Unavailability of treatment for the SARS-CoV-2 virus has raised concern among the population worldwide. This has led to many attempts to find alternative options to prevent the infection of the disease, including focusing on vaccines and drugs. The use of natural products and herbal extracts can be a better option in beating the virus and boosting up immunity. In the present paper, we have done a systematic in silico study of papain-like protease of COVID-19 virus with the chemical constituents of herbal plant Piper Longum. Screening of the pharmacokinetic properties is done with thirty-two phytoconstituents of Piper Longum which help us in selecting the most active components of the plant. After selection molecular docking is performed with Aristololactam (C₁₇H₁₁NO₄), Fargesin (C₂₁H₂₂O₆), l-asarinin (C₂₀H₁₈O₆), Lignans Machilin F (C₂₀H₂₂O₅), Piperundecalidine (C₂₃H₂₉NO₃), and Pluviatilol (C₂₀H₂₀O₆). Molecular dynamic (MD) is also performed with the inhibitor-receptor complex which suggest significant inhibition and a stable complex of I-Asarinin with PL^pro. Docking scores and simulation results suggest that I-Asarinin can act as a potential drug like candidate against COVID-19.

Neoechinulins are fungal and plant-derived chemicals extracted from Microsporum sp., Eurotium rubrum, Aspergillus sp., etc. Two analogues of neoechinulin, i.e., A and B, exerted extensive pharmacological properties described in this review. Neoechinulin is an indole alkaloid and has a double bond between C8/C9, which tends to contribute to its cytoprotective nature. Neoechinulin A exhibits protection to PC12 cells against nitrosative stress via increasing NAD(P)H reserve capacity and decreasing cellular GSH levels. It also confers protection via rescuing PC12 cells from rotenone-induced stress by lowering LDH leakage. This compound has great positive potential against neurodegenerative diseases by inhibiting SIN-1 induced cell death in neuronal cells. Together with these, neoechinulin A tends to inhibit Aβ42-induced microglial activation and confers protection against neuroinflammation. Alongside, it also inhibits cervical cancer cells by caspase-dependent apoptosis and via upregulation of apoptosis inducing genes like Bax, it suppresses LPS-induced inflammation in RAW264.7 macrophages and acts as an antidepressant. Whereas, another analogue, Neoechinulin B tends to interfere with the cellular mechanism thereby, inhibiting the entry of influenza A virus and it targets Liver X receptor (LXR) and decreases the infection rate of Hepatitis C. The present review describes the pharmaceutical properties of neoechinulins with notes on their molecular, cellular, and functional basis and their therapeutic properties.