Dental Caries: Plant Extracts to the Rescue

Vaishnavi Kardale, Bioinformatics Centre, Savitribai Phule Pune University

Oral health is fundamental to the health and wellbeing of an individual. Dental caries is a pathological process that causes tissue destruction. This disease affects quite a huge population across the globe. If left untreated caries can increase plaque retention and lead to severe periodontitis. Periodontitis causes gum infection which can cause damage to gum and jaw bone. Dental caries is a bacterial infestation caused by Streptococcus mutans, Streptococcus sanguinis, and Enterococcus faecalis. These bacterial species are all acidogenic, aciduric, and gram-positive. To treat the condition, commonly employed treatments include antibiotics like penicillin, tetracycline, metronidazole, chlorhexidine, and fluoride. Chlorhexidine is considered a gold standard in dental practice. It is most widely used as an antiseptic for mouth rinsing.

What’s wrong with antibiotics?

Although current treatments are still viable and work well. There is a sudden urge to look beyond antibiotics. The biggest concern among researchers is antibiotic resistance in microbes. Antimicrobial resistance is a global crisis that over time would only be more catastrophic. WHO predicts antimicrobial resistance to claim about 10 million across the globe per year by 2050. The rise of antibiotic-resistant bacteria threatens our entire health system. There has been a push for the development of new antibiotics and substitute treatments. This has propelled researchers to look for new active compounds. Isolating active ingredients from plants has gained a lot of popularity among scientists.

Plant Extract to the rescue

The growth of bacteria can be stunted in many ways such as by inhibition of protein synthesis, inhibition of DNA and RNA synthesis, inhibition of folate synthesis, membrane disruption, and inhibition of peptidoglycan formation. A group of researchers at the Universitas Padjadjaran in Indonesia worked on countering the bacteria causing dental caries using plant extracts from Ocimum basilicum L. Previous studies have shown that Ocimum basilicum is known to have antibacterial, antioxidant, anti-inflammatory, antifungal, and anticancer properties. Gram-positive bacteria have a thick peptidoglycan layer in their cell wall that helps in retaining their shape and defends them from constant fluctuations in osmotic pressure. MurA, MurB, and penicillin-binding protein (PDP) are essential for the synthesis of peptidoglycan. Sortase A (SrtA) enzyme is responsible for showing proteins on the surface of the cell membrane. This makes MurA, MurB, PBP, and SrtA potential targets to counter bacterial growth. The activity from extracts of Ocimum basilicum in acetone, methanol, and chloroform was evaluated against several bacteria.

What did the study show?

In this study, the extracts of Ocimum basilicum were separated and purified. β-sitosterol was found in the purified extract. β-sitosterol is a commonly found compound in plants. It is known to exhibit antibacterial activity. So its efficacy against Streptococcus mutans, Streptococcus sanguinis, and Enterococcus faecalis was tested. Molecular docking was carried out to ascertain the interaction between β-sitosterol as a ligand and protein as a receptor to determine its mechanism as an antimicrobial agent using MurA, MurB, PBP, and SrtA as targets. In vitro and in-silico studies to determine the interaction between β-sitosterol and protein target indicated a lower binding affinity value than native ligand and other positive controls for each protein. The studies show that β-sitosterol can be a potential antibacterial agent to counter dental caries. The researchers concluded that β-sitosterol can effectively inhibit the biosynthesis of peptidoglycan and prevent cell wall formation by inhibiting MurA and SrtA activity by having a lower binding affinity than the positive control and not being competitive with the positive control at the active site. The use of plants and herbs as a treatment is popular and historically and culturally significant to a lot of countries in Asia and Africa. The validation of these through scientific experimentation is an encouraging step in preserving ancient knowledge and also countering the catastrophic outcome of antimicrobial resistance that might occur in the future at the same time.

Also read: Anti-aging Protein in RBCs prevents mental disorders

References:

1. Evangelina IA, Herdiyati Y, Laviana A, Rikmasari R, Zubaedah C, Anisah, Kurnia D. 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. Adv Appl Bioinform Chem. 2021;14:103-115 https://doi.org/10.2147/AABC.S301488

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