MS-BACL: enhancing metabolic stability prediction through bond graph augmentation and contrastive learning.

MOTIVATION: Accurately predicting molecular metabolic stability is of great significance to drug research and development, ensuring drug safety and effectiveness. Existing deep learning methods, especially graph neural networks, can reveal the molecular structure of drugs and thus efficiently predict the metabolic stability of molecules. However, most of these methods focus on the message passing between adjacent atoms in the molecular graph, ignoring the relationship between bonds. This makes it difficult for these methods to estimate accurate molecular representations, thereby being limited in molecular metabolic stability prediction tasks. RESULTS: We propose the MS-BACL model based on bond graph augmentation technology and contrastive learning strategy, which can efficiently and reliably predict the metabolic stability of molecules. To our knowledge, this is the first time that bond-to-bond relationships in molecular graph structures have been considered in the task of metabolic stability prediction. We build a bond graph based on 'atom-bond-atom', and the model can simultaneously capture the information of atoms and bonds during the message propagation process. This enhances the model's ability to reveal the internal structure of the molecule, thereby improving the structural representation of the molecule. Furthermore, we perform contrastive learning training based on the molecular graph and its bond graph to learn the final molecular representation. Multiple sets of experimental results on public datasets show that the proposed MS-BACL model outperforms the state-of-the-art model. AVAILABILITY AND IMPLEMENTATION: The code and data are publicly available at https://github.com/taowang11/MS.

A cane toad (Rhinella marina) N-methyltransferase converts primary indolethylamines to tertiary psychedelic amines.

Psychedelic indolethylamines have emerged as potential medicines to treat several psychiatric pathologies. Natural sources of these compounds include 'magic mushrooms' (Psilocybe spp.), plants used to prepare ayahuasca, and toads. The skin and parotid glands of certain toads accumulate a variety of specialized metabolites including toxic guanidine alkaloids, lipophilic alkaloids, poisonous steroids, and hallucinogenic indolethylamines such as DMT, 5-methoxy-DMT, and bufotenin. The occurrence of psychedelics has contributed to the ceremonial use of toads, particularly among Mesoamerican peoples. Yet, the biosynthesis of psychedelic alkaloids has not been elucidated. Herein, we report a novel indolethylamine N-methyltransferase (RmNMT) from cane toad (Rhinella marina). The RmNMT sequence was used to identify a related NMT from the common toad, Bufo bufo. Close homologs from various frog species were inactive, suggesting a role for psychedelic indolethylamine biosynthesis in toads. Enzyme kinetic analyses and comparison with functionally similar enzymes showed that recombinant RmNMT was an effective catalyst and not product inhibited. The substrate promiscuity of RmNMT enabled the bioproduction of a variety of substituted indolethylamines at levels sufficient for purification, pharmacological screening, and metabolic stability assays. Since the therapeutic potential of psychedelics has been linked to activity at serotonergic receptors, we evaluated binding of derivatives at 5-HT1A and 5-HT2A receptors. Primary amines exhibited enhanced affinity at the 5-HT1A receptor compared with tertiary amines. With the exception of 6-substituted derivatives, N,N-dimethylation also protected against catabolism by liver microsomes.

Design, synthesis and evaluate of indazolylaminoquinazoline derivatives as potent Tropomyosin receptor kinase (TRK) inhibitors.

Tropomyosin receptor kinases (TRKs), the superfamily of transmembrane receptor tyrosine kinases, have recently become an attractive method for precision anticancer therapies since the approval of Larotrectinib and Entrectinib by FDA. Herein, we reported the discovery of a series of novel indazolylaminoquinazoline and indazolylaminoindazole as TRK inhibitors. The representative compound 30f exhibited good inhibitory activity against TRKWT, TRKG595R and TRKG667C with IC50 values of 0.55 nM, 25.1 nM and 5.4 nM, respectively. The compound also demonstrated potent superior to Larotrectinib antiproliferative activity against a panel of Ba/F3 cell lines transformed with both NTRK wild type and mutant fusions (IC50 = 10-200 nM). In addition, compound 30f exhibited good in vitro metabolic stability (T1/2 = 73.0 min), indicating that the quinazoline derivatives may have better metabolic stability. Finally, the binding mode of compound 30f predicted by molecular docking well explained the good enzyme inhibitory activity of indazolylaminoquinazoline compounds as TRK inhibitor. Thus, compound 30f can be used as a promising lead molecule for further structural optimization.

