Synthesis and Evaluation of Structurally Diverse C-2-Substituted Thienopyrimidine-Based Inhibitors of the Human Geranylgeranyl Pyrophosphate Synthase.

Novel analogues of C-2-substituted thienopyrimidine-based bisphosphonates (C2-ThP-BPs) are described that are potent inhibitors of the human geranylgeranyl pyrophosphate synthase (hGGPPS). Members of this class of compounds induce target-selective apoptosis of multiple myeloma (MM) cells and exhibit antimyeloma activity in vivo. A key structural element of these inhibitors is a linker moiety that connects their (((2-phenylthieno[2,3-d]pyrimidin-4-yl)amino)methylene)bisphosphonic acid core to various side chains. The structural diversity of this linker moiety, as well as the side chains attached to it, was investigated and found to significantly impact the toxicity of these compounds in MM cells. The most potent inhibitor identified was evaluated in mouse and rat for liver toxicity and systemic exposure, respectively, providing further optimism for the potential value of such compounds as human therapeutics.

Discovery of a Novel Fusarium Graminearum Mitogen-Activated Protein Kinase (FgGpmk1) Inhibitor for the Treatment of Fusarium Head Blight.

Mitogen-activated protein kinase FgGpmk1 plays vital roles in the development and virulence of Fusarium graminearum (F. graminearum), the causative agent of Fusarium head blight (FHB). However, to date, the druggability of FgGpmk1 still needs verification, and small molecules targeting FgGpmk1 have never been reported. Here, we reported the discovery of a novel inhibitor 94 targeting FgGpmk1. First, a novel hit (compound 21) with an EC50 value of 13.01 µg·mL-1 against conidial germination of F. graminearum was identified through virtual screening. Then, guided by molecular modeling, compound 94 with an EC50 value of 3.46 µg·mL-1 was discovered, and it can inhibit the phosphorylation level of FgGpmk1 and influence the nuclear localization of its downstream FgSte12. Moreover, 94 can inhibit deoxynivalenol biosynthesis without any damage to the host. This study reported a group of FgGpmk1 inhibitors with a novel scaffold, which paves the way for the development of potent fungicides to FHB management.

Design, Synthesis, and Biological Evaluation of Novel Pyrimido[4,5-b]indole Derivatives Against Gram-Negative Multidrug-Resistant Pathogens.

Due to the poor permeability across Gram-negative bacterial membranes and the troublesome bacterial efflux mechanism, only a few GyrB/ParE inhibitors with potent activity against Gram-negative pathogens have been reported. Among them, pyrimido[4,5-b]indole derivatives represented by GP-1 demonstrated excellent broad-spectrum antibacterial activity against both Gram-positive and Gram-negative bacteria but were limited by hERG inhibition and poor pharmacokinetics profile. To improve their drug-like properties, we designed a series of novel pyrimido[4,5-b]indole derivatives based on the tricyclic scaffold of GP-1 and the C-7 moiety of acorafloxacin. These efforts have culminated in the discovery of a promising compound 18r with reduced hERG liability and an improved PK profile. Compound 18r exhibited superior broad-spectrum in vitro antibacterial activity compared to GP-1, including a variety of clinical multidrug G- pathogens, especially Acinetobacter baumannii, and the in vivo efficacy was also demonstrated in a neutropenic mouse thigh model of infection with multidrug-resistant A. baumannii.

Design, Synthesis and Anticancer Activity of New Polycyclic: Imidazole, Thiazine, Oxathiine, Pyrrolo-Quinoxaline and Thienotriazolopyrimidine Derivatives.

In this article, we showed the synthesis of new polycyclic aromatic compounds, such as thienotriazolopyrimidinones, N-(thienotriazolopyrimidine) acetamide, 2-mercapto-thienotriazolo-pyrimidinones, 2-(((thieno-triazolopyrimidine) methyl) thio) thieno-triazolopyrimidines, thieno-pyrimidotriazolo-thiazines, pyrrolo-triazolo-thienopyrimidines, thienopyrimido-triazolopyrrolo-quinoxalines, thienopyrimido-triazolo-pyrrolo-oxathiino-quinoxalinones, 1,4-oxathiino-pyrrolo- triazolothienopyrimidinones, imidazopyrrolotriazolothienopyrimidines and 1,2,4-triazoloimidazo- pyrrolotriazolothienopyrimidindiones, based on the starting material 2,3-diamino-6-benzoyl-5- methylthieno[2,3-d]pyrimidin-4(3H)-one (3). The chemical structures were confirmed using many spectroscopic ways (IR, 1H, 13C, -NMR and MS) and elemental analyses. A series of thiazine, imidazole, pyrrole, thienotriazolopyrimidine derivatives were synthesized and evaluated for their antiproliferative activity against four human cancer cell lines, i.e., CNE2 (nasopharyngeal), KB (oral), MCF-7 (breast) and MGC-803 (gastric) carcinoma cells. The compounds 20, 19, 17, 16 and 11 showed significant cytotoxicity against types of human cancer cell lines.

