or until a clinical endpoint is reached (i.e., ‘negative’ or ‘positive’ event). Participants who are officially discharged from hospital care will no longer receive study medication.

Main outcomes

Primary study endpoint:

The proportion of participants with ‘negative’ events up to 28 days.

‘Negative’ events are defined as respiratory deterioration and all-cause mortality. For the purpose of this study, respiratory deterioration will be defined as any of the following:

Requiring mechanical ventilation (including cases that will not be intubated due to resource restrictions and triage).

Requiring extracorporeal membrane oxygenation (ECMO).

Requiring high-flow oxygen defined as delivery of oxygen at a flow of ≥16 L/min.

Only if the primary endpoint is significant at the primary final analysis the following

Key secondary endpoints will be tested in that order:

Proportion of participants with events of respiratory failure at Day 28

Proportion of participants with ‘positive’ events at Day 28.

Proportion of participants with events of all-cause mortality at Day 28

A ‘positive’ event is defined as the official discharge from hospital care by the department due to improvement in participant condition.

Secondary and exploratory endpoints:

In addition, a variety of functional measures and biomarkers (including the SpO2 / FiO2 ratio, viral load and markers related to inflammation, muscles, tissue and the RAS / MAS pathways) will also be collected.

Randomization

Randomization is performed using an IBM clinical development IWRS system during the baseline visit. Block-permuted randomization will be used to assign eligible participants in a 1:1 ratio.

In part 1, randomization will be stratified by RAS pathway modulator use (yes/no) and co-morbidities (none vs. 1 and above).

In Part 2, randomization will be stratified by centre, gender, RAS pathway modulator use (yes/no), co-morbidities (none vs. 1 and above), receiving Continuous Positive Airway Pressure/Bi-level Positive Airway Pressure (CPAP/BiPAP) at study entry (Yes/No) and suspicion of COVID-19 related myocarditis or pericarditis (present or not).

Blinding (masking)

Participants, caregivers, and the study team assessing the outcomes are blinded to group assignment. All therapeutic units (TU), BIO101 b.i.d. or placebo b.i.d., cannot be distinguished in compliance with the double-blind process. An independent data-monitoring committee (DMC) will conduct 2 interim analyses. A first one based on the data from part 1 and a second from the data from parts 1 and 2. The first will inform about BIO101 safety, to allow the start of recruitment into part 2 followed by an analysis of the efficacy data, to obtain an indication of activity. The second interim analysis will inform about the sample size that will be required for part 2, in order to achieve adequate statistical power.

Numbers to be randomised (sample size)

Number of participants randomized: up to 465, in total

Part 1: 50 (to obtain the proof of concept in COVID-19 patients).

Part 2: 310, potentially increased by 50% (up to 465, based on interim analysis 2) (to confirm the effects of BIO101 observed in part 1).

Trial Status

The current protocol Version is V 10.0, dated on 24.09.2020. The recruitment that started on September 1^st 2020 is ongoing and is anticipated to finish for the whole study by March2021.

Trial registration

The trial was registered before trial start in trial registries: EudraCT, No. 2020-001498-63, registered May 18, 2020; and Clinicaltrials.gov, identifier NCT04472728, registered July 15, 2020.

Full protocol

The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-020-04998-5.

High Performance Thin-Layer Chromatography of Plant Ecdysteroids Coupled with Desorption Electrospray Ionisation–Ion Mobility–Time of Flight High Resolution Mass Spectrometry (HPTLC/DESI/IM/ToFMS)

The use of high performance thin-layer chromatography (HPTLC) in combination with high resolution time of flight mass spectrometry (MS) for the detection, identification and imaging (HPTLC/MSI) of ecdysteroids (insect moulting hormones) present in a number of plant extracts obtained from members of the Silene family is demonstrated. DESI is shown to be a convenient method for the recovery of these polar polyhydroxylated steroids from the silica gel of the HPTLC plate for subsequent MS detection and imaging. The incorporation of an ion mobility separation (IMS) to the system to give HPTLC/IMS/MS provided additional drift time data which enabled more confident identification. Using HPTLC/DESI/IMS/MS, a range of ecdysteroids were detected and characterized in extracts of S. otitis, S nutans, S. maritime, S. viridiflora and S. fimbriata.

