Search Results (119)

Sesquiterpenoids are widely distributed in the genus Dysoxylum (Meliaceae) and have attracted attention because of their diverse biological activities, including antibiofilm properties. This study aimed to isolate and characterize sesquiterpenoids from the n-hexane extracts of Dysoxylum acutangulum Miq. and Dysoxylum cauliflorum Hiern twigs, followed by evaluation of their antibiofilm activity against Streptococcus mutans. Chromatographic separation of the n-hexane extract of D. acutangulum afforded spathulenol (1), β-caryophyllene oxide (3), and a mixture of epimeric sesquiterpenoids consisting of 10-oxo-isodauc-3-en-15-al (2a, major) and sinulin A (2b, minor), while humulene diepoxide A (4) was isolated from D. cauliflorum. Structural elucidation was carried out using MS, IR, and extensive NMR spectroscopic analyses, and by comparison with reported data. The major and minor epimers of compound 2 were distinguished based on diagnostic NMR signal intensities and comparison with literature data. Notably, all isolated compounds are reported herein for the first time from their respective Dysoxylum species. Compound 1, the epimeric mixture 2a/2b, and compound 4 exhibited weak antibiofilm activity against S. mutans, with minimum biofilm inhibitory concentration (MBIC) values ranging from 250 to 500 µg/mL, whereas chlorhexidine exhibited superior antibiofilm activity at 62.5 µg/mL. Molecular docking against Sortase A and GtfB revealed moderate binding affinities and suggested plausible interactions with biofilm-associated targets. These findings provide additional chemotaxonomic information on Dysoxylum species and preliminary insight into the antibiofilm potential of their sesquiterpenoids, particularly for compounds with limited previous antibiofilm reports. Full article

Background: Bacterial skin infections in companion animals, particularly those involving multidrug-resistant Pseudomonas aeruginosa and methicillin-resistant Staphylococcus, pose significant therapeutic challenges due to rising resistance and biofilm formation. While Piper betle is well-recognized in human medicine, data on its efficacy against veterinary isolates—and the comparative phytochemistry and potency of its extracts versus essential oils—remains scarce. Objective: This study evaluated the antimicrobial and antibiofilm efficacy of an ethanolic P. betle leaf extract compared to a panel of representative essential oils—including P. betle leaf oil, clove, tea tree, and plai—against 73 feline and canine clinical isolates. Methods: Minimum inhibitory (MIC) and bactericidal (MBC) concentrations were determined via broth microdilution. Biofilm inhibition was assessed using crystal violet staining to determine the minimum biofilm inhibitory concentration (MBIC). Phytochemical profiles were characterized using gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–quadrupole time-of-flight mass spectrometry (LC–MS/MS-QTOF). Results: P. betle leaf extract exhibited superior anti-pseudomonad activity (mean MIC: 1.5 mg/mL; MBC: 1.9 mg/mL), demonstrating significantly greater potency than the tested essential oils. Among the essential oils, clove oil was the most effective against Staphylococcus strains (mean MIC: 0.8 mg/mL; MBC: 1.2 mg/mL). Despite 74.4% of P. aeruginosa and 90.0% of Staphylococcus spp. being strong biofilm producers, the P. betle extract demonstrated the highest inhibitory potency against P. aeruginosa (MBIC: 0.7 mg/mL) and, alongside clove oil, showed superior efficacy against Staphylococcus spp. (MBICs: 0.3 and 0.7 mg/mL, respectively). GC–MS analysis identified chavibetol (confirmed via standard spiking) and hydroxychavicol as the primary extract constituents. LC–MS/MS-QTOF profiling further revealed a prominent phenolic profile, including 2,3-dihydroxybenzoic acid and 3,4-dihydroxybenzaldehyde. Comparative analysis suggests that while clove oil efficacy is primarily driven by high eugenol content, the broad-spectrum potency of the P. betle extract arises from a complex phenolic richness, specifically the synergistic presence of hydroxychavicol and chavibetol. Conclusions: These findings confirm the robust potential of P. betle extract as a promising plant-based antiseptic for managing biofilm-associated infections and mitigating antimicrobial resistance in veterinary medicine. Full article

