Coumarin as an Elite Scaffold in Anti-Breast Cancer Drug Development: Design Strategies, Mechanistic Insights, and Structure-Activity Relationships.

Breast cancer is the most common cancer among women. Currently, it poses a significant threat to the healthcare system due to the emerging resistance and toxicity of available drug candidates in clinical practice, thus generating an urgent need for the development of new potent and safer anti-breast cancer drug candidates. Coumarin (chromone-2-one) is an elite ring system widely distributed among natural products and possesses a broad range of pharmacological properties. The unique distribution and pharmacological efficacy of coumarins attract natural product hunters, resulting in the identification of numerous natural coumarins from different natural sources in the last three decades, especially those with anti-breast cancer properties. Inspired by this, numerous synthetic derivatives based on coumarins have been developed by medicinal chemists all around the globe, showing promising anti-breast cancer efficacy. This review is primarily focused on the development of coumarin-inspired anti-breast cancer agents in the last three decades, especially highlighting design strategies, mechanistic insights, and their structure-activity relationship. Natural coumarins having anti-breast cancer efficacy are also briefly highlighted. This review will act as a guideline for researchers and medicinal chemists in designing optimum coumarin-based potent and safer anti-breast cancer agents.

Antimicrobial and antibiofilm effects of shikonin with tea tree oil nanoemulsion against Candida albicans and Staphylococcus aureus.

The current work aims to develop a shikonin and tea tree oil loaded nanoemulsion system stabilized by a mixture of GRAS grade surfactants (Tween 20 and monoolein) and a cosurfactant (Transcutol P). This system was designed to address the poor aqueous solubility and photostability issues of shikonin. The authenticity of shikonin employed in this study was confirmed using nuclear magnetic resonance (NMR) spectroscopy. The optimized nanoemulsion exhibited highly favorable characteristics in terms of zeta potential (-23.8 mV), polydispersity index (0.216) and particle size (22.97 nm). These findings were corroborated by transmission electron microscopy (TEM) micrographs which confirmed the spherical and uniform nature of the nanoemulsion globules. Moreover, attenuated total reflectance (ATR) and X-ray diffraction analysis (XRD) analysis affirmed improved chemical stability and amorphization, respectively. Photodegradation studies were performed by exposing pure shikonin and the developed nanoemulsion to ultraviolet light for 1 h using a UV lamp, followed by high performance liquid chromatography (HPLC) analysis. The results confirmed that the developed nanoemulsion system imparts photoprotection to pure shikonin in the encapsulated system. Furthermore, the research investigated the effect of the nanoemulsion on biofilms formed by Candida albicans and methicillin resistant Staphylococcus aureus (MRSA). Scanning electron microscopy, florescence microscopy and phase contrast microscopy unveiled a remarkable reduction in biofilm area, accompanied by disruptions in the cell wall and abnormalities on the cell surface of the tested microorganisms. In conclusion, the nanoencapsulation of shikonin with tea tree oil as the lipid phase showcased significantly enhanced antimicrobial and antibiofilm potential compared to pure shikonin against resistant strains of Candida albicans and Staphylococcus aureus.

Mechanistic insight and structure activity relationship of isatin-based derivatives in development of anti-breast cancer agents.

Breast cancer is most common in women and most difficult to manage that causes highest mortality and morbidity among all diseases and posing significant threat to mankind as well as burden on healthcare system. In 2020, 2.3 million women were diagnosed with breast cancer and it was responsible for 685,000 deaths globally, suggesting the severity of this disease. Apart from that, relapsing of cases and resistance among available anticancer drugs along with associated side effects making the situation even worse. Therefore, it is a global emergency to develop potent and safer antibreast cancer agents. Isatin is most versatile and flying one nucleus which is an integral competent and various anticancer agent in clinical practice and widely used by various research groups around the globe for development of novel, potent, and safer antibreast cancer agents. This review will shed light on the structural insights and antiproliferative potential of various isatin-based derivatives developed for targeting breast cancer in last three decades that will help researchers in design and development of novel, potent, and safer isatin-based antibreast cancer agents.

