Bio-Mechanism Inhibitory Prediction of β-Sitosterol from Kemangi (Ocimum basilicum L.) as an Inhibitor of MurA Enzyme of Oral Bacteria: In vitro and in silico Study

Abstract

Background Dental caries is a widespread disease that causes dental tissue destruction and leads to local and general complications. Gram-positive bacteria including Streptococcus mutans , Streptococcus sanguinis , and Enterococcus faecalis take part in dental caries formation. Gram-positive bacteria have cell walls that consistof a thick layer of peptidoglycan which maintains the strength and rigidity of the bacteria, as well as bacteria guard from internal osmotic pressure. The biosynthesis of peptidoglycan involves many enzymes, including the Mur family, penicillin binding protein (PBP), and sortases. Purpose This research has the intention to screen and examine the antibacterial compound of edible plant Kemangi ( Ocimum basilicum L.) in terms of how it fights against some oral pathogenic bacteria of E. faecalis ATCC 29212, S. mutans ATCC 25175, and S. sanguinis ATCC 10566. Materials and Methods The O. basilicum L. was macerated by several organic solvents to obtain the extracts, before then being purified using several combinations of chromatography methods and the compound was discovered via spectroscopic methods. For the assay against bacteria, the extracts and compounds were tested using agar well diffusion and microdilution assay. Results The isolated compound was identified as β-sitosterol. The compound activity against bacteria was evaluated by in vitro assay against S. sanguinis ATCC 10566 and E. faecalis ATCC 29212 with the MIC and MBC value of 25,000 and 50,000 ppm, respectively. The compound was also tested by in silico study using the molecular docking method. The molecular interaction between β-sitosterol and the protein target showed a lower binding affinity value than the native ligand and other positive controls for each protein. Based on the amino acid residue bound to the ligands, β-sitosterol on MurA and SrtA is not competitive to the positive control, showing potential as a natural antibacterial agent. Meanwhile, on the MurB and PBP, β-sitosterol and positive control do compete with each other. Conclusion The compound, isolated from O. basilicum L. leaf, was determined as β-sitosterol, which has the molecular formula C 29 H 50 O. The antibacterial activity of β-sitosterol by in vitro assay showed weak antibacterial activity, yet exhibited the potential to inhibit the biosynthesis of peptidoglycan and prevent bacteria cell wall formation by inhibiting MurA and SrtA activity via docking simulation.

Antibacterial Activity of Lemon Basil (Ocimum citriodorum) and Key Lime (Citrus aurantifolia S.) Extract Combination on Streptococcus mutants

“…Another compound that also has an antibacterial effect in lemon basil that has been studied was β-sitosterol(C 29 H 50 O). Even though it showed antibacterial activity by in vitro assay, yet performed its ability inhibiting of peptidoglycan biosynthesis and prevent the formation of the bacteria cell walls [26].…”

The Application of Small Molecules to the Control of Typical Species Associated With Oral Infectious Diseases

“…Ursolic acid, a plant-derived compound, shows inhibitory effects on EPS synthesis and biofilm formation of S. mutans ( Kim et al., 2013 ; Lyu et al., 2021b ). Astilbin, a flavanone compound from Rhizoma Smilacis Glabrae and β-sitosterol from kemangi, can inhibit SrtA activity and thus reduces the biofilm formation of S. mutans ( Wang et al., 2019 ; Evangelina et al., 2021 ).…”

Kemangi (Ocimum basilicum L.): Kandungan Kimia, Teknik Ekstraksi, dan Uji Aktivitas Antibakteri

“…Evangelina et al, [43] melakukan uji aktivitas antibakteri menggunakan metode difusi cakram Kirby-Bauer. Methanol digunakan untuk mengencerkan semua sampel kecuali fraksi air dan kontrol positif (klorheksidin) diencerkan dalam air.…”