In-Vitro and In-Silico Anti-Cariogenic Bacterial Activity of Selected Spices Commonly Consumed in South-West Nigeria

Dental caries is a preventable oral disease simply by practicing good oral hygiene; however, this disease remains a global health challenge due to the difficulties in management and treatment. Onion, ginger, and nutmeg extracts have been reported as potent antibiotics. Thus, the study investigated the efficacy of these three spices against cariogenic bacteria. Samples were collected from consented caried-patients at the Olabisi Onabanjo University Teaching Hospital (OOUTH), Sagamu, Ogun State, Nigeria. Disc and agar well diffusion methods were used to evaluate the antibiotic sensitivity of the spices against the isolates, respectively. The anti-cariogenic potential of significant compounds in each of the spices was further assessed against four bacterial target proteins (DNA gyrase B, dihydrofolate reductase (DHF), D-alanine: D-alanine ligase (Ddl1), and Isoleucyl-tRNA synthetase (IARS). Out of 100 samples collected, hundred and sixty-six (166) isolates were recovered: Pseudomonas aeruginosa (105), Staphylococcus aureus (52), and Streptococcus mutans (9). In-silico studies revealed that kaempferol in onion, luteolin 7-O-glucoside in ginger, and macelignan in nutmeg had high binding affinities for the four target proteins (∆G> -7 kcal/mol). At 100% concentration, onions showed a higher zone of inhibition (20-22 mm) against the tested bacteria. In comparison, diameter zones of 20.33 mm and 20.67 mm for ginger, and 19.67 mm and 16.67 mm for nutmeg were observed against Streptococcus mutans and Pseudomonas aeruginosa, respectively. It was also observed that at higher concentrations of 100%, the tested spices had a higher inhibitory effect against the tested bacteria than the control antibiotics.