Synthesis of a novel class of substituted benzothiophene or benzofuran derivatives as BMP-2 up-regulators and evaluation of the BMP-2-up-regulating effects in vitro and the effects on glucocorticoid-induced osteoporosis in rats

Efficacy, Mechanism, and Structure-Activity Relationship of 6-Methoxy Benzofuran Derivatives as a Useful Tool for Senile Osteoporosis

Most patients with senile osteoporosis (SOP) are severely deficient in bone mass, and treatments using bone resorption inhibitors, such as bisphosphonates, have shown limited efficacy. Small-molecule osteogenesis-promoting drugs are required to improve the treatment for this disease. Previously, we demonstrated that a compound with a benzofuran-like structure promoted bone formation by upregulating BMP-2, and it exhibited a therapeutic effect in SAMP-6 mice, glucocorticoid-induced osteoporosis rats, and ovariectomized rats. In this study, aged C57 and SAMP-6 mice models were used to investigate the therapeutic and preventive effects of compound 125 on SOP. scRNA-seq analysis showed that BMP-2 upregulation is the mechanism through which 125 accelerates bone turnover and increases the proportion of osteoblasts. We evaluated the structure-activity relationship of the candidate drugs and found that the derivative I-9 showed significantly higher efficacy than 125 and teriparatide in the zebrafish osteoporosis model. This study provides a foundation for the development of SOP drugs.

Discovery of Some Heterocyclic Molecules as Bone Morphogenetic Protein 2 (BMP-2)-Inducible Kinase Inhibitors: Virtual Screening, ADME Properties, and Molecular Docking Simulations

Bone morphogenetic proteins (BMPs) are growth factors that have a vital role in the production of bone, cartilage, ligaments, and tendons. Tumors’ upregulation of bone morphogenetic proteins (BMPs) and their receptors are key features of cancer progression. Regulation of the BMP kinase system is a new promising strategy for the development of anti-cancer drugs. In this work, based on a careful literature study, a library of benzothiophene and benzofuran derivatives was subjected to different computational techniques to study the effect of chemical structure changes on the ability of these two scaffolds to target BMP-2 inducible kinase, and to reach promising candidates with proposed activity against BMP-2 inducible kinase. The results of screening against Lipinski’s and Veber’s Rules produced twenty-one outside eighty-four compounds having drug-like molecular nature. Computational ADMET studies favored ten compounds (11, 26, 27, 29, 30, 31, 34, 35, 65, and 72) with good pharmacokinetic profile. Computational toxicity studies excluded compound 34 to elect nine compounds for molecular docking studies which displayed eight compounds (26, 27, 29, 30, 31, 35, 65, and 72) as promising BMP-2 inducible kinase inhibitors. The nine fascinating compounds will be subjected to extensive screening against serine/threonine kinases to explore their potential against these critical proteins. These promising candidates based on benzothiophene and benzofuran scaffolds deserve further clinical investigation as BMP-2 kinase inhibitors for the treatment of cancer.

Bone Regeneration in Osteoporosis via Carbon Nanotube-Based Bone Morphogenetic Protein-2

We constructed a bone morphogenetic protein 2 (BMP-2)@Carbon nanotube (CNT) delivery system to explore the feasibility of a nanodrug delivery system in the treatment of osteoporosis (OP). Osteoblasts were cultured and OP mouse models were constructed to evaluate the osteogenesis of nano-BMP-2 in OP therapy. In physicochemical property tests, we found that BMP-2 was effectively loaded into CNT to form nanoparticles (NPs) with a particle size of 100 nm. Additionally, we found that nano-BMP-2 had good stability and could effectively prolong BMP-2 release time. In cellular experiments, we found that nano-BMP-2 could penetrate osteoblasts more effectively than BMP-2 alone, and with the increase of BMP-2 loading, the amount of BMP-2 penetrating osteoblasts increased with an optimal loading of 100 μg. We determined that nano-BMP-2 could increase proliferation activity of osteoblasts to better promote OP repair. In our vivo experiments, we found that nano-BMP-2 was effectively excreted through the kidney and mainly distributed in bone tissue. Moreover, CNT effectively prolonged the half-life of BMP-2 and was safe to introduce through intramuscular injection and did not cause obvious inflammatory reactions. Following treatment, nano-BMP-2 increased body weight, femur weight, and femoral head diameter in OP mouse models. Furthermore, bone trabecular was arranged in a close and orderly fashion and was uniform in thickness in OP mice treated with nano-BMP-2. OP mice had improved bone mineral density, trabecular thickness, trabecular number, and cortical bone thickness in their metaphyseal regions, implying nano-BMP-2 treatment led to improved OP symptoms. Therefore, BMP-2@CNT may be a beneficial choice for treatment of OP.

