In silico, in vitro screening of plant extracts for anti-SARS-CoV-2 activity and evaluation of their acute and sub-acute toxicity

BACKGROUND

In the absence of a specific drug for COVID 19, treatment with plant extracts could be an option worthy of further investigation and has motivated to evaluate the safety and anti-SARS-CoV-2 activity of plant extracts.

PURPOSE

To screen the phytochemicals for anti-SARS-CoV-2 in silico and evaluate their safety and efficacy in vitro and in vivo.

METHOD

The phytochemicals for anti-SARS-CoV-2 were screened in silico using molecular docking. The hits generated from in silico screening were subjected for extraction, isolation and purification. The anti-SARS-CoV-2 activity of Zanthoxylum piperitum (E1), Withania somnifera (E2), Calophyllum inophyllum (E3), Andrographis paniculata (E4), Centella asiatica (E5) ethanol extracts. The aerial parts were used for E1, E3, E4, E5 and root was used for E2. The in vitro safety and anti-SARS-CoV-2 activity of plant methanol extracts were performed in VeroE6 cells using Remdesivir as positive control. The acute and sub-acute toxicity study was performed in Wistar male and female rats.

RESULTS

The percentage of cell viability for E4, E5 and E2 treated VeroE6 cells were remarkably good on the 24th and 48th hour of treatment. The in vitro anti-SARS-CoV-2 activity of E4, E5 and E2 were significant for both E gene and N gene. The percentage of SARS-CoV-2 inhibition for E4 was better than Remdesivir. For E gene and N gene, Remdesivir showed IC₅₀ of 0.15 µM and 0.11 µM respectively, For E gene and N gene, E4 showed IC₅₀ of 1.18 µg and 1.16 µg respectively. Taking the clue from in vitro findings, the E4, E5 and E2 were combined (E 4.5.2) and evaluated for acute and sub-acute toxicity in Wistar male and female rats. No statistically significant difference in haematological, biochemical and histopathological parameters were noticed.

CONCLUSION

The study demonstrated the anti-SARS-CoV-2 activity in vitro and safety of plant extracts in both in vitro and in vivo experimental conditions.

Synthesis, structural, biological andin silicostudies of new 5-arylidene-4-thiazolidinone derivatives as possible anticancer, antimicrobial and antitubercular agents

Thiazolidinone–sulfonamide hybrids emerged as promising anticancer and antitubercular agents, and their anticancer activity was confirmed by docking studies.

Neutralization of Naja naja venom induced lethality, edema and myonecrosis by ethanolic root extract of Coix lacryma-jobi

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Oral administration of ethanolic root extract (ERE) at dose levels 100, 200 and 400 mg/kg effectively inhibits Naja naja venom-induced lethality in mice as well as venom-induced proteolysis, fibrinogenolysis, DNase activity.

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ERE at a dose of 200 mg/kg inhibits myotoxicity induced by Naja naja venom measured by creatine kinase activity in rats.

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Molecular docking studies revealed that stigmasterol isolated from the ERE is probably responsible for inhibition of Naja naja venom PLA₂.

Coix lacryma-jobi, commonly known as job’s tear, is a tall grain-bearing tropical plant of the family Poaceae. The ethanolic root extract (ERE) of the plant was investigated for the first time for anti-venom activity against Indian cobra Naja naja venom.

In-vitro studies were conducted to determine neutralization of phospholipase A₂ (PLA₂) activity of the Naja naja venom by the ERE. ERE showed significant inhibition of PLA₂ activity, which was further confirmed from effective neutralization of human red blood cells (HRBC) lysis induced by the venom. In addition, venom-induced proteolysis, fibrinogenolysis, DNase activity were also neutralized by the ERE, which contained carbohydrates, glycolides, resins and tannins.

Oral administration of ERE at doses levels 100, 200 and 400 mg/kg effectively inhibited Naja naja venom-induced lethality in mice. Myotoxicity induced by Naja naja venom, measured by creatine kinase activity in rats was significantly neutralized by the ERE at a dose of 200 mg/kg.

Stigmasterol, as one of the component isolated from the ERE, was found to have venom phospholipase A₂ inhibition potential, which was confirmed by molecular docking studies with PLA₂. In summary, these studies indicate the ability of ERE of Coix lacryma-jobi to effectively neutralize the toxic effects of the venom is, in part, contributed by the inhibition of PLA₂ activity among other venom-derived factors.