The metabolism of 20-hydroxyecdysone in mice: relevance to pharmacological effects and gene switch applications of ecdysteroids

Ecdysteroids exert many pharmacological effects in mammals (including humans), most of which appear beneficial, but their mechanism of action is far from understood. Whether they act directly and/or after the formation of metabolites is still an open question. The need to investigate this question has gained extra impetus because of the recent development of ecdysteroid-based gene-therapy systems for mammals. In order to investigate the metabolic fate of ecdysteroids in mice, [1α,2α-(3)H]20-hydroxyecdysone was prepared and injected intraperitoneally to mice. Their excretory products (urine+faeces) were collected and the different tritiated metabolites were isolated and identified. The pattern of ecdysteroid metabolites is very complex, but no conjugates were found, in contrast to the classical fate of the (less polar) endogenous vertebrate steroid hormones. Primary reactions involve dehydroxylation at C-14 and side-chain cleavage between C-20 and C-22, thereby yielding 14-deoxy-20-hydroxyecdysone, poststerone and 14-deoxypoststerone. These metabolites then undergo several reactions of reduction involving, in particular, the 6-keto-group. A novel major metabolite has been identified as 2β,3β,6α,22R,25-pentahydroxy-5β-cholest-8(14)-ene. The formation of this and the other major metabolites is discussed in relation to the various effects of ecdysteroids already demonstrated on vertebrates.

Practical uses for ecdysteroids in mammals including humans: an update

Ecdysteroids are widely used as inducers for gene-switch systems based on insect ecdysteroid receptors and genes of interest placed under the control of ecdysteroid-response elements. We review here these systems, which are currently mainly used in vitro with cultured cells in order to analyse the role of a wide array of genes, but which are expected to represent the basis for future gene therapy strategies. Such developments raise several questions, which are addressed in detail. First, the metabolic fate of ecdysteroids in mammals, including humans, is only poorly known, and the rapid catabolism of ecdysteroids may impede their use as in vivo inducers. A second set of questions arose in fact much earlier with the pioneering "heterophylic" studies of Burdette in the early sixties on the pharmacological effects of ecdysteroids on mammals. These and subsequent studies showed a wide range of effects, most of them being beneficial for the organism (e.g. hypoglycaemic, hypocholesterolaemic, anabolic). These effects are reviewed and critically analysed, and some hypotheses are proposed to explain the putative mechanisms involved. All of these pharmacological effects have led to the development of a wide array of ecdysteroid-containing preparations, which are primarily used for their anabolic and/or "adaptogenic" properties on humans (or horses or dogs). In the same way, increasing numbers of patents have been deposited concerning various beneficial effects of ecdysteroids in many medical or cosmetic domains, which make ecdysteroids very attractive candidates for several practical uses. It may be questioned whether all these pharmacological actions are compatible with the development of ecdysteroid-inducible gene switches for gene therapy, and also if ecdysteroids should be classified among doping substances.

Practical uses for ecdysteroids in mammals including humans: an update

Ecdysteroids are widely used as inducers for gene-switch systems based on insect ecdysteroid receptors and genes of interest placed under the control of ecdysteroid-response elements. We review here these systems, which are currently mainly used in vitro with cultured cells in order to analyse the role of a wide array of genes, but which are expected to represent the basis for future gene therapy strategies. Such developments raise several questions, which are addressed in detail. First, the metabolic fate of ecdysteroids in mammals, including humans, is only poorly known, and the rapid catabolism of ecdysteroids may impede their use as in vivo inducers. A second set of questions arose in fact much earlier with the pioneering "heterophylic" studies of Burdette in the early sixties on the pharmacological effects of ecdysteroids on mammals. These and subsequent studies showed a wide range of effects, most of them being beneficial for the organism (e.g. hypoglycaemic, hypocholesterolaemic, anabolic). These effects are reviewed and critically analysed, and some hypotheses are proposed to explain the putative mechanisms involved. All of these pharmacological effects have led to the development of a wide array of ecdysteroid-containing preparations, which are primarily used for their anabolic and/or "adaptogenic" properties on humans (or horses or dogs). In the same way, increasing numbers of patents have been deposited concerning various beneficial effects of ecdysteroids in many medical or cosmetic domains, which make ecdysteroids very attractive candidates for several practical uses. It may be questioned whether all these pharmacological actions are compatible with the development of ecdysteroid-inducible gene switches for gene therapy, and also if ecdysteroids should be classified among doping substances.

Phytoecdysteroids from the juice of Serratula coronata L. (Asteraceae)

Seven phytoecdysteroids have been isolated from Serratula coronata L. One of them is a new phytoecdysteroid, 3-epi-20-hydroxyecdysone. Two further ecdysteroids, 20-hydroxyecdysone 22-acetate and taxisterone, are isolated from this species for the first time in addition to the typical S. coronata ecdysteroids, 20-hydroxyecdysone, ecdysone, ajugasterone C and polypodine B. The juice squeezed from aerial parts of fresh plants of S. coronata was extracted with ethyl acetate. The ecdysteroids were isolated by a combination of chromatographic techniques (mainly HPLC) and identified by 1D and 2D (1)H and (13)C NMR experiments and mass-spectrometry. The biological activities of 3-epi-20-hydroxyecdysone (EC(50)=1.6 x 10(-7) M), taxisterone (EC(50)=9.5 x 10(-8) M) and ajugasterone C (EC(50)=6.2 x 10(-8) M) have been determined in the Drosophila melanogaster B(II) bioassay for ecdysteroid agonist activity.