Benzofuran: A Key Heterocycle - Ring Closure And Beyond

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The benzofuranyl motif present in compounds exhibits various medicinal properties and non-drug applications. These derivatives are naturally occurring compounds or synthetic materials, which cover a broad spectrum of pharmacological activities like anti-inflammatory, anti-diabetic, anti- depressant, anti-HIV, anti-microbial, anti-proliferative, anti-convulsant, cytotoxic, analgesic, etc. Few of the commercially interesting compounds from this class are, ailanthoidol (anti-inflammatory), amiodarone, dronedarone, celivarone (anti-arrhythmic), bufuralol (muscular airways relaxant), morphine, 5-(2-aminopropyl)benzofuran; 5-APB, 6-(2-aminopropyl)benzofuran; 6-APB (CNS), rifampicin (antibiotic), etc., whereas, some of the non-drug applications are in perfumery industry (bergapten) and as tannin activators in sunscreen preparations (psoralen, 8-methoxypsoralen, and angelicin). Considering these interesting biological activities and commercial utilities, a review on the synthetic aspects of this privileged scaffold was attempted. For the benefit of natural product-based drug discovery, available sources of these derivatives, extraction process and reported biological activities have also been outlined in this review.

Novel phthalimide based analogues: design, synthesis, biological evaluation, and molecular docking studies

Pyrazolylphthalimide derivative 4 was synthesized and reacted with different reagents to afford the target compounds imidazopyrazoles 5-7, pyrazolopyrimidines 9, 12, 14 and pyrazolotriazines 16, 17 containing phthalimide moiety. The prepared compounds were established by different spectral data and elemental analyses. Additionally, all synthesized derivatives were screened for their antibacterial activity against four types of Gram + ve and Gram-ve strains, and for antifungal activity against two fungi micro-organisms by well diffusion method. Moreover, the antiproliferative activity was tested for all compounds against human liver (HepG-2) cell line in comparison with the reference vinblastine. Moreover, drug-likeness and toxicity risk parameters of the newly synthesized compounds were calculated using in silico studies. The data from structure-actvity relationship (SAR) analysis suggested that phthalimide derivative bearing 3-aminopyrazolone moiety, 4 illustrated the best antimicrobial and antitumor activities and might be considered as a lead for further optimization. To investigate the mechanism of the antimicrobial and anticancer activities, enzymatic assay and molecular docking studies were carried out on E. coli topoisomerase II DNA gyrase B and VEGFR-2 enzymes.

Novel cathepsin K inhibitors block osteoclasts in vitro and increase spinal bone density in zebrafish

Cathepsin K (Cat K) is a predominant cysteine protease and highly potent collagenase expressed in osteoclasts. Cat K inhibitors are anti-resorptive agents to treat osteoporosis. A novel scaffold of cathepsin K inhibitors, exemplified by lead compound 1x, was used as the template for designing and synthesizing a total of 61 derivatives that have not been reported before. An exploratory structure–activity relationship analysis identified the potent Cat K inhibitor A22, which displayed an IC₅₀ value of 0.44 μM against Cat K. A22 was very specific for Cat K and caused a significantly higher in vitro inhibition of the enzyme as compared to that of lead compound 1x. A surface plasmon resonance analysis confirmed in vitro binding of A22 to Cat K. Molecular docking studies indicated several favourable interaction sites for A22 within the active pocket of Cat K. Furthermore, A22 also blocked active osteoclasts in vitro and increased spinal bone density in zebrafish, in which it showed an activity that was higher than that of the marketed therapeutic bone metabolizer etidronate disodium. A22 represents a very promising lead compound for the development of novel antiresorptive agents functioning as orthosteric inhibitors of Cat K.

Cathepsin K (Cat K) is a predominant cysteine protease and highly potent collagenase expressed in osteoclasts.