Efficient biogenesis of Cu2O nanoparticles using extract of Camellia sinensis leaf: Evaluation of catalytic, cytotoxicity, antioxidant, and anti-human ovarian cancer properties.

At the moment, metallic nanoparticles especially copper nanoparticles are administrated for the cure of different disorders, such as tumor and cancer. In recent years, many chemotherapeutic supplements have been formulated by copper nanoparticles. In the present study, copper nanoparticles were prepared and synthesized in aqueous medium using Camellia sinensis leaf extract. The as-prepared Cu2O nanoparticles was thoroughly characterized using XRD, FT-IR, FESEM, EDX, TEM and X-ray elemental mapping techniques. The as-synthesized Cu2O/C. sinensis NPs applied as novel nanocatalyst for the synthesis of annulated fused pyrano[2,3-d]pyrimidinones via a one-pot, three-component condensation of a barbituric acid, aromatic aldehydes, and malonitrile or ethylcyanoacetate under mild condition at 25 °C. Main properties of this facile method are the involves an easy work-up procedure, avoidance of hazardous or polluting chemicals, significant yields under mild conditions, and one-pot reaction. We assessed the anti-human ovarian cancer potentials of these nanoparticles against Caov-3, SW-626, and SK-OV-3 cell lines. For investigating the antioxidant activities of CuCl2⋅2H2O, C. sinensis, and copper nanoparticles, the DPPH free radical test was used. For the determining of anti-human ovarian cancer properties of CuCl2⋅2H2O, Camellia sinensis leaf aqueous extract, copper nanoparticles, and Carboplatin (Standard positive control), MTT assay was used on normal (HUVECs) and human ovarian cancer (Caov-3, SW-626, and SK-OV-3) cell lines. Copper nanoparticles had high cell death and anti-human ovarian cancer properties against Caov-3, SW-626, and SK-OV-3 cell lines. Among the above cell lines, the best result was gained in the cell line of SW-626. According to the above findings, it looks copper nanoparticles green-synthesized by Camellia sinensis leaf aqueous extract have the potential to be used as a chemotherapeutic material for human ovarian cancers.

Synthesis, ADMET prediction and reverse screening study of 3,4,5-trimethoxy phenyl ring pendant sulfur-containing cyanopyrimidine derivatives as promising apoptosis inducing anticancer agents.

Cancer remains considered as one of the leading global health problems either due to meagre and suboptimal therapeutic response of chemotherapeutic agents or due to the emergence of spontaneous complex multidrug resistance in cancer cells. This created a persistent need for the development of new anticancer agents. Enthralled by the high success rate for natural product-based drug discovery and current research scenario, we synthesized a new series of 3,4,5-trimethoxy phenyl ring pendant sulfur-containingcyanopyrimidine derivatives clubbed with different amines intending to search an anticancer lead compound. To probe the anti-proliferative spectrum of the synthesized derivatives, an in-vitro evaluation was piloted against a panel of 60 cancer cell lines at the National Cancer Institute (NCI) representing major types of cancer diseases. Most of the derivatives showed good to moderate anti-proliferative activity. The results revealed that compound 4e displayed the most promising broad-spectrum anticancer activity with high growth inhibition of various cell lines representing multiple cancers diseases. Mechanistic investigation of compound 4e in human breast cancer MDA-MB-231 cells showed that compound 4e triggers cell death through the induction of apoptosis. ADMET studies and reverse screening were also performed to identify the potential targets of designed molecules. It was concluded that 3,4,5-trimethoxy phenyl ring pendant sulfur-containingcyanopyrimidine derivative 4e could act as a promising hit molecule for further development of novel anticancer therapeutics.

Pharmacophore modeling, design, and synthesis of potent antihypertensives, oxazolo/thiazolo-[3,2-a]-pyrimidin-3(2H)-one, and 1,5-dihydroimidazo-[1,2-a]-pyrimidin-3(2H)-one derivatives: A pilot trial.

