Mini Reviews in Medicinal Chemistry - Volume 23, Issue 7, 2023

Flavonoids are associated with many plants and dietary foods; their chemical study has always attracted the interest of chemists working in the area of natural products and synthetic chemistry. Research in phytochemistry has produced many useful drugs. The analogs of flavonoids exhibit anticancer, anti-tuberculosis, anti-diabetic, antiviral, antibacterial, antioxidant, anti-inflammatory, antiproliferative, anti-spermatogenic, and antipsychotic activities. This review article highlights flavonoids' significance and medicinal application and displays a comparative overview of the biological activities of flavonoids and flavonoid derivatives. It covers almost all necessary reports for future directions in drug discovery.

C-X-C-motif chemokine receptor 4 (CXCR4) is a novel predictive biomarker for metastasis and poor prognosis in individuals with malignancies. CXCL12 is the only cognate ligand of CXCR4. CXCL12/CXCR4 signaling pathways are involved in the cross-talk among cancer cells, T cells, stromal cells, and their microenvironments, including the regulation and direction of T cell migration (chemotaxis), proliferation, and differentiation of immature progenitor stem cells. As CXCR4 overexpression is related to tumor prognosis, it is essential to quantitatively evaluate CXCR4 expression levels in vivo. ⁶⁸Ga-Pentixafor, as a radiolabeled tracer, shows high specificity and affinity for CXCR4 in tumors. Thus, CXCR4-directed imaging with ⁶⁸Ga-Pentixafor has been investigated to evaluate CXCR4 expression in patients non-invasively. In recent years, many small cohorts, including those of individuals with hematologic malignancies, solid tumors, and cardiovascular and infectious diseases, have been reported. So far, ⁶⁸Ga-Pentixafor has been used successfully in individuals with hematologic malignancies. In addition, Lutetium-177 (¹⁷⁷Lu) or Yttrium-90 (⁹⁰Y)-labeled Pentixather (an analog of Pentixafor) suggested high potential applicability in tumor endoradiotherapy (ERT) with CXCR4 overexpression. Patients with advanced-stage multiple myeloma, refractory acute leukemia, and diffuse large B-cell lymphoma received a certain amount of ¹⁷⁷Lu-Pentixather or ⁹⁰Y-Pentixather. This review aimed to overview the current CXCR4-directed positron emission computed tomography (PET) molecular imaging based on Pentixafor in several diseases and ERT.

Ginseng, the roots and/or rhizomes of Panax spp.(Araliaceae), has been used as a popular herbal medicine in East Asia for at least two millennia. As a functional food and healthenhancing supplement, ginseng has been shown to have a wide range of pharmacological effects on cognition and blood circulation as well as antioxidant, antitumor, and anti-fatigue effects. The main active properties of ginseng are considered to be the triterpene saponins, often referred to as ginsenosides, which are the basis for their wide-ranging pharmacological effects. Four of these glycosides, including protopanaxadiol, protopanaxatriol, ocotillol, and oleanolic acid, are the most common saponins found in ginseng. Compared to other ginsenosides, the C-20 chimeric ginsenosides, including Rg3, Rh2, Rg2, Rh1, PF11, C-20, and C-24, as well as epimeric ocotillol-type saponins and their derivatives exhibit significant, steric differences in biological activity and metabolism. 20(R)-ginseng saponins, one class of important rare ginsenosides, have antitumor, antioxidative, antifatigue, neuroprotective and osteoclastogenesis inhibitory effects. However, 20(R)- ginsenosides are rare in natural products and are usually prepared from 20(S)-isomers through chemical differential isomerization and microbial transformation. The C20 configuration of 20(R)-ginseng saponins is usually determined by ¹³C NMR and X-ray single-crystal diffraction. There are regular differences in the chemical shift values of some of the carbons of the 20(S)- and 20(R)-epimers, including C-17, C-21, and C-22. Owing to their chemical structure and pharmacological and stereoselective properties, 20(R)-ginseng saponins have attracted a great deal of attention in recent years. Herein, the stereoscopic differences in the identification, bioactivity, and metabolism of C-20 and C-24 epimeric ginseng saponins are summarized.