Chromatographic procedures for the isolation of plant steroids

In this review, we consider the general principles and specific methods for the purification of different classes of phytosteroids which have been isolated from plant sources: brassinosteroids, bufadienolides, cardenolides, cucurbitacins, ecdysteroids, steroidal saponins, steroidal alkaloids, vertebrate-type steroids and withanolides. For each class we give a brief summary of the characteristic structural features, their distribution in the plant world and their biological effects and applications. Most classes are associated with one or a few plant families, e.g., the withanolides with the Solanaceae, but others, e.g., the saponins, are very widespread. Where a compound class has been extensively studied, a large number of analogues are present across a range of species. We discuss the general principles for the isolation of plant steroids. The predominant methods for isolation are solvent extraction/partition followed by column chromatography and thin-layer chromatography/HPLC.

Identification and quantitative analysis of the phytoecdysteroids in Silene species (Caryophyllaceae) by high-performance liquid chromatography. Novel ecdysteroids from S. pseudotites

Many species in the genus Silene (Caryophyllaceae) have previously been shown to contain ecdysteroids and this genus is recognised as a good source of novel ecdysteroid analogues. We have used ecdysteroid-specific radioimmunoassays and the microplate-based Drosophila melanogaster B(II) cell bioassay for ecdysteroid agonist and antagonist activities to identify further phytoecdysteroid-containing species in this genus. The main ecdysteroid components from 10 Silene species (S. antirrhina, S. chlorifolia, S. cretica, S. disticha, S. echinata, S. italica, S. portensis, S. pseudotites, S. radicosa, S. regia) were isolated and identified, mainly by normal-phase and reversed-phase high-performance liquid chromatography. The amount of each ecdysteroid was determined by comparing chromatogram peak areas with those for reference 20-hydroxyecdysone (20E) on reversed-phase HPLC. 20E is the most abundant ecdysteroid in each of the Silene extracts. Polypodine B, 2-deoxy-20-hydroxyecdysone and ecdysone are also common ecdysteroids in these Silene species, but the proportions of these ecdysteroids vary between the Silene species. HPLC proved to be a quick and effective way to screen Silene species, determine ecdysteroid profiles and, hence, identify extracts containing novel analogues. An extract of the aerial parts of S. pseudotites was found to contain several new ecdysteroids. These have been isolated and identified spectroscopically (by NMR and mass spectrometry) as 2-deoxyecdysone 22beta-D-glucoside, 2-deoxy-20,26-dihydroxyecdysone and 2-deoxypolypodine B 3beta-D-glucoside. Additionally, (5alpha-H)-2-deoxyintegristerone A (5alpha-2H 91%, 5alpha-1H 9%) was isolated as an artefact. This study contributes to the understanding of ecdysteroid distribution in Silene species and provides further information on the chemotaxonomic significance of ecdysteroids in Silene species.

[Structural diversity of ecdysteroids of Lychnis flos-cuculi]

Eleven ecdysteroids have been isolated from Lychnis floscuculi; we are the first who report eight ecdysteroids of the eleven compounds in this plant. Two of these ecdysteroids, dihydrorubrosterone and 20-hydroxyecdysone 3-acetate are newly discovered natural products. The success of isolation of these new ecdysteroids has been based on the use of separation methods in a proper order; these separation procedures were completing each others. At the beginning steps of isolation simple separation methods were used, such a solvent-solvent distribution and fractionated precipitation. Two third of the contaminants were removed thereby. High capacity low resolution methods were used then, such as classical adsorption column chromatography and preparative thin-layer chromatography. The major component (20-hydroxyecdyssone) and certain minor ecdysteroids (polypodine B and rubrosterone) were isolated in pure form here. Purification of the further minor components (poststerone, 2-deoxy-20-hydroxyecdysone, vitikosterone E, dihydrorubrosterone, makisterone A, taxisterone, 20-hydroxyecdysone 2-acetate, 20-hydroxyecdysone 3-acetate) required HPLC and other absorption chromatographic methods. Our recent separation scheme means a generally applicable guiding principle for isolation of any plant ecdysteroid, major and minor alike. Structural identification of the known ecdysteroids was based on their spectral data and that of their literature information. Structural elucidation of 20-hydroxyecdysone 3-acetate was done by the help of a standard component prepared by acetylation of 20-hydroxyecdysone. From the mixture of seven acetates the corresponding compound (20-hydroxyecdysone 3-acetate) was isolated, and used for identification. Structural diversity of ecdysteroids of Lychnis flos-cuculi is evaluated, and a tentative explanation is introduced for the formation and biosynthesis of the versatility of phytoecdysteroids.