An improved pharmacophore model, molecular properties, geometric analyses, and SAR led to synthesize oxazolo/thiazolo-[3,2-a]-pyrimidin-3(2H)-one, and 1,5-dihydroimidazo-[1,2-a]-pyrimidin-3(2H)-one derivatives exhibiting potent anti-hypertensive activity. The 6-ethoxycarbonyl-2,7-dimethyl-5-phenyl-1,5-dihydroimidazo[3,2-a]pyrimidin-3(2H)-one (4g), and 6-ethoxycarbonyl-2,7-dimethyl-5-(3-methyl-phenyl)-1,5-dihydroimidazo[3,2-a]pyrimidin-3(2H)-one (4h) showed significant reduction in mean arterial blood pressure (MABP, mm/Hg) of 79.78%, and 92.95% in 6 and 12 h durations, respectively, at 1.5 mg/kg body-weight dose, while at 3.0 mg/kg body-weight dose, the MABP reduction was achieved at 95.46%, and 92.02%, respectively, in 6 and 12 h durations, as compared to the standard drug, nifedipine.

Targeting Her2-insYVMA with Covalent Inhibitors-A Focused Compound Screening and Structure-Based Design Approach.

Mutated or amplified Her2 serves as a driver of non-small cell lung cancer or mediates resistance toward the inhibition of its family member epidermal growth factor receptor with small-molecule inhibitors. To date, small-molecule inhibitors targeting Her2 which can be used in clinical routine are lacking, and therefore, the development of novel inhibitors was undertaken. In this study, the well-established pyrrolopyrimidine scaffold was modified with structural motifs identified from a screening campaign with more than 1600 compounds, which were applied against wild-type Her2 and its mutant variant Her2-A775_G776insYVMA. The resulting inhibitors were designed to covalently target a reactive cysteine in the binding site of Her2 and were further optimized by means of structure-based drug design utilizing a set of obtained complex crystal structures. In addition, the analysis of binding kinetics and absorption, distribution, metabolism, and excretion parameters as well as mass spectrometry experiments and western blot analysis substantiated our approach.

Design, synthesis and evaluation of phenylthiazole and phenylthiophene pyrimidindiamine derivatives targeting the bacterial membrane.

As the continuous rise in the incidence of antibiotic resistance, it is urgent to develop novel chemical scaffolds with antibacterial activities to control the spread of resistance to conventional antibiotics. In this study, a series of phenylthiazole and phenylthiophene pyrimidindiamine derivatives were designed and synthesized by modifying the hit compound (N2-isobutyl-N4-((4-methyl-2-phenylthiazol-5-yl)methyl) pyrimidine-2,4-diamine) and their antibacterial activities were evaluated both in vitro and in vivo. Among the tested compounds, compound 14g (N4-((5-(3-bromophenyl)thiophen-2-yl)methyl)-N2-isobutylpyrimidine-2,4-diamine) displayed the best antibacterial activities, which was not only capable of inhibiting E. coli and S. aureus growth at concentrations as low as 2 and 3 µg/mL in vitro, but also efficacious in a mice model of bacteremia in vivo. Unlike conventional antibiotics, compound 14g was elucidated to mainly destroy the bacterial cell membrane, with the dissipation of membrane potential and leakage of contents, ultimately leading to cell death. The destruction of cell structure is challenging to induce bacterial resistance, which suggested that compound 14g may be a kind of promising alternatives to antibiotics against bacteria.

Drug Repurposing Approach for Developing Novel Therapy Against Mupirocin-Resistant Staphylococcus aureus.

Multidrug resistance (MDR) is a major health issue for the treatment of infectious diseases throughout the world. Staphylococcus aureus (S. aureus) is a Gram-positive bacteria, responsible for various local and systemic infections in humans. The continuous and abrupt use of antibiotics against bacteria such as S. aureus results in the development of resistant strains. Presently, mupirocin (MUP) is the drug of choice against S. aureus and MDR (methicillin-resistant). However, S. aureus has acquired resistance against MUP as well due to isoleucyl-tRNA synthetase (IleS) mutation at sites 588 and 631. Thus, the aim of the present study was to discover novel bioactives against MUP-resistant S. aureus using in silico drug repurposing approaches. In silico drug repurposing techniques were used to obtain suitable bioactive lead molecules such as buclizine, tasosartan, emetine, medrysone, and so on. These lead molecules might be able to resolve this issue. These leads were obtained through molecular docking simulation based virtual screening, which could be promising for the treatment of MUP-resistant S. aureus. The findings of the present work need to be validated further through in vitro and in vivo studies for their clinical application.

