Molecular scaffolds from mother nature as possible lead compounds in drug design and discovery against coronaviruses: A landscape analysis of published literature and molecular docking studies

AVPCD: a plant-derived medicine database of antiviral phytochemicals for cancer, Covid-19, malaria and HIV

Serious illnesses caused by viruses are becoming the world's most critical public health issues and lead millions of deaths each year in the world. Thousands of studies confirmed that the plant-derived medicines could play positive therapeutic effects on the patients with viral diseases. Since thousands of antiviral phytochemicals have been identified as lifesaving drugs in medical research, a comprehensive database is highly desirable to integrate the medicinal plants with their different medicinal properties. Therefore, we provided a friendly antiviral phytochemical database AVPCD covering 2537 antiviral phytochemicals from 383 medicinal compounds and 319 different families with annotation of their scientific, family and common names, along with the parts used, disease information, active compounds, links of relevant articles for COVID-19, cancer, HIV and malaria. Furthermore, each compound in AVPCD was annotated with its 2D and 3D structure, molecular formula, molecular weight, isomeric SMILES, InChI, InChI Key and IUPAC name and 21 other properties. Each compound was annotated with more than 20 properties. Specifically, a scoring method was designed to measure the confidence of each phytochemical for the viral diseases. In addition, we constructed a user-friendly platform with several powerful modules for searching and browsing the details of all phytochemicals. We believe this database will facilitate global researchers, drug developers and health practitioners in obtaining useful information against viral diseases.

The Main Protease of SARS-CoV-2 as a Target for Phytochemicals against Coronavirus

In late December 2019, the first cases of COVID-19 emerged as an outbreak in Wuhan, China that later spread vastly around the world, evolving into a pandemic and one of the worst global health crises in modern history. The causative agent was identified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although several vaccines were authorized for emergency use, constantly emerging new viral mutants and limited treatment options for COVID-19 drastically highlighted the need for developing an efficient treatment for this disease. One of the most important viral components to target for this purpose is the main protease of the coronavirus (Mpro). This enzyme is an excellent target for a potential drug, as it is essential for viral replication and has no closely related homologues in humans, making its inhibitors unlikely to be toxic. Our review describes a variety of approaches that could be applied in search of potential inhibitors among plant-derived compounds, including virtual in silico screening (a data-driven approach), which could be structure-based or fragment-guided, the classical approach of high-throughput screening, and antiviral activity cell-based assays. We will focus on several classes of compounds reported to be potential inhibitors of Mpro, including phenols and polyphenols, alkaloids, and terpenoids.

Characterization of Aurintricarboxylic Acid (ATA) Interactions with Plasma Transporter Protein and SARS-CoV-2 Viral Targets: Correlation of Functional Activity and Binding Energetics

In an effort to identify functional-energetic correlations leading to the development of efficient anti-SARS-CoV-2 therapeutic agents, we have designed synthetic analogs of aurintricarboxylic acid (ATA), a heterogeneous polymeric mixture of structurally related linear homologs known to exhibit a host of biological properties, including antiviral activity. These derivatives are evaluated for their ability to interact with a plasma transporter protein (human serum albumin), eukaryotic (yeast) ribosomes, and a SARS-CoV-2 target, the RNA-dependent RNA polymerase (RdRp). The resultant data are critical for characterizing drug distribution, bioavailability, and effective inhibition of host and viral targets. Promising lead compounds are selected on the basis of their binding energetics which have been characterized and correlated with functional activities as assessed by inhibition of RNA replication and protein synthesis. Our results reveal that the activity of heterogeneous ATA is mimicked by linear compounds of defined molecular weight, with a dichlorohexamer salicylic-acid derivative exhibiting the highest potency. These findings are instrumental for optimizing the design of structurally defined ATA analogs that fulfill the requirements of an antiviral drug with respect to bioavailability, homogeneity, and potency, thereby expanding the arsenal of therapeutic regimens that are currently available to address the urgent need for effective SARS-CoV-2 treatment strategies.

The Analogs of Furanyl Methylidene Rhodanine Exhibit Broad-Spectrum Inhibitory and Inactivating Activities against Enveloped Viruses, including SARS-CoV-2 and Its Variants

In recent years, infectious diseases caused by viral infections have seriously endangered human health, especially COVID-19, caused by SARS-CoV-2, which continues to spread worldwide. The development of broad-spectrum antiviral inhibitors is urgently needed. Here, we report a series of small-molecule compounds that proved effective against human coronaviruses (HCoV), such as SARS-CoV-2 and its variants of concern (VOCs), including Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529), SARS-CoV, MERS-CoV, HCoV-OC43, and other viruses with class I viral fusion proteins, such as influenza virus, Ebola virus (EBOV), Nipah virus (NiV), and Lassa fever virus (LASV). They are also effective against class II enveloped viruses represented by ZIKV and class III enveloped viruses represented by vesicular stomatitis virus (VSV). Further studies have shown that these compounds may exert antiviral effects through a variety of mechanisms, including inhibiting the formation of the six-helix bundle, which is a typical feature of enveloped virus fusion with cell membranes, and/or targeting viral membrane to inactivate cell-free virions. These compounds are expected to become drug candidates against SARS-CoV-2 and other enveloped viruses.

Chemical Constituents and Pharmacological Activities of Steroid Saponins Isolated from Rhizoma Paridis

Rhizoma Paridis, the rhizome of liliaceous plants Paris polyphylla, is one of the most commonly used herbal drugs in China. Phytochemical and pharmacological studies have shown that steroid saponins were the major effective ingredients of Rhizoma Paridis to exert antitumor, anti-inflammatory, hemostasis, and antifibrosis functions. In this review, we discussed the chemical structures of steroid saponins and their related biological activity and mechanisms in cellular and animal models, aiming to provide a reference for future comprehensive exploitation and development of saponins.