Studying the effect of the effectiveness of antibiotics and the alcoholic extract of the plant Mentha spicata in eliminating tooth decay bacteria Streptococcus mutans and its effective role as an antioxidant

Abstract

The study was conducted in Nasiriyah, Dhi Qar Governorate, Iraq, during 2025, from April to September. The study spanned approximately six months, encompassing the period from plant cultivation to drying prior to extraction.

The study demonstrated that alcoholic extracts of Mentha spicata possess excellent inhibitory activity against pathogenic bacteria and are safe for pharmaceutical use. Therefore, medicinal plants are used as antimicrobial agents.

An alcoholic extract of Mentha spicata was prepared. Twenty grams of the dried plant powder were weighed and 200 mL of ethanol was added to it at 45°C for 24 hours. The extract was then placed in a Soxhlet extractor and filtered using Whatman No. 1 filter paper (England). The sample was poured into glass Petri dishes, and the dry powder was stored in airtight glass containers and refrigerated at 4°C until use.

The efficacy of the ethanolic plant extracts against pathogenic Streptococcus mutans was tested at concentrations of 25, 50, and 100 mg/ml. The bacteria's susceptibility to the three commonly used antibiotics—amikacin (AK), gentamicin (CN), and ciprofloxacin (CIP)—was also tested. Because Streptococcus mutans is inherently less resistant to amikacin and gentamicin, other commonly used antibiotics, such as ciprofloxacin, were added to the treatment regimen for a broad spectrum of infections. Information on the reference system for interpreting antibiotic susceptibility should be provided, The DPPH assay is one of the most widely used techniques for evaluating the antioxidant properties of plant extracts. The alcoholic extract exhibited higher levels of inhibition than ascorbic acid, indicating the plant's high antioxidant activity.

The ethanolic extract showed concentration-dependent inhibitory activity against Streptococcus mutans, reaching a maximum concentration of 100 mg/ml. In antibiotic studies, ciprofloxacin was found to be the most effective antibiotic. Specifically, the plant extract at a concentration of 100 mg/ml demonstrated an inhibitory effect similar to that of ciprofloxacin. The ethanolic extract also showed good DPPH activity (87.84%) at 100 mg/ml, while ascorbic acid showed 82.04% DPPH activity at the same concentration.