Identification of a New α-Synuclein Aggregation Inhibitor via Mass Spectrometry Based Screening.

The aggregation of disordered α-synuclein protein is pathogenically connected with Parkinson's disease. Therefore, discovering molecules that can inhibit the misfolding and aggregation of α-synuclein is an active research area in PD drug development. A key property of such required therapeutic agents is specific binding to the target protein. Mass spectrometry allows rapid detection of direct interactions between molecules and proteins and is an ideal technique for discovering specific α-synuclein binders. Here, by setting up an automated mass spectrometry-based screening system, we were able to screen over 2500 compounds and identify a new α-synuclein inhibitor, 3-[(3-methoxyphenyl)carbamoyl]-7-[( E)-2-phenylethenyl]-4,7-dihydropyrazolo [1,5- a]pyrimidine-5-carboxylic acid (compound 2). This compound not only significantly inhibits the misfolding and aggregation of α-synuclein and protects neuroblastoma cells from α-synuclein toxicity, but also has a more specific binding site compared with positive controls. Our work for the first time reports the inhibition of compound 2 on α-synuclein aggregation and also consolidates the capability of mass spectrometry to discover α-synuclein aggregation inhibitors.

Design, synthesis and evaluation of novel 7H-pyrrolo[2,3-d]pyrimidin-4-amine derivatives as potent, selective and reversible Bruton's tyrosine kinase (BTK) inhibitors for the treatment of rheumatoid arthritis.

A series of 7H-pyrrolo[2,3-d]pyrimidine derivatives were designed and synthesized as reversible BTK inhibitors, and evaluated their kinase selectivity, anti-proliferation against the B-cell lymphoma cell lines (Ramos, Jeko-1) and cell line BTK enhanced (Daudi) in vitro. Among them, compound 28a exhibited the most excellent potency (IC50 = 3.0 nM against BTK enzyme, 8.52 µM, 11.10 µM and 7.04 µM against Ramos, Jeko-1, Daudi cells, respectively), good kinase selectivity and inhibited BTK Y223 auto-phosphorylation and PLCγ2 Tyr1217 phosphorylation. Importantly, 28a showed efficacy anti-arthritic effect on collagen-induced arthritis (CIA) model in vivo. 28a 60 mg/kg dose level once a day group displayed markedly reduced joint damage and cellular infiltration without any bone and cartilage morphology change.

Design, Synthesis and Therapeutic Potential of Some 6, 6'-(1,4- phenylene)bis(4-(4-bromophenyl)pyrimidin-2-amine)analogues.

BACKGROUND: A series of 6, 6'-(1,4-phenylene)bis(4-(4-bromophenyl)pyrimidin-2-amine) derivatives has been synthesized by Claisen-Schmidt condensation and its chemical structures was confirmed by FT-IR, 1H/13C-NMR spectral and elemental analyses. The molecular docking study was carried out to find the interaction between active bis-pyrimidine compounds with CDK-8 protein. The in vitro antimicrobial potential of the synthesized compounds was determined against Gram-positive and Gram-negative bacterial species as well fungal species by tube dilution technique. Antimicrobial results indicated that compound 11y was found to be most potent one against E. coli (MICec = 0.67 µmol/mL) and C. albicans (MICca = 0.17 µmol/mL) and its activity was comparable to norfloxacin (MIC = 0.47 µmol/mL) and fluconazole (MIC = 0.50 µmol/mL), respectively. CONCLUSION: Anticancer screening of the synthesized compounds using Sulforhodamine B (SRB) assay demonstrated that compounds 2y (IC50 = 0.01 µmol/mL) and 4y (IC50= 0.02 µmol/mL) have high antiproliferative potential against human colorectal carcinoma cancer cell line than the reference drug (5- fluorouracil) and these compounds also showed best dock score with better potency within the ATP binding pocket and may also be used lead for rational drug designing.

Identification of new inhibitors of Mdm2-p53 interaction via pharmacophore and structure-based virtual screening.

