Valorization of Adhatoda vasica leaves: Extraction, in vitro analyses and in silico approaches

Abstract

Adhatoda vasica (also called Vasaka) is a traditional medicinal herb used traditionally for the relief of cough, asthma, nasal congestion, bronchial inflammation, upper respiratory infections, bleeding disorders, skin diseases, leprosy, tuberculosis, diabetes, allergic conditions, rheumatism, tumor, and many more diseases. The present study aims to investigate the biological activities of vasicine, a potent alkaloid from A. vasica with different biological/ pharmacological assays and in silico techniques. Vasicine showed antimicrobial activity as evidenced fromthe colony-forming unit assay. It showed antioxidant activity in ABTS scavenging assay (IC₅₀ = 11.5 μg/ml), ferric reducing power assay (IC₅₀ = 15 μg/ml), DPPH radical scavenging assay (IC₅₀ = 18.2 μg/ml), hydroxyl radical scavenging assay (IC₅₀ = 22 μg/ml), and hydrogen peroxide assay (IC₅₀ = 27.8 μg/ml). It also showed anti-inflammatory activity in proteinase inhibitory assay (IC₅₀ = 76 μg/ml), BSA method (IC₅₀ = 51.7 μg/ml), egg albumin method (IC₅₀ = 53.2 μg/ml), and lipooxygenase inhibition assay (IC₅₀ = 76 μg/ml). Vasicine showed antidiabetic activity in α-amylase inhibition assay (IC₅₀ = 47.6 μg/ml), α-glucosidase inhibition assay (IC₅₀ = 49.68 μg/ml), and non-enzymatic glycosylation of hemoglobin assay. It showed antiviral activity against HIV-protease (IC₅₀ = 38.5 μg/ml). Vasicine also showed anticancer activity against lung cancer cells (IC₅₀ = 46.5 μg/ml) and human fibroblast cells (IC₅₀ = 82.5 μg/ml). In silico studies revealed that similar to the native ligands, vasicine also showed a low binding energy, i.e., good binding affinity for the active binding sites and interacted with α-amylase (-6.7 kcal/mol), α-glucosidase (-7.6 kcal/mol), cyclooxygenase (-7.4 kcal/mol), epidermal growth factor receptor (-6.4 kcal/mol), lipooxygenase (-6.9 kcal/mol), and HIV-protease (-6.4 kcal/mol). The present study ascertains the potential of vasicine as a bioactive compound isolated from A. vasica having therapeutic usefulness in many human diseases.

Keywords: Adhatoda vasica; in silico; in vitro; pharmacological activities; vasicine.

Figure 1

Flower and leaves of Adhatodavasica.

Figure 2

Chemical structure of vasicine.

Figure 3

Anti-microbial Activity of vasicine for E. coli and Bacillus badius.

Figure 4

(A) Percentage inhibition and (B) IC₅₀ value of vasicine in the antioxidant assay. ABTS, 2, 2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) scavenging Activity; FRAP, Ferric Reducing Antioxidant Power Assay; DPPH, 1,1 Diphenyl-2-picrylhydrazyl Radical Scavenging Activity; HRA, Hydroxyl Radical Scavenging Assay; HPA, Hydrogen Peroxide Assay.

Figure 5

(A) Percentage inhibition and (B) IC₅₀ value of vasicine in proteinase inhibitory activity (PIA), lipooxygenase inhibition assay (LOX), BSA using method (BSA), egg albumin method (EA).

Figure 6

(A) Percentage inhibition and (B) IC₅₀ Value of vasicine. AAI, α-amylase inhibition assay; AGI, α-glucosidase enzyme; NEGH, non-enzymatic glycosylation of hemoglobin assay.

Figure 7

HIV-protease inhibitory activity of vasicine and the standard drug.

Figure 8

(A) Direct microscopic view on the anticancer activity of vasicine on lung cancer cell lines at various concentrations (6.25, 12.5, 25, 50, 100 μg/ml) in comparison with the control value. (B) Cell viability (%) in MTT assay (IC₅₀ = 46.5 μg/ml).

Figure 9

(A) Direct microscopic view of cytotoxic activity of vasicine at various concentrations (6.25, 12.5, 25, 50, 100 μg/ml) in comparison with the control value. (B) Cell viability (%) in MTT assay on Human Fibroblast Cell line (IC₅₀ Value = 82.5 μg/ml).

Figure 10

2D ligand interactions of vasicine with the different amino acid residues at the active binding sites of (A) α-amylase, (B) α-glucosidase, (C) cyclooxygenase, (D) epidermal growth factor and receptor, (E) HIV protease, and (F) lipooxygenase.