Acaryochloris marina is a distinctive cyanobacterium that uses chlorophyll d as its primary photosynthetic pigment and possesses two major light-harvesting systems: membrane-integral chlorophyll-binding Pcb/CBP complexes and water-soluble phycobiliproteins. How these antenna systems respond at the transcriptome level to contrasting light environments remains incompletely characterized. Here, we re-analyzed a publicly available RNA-seq dataset for A. marina MBIC11017 (NCBI BioProject PRJNA1130970), comparing cells grown under low-irradiance far-red light (LL-FR; 1.5–2 µmol photons m⁻² s⁻¹, 710-nm peak) and high-irradiance white light (HL-WL; 30–35 µmol photons m⁻² s⁻¹). Because light quality and irradiance both differ in this experimental design, the two effects cannot be separated; all transcriptional changes are therefore interpreted as responses to the combined LL-FR versus HL-WL contrast rather than to far-red wavelength alone. Of 8439 expressed genes, 1810 (21.4%) were significantly differentially expressed (adjusted p < 0.05). Using GFF-verified locus tags which corrected mis-annotations propagated in earlier analyses, the PS-I core gene set showed a mean log₂ fold-change of +1.96 (3.9-fold; 11/11 loci significant), whereas the PS-II core gene set showed a mean log₂ fold-change of +1.10 (2.1-fold; 12/20 loci significant). Light-harvesting genes showed the strongest response: 17/18 phycobiliprotein-pathway genes in KEGG amr00196 were upregulated, together with multiple putative Pcb/CBP loci (mean antenna log₂FC = +3.51; 11.4-fold). Weighted gene co-expression network analysis placed the antenna-associate genes examined here within a module positively correlated with the LL-FR condition (r = 0.802, p = 0.017), and STRING analysis supported an enriched network of predicted or known protein associations (1115 nodes, 4763 edges; PPI enrichment p < 1.0 × 10⁻¹⁶). Recent matched-irradiance experiments indicate that, at equal photon flux, far-red wavelengths reduce phycobilisome content relative to white light. The transcriptional pattern reported here is therefore most parsimoniously interpreted as predominantly a low-irradiance response, with possible wavelength-associated CA5 contributions that cannot be isolated in the present design. Overall, the analysis reveals coordinated transcript-level changes across plasmid-encoded reacquired phycobiliprotein genes, chromosomal Pcb/CBP loci, chlorophyll biosynthesis genes, and photosystem core genes, consistent with coordinated regulation of light-harvesting components in A. marina. Full article

Background: Candida tropicalis is a pathogenic yeast species responsible for infections within the Candida genus and is identified as the most virulent species after C. albicans, partly due to its ability to form biofilms. Objective: This study analyzes the antifungal efficacy of a newly synthesized dendron, BD132 dendron, against C. tropicalis. Results: The compound showed a strong antifungal activity with promising minimum inhibitory concentration (MIC) and minimum biofilm inhibitory concentration (MBIC) values. Combination therapy with AgNO₃ and amphotericin B showed additive and synergistic effects, respectively, enhancing antifungal efficacy and potentially reducing cytotoxicity. The dendron did not alter key enzyme activities, and scanning electron microscopy revealed significant morphological alterations, including increased cell size and surface damage, indicating membrane disruption. In addition, the BD132 dendron did not induce resistance, and stability studies indicated a slight MIC decrease at 4 °C and −20 °C after 15 days, with stable minimum fungicidal concentration (MFC), suggesting potential for long-term use. Conclusions: These findings highlight the potential of this dendron in combination therapies to treat C. tropicalis infections. Full article