PI3Kδ and mTOR dual inhibitors: Design, synthesis and anticancer evaluation of 3-substituted aminomethylquinoline analogues.

Phosphatidylinositide-3-kinase (PI3K) and the mammalian target of rapamycin (mTOR) have recently been identified as potential cancer targets. In our work, a new family of quinoline analogues was designed, developed, and evaluated as dual inhibitors of PI3Kδ/mTOR. The preliminary biological activity analysis led to the discovery of the lead compounds 5h and 5e. Compounds 5h and 5e exhibited excellent anti-tumor potency with IC50 of 0.26 µM and 0.34 µM against Ramos cells, respectively. Importantly, based on the enzymatic activity assay results, compounds 5h and 5e were identified as dual inhibitors of PI3Kδ and mTOR, with IC50 values of 0.042 µM and 0.056 µM for PI3Kδ and 0.059 µM and 0.073 µM for mTOR, respectively. Furthermore, these compounds showed superior selectivity for blocking PI3Kδ compared to other PI3K isoforms (α, ß, and γ), supporting the concept of developing inhibitors that specifically target PI3Kδ/mTOR. The most effective compound 5h was chosen for additional biological testing. At a low dose of 0.5 µM, a western blot investigation confirmed the anticancer effects by inhibiting the PAM cascade, which in turn reduced downstream biomarkers pAkt (Ser473), pAkt (Thr308), and pRPS6 (Ser235/236). Furthermore, it increased apoptosis at the early (10.03 times) and late (17.95 times) stages in the Annexin-V assay as compared to the standard. In addition, the expression of p53, caspase-3, caspase-9, and the Bax/BCl-2 ratio were all significantly increased by compound 5h in the ELISA assay. Based on these results, it appears that 5h may activate the intrinsic apoptosis pathway, which in turn triggers cell death. Furthermore, the anticancer effects could be attributed to the inhibition of PI3Kδ/mTOR, as shown by docking interactions. Lastly, it demonstrated improved in vitro metabolic stability and passed the in silico ADMET/drug-likeness test. This profile recommends 5h for future in vivo PK-PD and efficacy investigations in animal cancer models.

The new N2, N4-diphenylpyridine-2,4-diamine deuterated derivatives as EGFR inhibitors to overcome C797S-mediated resistance.

A series of new deuterated and non-deuterated N2, N4-diphenylpyridine - 2,4-diamine derivatives were synthesized and evaluated as EGFR C797S-mediated resistance inhibitors. Most of these compounds exhibited potent antiproliferative activity against Baf3-EGFR L858R/T790M/C797S and Baf3-EGFR Del19/T790M/C797S cancel cell lines, with IC50 values in the nanomolar concentration range. Among them, compound 14l represented the most active compound with IC50 values of 8-11 nM. Interestingly, metabolic stability assay with rat liver microsomes indicated that the half-life of the deuterated derivative 14o was significantly increased compared to that of 14l. In xenograft mice models, 14o inhibited tumor growth with excellent inhibitory rate of 75.1 % at the dosage of 40 mg/kg, comparing 73.2 % of the TGI with its non-deuterated compound 14l, at a dosage of 80 mg/kg. Mechanism studies revealed that 14o was a potent EGFR L858R/T790M/C797S and EGFR Del19/T790M/C797S kinase inhibitor, which could downregulate the protein phosphorylation of EGFR and m-TOR signaling pathways, arrest cell cycle at G2/M phase by affecting the expression of CDC25C, and promote cell apoptosis by regulating the expression of cleaved caspase-3. In summary, 14o could serve as a promising deuterated compound for the development of highly efficient anticancer agents.

An ultra-fast green ultra-high-performance liquid chromatography-tandem mass spectrometry method for estimating the in vitro metabolic stability of zotizalkib in human liver microsomes.

Zotizalkib (ZTK, TPX-0131) is a fourth-generation highly effective inhibitor of wild-type anaplastic lymphoma kinase (ALK) and ALK-resistant mutations that can penetrate the central nervous system. It exhibited greater potency compared to all five officially approved ALK inhibitors. The aim of this study was to develop a rapid, accurate, eco-friendly, and highly sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for measuring the concentration of ZTK in human liver microsomes (HLMs). The validation aspects of the current UHPLC-MS/MS methodology in the HLMs were conducted in accordance with the bioanalytical method validation standards specified by the US Food and Drug Administration. ZTK and encorafenib were separated using an Agilent C8 column (Eclipse Plus) and an isocratic mobile phase. The calibration curve for the developed ZTK exhibited a linear relationship within the concentration range of 1-3000 ng/mL. The results from the Analytical Green-ness Metric Approach program (0.76) suggested that the created method demonstrated a significant degree of environmental sustainability. The in vitro half-life (t1/2) and intrinsic clearance (Clint) of ZTK were determined to be 15.79 min and 51.35 mL/min/kg, respectively that suggests the ZTK exhibits characteristics similar to those of a medication with a high extraction ratio. These approaches are crucial for the progress of novel pharmaceutical development, especially in improving metabolic stability.

