Novel epidithiodiketopiperazines as anti-viral zinc ejectors of the Feline Immunodeficiency Virus (FIV) nucleocapsid protein as a model for HIV infection

Synthesis and evaluation of 1,2,3-dithiazole inhibitors of the nucleocapsid protein of feline immunodeficiency virus (FIV) as a model for HIV infection

We disclose a series of potent anti-viral 1,2,3-dithiazoles, accessed through a succinct synthetic approach from 4,5-dichloro-1,2,3-dithiazolium chloride (Appel's salt). A series of small libraries of compounds were screened against feline immunodeficiency virus (FIV) infected cells as a model for HIV. This approach highlighted new structure activity relationship understanding and led to the development of sub-micro molar anti-viral compounds with reduced toxicity. In addition, insight into the mechanistic progress of this system is provided via advanced QM-MM modelling. The 1,2,3-dithiazole represents a versatile scaffold with potential for further development to treat both FIV and HIV.

Role of animal models in biomedical research: a review

The animal model deals with the species other than the human, as it can imitate the disease progression, its’ diagnosis as well as a treatment similar to human. Discovery of a drug and/or component, equipment, their toxicological studies, dose, side effects are in vivo studied for future use in humans considering its’ ethical issues. Here lies the importance of the animal model for its enormous use in biomedical research. Animal models have many facets that mimic various disease conditions in humans like systemic autoimmune diseases, rheumatoid arthritis, epilepsy, Alzheimer’s disease, cardiovascular diseases, Atherosclerosis, diabetes, etc., and many more. Besides, the model has tremendous importance in drug development, development of medical devices, tissue engineering, wound healing, and bone and cartilage regeneration studies, as a model in vascular surgeries as well as the model for vertebral disc regeneration surgery. Though, all the models have some advantages as well as challenges, but, present review has emphasized the importance of various small and large animal models in pharmaceutical drug development, transgenic animal models, models for medical device developments, studies for various human diseases, bone and cartilage regeneration model, diabetic and burn wound model as well as surgical models like vascular surgeries and surgeries for intervertebral disc degeneration considering all the ethical issues of that specific animal model. Despite, the process of using the animal model has facilitated researchers to carry out the researches that would have been impossible to accomplish in human considering the ethical prohibitions.

Inhibitors of thiol-mediated uptake

Ellman's reagent has caused substantial confusion and concern as a probe for thiol-mediated uptake because it is the only established inhibitor available but works neither efficiently nor reliably. Here we use fluorescent cyclic oligochalcogenides that enter cells by thiol-mediated uptake to systematically screen for more potent inhibitors, including epidithiodiketopiperazines, benzopolysulfanes, disulfide-bridged γ-turned peptides, heteroaromatic sulfones and cyclic thiosulfonates, thiosulfinates and disulfides. With nanomolar activity, the best inhibitors identified are more than 5000 times better than Ellman's reagent. Different activities found with different reporters reveal thiol-mediated uptake as a complex multitarget process. Preliminary results on the inhibition of the cellular uptake of pseudo-lentivectors expressing SARS-CoV-2 spike protein do not exclude potential of efficient inhibitors of thiol-mediated uptake for the development of new antivirals.

Thiol-reactive inhibitors for the cellular entry of cyclic oligochalcogenide (COC) transporters and SARS-CoV-2 spike pseudo-lentivirus are reported.

n→π* Interactions Modulate the Disulfide Reduction Potential of Epidithiodiketopiperazines

Epithiodiketopiperazines (ETPs) are a structurally complex class of fungal natural products with potent anticancer activity. In ETPs, the diketopiperazine ring is spanned by a disulfide bond that is constrained in a high-energy eclipsed conformation. We employed computational, synthetic, and spectroscopic methods to investigate the physicochemical attributes of this atypical disulfide bond. We find that the disulfide bond is stabilized by two n→π* interactions, each with large energies (3-5 kcal/mol). The n→π* interactions in ETPs make disulfide reduction much more difficult, endowing stability in physiological environments in a manner that could impact their biological activity. These data reveal a previously unappreciated means to stabilize a disulfide bond and highlight the utility of the n→π* interaction in molecular design.

Synthesis of Potent Cytotoxic Epidithiodiketopiperazines Designed for Derivatization

We describe our design, synthesis, and chemical study of a set of functional epidithiodiketopiperazines (ETPs) and evaluation of their activity against five human cancer cell lines. Our structure-activity relationship-guided substitution of ETP alkaloids offers versatile derivatization while maintaining potent anticancer activity, offering exciting opportunity for their use as there are no examples of complex and potently anticancer (nM) ETPs being directly used as conjugatable probes or warheads. Our synthetic solutions to strategically designed ETPs with functional linkers required advances in stereoselective late-stage oxidation and thiolation chemistry in complex settings, including the application of novel reagents for dihydroxylation and cis-sulfidation of diketopiperazines. We demonstrate that complex ETPs equipped with a strategically substituted azide functional group are readily derivatized to the corresponding ETP-triazoles without compromising anticancer activity. Our chemical stability studies of ETPs along with cytotoxic evaluation of our designed ETPs against A549, DU 145, HeLa, HCT 116, and MCF7 human cancer cell lines provide insights into the impact of structural features on potency and chemical stability, informing future utility of ETPs in chemical and biological studies.