Viruses are still the most prevalent infectious pathogens on a worldwide scale, with many of them causing life-threatening illnesses in humans. Influenza viruses, because of their significant morbidity and mortality, continue to pose a major threat to human health. According to WHO statistics, seasonal influenza virus epidemics are predicted to cause over 2 million severe illness cases with high death rates yearly. The whole world has been suffering from the COVID-19 epidemic for two years and is still suffering so far, and the deaths from this virus have exceeded three million cases. Because the great majority of viral infections do not have a specific medication or vaccination, discovering novel medicines remains a vital task. This review covers reports in the patent literature from 1980 to the end of 2021 on the antiviral activities of pyrimidine moieties. The patent database, SciFinder, was used to locate patent applications. A large variety of pyrimidine molecules have been produced and tested for antiviral activity over the last decade. These molecules were reported to inhibit a wide range of viruses, including influenza virus, respiratory syncytial virus, rhinovirus, dengue virus, herpes virus, hepatitis B and C, and human immunodeficiency virus. The cytotoxicity of the developed pyrimidine derivatives was tested in almost all reported studies and the selectivity index was calculated to show the selectivity and safety of such molecules. From the remarkable activity of pyrimidine compounds as antivirals for several dangerous viruses, we expect that these derivatives will be used as potent drugs in the very near future.

Due to the importance of control and prevention of COVID-19-correlated long-term symptoms, the present review article has summarized what has been currently known regarding the molecular and cellular mechanisms linking COVID-19 to important long-term complications including psychological complications, liver and gastrointestinal manifestations, oral signs as well as even diabetes. COVID-19 can directly affect the body cells through their Angiotensin-converting enzyme 2 (ACE-2) to induce inflammatory responses and cytokine storm. The cytokines cause the release of reactive oxygen species (ROS) and subsequently initiate and promote cell injuries. Another way, COVID-19-associated dysbiosis may be involved in GI pathogenesis. In addition, SARS-CoV-2 reduces butyrate-secreting bacteria and leads to the induction of hyperinflammation. Moreover, SARS-CoV-2-mediated endoplasmic reticulum stress induces de novo lipogenesis in hepatocytes, which leads to hepatic steatosis and inhibits autophagy via increasing mTOR. In pancreas tissue, the virus damages beta-cells and impairs insulin secretion. SARS-COV-2 may change the ACE2 activity by modifying ANGII levels in taste buds which leads to gustatory dysfunction. SARS-CoV-2 infection and its resulting stress can lead to severe inflammation that can subsequently alter neurotransmitter signals. This, in turn, negatively affects the structure of neurons and leads to mood and anxiety disorders. In conclusion, all the pathways mentioned earlier can play a crucial role in the disease's pathogenesis and related comorbidities. However, more studies are needed to clarify the underlying mechanism of the pathogenesis of the new coming virus.

Alzheimer's disease (AD) is a multifactorial, irreversible, and age-related neurodegenerative disorder among the elderly. AD attracts attention due to its complex pathogenesis, morbidity and mortality rates, and the limitations of drugs used in the treatment of AD. Cholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonists are used in the clinic. While tacrine, donepezil, galantamine, and rivastigmine are cholinesterase inhibitors, memantine is a non-competitive NMDA receptor antagonist. However, these drugs could not delay the progress of AD. The traditional clinical approach which is the one drug-one target concept is not entirely effective in the treatment of AD. Also, it is of high-priority to develop potent and novel anti-AD drugs by the design concept of multitarget directed ligands (MTDLs) which combine pharmacophores interacting with different pathways in AD. This article provides an overview of the noteworthy structural modifications made to tacrine to develop novel candidates for anti-Alzheimer drugs. Due to the complex pathology of AD, multifunctional tacrine-based ligands targeting different hallmarks, β-amyloid, tau protein, N-methyl-Daspartate receptor, cholinesterases, monoamine oxidases, secretases, have been studied. Here, tacrinebased derivatives including heterocyclic structures such as dihydroxypyridine, chromene, coumarin, pyrazole, triazole, tetrahydroquinolone, dipicolylamine, arylisoxazole were reported with promising anti-AD effects compared to tacrine. In vitro and in vivo assays showed that new tacrine-based hybrids, which are selective, neuroprotective, and non-hepatotoxic, might be considered as remarkable anti-AD drug candidates for further clinical studies.

Alzheimer’s disease (AD) is a neurodegenerative, progressive, and fatal disorder characterized by marked atrophy of the cerebral cortex and loss of basal forebrain cholinergic neurons. The main pathological features of AD are related to neuronal degeneration and include extracellular deposition of amyloid beta plaques (Aβ plaques), intracellular formation of neurofibrillary tangles (NFTs), and neuroinflammation. So far, drugs used to treat AD have symptomatic and palliative pharmacological effects, disappearing with continued use due to neuron degeneration and death. Therefore, there are still problems with an effective drug for treating AD. Few approaches evaluate the action of natural products other than alkaloids on the molecular targets of β-amyloid protein (Aβ protein) and/or tau protein, which are important targets for developing neuroprotective drugs that will effectively contribute to finding a prophylactic drug for AD. This review gathers and categorizes classes of natural products, excluding alkaloids, which in silico analysis (molecular docking) and in vitro and/or in vivo assays can inhibit the BACE1 and GSK-3β enzymes involved in AD.