Mini Reviews in Medicinal Chemistry - Volume 19, Issue 12, 2019

Tumor-targeting peptides have been generally developed for the overexpression of tumor specific receptors in cancer cells. The use of specific radiolabeled peptide allows tumor visualization by single photon emission computed tomography (SPECT) and positron emission tomography (PET) tools. The high affinity and specific binding of radiolabeled peptide are focusing on tumoral receptors. The character of the peptide itself, in particular, its complex molecular structure and behaviors influence on its specific interaction with receptors which are overexpressed in tumor. This review summarizes various strategies which are applied for the expansion of radiolabeled peptides for tumor targeting based on in vitro and in vivo specific tumor data and then their data were compared to find any correlation between these experiments. With a careful look at previous studies, it can be found that in vitro unblock-block ratio was unable to correlate the tumor to muscle ratio and the success of radiolabeled peptide for in vivo tumor targeting. The introduction of modifiers’ approaches, nature of peptides, and type of chelators and co-ligands have mixed effect on the in vitro and in vivo specificity of radiolabeled peptides.

Cancer has become one of the most deadly noncommunicable diseases globally. Several modalities used to treat cancer patients exist today yet many have failed to prove high efficacy with low side effects. The most common example of such modalities is the use of chemotherapeutic drugs to treat cancerous cells and deter their uncontrolled proliferation. In addition to the destruction of cancerous tissues, chemotherapy destroys healthy tissues as it lacks the specificity to annihilate cancerous cells only and preferentially, which result in adverse side effects including nausea, hair fall and myocardial infarction. To prevent the side effects of non-selective chemotherapy, cancer therapy research has been focused on the implementation of nanocarrier systems that act as vehicles to encapsulate drugs and selectively transport their agent to the tumor site. In this paper, we shed light on liposomes along with three anticancer drug delivery approaches: passive, active and ultrasound-triggered drug delivery.

Nerve agents belong to the most dangerous chemical warfare agents and can be/were misused by terrorists. Effective prophylaxis and treatment is necessary to diminish their effect. General principles of prophylaxis are summarized (protection against acetylcholinesterase inhibition, detoxification, treatment “in advance” and use of different drugs). They are based on the knowledge of mechanism of action of nerve agents. Among different examinations, it is necessary to test prophylactic effectivity in vivo and compare the results with protection in vitro. Chemical and biological approaches to the development of new prophylactics would be applied simultaneously during this research. Though the number of possible prophylactics is relatively high, the only four drugs were introduced into military medical practice. At present, pyridostigmine seems to be common prophylactic antidote; prophylactics panpal (tablets with pyridostigmine, trihexyphenidyl and benactyzine), transant (transdermal patch containing HI-6) are other means introduced into different armies as prophylactics. Scavenger commercionally available is Protexia®. Future development will be focused on scavengers, and on other drugs either reversible cholinesterase inhibitors (e.g., huperzine A, gallantamine, physostigmine, acridine derivatives) or other compounds.

Pathogenic free-living amoeba are known to cause a devastating infection of the central nervous system and are often referred to as “brain-eating amoebae”. The mortality rate of more than 90% and free-living nature of these amoebae is a cause for concern. It is distressing that the mortality rate has remained the same over the past few decades, highlighting the lack of interest by the pharmaceutical industry. With the threat of global warming and increased outdoor activities of public, there is a need for renewed interest in identifying potential anti-amoebic compounds for successful prognosis. Here, we discuss the available chemotherapeutic options and opportunities for potential strategies in the treatment and diagnosis of these life-threatening infections.

Bisphosphonates (BPs) are stable analogues of the Inorganic Pyrophosphate (PPi), an endogenous regulator of bone mineralization, which can resist the hydrolysis in the gastrointestinal tract. Their conformation allows targeting the bone as a result of their three-dimensional structure, which makes them primary agents against osteoclast-mediated bone loss. They are used in many bone pathological conditions, like bone metastasis, because of its ability to modulate bone metabolism into a less favorable place to cancer cell growth, through the inhibition of osteoclastogenesis and bone resorption. This review is focused on the mechanisms of action through which BPs affect the cellular activity and survival, mainly on their antitumoral effects. In conclusion, BPs are considered the primary therapy for skeletal disorders due to its high affinity for bone, but now they are also considered as potential antitumor agents due to its ability to induce tumor cell apoptosis, inhibition of cell adhesion, invasion and proliferation, modulation of the immune system to target and eliminate cancer cells as well as affect the angiogenic mechanisms. Like any other drug, they also have some adverse effects, but the most common, the acute phase reaction, can be minimized with the intake of calcium and vitamin D.

Tuberculosis (TB) takes the second place among the reasons for mortality from infectious diseases. For this reason, the problem of tuberculosis treatment requires urgent attention all over the world. Some 2-amino substituted 1,3-benzothiazin-4-ones (2-amino-1,3-BTZs) represent a promising new class of antitubercular agents. Other 1,3-benzothiazin-4-one derivatives, mostly 2-aryl and 2- (pyridin-2-yl) ones, are attractive due to their ability to suppress oxidative stress-induced cardiomyocyte apoptosis. This review covers the synthetic approaches to 2-amino- and 2-aryl(heteryl) substituted 1,3-benzothiazin-4-ones (1,3-BTZs). A brief overview of structure-activity relationships is presented.

Background: The function of Carbonic anhydrase is to facilitate the physiological process i.e. interconversion of CO2 to HCO3 - by hydration. Carbonic anhydrase enzyme plays a vital role in different physiological processes to regulate pH as well as regulate the inner environment of CO2 and secretion of electrolytes. Methods: Six representatives of amidophosphate derivatives (L1-L6) were synthesized and evaluated for their biological activities against carbonic anhydrase enzyme. Results: Out of six derivatives, L1 (IC50 = 12.5 ± 1.35 μM), and L2 (IC50 = 3.12 ± 0.45 μM) showed potent activity against BCA-II. While (L3, L4 and L5) showed weak inhibitory activity with IC50 values of 24.5 ± 2.25, 55.5± 1.60, and 75.5 ± 1.25 μM, respectively and were found to be weak inhibitors of carbonic anhydrase as compared to acetazolamide (IC50 =0.12± 0.03μM), used as standard inhibitor. A computational Petra/Osiris/Molinspiration/DFT (POM/DFT) based model has been expanded for the determination of physicochemical parameters governing the bioactivity amidophosphate derivatives (L1-L6) containing (O1 --- O2) pharmacophore site. The six compounds (L1-L6) analyzed here were previously experimentally and now virtually screened for their anti-carbonic anhydrase activity. Conclusion: The highest anti-carbonic anhydrase activity was obtained for compound L2, which exhibited excellent bioactivity (% of inhibition = 95%), comparable to acetazolamide (% of inhibition = 89%). The compound L3 represents increased activity as compared to its analogues (L4-L6). The increase of bioactivity from L3 to L4-L6 could be attributed to the presence of a minimum of steric effect of substituents of P=O moiety which plays a decisive template part in the organization of anti-carbonic anhydrase (O1---O2) phramacophore site. Moreover, it is inexpensive, has little side effects and possible inclusions in selective anti-carbonic anhydrase agents design.