Sub-ambient temperature effects on the separation of monosaccharides by high-performance anion-exchange chromatography with pulse amperometric detection. Application to marine chemistry

The effects of column temperature in the range 10-45 degrees C using high-performance anion-exchange chromatography (HPAEC) and pulse amperometric detection are described for the determination of monosaccharides. The influence of temperature was tested with an isocratic elution of NaOH at concentrations varying from 2.5 to 20 mM and with a post-column addition of 1 M NaOH. The results showed that small changes of temperature greatly affect retention times and resolution (Rs) of monosaccharides and particularly those of the both pairs xylose-mannose and rhamnose-arabinose which cannot be simultaneously detected at usual room temperature (approximately 25 degrees C). Our results suggest that a subambient temperature of 17 degrees C and an eluent concentration of 19 mM are the more appropriate conditions for an acceptable separation (R(s rha/ara) = 1.02, R(s man/xyl) = 0.70) in a short analytical run time (35 min). The results showed that within the range of temperatures studied, enthalpy and entropy are invariant of temperature indicating that changes in the retention processes are mainly due to temperature than other associated changes in the system. This study demonstrated the importance of controlling temperature during HPAEC of monosaccharides, both to accomplish highly reproducible retention times and to achieve optimal separation of sugars. This method gave acceptable results for detection of marine sugars.

Molecular cloning of a novel crustacean member of the aldoketoreductase superfamily, differentially expressed in the antennal glands

Biochemical studies on ecdysteroid metabolism in arthropods suggest that aldoketoreductase enzymes (AKRs) may be involved in this pathway, but very few molecular data are available on these oxidoreductases in invertebrates. Looking for such enzymes in the crayfish Orconectes limosus, we have used a PCR strategy with primers deduced from a recent insect 3beta-reductase sequence, and from mammalian 5beta-reductase sequences. A full-length cDNA, corresponding to a putative AKR, was isolated from crayfish antennal gland. This cDNA contains an open-reading frame of 1008 bp, encoding a predicted protein of 336 amino acids. Northern blots indicated a restricted expression of the transcript in the antennal glands, quite constant during the molting cycle, and in situ hybridization demonstrated a strong expression of the transcript in the labyrinth. This is to date the first member of the AKRs superfamily characterized in a crustacean species, and the putative function of the corresponding enzyme is discussed.

Spectroscopic characterisation and identification of ecdysteroids using high-performance liquid chromatography combined with on-line UV--diode array, FT-infrared and 1H-nuclear magnetic resonance spectroscopy and time of flight mass spectrometry

A prototype multiply hyphenated reversed-phase HPLC system has been applied to the analysis of a mixture of pure ecdysteroids and an ecdysteroid-containing plant extract. Characterisation was achieved via a combination of diode array UV, 1H NMR, FT-IR spectroscopy and time of flight (TOF) mass spectrometry. This combination of spectrometers allowed the collection of UV, 1H NMR, IR and mass spectra for a mixture of pure standards enabling almost complete structural characterisation to be performed. The technique was then applied to a partially purified plant extract in which 20-hydroxyecdysone and polypodine B were identified despite incomplete chromatographic resolution and the presence of co-chromatographing interferents. The experimental difficulties in the use of such a systems for these analytes are described.

Isolation of 5 alpha- and 5 beta-dihydrorubrosterone from Silene otites L. (Wib)

5 alpha-Dihydrorubrosterone (2 beta, 3 beta, 14 alpha, 17 beta-tetrahydroxy-5 alpha-androst-7-ene-6-one), a new 19-carbon 5 alpha-ecdysteroid, was isolated together with its 5 beta counterpart from the aerial parts of Silene otites L. (Wib.) (Caryophyllaceae) by a combination of solvent partition, low-pressure column chromatography, thin-layer chromatography (normal-phase and reversed-phase) and finally HPLC. Mass spectrometry and nuclear magnetic resonance spectroscopic procedures were used for compound characterization.

Sileneoside H, a new phytoecdysteroid from Silene brahuica

Sileneoside H (1), a new phytoecdysteroid, has been isolated from the roots of Silene brahuica and identified as 22-O-alpha-D-galactosylintegristerone A 25-acetate by MS and NMR analysis.

Biotransformations of putative phytoecdysteroid biosynthetic precursors in tissue cultures of Polypodium vulgare