BACKGROUND: The tumor suppressor protein p53 plays an important role in preventing tumor formation and progression through its involvement in cell division control and initiation of apoptosis. Mdm2 protein controls the activity of p53 protein through working as ubiquitin E3 ligase promoting p53 degradation through the proteasome degradation pathway. Inhibitors for Mdm2-p53 interaction have restored the activity of p53 protein and induced cancer fighting properties in the cell. PURPOSE: The objective of this study is to use computer-aided drug discovery techniques to search for new Mdm2-p53 interaction inhibitors. METHODS: A set of pharmacophoric features were created based on a standard Mdm2 inhibitor and this was used to screen a commercial drug-like ligand library; then potential inhibitors were docked and ranked in a multi-step protocol using GLIDE. Top ranked ligands from docking were evaluated for their inhibition activity of Mdm2-p53 interaction using ELISA testing. RESULTS: Several compounds showed inhibition activity at the submicromolar level, which is comparable to the standard inhibitor Nutlin-3a. Furthermore, the discovered inhibitors were evaluated for their anticancer activities against different breast cancer cell lines, and they showed an interesting inhibition pattern. CONCLUSION: The reported inhibitors can represent a starting point for further SAR studies in the future and can help in the discovery of new anticancer agents.

YLT-11, a novel PLK4 inhibitor, inhibits human breast cancer growth via inducing maladjusted centriole duplication and mitotic defect.

Polo-like kinase 4 (PLK4) is indispensable for precise control of centriole duplication. Abnormal expression of PLK4 has been reported in many human cancers, and inhibition of PLK4 activity results in their mitotic arrest and apoptosis. Therefore, PLK4 may be a valid therapeutic target for antitumor therapy. However, clinically available small-molecule inhibitors targeting PLK4 are deficient and their underlying mechanisms still remain not fully clear. Herein, the effects of YLT-11 on breast cancer cells and the associated mechanism were investigated. In vitro, YLT-11 exhibited significant antiproliferation activities against breast cancer cells. Meanwhile, cells treated with YLT-11 exhibited effects consistent with PLK4 kinase inhibition, including dysregulated centriole duplication and mitotic defects, sequentially making tumor cells more vulnerable to chemotherapy. Furthermore, YLT-11 could strongly regulate downstream factors of PLK4, which was involved in cell cycle regulation, ultimately inducing apoptosis of breast cancer cell. In vivo, oral administration of YLT-11 significantly suppressed the tumor growth in human breast cancer xenograft models at doses that are well tolerated. In summary, the preclinical data show that YLT-11 could be a promising candidate drug for breast tumor therapy.

Design, Synthesis and Screening of 4,6-Diaryl Pyridine and Pyrimidine Derivatives as Potential Cytotoxic Molecules.

A new series of pyridine and pyrimidine derivatives is designed and synthesized as potential antitumor molecules. The tested compounds show promising in vitro cytotoxic activity against HL-60 cell line as eight compounds: 4, 6, 11, 13, 14, 15, 18 and 21 exhibit potent cytotoxic activity in sub-micromolar concentration higher than the combretastatin A4 (CA-4). Compound 21 shows a cytotoxic activity 5-fold more potent than CA-4 on HL-60 cells. DNA-Flow cytometry cell cycle analysis and annexin-V assay on HL-60 cells show that compounds 4, 18 and 21 exhibit potent cell growth inhibition, cell cycle arrest at G2/M phase and pro-apoptotic inducing activities. The percentage inhibition assay of ß-tubulin polymerization on HL-60 cells shows that the antitumor activity of the tested compounds appears to correlate well with its ability to inhibit ß-tubulin polymerization. In addition, enzyme-linked immunosorbene assay (ELlSA) measurement for compound 21 shows apoptotic inducing activities through significant up regulation of p53, Bax/Bcl-2 ratio and caspase-3 proteins parallel to down regulation of the level of survivin proteins.

Discovery of 2-[(E)-2-(7-Fluoro-3-methylquinoxalin-2-yl)vinyl]-6-pyrrolidin-1-yl-N-(tetrahydro-2H-pyran-4-yl)pyrimidin-4-amine Hydrochloride as a Highly Selective PDE10A Inhibitor.