Improved preclinical drug metabolism and pharmacokinetics of pibothiadine (HEC121210), a novel hepatitis B virus capsid assembly modulator.

Pibothiadine (PBD; HEC121120) is a novel hepatitis B virus capsid assembly modulator based on GLS4 (morphothiadine) and has inhibitory activities against resistant strains.To assess the overall preclinical drug metabolism and pharmacokinetics (DMPK) properties of PBD, in vivo pharmacokinetics studies in rats and dogs have been performed along with a series of in vitro metabolism assays.The oral bioavailability of PBD in rats and dogs might be related to its medium permeability in Caco-2 cells and largely be impacted by the pH-dependent solubility. PBD was highly distributed to the liver where the local exposure was 16.4 fold of the system exposure. PBD showed relatively low metabolic rate in recombinant human cytochrome P450 enzymes, whereas low to moderate in vitro clearance in liver microsomes and low (dog) to moderate (rat) in vivo clearance. Furthermore, ß-oxidation and dehydrogenation were proposed as the primary metabolic pathways of PBD in rats.Compared to GLS4, the higher systemic exposure of PBD might be attributed to its improved oral absorption and metabolic stability. In addition, the enhanced liver/plasma exposure ratio could further increase the local exposure around the target. These improved DMPK properties might indicate better development of PBD in the clinical phase.

Bis(Disulfide)-Bridged Somatostatin-14 Analogs and Their [111In]In-Radioligands: Synthesis and Preclinical Profile.

The overexpression of one or more somatostatin receptors (SST1-5R) in human tumors has provided an opportunity for diagnosis and therapy with somatostatin-like radionuclide carriers. The application of "pansomatostatin" analogs is expected to broaden the clinical indications and upgrade the diagnostic/therapeutic efficacy of currently applied SST2R-prefering radioligands. In pursuit of this goal, we now introduce two bicyclic somatostatin-14 (SS14) analogs, AT5S (DOTA-Ala1-Gly2-c[Cys3-Lys4-Asn5-c[Cys6-Phe7-DTrp8-Lys9-Thr10-Cys11]-Thr12-Ser13-Cys14]) and AT6S (DOTA-Ala1-Gly2-c[Cys3-Lys4-c[Cys5-Phe6-Phe7-DTrp8-Lys9-Thr10-Phe11-Cys12]-Ser13-Cys14]), suitable for labeling with trivalent radiometals and designed to sustain in vivo degradation. Both AT5S and AT6S and the respective [111In]In-AT5S and [111In]In-AT6S were evaluated in a series of in vitro assays, while radioligand stability and biodistribution were studied in mice. The 8/12-mer bicyclic AT6S showed expanded affinity for all SST1-5R and agonistic properties at the SST2R, whereas AT5S lost all affinity to SST1-5R. Both [111In]In-AT5S and [111In]In-AT6S remained stable in the peripheral blood of mice, while [111In]In-AT6S displayed low, but specific uptake in AR4-2J tumors and higher uptake in HEK293-SST3R tumors in mice. In summary, high radioligand stability was acquired by the two disulfide bridges introduced into the SS14 motif, but only the 8/12-mer ring AT6S retained a pansomatostatin profile. In consequence, [111In]In-AT6S targeted SST2R-/SST3R-positive xenografts in mice. These results call for further research on pansomatostatin-like radioligands for cancer theranostics.

AR71, Histamine H3 Receptor Ligand-In Vitro and In Vivo Evaluation (Anti-Inflammatory Activity, Metabolic Stability, Toxicity, and Analgesic Action).