Incubation of calli and prothalli of Polypodium vulgare with different tritium-labelled ecdysteroids has led to modification of some previous assumptions about the biosynthesis of ecdysteroids in plants. Thus, 25-deoxy-20-hydroxyecdysone was transformed efficiently in both tissues into 20-hydroxyecdysone (20E), but no 25-deoxyecdysteroids such as pterosterone and inokosterone were formed. Likewise, incubation of 2-deoxyecdysone (2dE) produced exclusively ecdysone (E) and 20E, indicating a high 2-hydroxylase activity in both tissues, despite calli not producing phytoecdysteroids. This 2-hydroxylation was also evident in the transformation of 2,22-dideoxyecdysone (2,22dE) into 22-deoxyecdysone (22dE). Different ecdysteroids that do not occur in P. vulgare were formed in the incubation of 3-dehydro-2,22,25-trideoxyecdysone (3D2,22,25dE) by 3alpha-reduction and 3beta-reduction and 25-hydroxylation processes. The fact that 22,25-dideoxyecdysone and 22dE were the only 2-hydroxylated products formed in this case suggests that only compounds bearing a 3beta-hydroxyl group are substrates for the 2-hydroxylase. Surprisingly, 22-hydroxylation was never observed with either 2,22dE or 3D2,22,25dE, raising the possibility that it could occur at an early step in the biosynthetic pathway. In this respect, labelled 22R-hydroxycholesterol was efficiently converted into E and 20E, whereas 22S-hydroxycholesterol was not transformed into ecdysteroids, because of its unsuitable configuration at C22. Finally, the conversion of 25-hydroxycholesterol into E and 20E was greatly enhanced after thermal treatment of prothalli which induces the release of previously stored ecdysteroids. Thus, P. vulgare prothalli and calli appear to be particularly suitable models for the study of ecdysteroid biosynthesis and its regulation in plants.

Cloning of a novel cytochrome P450 (CYP4C15) differentially expressed in the steroidogenic glands of an arthropod

Biosynthesis of ecdysteroids, arthropod steroid molting hormones, proceeds from dietary cholesterol through a complex and still incompletely elucidated pathway. Most of the known steps are catalyzed by cytochrome P450 enzymes (CYPs) but none of their genes has yet been identified. We have established a cDNA library of crayfish steroidogenic glands (Y organs). A full length CYP-cDNA was characterized containing a 1539 bp open reading frame encoding a predicted protein of 513 amino acid residues. This novel CYP was assigned to the CYP4 family and designated CYP4C15. Northern blots demonstrated predominant expression of this gene in the active molting glands, suggesting a role in ecdysteroid biosynthesis rather than detoxification.

Improvement in the Iatroscan thin-layer chromatographic-flame ionisation detection analysis of marine lipids. Separation and quantitation of monoacylglycerols and diacylglycerols in standards and natural samples

Mono- and diacylglycerols are important intermediates in glycerolipid biodegradation and intracellular signalling pathways. A method for mass determination of these lipid classes in marine particles was developed using the Iatroscan, which combines thin layer chromatography (TLC) and flame ionisation detection (FID) techniques. We improved existing protocols by adding two elution steps: hexane-diethyl-ether-formic acid (70:30:0.2, v/v/v) after triacylglycerol and free fatty acid scan, and acetone 100% followed by chloroform-acetone-formic acid (99:1:0.2, v/v/v) after 1,2 diacylglycerols. Diacylglycerol isomers 1,2 and 1,3 were separated from each other, as well as from free sterols in standards and marine lipids from sediment trap particles. Monoacylglycerols were separated from pigments and galactosyl-lipids in the same trap samples and in a rich pigment phytoplankton extract of Dunaliella viridis. Quantitation of each class in samples was performed after calibration with 0.5 to 2 micrograms of standards. As many as 17 lipid classes can be identified and quantified in samples using this proposed six-step development.

Isolation and Structural Elucidation of Two Plant Ecdysteroids, Gerardiasterone and 22-Epi-20-hydroxyecdysone

Two minor plant ecdysteroids, 22-epi-20-hydroxyecdysone (1) and gerardiasterone (2), were isolated from Serratula tinctoria L. (Compositae). The first compound, a new natural product, was characterized by an unusual stereochemistry at C-22 (i.e., 22S). The second compound was identified as (20R,23S)-20,23-dihydroxyecdysone, a compound previously isolated from the Zooanthid Gerardia savaglia.

Cucurbitacins are insect steroid hormone antagonists acting at the ecdysteroid receptor

Two triterpenoids, cucurbitacins B and D, have been isolated from seeds of Iberis umbellata (Cruciferae) and shown to be responsible for the antagonistic activity of a methanolic extract of this species in preventing the 20-hydroxyecdysone (20E)-induced morphological changes in the Drosophila melanogaster BII permanent cell line. With a 20E concentration of 50 nM, cucurbitacins B and D give 50% responses at 1.5 and 10 microM respectively. Both cucurbitacins are able to displace specifically bound radiolabelled 25-deoxy-20-hydroxyecdysone (ponasterone A) from a cell-free preparation of the BII cells containing ecdysteroid receptors. The Kd values for cucurbitacins B and D (5 and 50 microM respectively) are similar to the concentrations required to antagonize 20E activity with whole cells. Cucurbitacin B (cucB) prevents stimulation by 20E of an ecdysteroid-responsive reporter gene in a transfection assay. CucB also prevents the formation of the Drosophila ecdysteroid receptor/Ultraspiracle/20E complex with the hsp27 ecdysteroid response element as demonstrated by gel-shift assay. This is therefore the first definitive evidence for the existence of antagonists acting at the ecdysteroid receptor. Preliminary structure/activity studies indicate the importance of the Delta23-22-oxo functional grouping in the side chain for antagonistic activity. Hexanorcucurbitacin D, which lacks carbon atoms C-22 to C-27, is found to be a weak agonist rather than an antagonist. Moreover, the side chain analogue 5-methylhex-3-en-2-one possesses weak antagonistic activity.

