In Vitro Evaluation of Ethanolic Medicinal Plant Extracts from the Aseer Region Against Selected Cultured Oral Bacterial Isolates from Healthy Volunteers

This work provides an in vitro assessment of the antibacterial efficacy of ethanolic extracts derived from four medicinal plants historically utilized in the Aseer region (<i>Foeniculum vulgare</i>, <i>Solanum incanum</i>, <i>Forsskaolea tenacissima</i>, and <i>Abutilon pannosum</i>) against cultured oral bacterial isolates obtained from healthy volunteers. Oral samples from a subset of 50 healthy female participants were included in this analysis, yielding independent cultured bacterial isolates. Isolates were identified using morphological and biochemical characterization combined with partial 16S rRNA gene sequencing and included representatives of common oral-associated genera. Antibacterial activity was assessed using agar disk diffusion and broth microdilution assays. <i>Abutilon pannosum</i> and <i>Solanum incanum</i> had lower values of MIC (range of 16-128 µg/mL), whereas <i>Forsskaolea tenacissima</i> had higher values of MIC (maximum to >512 µg/mL) with the tested isolates. Qualitative microscopic observations and crystal violet biofilm staining showed extract-associated varying cellular morphology, aggregation patterns and surface coverage under sub-inhibitory conditions. Representative isolate scanning electron microscopy (SEM) qualitatively validated descriptive cell surface morphology and organization changes. The research presents preliminary in vitro results of inconsistent antibacterial and antibiofilm effects of crude ethanolic extracts of four plants in the Aseer region on a small (<i>n</i> = 13) group of cultured oral bacteria isolates in healthy volunteers, which requires fractionation and further testing.