4-methylthiobutyl isothiocyanate synergize the antiproliferative and pro-apoptotic effects of paclitaxel in human breast cancer cells.

Multidrug resistance (MDR) is considered as a major obstacle in achieving an effective treatment of breast cancer. Paclitaxel has been used to treat cancers of the cervical, breast, ovarian and brain but MDR limits its therapeutic potential. Phytochemicals have received much interest in recent decades especially in combination approaches to tackle MDR due to their negligible harm to healthy cells and synergistic potential. Considering this notion, the present study aimed at investigating the synergistic activity of 4-MTBITC and PTX against a panel of breast cancer cells. Our results revealed that the combination had a significant antiproliferative activity against T-47D cells. Mechanistic studies revealed that 4-MTBITC and PTX also promoted the production of reactive oxygen species (ROS) and reduced mitochondrial membrane potential. In the presence of 4-MTBITC- PTX, T-47D cells were found to be arrested in the G2/M phase which also confirmed the enhancement of late apoptotic cell population in the flow cytometer analysis. In western blot experiment, the combination had a significant decrease in Bcl-xl protein level, whereas a higher level of p53, cleaved caspase-3, and cleaved caspase-9 proteins compared to individual treatment in T-47D cells. The RT-qPCR analysis also showed that the combination had significant upregulation in the gene expression of p53, cytochrome-c, Apaf-1 and downregulation in the expression of Bcl-2 gene in T-47D cells. Hence, all the results showed that a combination of 4-MTBITC-PTX significantly enhanced the apoptosis pathway in the T-47D cell line which indicates its clinical application for the treatment of breast cancer.Abbreviations: Apaf-1: Apoptotic protease activating factor 1; AO/EB: Acridine orange/ethidium bromide; Bcl-2: B-cell lymphoma 2; CI: Combination Index; Cyt-c: Cytochrome c; CO2: Carbon dioxide; DCFH-DA 2,7-Dichloroflourescein diacetate; DMEM: Dulbecco's modified Eagle's medium; ELISA: Enzyme-linked immunosorbent assay; EA: Early apoptosis; EDTA: Ethylenediaminetetraacetic acid; L929: Normal mouse fibroblast cells; LA: Late apoptosis; L: Live; 4-MTBITC: 4-methylthiobutyl isothiocyanate; MCF-7: Human breast cancer cells; MDA-MB-231: Human triple negative breast cancer cells; MMP: Mitochondria membrane potential; MTT: 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenylte-trazolium bromide; NCCS: National Centre for Cell Science; N: Necrotic; PTX Paclitaxel; PVDF: Polyvinylidene fluoride; PAGE: Polyacrylamide gel electrophoresis; PBS: Phosphate-buffered saline; RPMI-1640: Roswell Park Memorial Institute Medium- 1640; RT-qPCR: Quantitative real-time polymerase chain reaction; ROS: Reactive oxygen species; Rh-123: Rhodamine123; g Relative centrifugal force; SDS: Sodium dodecyl sulphate; SEM: Scanning electron microscopy; T-47D: Human estrogen positive breast cancer cells; WB: Western blotting.

Frankincense oil-loaded nanoemulsion formulation of paclitaxel and erucin: A synergistic combination for ameliorating drug resistance in breast cancer: In vitro and in vivo study.

