Acmella paniculata, popularly known as the toothache plant, has been widely used as a traditional medicine to help treat diseases associated with toothache and gum infections. Streptococcus mutans is a common bacterium that can cause dental caries. This study aims to determine the antibacterial activity of A. paniculata extracts against S. mutans. Eight samples of A. paniculata leaves and flowers had been successfully extracted using n-hexane, dichloromethane, acetone and methanol. All samples were tested for antibacterial activity using the disc diffusion assay, the minimum inhibitory concentration (MIC), and the minimum bactericidal concentration (MBC). From the screening, only n-hexane leaves extract (APLHE), methanol leaves extract (APLME), n-hexane flower extract (APFHE) and dichloromethane flower extract (APFDE) exhibited antibacterial activity against S. mutans. Therefore, all four samples were tested with an antibiofilm and time-kill assay to determine the reduction activity and time-kill rate against S. mutans. The results showed that flower extracts exhibit more antibacterial activity against S. mutans when compared with leaves extracts. Thus, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the morphology of S. mutans under treatment with APFHE and APFDE. According to both micrograph observations, the shape of S. mutans changed from coccus and rounded to elongated and lysed after treatments. Then, by using GCMS, the major phytochemical compound found in both APFHE and APFDE is fatty acids (such as hexadecanoic acid, oleic acid, and linoleic acid). Finally, transcriptomic analysis was performed on S. mutans that had been treated with APFDE. The results proved that APFDE affected the biosynthesis of peptidoglycan, gene expression, quorum sensing, citrate cycle and glycolysis pathway of S. mutans. In conclusion, the antibacterial activity of APFDE disrupted various biological processes and pathways of S. mutans.

This study aims to characterize silver nanoparticles-kaempferol (AgNP-K) and its antibacterial activities against methicillin-resistant Staphylococcus aureus (MRSA). Nowadays, MRSA is a worldwide public health threat due to the resistance towards current antibiotics. Kaempferol was chosen due to its antibacterial capability. Green synthesis methods have been used to synthesize AgNP-K with the influence of temperature and different concentrations of silver nitrate and kaempferol (AgNO3:kaempferol). Sample C (AgNP-K 1:1 60/168) was synthesized with 1 mM concentration of kaempferol meanwhile sample Y (AgNP-K 1:2 60/168) with 2 mM of kaempferol. Characterization of sample C and sample Y were performed using UVVisible Spectroscopy (UV-Vis), zetasizer, transmission electron microscope (TEM), scanning electron microscope with a dispersive X-ray spectrometer (SEM-EDX), X-ray diffraction (XRD) and fourier transform infrared (FTIR). The presence of dark-brown colour in the solution indicated the formation of AgNP-K. UV-Visible absorption spectrum of the synthesized AgNP-K, sample C and sample Y showed a broad peak at range of 390 nm - 530 nm of wavelength. TEM, zetasizer and SEM-EDX results showed physical properties of sample C and sample Y such as morphology and size. The morphology analysis showed sample C and sample Y were in spherical shape. The size for sample C showed by zetasizer and TEM was 120.4 nm and 21.1487 ± 4.0183 nm respectively. Meanwhile, sample Y was 226.5 nm for zetasizer and 28.3604 ± 5.3418 nm in TEM. XRD analysis confirmed that AgNP-K was in crystalline phase structure, while FTIR showed (-OH) group absence in sample C and sample Y thus indicating that kaempferol was successfully incorporated with silver. Antibacterial activities of five samples (sample C, sample Y, commercial AgNP, kaempferol and vancomycin) with different concentrations (1.25, 2.5, 5, and 10 mg/mL) against MRSA were performed by using disc diffusion assay (DDA), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assay and time-kill assay. In DDA analysis, AgNP-K showed greater antibacterial activities against MRSA compared to kaempferol and commercial AgNP. The range values of MIC and MBC on both sample C and sample Y against MRSA were 1.25 mg/mL – 5 mg/mL, respectively. Time-kill assay analysis showed AgNP-K displayed bacteriostatic activity while bactericidal from MIC and MBC results towards MRSA. As conclusion, AgNP-K had been successfully synthesized from green synthesis method and performed characterization method by six (6) different instruments. From biological assay conducted showed that AgNP-K exhibited antibacterial activity against MRSA. As conclusions, silver nanoparticleskaempferol (AgNP-K), sample C exhibited better antibacterial activity when compared with sample Y kaempferol and commercial AgNP against MRSA.

Oral diseases are commonly found in the human population caused by the accumulation of bacterial plaque. There is still lacking of study regarding types of oral bacteria in the Malaysian population. Streptococcus mutans (S. mutans) is one of oral streptococci which initiate periodontal disease as an early colonizer. Over time, Gram-negative anaerobes become more established, especially Porphyromonas gingivalis (P. gingivalis). Nevertheless, bacteria can develop antibiotic resistance to medicinal drugs over time. However, Salvadora persica (S. persica) or known as miswak is acknowledged significantly due to the presence of bioactive compounds that contain inhibitory activity against oral bacteria. The main objective in this study is to identify oral bacteria from subgingival plaque and determine the antibacterial activities of Salvadora persica Stem Extracts (SPSE) against selected oral bacteria. The specific objective of this study is to identify the type of oral bacteria in subgingival plaque using 16S rRNA sequencing, to determine the antibacterial activities of SPSE against selected oral bacteria and to investigate the phytochemistry compositions of SPSE using Gas Chromatography Mass Spectrometry (GCMS). This study successfully isolated 176 oral bacteria from 10 subgingival plaque samples. A total of 17 oral bacteria had been identified from all samples. About 97 Gram-negative bacteria were successfully isolated from all samples. The majority of the bacteria are Gram-positive which is Streptococcus species and others are Gram-negative bacteria, including P. gingivalis, A. actinomycetemcomitans and K. pneumoniae. SPSE were produced using n-hexane, DCM, acetone, ethanol, and methanol. Antibacterial activities of SPSE-n-hexane, SPSE-DCM, SPSE-acetone, SPSE-ethanol, and SPSE-methanol were determined by performing three different techniques, such as disc diffusion assay (DDA), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against S. mutans and P. gingivalis. Gas chromatography mass spectrometry (GCMS) was analysed to investigate the phytochemistry composition in SPSE that can inhibit the growth of S. mutans and P. gingivalis. From the results, there is a significant difference between the type of solvents used in SPSE and the diameter of the inhibition zone for S. mutans and P. gingivalis (p < 0.001). For MIC results, S. mutans were inhibited with SPSE-n-hexane at 3.125 mg/mL. Meanwhile, S. mutans were killed with 6.25 mg/mL of SPSE-n-hexane. In GCMS analysis, the major phytochemical of all extracts was benzoic acid, hexadecanoic acid and octadecanoic acid. In conclusion, S. persica is highly recommended as one of the oral hygiene tools to treat oral diseases due to its effectiveness in inhibiting the growth of oral bacteria.