New minor ecdysteroids from Silene otites (L.) Wib

Six minor new ecdysteroid components have been isolated from Silene otites (L.) Wib. by a combination of chromatographic methods. Three of them (2-deoxy-20-hydroxyecdysone 3,22-diacetate, 5 alpha-2-deoxy-20-hydroxyecdysone 3-acetate, and 2-deoxy-20-hydroxyecdysone 3-crotonate) are new natural products.

24(24(1))[Z]-dehydroamarasterone B, a phytoecdysteroid from seeds of Leuzea carthamoides

A new phytoecdysteroid, 24(24(1))[Z]-dehydroamarasterone B, has been isolated from seeds of Leuzea (Rhaponticum) carthamoides. It has been unambiguously identified by CIMS, 13C NMR and 1H NMR spectroscopy. The biological activity of the ecdysteroid has been determined in the Drosophila melanogaster BII bioassay. The ED50 (5.2 x 10(-7) M) is 70-fold higher than that for 20-hydroxyecdysone (7.5 x 10(-9) M).

Action of different ecdysteroids on the regulation of mRNAs for the ecdysone receptor, MHR3, dopa decarboxylase, and a larval cuticle protein in the larval epidermis of the tobacco hornworm, Manduca sexta

To determine which ecdysteroids may be biologically active in the larval epidermis of the tobacco hornworm, Manduca sexta, we studied the action of several known ecdysteroids and metabolites on the expression of the genes encoding the ecdysone receptor (EcR), Manduca hormone receptor 3 (MHR3), dopa decarboxylase (DDC), and a larval cuticle protein (LCP-14). Both Day 2 fourth- and Day 2 fifth-instar larval epidermis contained significant 3 beta-reductase activity which metabolized 3-dehydroecdysone (3DE) and 3-dehydro-20-hydroxyecdysone (3D20E) to ecdysone (E) and 20-hydroxyecdysone (20E), respectively, but had only very low amounts of ecdysone oxidase activity (E to 3DE) and no detectable ecdysone 20-monooxygenase activity (E to 20E). When the expression of the various genes was studied in the epidermis in vitro, 20E and 3D20E had similar effects, whereas E, 3DE, 26-hydroxyecdysone and 20,26-dihydroxyecdysone were ineffective. Exposure of Day 2 fifth-instar epidermis to 500 ng/ml of either 20E or 3D20E for 24 hr caused a rapid, biphasic increase in EcR-B1 mRNA. By contrast, EcR-A mRNA showed a less rapid initial increase followed by a slow steady rise and was less responsive to 3D20E. Ecdysone in a 1:1 mixture with 20E effectively halved the concentration of 20E needed to induce EcR-B1 mRNA but showed no synergism in the induction of EcR-A mRNA. The induction of MHR3 mRNA and of DDC mRNA in Day 2 fourth-instar epidermis as well as the suppression of DDC and LCP-14 gene expression by 3D20E was indistinguishable from that of 20E. Therefore, for Manduca larval epidermis, only 20E and 3D20E are biologically active ecdysteroids. Since the 3D20E can be converted to 20E by the epidermis, its effects are likely mediated by 20E.

Involvement of a 3beta-hydroxysteroid dehydrogenase activity in ecdysteroid biosynthesis

Ecdysteroid biosynthesis was analyzed in vitro using dissociated Y-organ cells from the shore crab Carcinus maenas. 3-Dehydroecdysone (3DE) was detected as a minor secretory product, in addition to the formerly identified end-products 25-deoxyecdysone and ecdysone (E). In conversion studies, 3DE was formed from tritiated 5beta-ketodiol (2,22,25-trideoxyecdysone), 2,22-deoxyecdysone and 2-deoxyecdysone but not from E. Further experiments were performed in order to understand the interconversions between 3-oxo and 3beta-OH compounds in the crab Y-organ. The enzyme involved in 3beta-dehydrogenation was not ecdysone oxidase, a soluble enzyme found in peripheral tissues of many arthropods but it presented strong similarities with 3beta-hydroxysteroid dehydrogenase enzymes from vertebrates: it was membrane-bound and NAD+-dependent. Moreover, a NADH-dependent 3beta-reduction of several 3-oxo-ecdysteroids was obtained using the same microsomal fraction (100,000 x g pellet) of Y-organs, indicating that the reaction might be reversible. As this activity was specific of molting glands, we hypothesize that there is at least one 3beta-hydroxysteroid dehydrogenase enzyme involved in the biosynthetic pathway of ecdysteroids.