Nanoformulation-based combinational drug delivery systems are well known to overcome drug resistance in cancer management. Among them, nanoemulsions are well-known and thermodynamically stable drug delivery systems suitable for carrying hydrophobic drugs and phytoconstituents to tackle drug-resistant cancers. In the present study, we have investigated the effect of paclitaxel in combination with erucin (natural isothiocyanate isolated from the seeds of Eruca sativa) loaded in the frankincense oil-based nanoemulsion formulation. The choice of frankincense oil for the current study was based on reported research investigations stating its magnificient therapeutic potential against breast cancer. Optimized nanoemulsion of paclitaxel (PTX) and erucin (ER) combination (EPNE) provided sustained release and exhibited enhanced cytotoxicity towards human epithelial breast cancer cells (T-47D) as compared to individual ER and PTX. EPNE was further assessed for its antitumor activity in the 7,12-dimethylbenz(a)anthracene (DMBA)-induced breast cancer mice model. EPNE significantly decreased the levels of hepatic and renal parameters along with oxidative stress in breast cancer mice. Furthermore, EPNE also showed decreased levels of inflammatory cytokines TNF-α, IL-6. Histopathological examinations revealed restoration of the tumorous breast to normal tissues in EPNE-treated breast cancer mice. Therefore, EPNE can act as a viable lead and therapeutic option for drug-resistant breast cancer.

Formulation Strategies and Therapeutic Applications of Shikonin and Related Derivatives.

Shikonin and its derivatives are excellent representatives of biologically active naphthoquinones. A wide range of investigations carried out in the last few decades validated their pharmacological efficacy. Besides having magnificent therapeutic potential, shikonin and its derivatives suffer from various pharmacokinetic, toxicity, and stability issues like poor bioavailability, nephrotoxicity, photodegradation, etc. Recently, various research groups have developed an extensive range of formulations to tackle these issues to ease their path to clinical practice. The latest formulation approaches have been focused on exploiting the unique features of novel functional excipients, which in turn escalate the therapeutic effect of shikonin. Moreover, the codelivery approach in various drug delivery systems has been taken into consideration in a recent while to reduce toxicity associated with shikonin and its derivatives. This review sheds light on the essential reports and patents published related to the array of formulations containing shikonin and its derivatives.

Design, synthesis, and biological evaluation of novel morpholinated isatin-quinoline hybrids as potent anti-breast cancer agents.

Keeping in view the emerging need for potent and safer anti-breast cancer agents as well as the pharmacological attributes of isatin, quinolone, and morpholine derivatives, novel hydrazine-linked morpholinated isatin-quinoline hybrids were designed, synthesized, and evaluated as anti-breast cancer agents. The synthesized hybrid compounds were preliminarily screened against two breast cancer cell lines (MCF-7 and MDA-MB-231). Almost all synthetics showed potent inhibitory potential against hormone-positive MCF-7 cells while being inactive against hormone-negative MDA-MB-231 cells. Potent compounds were further evaluated against the L929 (noncancerous skin fibroblast) cell line and found to be highly selective for MCF-7 cells over L929 cells. Cell cycle analysis confirmed that the most potent compound AS-4 (MCF-7: GI50 = 4.36 µM) causes mitotic arrest at the G2 /M phase. Due to higher selectivity toward estrogen receptor alpha (ERα)-dependent MCF-7 cells, various binding interactions of AS-4 with ERα are also streamlined, suggesting the capability of AS-4 to completely block ERα. Overall, the study suggests that AS-4 can act as a potential lead for further development of potent and safer anti-breast cancer agents.

Design, Synthesis, biological investigations and molecular interactions of triazole linked tacrine glycoconjugates as Acetylcholinesterase inhibitors with reduced hepatotoxicity.

Tacrine is a known Acetylcholinesterase (AChE) inhibitors having hepatotoxicity as main liability associated with it. The present study aims to reduce its hepatotoxicity by synthesizing tacrine linked triazole glycoconjugates via Huisgen's [3 + 2] cycloaddition of anomeric azides and terminal acetylenes derived from tacrine. A series of triazole based glycoconjugates containing both acetylated (A-1 to A-7) and free sugar hydroxyl groups (A-8 to A-14) at the amino position of tacrine were synthesized in good yield taking aid from molecular docking studies and evaluated for their in vitro AChE inhibition activity as well as hepatotoxicity. All the hybrids were found to be non-toxic on HePG2 cell line at 200 µM (100 % cell viability) as compared to tacrine (35 % cell viability) after 24 h of incubation period. Enzyme kinetic studies carried out for one of the potent hybrids in the series A-1 (IC50 0.4 µM) revealed its mixed inhibition approach. Thus, compound A-1 can be used as principle template to further explore the mechanism of action of different targets involved in Alzheimer's disease (AD) which stands as an adequate chemical probe to be launched in an AD drug discovery program.