The future of therapy for neurodegenerative diseases (NDs) relies on new strategies targeting multiple pharmacological pathways. Our research led to obtaining the compound AR71 [(E)-3-(3,4,5-trimethoxyphenyl)-1-(4-(3-(piperidin-1-yl)propoxy)phenyl)prop-2-en-1-one], which has high affinity for human H3R (Ki = 24 nM) and selectivity towards histamine H1 and H4 receptors (Ki > 2500 nM), and showed anti-inflammatory activity in a model of lipopolysaccharide-induced inflammation in BV-2 cells. The presented tests confirmed its antagonist/inverse agonist activity profile and good metabolic stability while docking studies showed the binding mode to histamine H1, H3, and H4 receptors. In in vitro tests, cytotoxicity was evaluated at three cell lines (neuroblastoma, astrocytes, and human peripheral blood mononuclear cells), and a neuroprotective effect was observed in rotenone-induced toxicity. In vivo experiments in a mouse neuropathic pain model demonstrated the highest analgesic effects of AR71 at the dose of 20 mg/kg body weight. Additionally, AR71 showed antiproliferative activity in higher concentrations. These findings suggest the need for further evaluation of AR71's therapeutic potential in treating ND and CNS cancer using animal experimental models.

An Investigation into the In Vitro Metabolic Stability of Aryl Sulfonyl Fluorides for their Application in Medicinal Chemistry and Radiochemistry.

Molecules that feature a sulfonyl fluoride (SO2F) moiety have been gaining increasing interest due to their unique reactivity and potential applications in synthetic chemistry, medicinal chemistry, and other biological uses. A particular interest is towards 18F-radiochemistry where sulfonyl fluorides can be used as a method to radiolabel biomolecules or can be used as radiofluoride relay reagents that facilitate radiolabeling of other molecules. The low metabolic stability of sulfonyl fluoride S-F bonds, however, presents an issue and limits the applicability of sulfonyl fluorides. The aim of this work was to increase understanding of what features contribute to the metabolic instability of the S-F bond in model aryl sulfonyl fluorides and identify approaches to increasing sulfonyl fluoride stability for 18F-radiochemistry and other medicinal, synthetic chemistry and biological applications. To undertake this, 14 model aryl sulfonyl fluorides compounds with varying functional groups and substitution patterns were investigated, and their stabilities were examined in various media, including phosphate-buffered saline and rat serum as a model for biological conditions. The results indicate that both electronic and steric factors affect the stability of the S-F bond, with the 2,4,6-trisubstituted model aryl sulfonyl fluorides examined displaying the highest in vitro metabolic stability.

Multispecies Machine Learning Predictions of In Vitro Intrinsic Clearance with Uncertainty Quantification Analyses.

In pharmaceutical research, compounds are optimized for metabolic stability to avoid a too fast elimination of the drug. Intrinsic clearance (CLint) measured in liver microsomes or hepatocytes is an important parameter during lead optimization. In this work, machine learning models were developed to relate the compound structure to microsomal metabolic stability and predict CLint for new compounds. A multitask (MT) learning architecture was introduced to model the CLint of six species simultaneously, giving as a result a multispecies machine learning model. MT graph neural network (MT-GNN) regression was identified as the top-performing method, and an ensemble of 10 MT-GNN models was evaluated prospectively. Geometric mean fold errors were consistently smaller than 2-fold. Moreover, high precision values were obtained in the prediction of "high" (>300 µL/min/mg) and "low" (<100 µL/min/mg) CLint compounds. Precision values ranged from 80 to 94% for low CLint predictions and from 75 to 97% for high CLint predictions, depending on the species. Uncertainty on experimental values and model predictions was systematically quantified. Experimental variability (aleatoric uncertainty) of all historical Novartis in vitro clearance experiments was analyzed. Interestingly, MT-GNN models' performance approached assays' experimental variability. Moreover, uncertainty estimation in predictions (epistemic uncertainty) enabled identifying predictions associated with lower and higher error. Taken together, our manuscript combines a multispecies deep learning model and large-scale uncertainty analyses to improve CLint predictions and facilitate early informed decisions for compound prioritization.

Optimizing metabolic stability of phosphodiesterase 5 inhibitors: Discovery of a potent N-(pyridin-3-ylmethyl)quinoline derivative targeting synaptic plasticity.

Phosphodiesterase 5 (PDE5) is a cyclic guanosine monophosphate-degrading enzyme involved in numerous biological pathways. Inhibitors of PDE5 are important therapeutics for the treatment of neurodegenerative diseases, including Alzheimer's disease (AD). We previously reported the first generation of quinoline-based PDE5 inhibitors for the treatment of AD. However, the short in vitro microsomal stability rendered them unsuitable drug candidates. Here we report a series of new quinoline-based PDE5 inhibitors. Among them, compound 4b, 8-cyclopropyl-3-(hydroxymethyl)-4-(((6-methoxypyridin-3-yl)methyl)amino)quinoline-6-carbonitrile, shows a PDE5 IC50 of 20 nM and improved in vitro microsomal stability (t1/2 = 44.6 min) as well as excellent efficacy in restoring long-term potentiation, a type of synaptic plasticity to underlie memory formation, in electrophysiology experiments with a mouse model of AD. These results provide an insight into the development of a new class of PDE5 inhibitors for the treatment of AD.