Background/Objectives: Longer lifetime exposure to endogenous estradiol (L_EE2) has been associated with lower risk of age-related cognitive decline and dementia. Complementary to cognitive decline, behavioral and functional decline are also predictive of dementia risk; however, the association between L_EE2 and these domains is underexplored. We investigated whether L_EE2 is correlated with later-life changes in behavior and function. Methods: Baseline data from 1156 females enrolled in the CAN-PROTECT study were analyzed. L_EE2 was estimated based on the length of the reproductive period (menopause age–menarche age) plus years pregnant and scaled in 5-year increments. Objective cognition was measured using the CAN-PROTECT neuropsychological battery, while subjective cognition, behavior, and function were measured using the Revised Everyday Cognition (ECog-II) scale, Mild Behavioral Impairment Checklist (MBI-C), and Standard Assessment of Global Everyday Activities (SAGEA) scale, respectively. Linear regressions modeled the association between L_EE2 and neuropsychological performance. Three separate negative binomial regression models examined the association between L_EE2 and ECog-II, MBI-C, and SAGEA total scores. All models adjusted for menopause hormone therapy, menopause type, age at first childbirth, body mass index, age, education, and ethnocultural background. Results: Each five-year increase in L_EE2 was associated with a lower MBI-C score (count ratio [CR] = 0.89, 95% CI [0.82, 0.97]) and lower SAGEA score (CR = 0.91, 95% CI [0.84, 0.98]). L_EE2 was not significantly associated with any objective or subjective cognitive measures. Conclusions: Longer L_EE2 may associate with lower severity of later-life behavioral and functional symptoms in older women. Full article

Background: Nigella sativa (black cumin) seeds are renowned for their ethnomedicinal significance and are rich in bioactive phytochemicals, which contribute to food preservation and the prevention of various diseases through their antimicrobial and antioxidant properties. Accordingly, this study aimed to characterize the phytochemical composition of N. sativa seed extracts, isolate thymoquinone, and assess their antibacterial, antibiofilm, antioxidant, anti-inflammatory and antidiabetic activities. Methods: Nigella sativa seed extracts were prepared using solvents of increasing polarity and analyzed for phytochemical content. Metabolite profiling was performed using UHPLC/QTOF-MS. Thymoquinone, the major constituent, was isolated via thin-layer chromatography (TLC), further purified using semi-preparative reverse-phase high-performance liquid chromatography (RP-HPLC), and evaluated in vitro for antibacterial, antibiofilm, antioxidant, anti-inflammatory, and antidiabetic activities. Results: Extraction yields ranged from 5.5% to 8.4% (w/w), with methanol yielding the highest phenol (6.34 ± 0.31 mg GAE/mL) and flavonoid (5.12 ± 0.26 mg QE/mL) contents. UHPLC/QTOF-MS revealed a chemically diverse profile dominated by thymoquinone (58% relative abundance), alongside p-cymene, carvacrol, longifolene, and nigellidine. Thymoquinone (Rf = 0.56) was initially isolated from the methanolic extract with a yield of 270 mg/g and further purified from preparative TLC fractions using semi-preparative RP-HPLC, affording 82 mg of >95% pure compound with a 68.3% recovery, suitable for subsequent biological assays. It inhibited Gram-positive and Gram-negative bacteria, with MICs of 62.5 µg/mL against Staphylococcus aureus, Bacillus subtilis, and Listeria monocytogenes; 125–250 µg/mL against Escherichia coli and Salmonella typhimurium; and 500 µg/mL against Pseudomonas aeruginosa. Thymoquinone reduced biofilm formation (>80% at 25–50 µg/mL; MBIC₅₀ ≈ 5.4–11.6 µg/mL), exhibited antioxidant activity (DPPH IC₅₀ = 52.3 ± 2. 1 µg/mL; ABTS IC₅₀ = 41.6 ± 1.9 µg/mL), stabilized erythrocyte membranes (IC₅₀ ≈ 14.8 µg/mL), and inhibited carbohydrate-hydrolyzing enzymes, with stronger inhibition of α-glucosidase (~92%) than α-amylase (~84%) at 128 µg/mL. Conclusions: Thymoquinone is a major bioactive constituent of N. sativa seeds, exhibiting consistent multi-target in vitro activity. These findings highlight its functional relevance and in vivo investigations to establish therapeutic potential. Full article

