Antimicrobial activity and cytotoxicity of fifty one extracts of different parts of 14 plants were studied. Ethanol, methanol, aqueous, butanol, and n-hexane extracts were tested against three Gram negative, two Gram positive bacteria, and two fungi. Cytotoxicity and phytochemical screening were determined using MTT and TLC assays, respectively. Of the fifty one extracts, twenty two showed activities against different microorganisms with MICs ranging from 62.5 to 1000 µg/mL. The highest activity (100% inhibition) was for a butanol extract of Rosa damascena receptacles against Salmonella typhimurium and Bacillus cereus (MIC of 62.5 and 250 µg/mL) respectively. Butanol extract of Narcissus tazetta aerial parts and aqueous extract of Rosa damascena receptacles were both active against Candida albicans (MIC of 125 µg/mL). Methicillin-resistant Staphylococcus aureus was inhibited by butanol, aqueous extracts of Rosa damascena receptacles and butanol extract of Inula viscosa flowers (MIC of 500, 500, and 250 µg/mL) respectively. Rosa damascena receptacles and Verbascum sinaiticum flowers ethanol extract showed lowest cytoxicity against Vero cell line (IC50 of 454.11and 367.11). Most toxic was the ethanol extract of Ononis hirta aerial parts (IC50 72.50 µg/mL). Flavonoids and terpenoids were present in all plants. Ononis hirta and Narcissus tazetta contained alkaloids. The results validate the use of these plants and report for the first time bioactivity of Rosa damascena receptacles and further justifies the use of such screening programs in the quest for new drugs.

Abstract:The antiproliferative and antimicrobial effects of thirteen compounds isolated from Inula viscosa (L.) were tested in this study. The antiproliferative activity was tested against three cell lines using the MTT assay. The microdilution method was used to study the antimicrobial activity against two Gram positive bacteria, two Gram negative bacteria and one fungus. The apoptotic activity was determined using a TUNEL colorimetric assay. Scanning electron microscopy was used to study the morphological changes in treated cancer cells and bacteria. Antiproliferative activity was observed in four flavonoids (nepetin, 3,3′-di-O-methylquercetin, hispidulin, and 3-O-methylquercetin). 3,3′-di-OMethylquercetin and 3-O-methylquercetin showed selective antiproliferative activity against MCF-7 cells, with IC 50 values of 10.11 and 11.23 µg/mL, respectively. Both compounds exert their antiproliferative effect by inducing apoptosis as indicted by the presence of DNA fragmentation, nuclear condensation, and formation of apoptotic bodies in treated cancer cells. The antimicrobial effect of Inula viscosa were also noticed in 3,3′-di-O-methylquercetin and 3-O-methyquercetin that inhibited Bacillus cereus at MIC of 62.5 and 125 µg/mL, respectively. Salmonella typhimurium was inhibited by both compounds at MIC of 125 µg/mL. 3,3′-di-O-Methylquercetin induced damage in bacterial cell walls and cytoplasmic membranes. Methylated quercetins isolated from Inula viscosa have improved anticancer and antimicrobial properties compared with other flavonoids and are promising as potential anticancer and antimicrobial agents.

Antimicrobial and antiquorum sensing (AQS) activities of fourteen ethanolic extracts of different parts of eight plants were screened against four Gram-positive, five Gram-negative bacteria and four fungi. Depending on the plant part extract used and the test microorganism, variable activities were recorded at 3 mg per disc. Among the Gram-positive bacteria tested, for example, activities of Laurus nobilis bark extract ranged between a 9.5 mm inhibition zone against Bacillus subtilis up to a 25 mm one against methicillin resistant Staphylococcus aureus. Staphylococcus aureus and Aspergillus fumigatus were the most susceptible among bacteria and fungi tested towards other plant parts. Of interest is the tangible antifungal activity of a Tecoma capensis flower extract, which is reported for the first time. However, minimum inhibitory concentrations (MIC's) for both bacteria and fungi were relatively high (0.5-3.0 mg). As for antiquorum sensing activity against Chromobacterium violaceum, superior activity (>17 mm QS inhibition) was associated with Sonchus oleraceus and Laurus nobilis extracts and weak to good activity (8-17 mm) was recorded for other plants. In conclusion, results indicate the potential of these plant extracts in treating microbial infections through cell growth inhibition or quorum sensing antagonism, which is reported for the first time, thus validating their medicinal use.

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Probiotics have a role in maintaining oral health through interaction with oral microbiome, thus contributing to healthy microbial equilibrium. The nature and composition of any individual microbiome impacts the general health, being a major contributor to oral health. The emergence of drug resistance and the side effects of available antimicrobials have restricted their use in an array of prophylactic options. Indeed, some new strategies to prevent oral diseases are based on manipulating oral microbiota, which is provided by probiotics. Currently, no sufficient substantial evidence exists to support the use of probiotics to prevent, treat or manage oral cavity diseases. At present, probiotic use did not cause adverse effects or increased risks of caries or periodontal diseases. This implicates no strong evidence against treatment using probiotics. In this review, we try to explore the use of probiotics in prevention, treatment and management of some oral cavity diseases and the possibilities of developing designer probiotics for the next generation of oral and throat complimentary healthcare.