Evidence for the involvement of 3-oxo-delta 4 intermediates in ecdysteroid biosynthesis

Although the involvement of 3-oxo-delta 4 compounds as intermediates in arthropod ecdysteroid biosynthesis has been postulated for a long time, it has not yet been directly demonstrated. In the present study, 3-oxo-delta 4-steroids have been synthesized and incubated in vitro with dissociated moulting gland cells from the crab Carcinus maenas. The tritiated compounds were converted into 3-dehydroecdysone, ecdysone and/or 25-deoxyecdysone, i.e. final ecdysteroids. This means that the 3-oxo-delta 4 compounds had undergone a 5 beta-reduction, to give the 5 beta-conformation of ecdysteroids. Our results suggest that the 3-oxo-delta 4-steroid 4,7-cholestadien-14 alpha-ol-3,6-dione may be an intermediate in the biosynthetic pathway. The 5 beta-reduction reaction involves a cytosolic enzyme which requires NADPH as electron donor and seems specific for 3-oxo-delta 4 substrates. This reaction was the most active in crab Y-organs, as compared with other tissues. The characteristics of the 5 beta-reductase (subcellular localization, substrate and cofactor requirements) appear similar to those of the vertebrate 3-oxo-delta 4-steroid 5 beta-reductase involved in steroid hormone catabolism and bile acid biosynthesis.

Immunohistochemical and biochemical analyses of 20,000-25,000-year-old fossil cartilage

A cracked, irregular pellicle adhering to fossilized bone excavated from the Enlène cave (Ariège) and estimated to date from 20,000-25,000 years BP was examined to verify its cartilaginous nature, suggested previously on the basis of optical and electron microscopic investigations. Immunolabeling of the organic component revealed the presence of type II and IX collagens, associated with residual glycosaminoglycans, in the external zone of the pellicle. The cartilaginous nature of the pellicle was also demonstrated by biochemical identification of type II collagen as the major protein in the demineralized sample: the amino acid compositions of insoluble and soluble fractions were similar to that of pure type II collagen; cyanogen-bromide-generated peptides, prepared after reduction of the sample, had an electrophoretic pattern similar to that of cyanogen bromide peptides derived from type II collagen. The amino acid sequences of four tryptic peptides were identical to the corresponding human type II sequences. It was impossible to isolate intact alpha chains. All of the solubilized fractions were composed of a wide range of low-molecular-mass peptides demonstrating significant degradation of the collagen molecules that was not reflected in the well-preserved fibrillar structure observed at the ultrastructural level. The mineral fraction, characterized by X-ray diffraction, consisted of apatite (as in sub-chondral bone) associated with contaminating poorly crystallized components originating from the cave sediment. Energy dispersive spectrometry showed that the cartilaginous zone contained three times less phosphorus and calcium than the underlying bone. These results confirm the cartilaginous nature of the sample and the preservation of tissue-specific components, and suggest that the process of fossilization is closely related to a mechanism of phosphatization.

Effects of ingested phytoecdysteroids in the female soft tick Ornithodoros moubata

The effects of the ingestion of some phytoecdysteroids were studied in the soft tick Ornithodoros moubata. Supernumerary moulting and malformations of first leg pairs were obtained with 22-oxo-20-hydroxy-ecdysone, 20-hydroxyecdysone-22-acetate, and 20-hydroxyecdysone-22-benzoate. Egg-yield was reduced with 20-hydroxyecdysone-22-acetate and carthamosterone. Finally, drying-out of eggs was observed with carthamosterone and 22-deoxy-20,26-dihydroxyecdysone. In addition, we demonstrated that there is a correlation between the number of completed gonotrophic cycles and the impossibility of inducing supernumerary moulting.

A convenient synthesis of 25-deoxyecdysone, a major secretory product of crustacean Y-organs and of 2,25-dideoxyecdysone, its putative immediate precursor

25-Deoxyecdysone, a major secretory product of Y-organs of at least several species of crustaceans and the immediate precursor of circulating ponasterone A in these animals, can easily be synthesized from ecdysone. The present four-step procedure involves the formation of a mixture of delta 24,25 and delta 25,26 intermediates which might also be used to prepare a labeled reference compound for metabolic or binding studies. Similarly, 2,25-dideoxyecdysone was prepared from 2-deoxyecdysone. These compounds have been used to identify metabolites of [3H]-2,22,25-trideoxyecdysone (= 5 beta-ketodiol) formed by Y-organs of the shore crab, Carcinus maenas.

What are the origins of ecdysteroids in gastropods?