The development of bone microstructure, metabolism and biomechanics in lumbar vertebra under short-term glucocorticoid exposure

Abstracts Objective: This study investigated the characteristics of bone microstructure, metabolism, and biomechanics in rat's lumbar vertebra undergoing short-term glucocorticoid administration. Methods: Forty 4-month-old female Sprague-Dawley rats were treated with either vehicle (Cont) or prednisone acetate (Pre) at 3.5 mg/kg/day, respectively for periods of 7 days and 21 days. The lumbar vertebras were processed for MicroCT scan, histomorphometry analysis, mechanical compression test, in addition to Dual-Energy X-ray absorptiometry scan, respectively. Results: The connective density (Conn. D) along with trabecular connection nodes decreased while trabecular termini increased in Pre at day 21 when compared to Cont at day 21 as well as Pre at day 0. The mineralizing surface (MS/BS), mineral apposition rate (MAR), bone formation rate (BFR), osteoblast surfaces (Ob.S/BS) were lower in Pre at day 21 than that in Cont at day 21, Pre at day 0 and Pre at day 7. Only the bending stiffness of compression test decreased in Pre group at day 21 compared to age-matched control. Conclusion: The results suggested that excess prednisone significantly inhibited bone formation and slightly depressed bone resorption in the lumbar vertebra of intact rats for the duration of 21 days. Accordingly, the trabecular spatial microstructure made an adjustment yet failed to maintain the anti-compression mechanical property.

Benzofuran-dihydropyridine hybrids: A new class of potential bone anabolic agents

A series of novel benzofuran-dihydropyridine hybrids were designed by molecular hybridization approach and evaluated for bone anabolic activities. Among the screened library, ethyl 4-(7-(sec-butyl)-2-(4-methylbenzoyl)benzofuran-5-yl)-2-methyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate (compound 21) significantly enhanced the ALP production and mineralized nodule formation, which are primary requisites in the process of in vitro osteogenesis. Oral administration of compound 21 at 10 mg.kg^-1 day^-1 for two weeks led to restoration of trabecular bone microarchitecture in drill hole fracture model by significantly increasing BV/TV and Tb.N. Furthermore, histological and molecular studies showed compound 21 triggering the new bone regeneration in a drill hole defect site by increasing BMP expression. Furthermore, molecular modeling studies were performed to gain insight into the binding approach, which revealed that both benzofuran and dihydropyridine moieties are essential to show similar binding interactions to fit into the active site of BMP2 receptor, an important target of the osteogenic agents. Our results suggest that compound 21 stimulates BMP2 synthesis in osteoblast cells that promotes new bone formation (∼40%) at the fracture site which helps in shorten the healing period.

An overview of benzo[b]thiophene-based medicinal chemistry

Among sulfur containing heterocycles, benzothiophene and its derivatives are at the focus as these candidates have structural similarities with active compounds to develop new potent lead molecules in drug design. Benzo[b]thiophene scaffold is one of the privileged structures in drug discovery as this core exhibits various biological activities allowing them to act as anti-microbial, anti-cancer, anti-inflammatory, anti-oxidant, anti-tubercular, anti-diabetic, anti-convulsant agents and many more. Further, numerous benzothiophene-based compounds as clinical drugs have been extensively used to treat various types of diseases with high therapeutic potency, which has led to their extensive developments. Due to the wide range of biological activities of benzothiophene, their structure activity relationships (SAR) have generated interest among medicinal chemists, and this has culminated in the discovery of several lead molecules against numerous diseases. The present review is endeavoring to highlight the progress in the various pharmacological activities of benzo[b]thiophene derivatives. It is hoped that this review will be helpful for new thoughts in the quest for rational designs of more active and less toxic benzothiophene-based medicinal drugs, as well as more effective diagnostic agents and pathologic probes. Also, SAR studies that highlight the chemical groups responsible for evoking the potential activities of benzothiophene derivatives are studied and compared.

Design, Synthesis, and Biological Evaluation of Novel Benzofuran Derivatives Bearing N-Aryl Piperazine Moiety

A series of novel hybrid compounds between benzofuran and N-aryl piperazine have been synthesized and screened in vitro for anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated RAW-264.7 macrophages and for anticancer activity against three human tumor cell lines. The results demonstrated that derivative 16 not only had inhibitory effect on the generation of NO (IC₅₀ = 5.28 μM), but also showed satisfactory and selective cytotoxic activity against human lung cancer line (A549) and gastric cancer cell (SGC7901) (IC₅₀ = 0.12 μM and 2.75 μM, respectively), which was identified as the most potent anti-inflammatory and anti-tumor agent in this study.