Synthesis, activity, metabolic stability and cell permeability of new cytosolic phospholipase A2α inhibitors with 1-indolyl-3-phenoxypropan-2-one structure.

Cytosolic phospholipase A2α (cPLA2α), the key enzyme of the arachidonic acid cascade, is considered to be an interesting target for the development of new anti-inflammatory drugs. Potent inhibitors of the enzyme include indole-5-carboxylic acids with propan-2-one residues in position 1 of the indole. Previously, it was found that central pharmacophoric elements of these compounds are their ketone and carboxylic acid groups, which unfortunately are subject to pronounced metabolism by carbonyl reductases and glucuronosyltransferases, respectively. Here we show that the metabolic stability of these inhibitors can be improved by introducing alkyl substituents in the vicinity of the ketone group or by increasing their rigidity. Furthermore, permeability tests with Caco-2 cells revealed that the indole derivatives have only low permeability, which can be attributed to their affinity to efflux transporters. Among other things, the polar ketone group in the center of the molecules seems to be a decisive factor for their reverse transport. After its removal, the permeability increased significantly. The enhancement in metabolic stability and permeability achieved by the structural variations carried out was accompanied by a more or less pronounced decrease in the inhibitory potency of the compounds against cPLA2α.

Design and synthesis of multivalent drug delivery system with CA IX inhibitors as ligands.

A multivalent ligand delivery system holds tremendous potential in the field of tumor-targeted drug delivery. It addresses the challenges posed by the low affinity between small molecule ligand receptors and the rapid metabolism of small molecule drug conjugates (SMDCs) in vivo. Notably, existing multivalent ligand systems have demonstrated significant anti-tumor activity in various tumor models. In this study, we have developed a novel multivalent ligand delivery system for SN38, utilizing acetazolamide, a carbonic anhydrase IX (CA IX) inhibitor, as the target ligand. Our multivalent ligand delivery systems exhibited superior metabolic stability and enhanced targeting specificity compared to SMDC molecules. Furthermore, they demonstrated improved anti-proliferation activity, addressing the existing challenges associated with the low receptor affinity and rapid metabolism of SMDCs.

Synthesis and pharmacokinetic properties of novel cPLA2α inhibitors with 1-(carboxyalkylpyrrolyl)-3-aryloxypropan-2-one structure.

Indole-5-carboxylic acids with 3-aryloxy-2­oxopropyl residues in position 1 have been shown to be potent inhibitors of cytosolic phospholipase A2α (cPLA2α), an enzyme involved in the formation of pro-inflammatory lipid mediators. Unfortunately, in animal experiments, only very low plasma concentrations could be achieved after peroral administration of this type of compound. Since insufficient metabolic stability was suspected as the cause, structural modifications were made to optimize this property. These included the conversion of the aromatic into an aliphatic carboxylic acid function as well as the rigidification of the lipophilic structural elements. A selected pyrrole-3-propionic acid was tested for its peroral in vivo bioavailability in mice. However, higher plasma concentrations could not be achieved also with this compound. Using the Caco2 cell permeation assay, substances investigated were found to be very good substrates for gastrointestinal efflux transporters, which explains their poor peroral absorption.

Exploration of novel four-membered-heterocycle constructed peptidyl proteasome inhibitors with improved metabolic stability for cancer treatment.

Peptides have limitations as active pharmaceutical agents due to rapid hydrolysis by proteases and poor cell permeability. To overcome these limitations, a series of peptidyl proteasome inhibitors embedded with four-membered heterocycles were designed to enhance their metabolic stabilities. All synthesized compounds were screened for their inhibitory activities against human 20S proteasome, and 12 target compounds displayed potent efficacy with IC50 values lower than 20 nM. Additionally, these compounds exhibited strong anti-proliferative activities against multiple myeloma (MM) cell lines (MM1S: 72, IC50 = 4.86 ± 1.34 nM; RPMI-8226: 67, IC50 = 12.32 ± 1.44). Metabolic stability assessments of SGF, SIF, plasma and blood were conducted, and the representative compound 73 revealed long half-lives (Plasma: T1/2 = 533 min; Blood: T1/2 > 1000 min) and good proteasome inhibitory activity in vivo. These results suggest that compound 73 serve as a lead compound for the development of more novel proteasome inhibitors.