Terrestrial gastropods contain ecdysteroids, the origins of which are unknown. Whether they are synthesized by the animals or they arise from the diet is an open question. To address this problem, labeled cholesterol and various molecules which are efficiently converted into ecdysone by arthropods were tested as possible ecdysone precursors in Stylommatophra (gastropods). None of these experiments led to ecdysone biosynthesis and although snails and slugs were shown to contain some of the enzymes required for a biosynthetic pathway (i.e., a 3-oxoecdysteroid 3 beta-reductase, a 25-hydroxylase, and a 20-hydroxylase), no 2-hydroxylase and 22-hydroxylase activity could be detected. An endogenous origin would imply that Stylommatophora use a biosynthetic pathway different from that of insects. A dietary origin for ecdysteroids is also possible since, when ingested, these molecules remain in animals for several days and undergo limited metabolic conversion.

Evidence for a conformational polymorphism of invertebrate neurohormones. D-amino acid residue in crustacean hyperglycemic peptides

Several large peptidic neurohormones have been isolated in crustaceans. In lobster and other related species, each of these neurohormones, and particularly the crustacean hyperglycemic hormone, occurs as two isoforms having the same peptidic sequence and molecular mass. We report here that these isoforms differ by the configuration of a single amino acid residue. The third residue (Phe3) of the lobster hyperglycemic hormones is in either the L- or D-configuration. In addition, we have shown that the biological activity of the two isoforms differs when considering the kinetics of their hyperglycemic effect.

Metabolism of ecdysone and 20-hydroxyecdysone in adult Drosophila melanogaster

The metabolism of [3H]ecdysone injected into adult female and male Drosophila melanogaster was investigated. The metabolites present in flies and faeces were analysed separately after incubation times of 1, 2 or 4 h. In female flies ecdysone-22-fatty acid acyl esters were the major metabolites followed by 3-dehydroecdysone, 26-hydroxyecdysone, ecdysonoic acid, 20-hydroxyecdysone and a negatively charged conjugate of ecdysone. In male flies the same compounds were formed, but their relative concentrations were somewhat different from those in female flies. All metabolites formed can be excreted. [3H]20-hydroxyecdysone was metabolized in much the same way: 20-hydroxyecdysone-22-acyl esters, 3-dehydro-20-hydroxyecdysone, 20-hydroxy-ecdysonoic acid and a negatively charged conjugate of 20-hydroxyecdysone were formed. However, 20,26-dihydroxyecdysone could not be detected after injection of [3H]20-hydroxyecdysone.

New Ecdysteroids from Serratula tinctoria

Six new ecdysteroids have been isolated from SERRATULA TINCTORIA; these are: the 2,22- and 3,22-diacetates of 20-hydroxyecdysone, 5beta-hydroxyrubrosterone, 3-epi-poststerone, 3-epi-rubrosterone, and 22-oxo-20-hydroxyecdysone. These minor compounds were found together with the known ecdysteroids, 20-hydroxyecdysone, its 2-, 3-, and 22-monoacetates, rubrosterone, poststerone, polypodine B (5beta,20-dihydroxyecdysone), pterosterone (25-deoxy-20,24-dihydroxyecdysone), and makisterone C (24-ethyl-20-hydroxyecdysone). All these ecdysteroids were isolated by a combination of several chromatographic techniques (liquid chromatography on alumina, DCCC, and HPLC), then identified using standard mass spectrometric and 2D (1)H-NMR techniques.

Stimulated production of ATP by H2O2 disproportionation in extracts from normal and xeroderma pigmentosum skins, and from normal, xeroderma pigmentosum, ataxia telangiectasia and simian virus 40 transformed cell lines

It has been previously shown that xeroderma pigmentosum (XP) skin biopsies and their established cell lines exhibit a decrease in catalase activity and enhanced formation of photo-produced H2O2. Several in vivo and in vitro thermodynamic results suggest that the energy of H2O2 disproportionation produced by catalase could be sufficient to synthesize ATP with or without the help of intact mitochondria. In this paper, we first studied the properties of H2O2-stimulated ATP production in extracts of normal and pathological XP skin biopsies and cell lines. In acellular extracts of normal skin biopsies and/or cell lines, ATP production can be increased 2- to 3-fold, but only with a narrow range of H2O2 concentration. In contrast, in extracts of pathological skins or cells, ATP production was only observed when using 10- to 1000-fold less H2O2 concentration as defined for normal extracts. Similar results were noted with two cell lines derived from patients afflicted with ataxia telangiectasia (AT), and with simian virus 40 (SV40) transformed lines of normal, XP and AT cells, Although we have no proof that such a process may exist in vivo, we would like to suggest that both H2O2-stimulated ATP production and catalase activity are good indicators of the degree of normality or abnormality of skin biopsies and/or cell lines.

Ecdysone catabolism in the white mouse

Ecdysone metabolism was investigated in the white mouse Mus musculus. It was shown to involve dehydroxylation at C-14, followed by reduction of ring B into a 6 alpha-hydroxy derivative and epimerization at C-3.