Green synthesis, characterisation and antibacterial activities of Strobilanthes crispus-mediated silver nanoparticles (SC-AGNPS) against selected bacteria.

This study aims to characterize and determine the antibacterial activities of synthesized Strobilanthes crispus-mediated AgNPs (SC-AgNPs) against Streptococcus mutans, Escherichia coli and Pseudomonas aeruginosa. S. crispus water extract acts as a reducing and capping agent in the synthesis of AgNPs. The synthesized AgNPs were characterized by using UV-Vis spectrophotometer, dynamic light scattering (DLS), field emission scanning electron microscope (FESEM), X-ray diffractometer (XRD) and Fourier transform infra-red (FTIR). FESEM images showed a rough surface with a spherical shape. The average size distribution of 75.25 nm with a polydispersity index (PDI) of 0.373. XRD analysis matched the face-centred cubic structure of silver. FTIR analysis revealed a shifted peak from 1404.99 to 1345.00 cm-1. MIC and MBC values of SC-AgNPs were 1.25 mg/mL and 2.5 mg/mL against E. coli, P. aeruginosa and S. mutans, respectively. Time-kill assay showed that SC-AgNPs significantly reduced bacterial growth as compared to non-treated bacteria. Morphologies of bacteria treated with SC-AgNPs were shrunk, lysed, irregular and smaller as compared to control. SC-AgNPs significantly disrupted the gene expression of eae A, gtf B and Pel A (p < 0.05). This study indicated that the synthesized SC-AgNPs were stable with enhanced antibacterial activities.

The effectiveness of miswak (Salvadora persica L. and Azadirachta indica A.Juss.) practices in reducing plaque and gingivitis among adults: A systematic review and meta-analysis.

ETHNOPHARMACOLOGICAL RELEVANCE: Salvadora persica L. and Azadirachtaindica A.Juss. are listed within the most common sources of miswak or chewing stick that widely used among Western Asia and Muslim populations worldwide. Miswak use in conjunction with toothbrush (adjunctive) has become apparent among the adults. Furthermore, miswak has been reported to have mechanical and pharmacological activities, and benefits to the oral health, by many studies. AIM OF THE STUDY: To assess the effectiveness of miswak in maintaining periodontal health among adults. MATERIALS AND METHODS: We searched for randomised controlled trials (RCTs) investigating the effect of miswak published in PubMed, EBSCOHOST (Dentistry & Oral Sciences), SCOPUS, and Cochrane Database for Systematic Review (CDSR) from inception to May 08, 2022. The primary outcomes of interest were changes in the periodontal health measured with plaque and gingivitis scores as well as subgingival bacteria load. The quality of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach while the estimates of effect were pooled using a random-effects model. RESULTS: Ten eligible articles were identified, of which 9 could be analysed quantitatively. The remaining report was included as part of the qualitative analysis. The meta-analysis showed that miswak was comparable with the toothbrush in reducing the mean plaque score (p= 0.08, SMD: 0.39, and 95% CI: -0.05 to 0.83) and mean gingivitis score (p= 0.37, SMD: 0.13, and 95% CI: -0.16 to 0.43). Even higher certainty of evidence for the effect of miswak on mean plaque reduction on labial surface of anterior teeth. However, the adjunctive effect of miswak was significantly more superior for reducing plaque (p= 0.01, SMD: 0.68, and 95% CI: 0.14 to 1.22) and gingivitis score (p= 0.04, SMD: 0.66, and 95% CI: 0.03 to 1.29). CONCLUSIONS: Miswak effectively reduced plaque and gingivitis scores to a level comparable to toothbrush when used exclusively. Adjunctive miswak use was particularly effective in improving periodontal health. However, the included studies inadequately reported on the method of toothbrushing using miswak and the frequency of miswak use. Therefore, further clinical studies are recommended to explore on the advantages and proper method of miswak practice for optima outcome and safety.

Transcriptomic Profile Analysis of Streptococcus mutans Response to Acmella paniculata Flower Extracts.

Background: Acmella paniculata has been used as a traditional medicine to treat oral health diseases such as dental caries and periodontitis. Streptococcus mutans is a common bacterium that initiates dental caries at an early stage. Aim: The aim of this study was to determine the mode of action of A. paniculata (extracts) against S. mutans growth. Methods: Time-kill assay has been done to investigate the rate of kill and effectiveness of Acmella paniculata (AP) extracts against S. mutans growth. Phytochemical analysis was done to identify major compounds in AP extracts using gas chromatography mass spectrometry (GCMS). Scanning and transmission electron microscopy (SEM and TEM) have been done to observe the morphological changes of treated bacteria. Transcriptomic profile analysis has been done using Next Gene Sequencing. Results: AP flower n-hexane (APFH) and AP flower dichloromethane (APFD) extracts acted as bactericidal agents after killing >3 log10 cfu/mL of S. mutans after 24 hours. Oleic and hexadecenoic acids were found to be the major compounds in APFD and APFH extracts, respectively. Photomicrographs from SEM and TEM of treated S. mutans show that the bacterial cell wall has been lysed and the cytoplasm content was decreased. Pathway analysis revealed that the APFD extract significantly affected biosynthesis peptidoglycan, gene expression, RNA processing, and macromolecule metabolism processes in S. mutans. Conclusion: Data analysis revealed that multiple mechanisms of action were involved in antibacterial activity of A. paniculata extracts toward S. mutans.

Silver nanoparticles Clinacanthus Nutans leaves extract induced apoptosis towards oral squamous cell carcinoma cell lines.

PURPOSE: The purpose of this study was to investigate apoptotic activity of silver nanoparticle Clinacanthus nutans (AgNps-CN) towards HSC-4 cell lines (oral squamous cell carcinoma cell lines). METHODS: Methods involved were MTT assay (cytotoxic activity), morphological cells analysis, flow cytometry and cell cycle analysis and western blot. RESULTS: MTT assay revealed IC50 concentration was 1.61 µg/mL, 3T3-L1 cell lines were used to determine whether AgNps-CN is cytotoxic to normal cells. At the highest concentration (3 µg/mL), no cytotoxic activity has been observed. Flow cytometry assay revealed AgNps-CN caused apoptosis effects towards HSC-4 cell lines with significant changes were observed at G1 phase when compared with untreated cells. Morphological cells analysis revealed that most of the cells exhibit apoptosis characteristics rather than necrosis. Protein study revealed that ratio of Bax/Bcl-2 increased mainly due to down-regulation of Bcl-2 expression. CONCLUSION: AgNps-CN have shown potential in inhibiting HSC-4 cell lines. IC50 was low compared to few studies involving biosynthesized of silver nanoparticles. Apoptosis effects were shown towards HSC-4 cell lines by the increased in Bax/Bcl-2 protein ratio. Further study such as PCR or in vivo studies are required.