In vitro Antioxidant and Antimicrobial Activities of Euphorbia thymifolia Extracts and Development of an Experimental Oral Rinse
Ladoh-Yemeda Christelle Flora
*
Department of Plant Biology, Faculty of Science, University of Douala, Douala, Cameroon and Department of Pharmaceutical Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon.
Yeba Bissikin Guilene Ludivine
Department of Pharmaceutical Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon and Biotechnology Laboratory, University Institute of Technology, University of Douala, Douala, Cameroon.
Voundi Olugu Steve Henri
Biotechnology Laboratory, University Institute of Technology, University of Douala, Douala, Cameroon.
Etame Loe Gisèle
Department of Pharmaceutical Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon.
*Author to whom correspondence should be addressed.
Abstract
Aims: Oral diseases are associated with complex microbial biofilms and oxidative inflammatory processes. This study evaluated the phytochemical profile, total phenolic content, DPPH radical-scavenging activity, and preliminary antimicrobial activity of aqueous and hydroethanolic extracts of Euphorbia thymifolia and examined the activity and quality attributes of experimental oral-rinse formulations.
Methodology: Aqueous and hydroethanolic extracts were subjected to qualitative phytochemical screening and determination of total phenolic content. Antioxidant activity was assessed by the DPPH assay. Agar well diffusion was used as a preliminary screening method against Streptococcus mitis, Streptococcus salivarius, Streptococcus mutans, Staphylococcus aureus, Escherichia coli, and Candida albicans. Experimental oral-rinse formulations were evaluated for inhibition-zone diameter, pH, density, and microbiological quality.
Results: Polyphenols, flavonoids, tannins, alkaloids, and saponins were detected in all extracts. The aqueous extract had an IC50 of 19.3 ± 2.1 µg/mL, followed by the 60:40 hydroethanolic extract at 21.5 ± 1.8 µg/mL. Extract inhibition zones ranged from 18.1 ± 0.2 to 23.4 ± 0.4 mm. Among extract-containing formulations, inhibition zones ranged from 12.8 ± 0.3 to 18.4 ± 0.4 mm. The formulations had a mean pH of 7.28 ± 0.02 and a mean density of 1.035 ± 0.01 g/mL. The total aerobic mesophilic count was 2.2 × 10³ CFU/g and exceeded the limit applied in the study, although the specified coliforms, yeasts and moulds, Escherichia coli, and Staphylococcus aureus were not detected.
Conclusion: Euphorbia thymifolia extracts demonstrated DPPH radical-scavenging and preliminary agar-diffusion activity under the conditions tested, and measurable activity remained after incorporation into experimental oral-rinse formulations. These findings support further chemical standardisation and quantitative antimicrobial investigation; however, the current results do not establish clinical efficacy, product stability, or oral safety. Optimisation of preservation and additional cytotoxicity, stability, biofilm, and in vivo studies are required.
Keywords: Euphorbia thymifolia, experimental oral rinse, antimicrobial screening, antioxidant activity, oral health