Most recent strategies targeting estrogen receptor alpha for the treatment of breast cancer.

Breast cancer is the most prominent, frequently diagnosed and leading cause of death among women. Estrogen is an agonist of estrogen receptor alpha (ER-α), expressed in mammary glands and is responsible for initiating many signalling pathways that lead to differentiation and development of breast tissue. Any mutations in these signalling pathways result in irregular growth of mammary tissue, leading to the development of tumour or cancer. All these observations attract the attention of researchers to antagonize ER-α receptor either by developing selective estrogen receptor modulators or by selective estrogen receptor degraders. Therefore, this article provides a brief overview of various factors that are responsible for provoking breast cancer in women and design strategies recently used by the various research groups across the world for antagonizing or demodulating ER-α.

Phytoconstituents from ten natural herbs as potent inhibitors of main protease enzyme of SARS-COV-2: In silico study.

Background: Lack of treatment of novel Coronavirus disease led to the search of specific antivirals that are capable to inhibit the replication of the virus. The plant kingdom has demonstrated to be an important source of new molecules with antiviral potential. Purpose: The present study aims to utilize various computational tools to identify the most eligible drug candidate that have capabilities to halt the replication of SARS-COV-2 virus by inhibiting Main protease (Mpro) enzyme. Methods: We have selected plants whose extracts have inhibitory potential against previously discovered coronaviruses. Their phytoconstituents were surveyed and a library of 100 molecules was prepared. Then, computational tools such as molecular docking, ADMET and molecular dynamic simulations were utilized to screen the compounds and evaluate them against Mpro enzyme. Results: All the phytoconstituents showed good binding affinities towards Mpro enzyme. Among them laurolitsine possesses the highest binding affinity i.e. -294.1533 kcal/mol. On ADMET analysis of best three ligands were simulated for 1.2 ns, then the stable ligand among them was further simulated for 20 ns. Results revealed that no conformational changes were observed in the laurolitsine w.r.t. protein residues and low RMSD value suggested that the Laurolitsine-protein complex was stable for 20 ns. Conclusion: Laurolitsine, an active constituent of roots of Lindera aggregata, was found to be having good ADMET profile and have capabilities to halt the activity of the enzyme. Therefore, this makes laurolitsine a good drug candidate for the treatment of COVID-19.

New coumarin-benzotriazole based hybrid molecules as inhibitors of acetylcholinesterase and amyloid aggregation.

A novel series of triazole tethered coumarin-benzotriazole hybrids based on donepezil skeleton has been designed and synthesized as multifunctional agents for the treatment of Alzheimer's disease (AD). Among the synthesized compounds 13b showed most potent acetylcholinesterase (AChE) inhibition (IC50 = 0.059 µΜ) with mixed type inhibition scenario. Structure-activity relationship revealed that three-carbon alkyl chain connecting coumarin and triazole is well tolerable for inhibitory potential. Hybrids obtained from 4-hydroxycoumarin and 1-benzotriazole were most potent AChE inhibitors. The inhibitory potential of all compounds against butyrylcholinesterase was also evaluated but all showed negligible activity suggesting that the hybrid molecules are selective AChE inhibitors. 13b (most potent AChE inhibitor) also showed copper-induced Aß1-42 aggregation inhibition (34.26% at 50 µΜ) and chelating properties for metal ions (Cu2+, Fe2+, and Zn2+) involved in AD pathogenesis along with DNA protective potential against degenerative actions of OH radicals. Molecular modelling studies confirm the potential of 13b in blocking both PAS and CAS of AChE. In addition, interactions of 13b with Aß1-42 monomer are also streamlined. Therefore, hybrid 13b can act as an effective hit lead molecule for further development of selective AChE inhibitors as multifunctional anti-Alzheimer's agents.