Phosphodiesterase (PDE) 10A is a dual hydrolase of cAMP and cGMP and highly expressed in striatal medium spiny neurons. Inhibition of PDE10A modulates the activity of medium spiny neurons (MSN) via the regulation of cAMP and cGMP. Signal control of MSN is considered associated with psychotic symptoms. Therefore PDE10A inhibitor is expected as a therapeutic method for psychosis disease such as schizophrenia. Avanafil (1) is a PDE5 inhibitor (treatment for erectile dysfunction) discovered by our company. We paid attention to the homology of PDE10A and PDE5 and took advantage of PDE5 inhibitor library to discover PDE10A inhibitors, and found a series of compounds that exhibit higher potency for PDE10A than PDE5. We transformed the afforded derivatives, which had weak inhibitory activity against PDE10A, and discovered stilbene as a PDE10A inhibitor. Brain penetration of this compound was improved by further conversion of N-containing heterocycles and their substituents. The afforded dimethylaminopyrimidine was effective for rat conditioned avoidance response (CAR) test; however, it did not exhibit good brain penetration. We performed in-depth optimization focusing on substituents of the quinoxaline ring, and produced 3-methyl-7-fluoro quinoxaline. This compound was the most effective in rat CAR test due to its strong PDE10A inhibitory activity and good pharmacokinetics.

Scaffold-based novel SHP2 allosteric inhibitors design using Receptor-Ligand pharmacophore model, virtual screening and molecular dynamics.

SHP2 is a potential target for the development of novel therapies for SHP2-dependent cancers. In our research, with the aid of the 'Receptor-Ligand Pharmacophore' technique, a 3D-QSAR method was carried out to explore structure activity relationship of SHP2 allosteric inhibitors. Structure-based drug design was employed to optimize SHP099, an efficacious, potent, and selective SHP2 allosteric inhibitor. A novel class of selective SHP2 allosteric inhibitors was discovered by using the powerful 'SBP', 'ADMET' and 'CDOCKER' techniques. By means of molecular dynamics simulations, it was observed that these novel inhibitors not only had the same function as SHP099 did in inhibiting SHP2, but also had more favorable conformation for binding to the receptor. Thus, this report may provide a new method in discovering novel and selective SHP2 allosteric inhibitors.

Efficient Access to Imidazo[1,2- a]pyridines/pyrazines/pyrimidines via Catalyst-Free Annulation Reaction under Microwave Irradiation in Green Solvent.

An expeditious catalyst-free heteroannulation reaction for imidazo[1,2- a]pyridines/pyrimidines/pyrazines was developed in green solvent under microwave irradiation. Using H2O-IPA as the reaction medium, various substituted 2-aminopyridines/pyrazines/pyrimidines underwent annulation reaction with α-bromoketones under microwave irradiation to provide the corresponding imidazo[1,2- a]pyridines/pyrimidines/pyrazines in excellent yields. The synthetic methodology appears to be very simple and superior to the already reported procedures with the high abundance of commercial reagents and great ability in expanding the molecular diversity. The present synthetic sequence is visualized as an environmentally benign process which allows the introduction of three points of structural diversity to expand chemical space with excellent purity and yields. The anti-inflammatory and antimicrobial activities of the derivatives were evaluated. Screening results uncovered three derivatives with strong inhibition of albumin denaturation and two derivatives were active on Proteus and Klebsiella bacteria. These positive bioassay results implied that the library of potential anti-inflammatory agents could be rapidly prepared in an ecofriendly manner, and provided new insights into drug discovery for medicinal chemists.

Synthesis of New Isoxazole-, Pyridazine-, Pyrimidopyrazines and Their Anti-Inflammatory and Analgesic Activity.

BACKGROUND: Isoxazoles, pyridazines, and pyrimidopyrazines have recently attracted attention due to their potent pharmacological activities. They exhibited anticancer, neuroprotective, analgesic and anti-inflammatory effects. OBJECTIVE: The study aimed to synthesize novel isoxazoles, pyridazines, and pyrimidopyrazines through efficient high yield protocol for evaluating their analgesics and anti-inflammatory activities. METHOD: A series of novel isoxazole-, pyridazine-, pyrimidopyrazine derivatives was prepared from 5,8-alkyl-1,3-dimethyl-5,6-dihydropyrimido[5,6-e]pyrazine-2,4,7-trione (1a,b) as the starting material. RESULTS: The prepared derivatives were synthesized in moderate to good yields (60-75%) in a stepwise efficient protocol under mild condition. These new compounds have been proven by several spectroscopic techniques as IR, 1D and 2D NMR techniques and mass analysis. The in vivo anti-inflammatory was assessed for the synthesized compounds using carrageenan-induced rat hind paw edema model. Also, the in vivo analgesic activity for these products was examined utilizing hot-plate and acetic acid-induced writhing response assays. CONCLUSION: The isoxazole derivatives (3a-f) showed the most forceful anti-inflammatory and analgesic activities. Pyrimidopyrazines (4a-f) demonstrated weaker but comparable antiinflammatory and analgesic activities to the positive controls.