Design, synthesis, and biological evaluation of pyrido[3,2-d]pyrimidine derivatives as novel ATR inhibitors.

Targeting ataxia telangiectasia mutated and Rad3-related (ATR) kinase is being pursued as a new therapeutic strategy for the treatment of advanced solid tumor with specific DNA damage response deficiency. Herein, we report a series of pyrido[3,2-d]pyrimidine derivatives with potent ATR inhibitory activity through structure-based drug design. Among them, the representative compound 10q exhibited excellent potency against ATR in both biochemical and cellular assays. More importantly, 10q exhibited good liver microsomes stability in different species and also showed moderate inhibitory activity against HT-29 cells in combination treatment with the ATM inhibitor AZD1390. Thus, this work provides a promising lead compound against ATR for further study.

Combination of losartan and puerarin induced pharmacokinetic interaction in hypertension rats enhances the antihypertensive effect of losartan.

The co-administration of losartan and puerarin in hypertension rat models was investigated aiming to evaluate their interaction and potential mechanism.Hypertension rat models were established with N (omega)-nitro-L-arginine methyl ester and the pharmacokinetics and antihypertensive effect of losartan were analyzed in normal and hypertension rats. In vitro, the metabolic stability of losartan was evaluated in rat liver microsomes, and the effect of puerarin on the activity of CYP2C9 and 3A4 was assessed in human liver microsomes.Puerarin significantly changed the pharmacokinetic profiling of losartan in hypertension rats, with the behaviour of increasing AUC, AUMC, Cmax, and prolonged t1/2. The antihypertensive effect of losartan was enhanced by the co-administration of puerarin, which reduced the systolic blood pressure and diastolic blood pressure below normal levels. In vitro, puerarin significantly improved the metabolic stability of losartan with a reduced intrinsic clearance rate. Puerarin also showed significant inhibitory effects on the activity of CYP2C9 and 3A4 with the IC50 of 17.15 and 7.69 µM, respectively.Losartan co-administered with puerarin increased the system exposure and metabolic stability of losartan and enhanced its antihypertensive effect. The inhibition of CYP2C9 and 3A4 by puerarin was the potential mechanism mediating their interaction.

Assessment of metabolic stability and pharmacokinetics by LC-MS/MS and establishment of the safe dose of IMID-2, a novel anticancer molecule under drug discovery.

Pyruvate kinase (PK) M2 activators ramp up glycolysis in cancer cells, leading to a reversal of the Warburg effect in cancer cells. A promising PKM2 activator molecule, IMID-2, developed by the National Institute of Pharmaceutical Education and Research-Ahmedabad showed promising anticancer activity against MCF-7 and COLO-205 cell lines, which represent breast and colon cancer. Its physicochemical properties, like solubility, ionization constant, partition coefficient and distribution constant, have already been established. Its metabolic pathway is also well established through in vitro and in vivo metabolite profiling and reported previously. In this study, we have evaluated the metabolic stability of IMID-2 using LC-MS/MS and investigated the safety aspect of the molecule through an acute oral toxicity study. In vivo studies in rats confirmed that the molecule is safe even at a dose level of 175 mg/kg. Furthermore, a pharmacokinetic study of IMID-2 was also carried out using LC-MS/MS to understand its absorption, distribution, metabolism, and excretion profile. The molecule was found to have promising bioavailability through the oral route. This research work is thus another step in the drug testing of this promising anticancer molecule. The molecule can be considered to be a potential anticancer lead based on the earlier report substantiated by current findings.

Isosteric Replacement of Ester Linkage of Lysophospholipids with Heteroaromatic Rings Retains Potency and Subtype Selectivity.

Our group has reported various derivatives of lysophosphatidylserine (LysoPS) as potent and subtype-selective agonists for G-protein-coupled receptors (GPCRs). However, the ester linkage between the glycerol moiety and fatty acid or fatty acid surrogate is present in all of them. In order to develop these LysoPS analogs as drug candidates, appropriate pharmacokinetic consideration is essential. Here, we found that the ester bond of LysoPS is highly susceptible to metabolic degradation in mouse blood. Accordingly, we examined isosteric replacement of the ester linkage with heteroaromatic rings. The resulting compounds showed excellent retention of potency and receptor subtype selectivity, as well as increased metabolic stability in vitro.