Saponins are steroidal or triterpenoid glycoside that is distinguished by the soap-forming nature. Different saponins have been characterized and purified and are gaining attention in cancer chemotherapy. Saponins possess high structural diversity, which is linked to the anticancer activities. Several studies have reported the role of saponins in cancer and the mechanism of actions, including cell-cycle arrest, antioxidant activity, cellular invasion inhibition, induction of apoptosis and autophagy. Despite the extensive research and significant anticancer effects of saponins, there are currently no known FDA-approved saponin-based anticancer drugs. This can be attributed to a number of limitations, including toxicities and drug-likeness properties. Recent studies have explored options such as combination therapy and drug delivery systems to ensure increased efficacy and decreased toxicity in saponin. This review discusses the current knowledge on different saponins, their anticancer activity and mechanisms of action, as well as promising research within the last two decades and recommendations for future studies.

Alzheimer disease (AD) is the most common form of dementia contributing to about 60-70% of cases. β-Site amyloid precursor protein cleaving enzyme-1 (BACE1) plays an important role in the onset of AD and has become one of the important drug targets for AD. This approach has led to the development of promising BACE1 inhibitors, many of which are going through different phases of clinical trials. Nonetheless, the high failure rate of lead drug candidates targeting BACE1 brought to the forefront the need for finding new drugs to uncover the mystery behind AD. This study focused on virtual screening of ~ 33,000 natural compounds to find potential BACE1 inhibitors. Multiple ligands pharmacophore model was generated using PHASE to screen retrieved compounds against a four-site (ADDR) hypothesis. Molecular docking was performed to predict the binding status of the natural compounds. Based on binding affinity, the top eight compounds were chosen for further analysis. The docked complexes were analyzed for binding free energy using PRIME MM/GBA calculation. The compounds were filtered for drug-likeness using ADME/TOX (absorption, distribution, metabolism, excretion and toxicity) prediction. AutoQSAR (automated quantitative structure activity relationship) was used to build a model for the prediction of compounds bioactivities. Despite retrieving a large number of compounds with favorable binding affinity, only a few were selected to be promising based on their ADME/TOX proprieties, binding free energy and predicted pIC 50. This study identified four natural compounds (NPC469686, NPC262328, NPC29763 and NPC86744) as novel BACE1 inhibitors. The insights obtained from this study could be employed to produce next-generation drug for AD.

SARS-CoV-2 is a new strain of Coronavirus that caused the pneumonia outbreak in Wuhan, China and has spread to over 200 countries of the world. It has received worldwide attention due to its virulence and high rate of infection. So far, several drugs have experimented against SARS-CoV-2, but the failure of these drugs to specifically interact with the viral protease necessitates urgent measure to boost up researches for the development of effective therapeutics against SARS-CoV-2. Papain-like protease (PLpro) of the viral polyproteins is essential for maturation and infectivity of the virus, making it one of the prime targets explored for SARS-CoV-2 drug design. This study was conducted to evaluate the efficacy of ~ 50,000 natural compounds retrieved from IBS database against COVID-19 PLpro using computer-aided drug design. Based on molecular dock scores, molecular interaction with active catalytic residues and molecular dynamics (MD) simulations studies, STOCK1N-69160 [(S)-2-((R)-4-((R)-2-amino-3-methylbutanamido)-3-(4-chlorophenyl) butanamido) propanoic acid hydrochloride] has been proposed as a novel inhibitor against COVID-19 PLpro. It demonstrated favourable docking score, the free energy of binding, interacted with key amino acid residues necessary for PLpro inhibition and also showed significant moderation for parameters investigated for ADME/tox (Adsorption, distribution, metabolism, excretion and toxicological) properties. The edge of the compound was further established by its stability in MD simulation conducted for 30 ns employing GROMACS software. We propose that STOCK1N-69160 is worth further investigation for preventing SARS-CoV-2. Graphic abstract

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