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Dental caries is an oral health problem associated with the activity of Streptococcus mutans. Water hyacinth (Eichhornia crassipes) contains bioactive compounds such as flavonoids, tannins, and alkaloids with antibacterial potential. This study aimed to evaluate the effectiveness of water hyacinth extract against the growth of Streptococcus mutans. The research method used was an in vitro experimental study with a post test only group design. A total of 24 samples were divided into four treatment groups with extract concentrations of 6.25%, 12.5%, 25%, and 50%. Antibacterial activity was tested using the disc diffusion method on Mueller Hinton Agar media. Data were analyzed using the Kruskal-Wallis and Mann-Whitney tests. The results showed that water hyacinth extract inhibited the growth of Streptococcus mutans. The largest inhibition zone was observed at 50% concentration, while the smallest was found at 6.25% concentration. Kruskal-Wallis analysis showed significant differences among groups (p<0.05). In conclusion, water hyacinth (Eichhornia crassipes) extract has antibacterial activity against Streptococcus mutans.

Background: Acne vulgaris is one of the most common skin problems and is closely associated with the activity of Propionibacterium acnes. Long-term use of antibiotics may lead to bacterial resistance; therefore, alternative antibacterial agents derived from natural products are needed. White rice (Oryza sativa L.) is known to contain bioactive compounds such as flavonoids, alkaloids, terpenoids, tannins, and saponins, which potentially exhibit antibacterial activity. Objective: This study aimed to evaluate the antibacterial activity of ethanol extract of white rice against the growth of Propionibacterium acnes. Methods: This research was conducted as a laboratory experimental study using a post-test only control group design. The ethanol extract of white rice was prepared by maceration using 70% ethanol. Antibacterial activity was evaluated using the disc diffusion method with extract concentrations of 100%, 50%, 25%, 12.5%, and 6.25%. Clindamycin was used as a positive control, while sterile distilled water served as a negative control. The parameter observed was the diameter of the inhibition zone. Result: The results of phytochemical screening showed that the ethanol extract of white rice (Oryza sativa L.) contains flavonoids, alkaloids, and terpenoids. Antibacterial activity test showed that the ethanol extract of white rice at concentrations of 100%, 50%, and 25% was able to inhibit the growth of Propionibacterium acnes by forming an inhibition zone, while at concentrations of 12.5% and 6.25% no inhibition zone was formed. The highest inhibition zone diameter was found at a concentration of 100%. The ethanol extract of white rice at concentrations of 100% (7.65 mm), 50% (6.77 mm), and 25% (6.15 mm) was able to inhibit the growth of Propionibacterium acnes, and was classified as having moderate inhibition. In contrast, at concentrations of 12.5% and 6.25%, the ethanol extract of white rice did not show any inhibitory activity detected in vitro using the disc diffusion method. The results of statistical analysis showed a p value <0.001, which means there was a significant difference in the diameter of the inhibition zone between the treatment groups. Conclusion: In conclusion, the ethanol extract of white rice exhibits antibacterial activity against Propionibacterium acnes in a concentration-dependent manner; however, its inhibitory effect remains lower than that of clindamycin.

Acne (Acne vulgaris) is one of the most common skin problems, affecting 80–85% of adolescents aged 15–18 years, with some cases persisting into adulthood. One of the associated bacteria is Staphylococcus epidermidis, a normal skin flora that can become an opportunistic pathogen. Bay leaves (Syzygium polyanthum) are known to contain secondary metabolites such as alkaloids, flavonoids, tannins, saponins, and essential oils with antibacterial activity. This study aimed to formulate ethanol extract of bay leaves into ointments with concentrations of 10%, 20%, and 30%, test their antibacterial activity against Staphylococcus epidermidis using the disc diffusion method, and evaluate their physical quality (organoleptic properties, homogeneity, pH, adhesion, and spreadability). Results showed that the ethanol extract of bay leaves contained alkaloids, flavonoids, saponins, and tannins. The ointments met topical quality standards with pH 5.8–6.9, adhesion time 36–41 seconds, and spreadability 6.9–8.1 cm. Antibacterial activity increased with higher concentrations: 7.8 mm (10%), 12 mm (20%), and 15 mm (30%), although still lower than the positive control (clindamycin, 34 mm). In conclusion, ethanol extract of bay leaves has potential as an active ingredient in topical anti-acne ointments, but further studies with higher concentrations, in vivo testing, and optimized formulations are needed to achieve efficacy comparable to synthetic antibiotics.