Quantum Chemical and Experimental Exploration of Biological Activity and Inhibitory Potential of New Acylated Oligosaccharides from Pistacia integerrima J. L. Stewart ex Brandis

The new biologically active integrisides A (1) and B (2) have been isolated from the methanolic extract of Pistacia integerrima J. L. Stewart ex Brandis. The antibacterial activity of both the integrities was tested against four pathogenic bacterial strains, two Gram-positive (Staphylococcus aureus, Streptococcus pyogenes) and two Gram-negative (Escherichia coli, Pseudomonas aeruginosa) as well as four fungal strains (Microsporum canis, Aspergillus clavatus, Candida albicans, and Candida glabrata). Both the isolated compounds showed significant results analogous with Imipenam and Miconazole standard drugs. Carbonic anhydrase-II inhibition of integriside A (1) and B (2) with IC50 value 1.56 µM and 2.85 µM respectively, as compared to standard drug acetazolamide (1.57 µM). Cholinesterase activity was carried out with acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) IC50 values of integriside A (1) (8.6, 4.8) and B (2) (0.91, 2.5) were found as compared with standard galanthamine (0.05, 0.92) and Eserine (0.6, 8.7). Here, various molecular descriptors, frontier molecular orbitals (FMO), electron affinity (E.A), ionization potential (IP), molecular electrostatic potential (MEP), and Hirshfeld analysis were carried out to understand the active sites and biological active nature of the integrisides A (1) and B (2). The energy gap, MEP, Hirshfeld analysis, and reactivity descriptors values demonstrate that the integriside A (1) and B (2) retain decent reactivity, which is in good agreement with current experimental and quantum chemical studies.