Methicillin-resistant Staphylococcus aureus (MRSA) produces virulence factors and causes hard-to-treat infections. This study aimed to evaluate the effect of trans-cinnamaldehyde (TC) on the selected virulence factors of MRSA: adhesion to host plasma and extracellular matrix proteins, protease, DNase and esterase production, and hemolytic activity. Our results showed that TC at ½ MBIC (Minimum Biofilm Inhibition Concentration) of 240 µg/mL or 60 µg/mL, depending on the isolate, significantly reduced MRSA adhesion. Inhibition varied between isolates, ranging from 26.1% to 41.3% (fibrinogen), 18.2% to 34.9% (elastin), 26.5% to 32.4% (laminin), and 17.1% to 30.5% (collagen). TC at ½ MIC (Minimum Inhibitory Concentration) of 30 µg/mL also significantly inhibited MRSA enzyme production, and reduced hemolytic activity (by 80.0–83.1%, depending on the isolate). TC may be an alternative to antibiotics for combating infections caused by S. aureus, as it not only reduces bacterial survival in the host but also reduces S. aureus virulence at subinhibitory concentrations. TC at higher concentrations exhibits cytotoxicity in human fibroblasts, limiting its topical use. Therefore, to exploit TC’s antibacterial potential, it is necessary to identify substances that act synergistically with it, enabling reduced effective doses. Full article

Background: Healthcare-associated infections (HAIs) caused by biofilm-forming Staphylococcus aureus and Staphylococcus epidermidis represent a major public health challenge due to their high resistance and involvement in skin, wound, and soft-tissue infections. In this context, silver nanoparticles (AgNPs) incorporated into Gluconacetobacter sp. bacterial cellulose hydrogel emerge as a promising alternative therapeutic strategy. Methods: AgNPs and hydrogels were synthesized and characterized using physicochemical and morphological analyses. Antibacterial activity was assessed by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) following CLSI guidelines, as well as by time–kill curve assays. Antibiofilm activity was evaluated through the determination of minimum biofilm inhibitory concentration (MBIC) and minimum biofilm eradication concentration (MBEC) using crystal violet staining, complemented by scanning electron microscopy (SEM) and Congo red agar method. Results: The hydrogel exhibited a three-dimensional microfibrillar structure characteristic of bacterial cellulose, while AgNPs showed rod-shaped, oval, and triangular morphologies, with particle sizes of 35 and 59 nm and positive zeta potentials. MIC and MBC values ranged from 6.25 to 50 µg/mL across all tested formulations and strains. Time–kill assays demonstrated significant bacterial population reductions after 6 to 9 h of exposure. MBIC values ranged from 0.78 to 50 µg/mL, whereas MBEC values ranged from 1.56 to >100 µg/mL. SEM analyses confirmed biofilm disruption, cell eradication, and a reduction in extracellular polysaccharides, particularly for AgNPs incorporated into the hydrogel. Conclusions: Overall, the results highlight the strong antibacterial and enhanced antibiofilm potential of AgNP-loaded bacterial cellulose hydrogel against S. aureus and S. epidermidis, supporting its potential application in infection treatment. Full article

The global rise in antimicrobial resistance among the ESKAPE pathogens represents a major challenge to public health. Here, we report the broad-spectrum antibacterial activity of the synthetic antimicrobial and pore-forming peptide C14R against all six ESKAPE species. Using a radial diffusion assay and resazurin-based viability testing, C14R exhibited a potent bactericidal effect with minimum inhibitory concentrations (MICs), defined as the lowest concentration of an antimicrobial agent that completely inhibits visible growth of planktonic microorganisms, ranging from 3.4 µg/mL (Enterococcus faecium, vancomycin-resistant) to 45.2 µg/mL (Klebsiella quasipneumoniae, ESBL). C14R also inhibited biofilm formation by Gram-positive pathogens, with minimum biofilm inhibitory concentrations (MBICs), referring to the minimal concentration required to prevent the development of biofilms, of 15.0 µg/mL (Staphylococcus aureus, MRSA) and 22.0 µg/mL (E. faecium, VRE), whereas Gram-negative biofilms showed higher tolerance. Together, these findings demonstrate that C14R retains high activity against multidrug-resistant ESKAPE strains, highlighting its potential as a lead compound for the development of next-generation antimicrobial drugs to expand the portfolio of available antibiotics and brace health systems against emerging severe infections. Full article

Objective: Based on our previous findings, we designed new molecules by extending functionalized pyrazole derivatives containing iodine atoms, which are linked via an amino bond to halogen-substituted phenyl groups. In addition, these newly developed pyrazole compounds exhibit anti-tumor, antibacterial, and anti-biofilm activities. Methods: Three new series of pyrazole compounds were designed. Fifteen novel pyrazole derivatives, distributed across three series (4a–d, 5a–d, and 6a–g), were synthesized and structurally characterized by ¹H-NMR, ¹³C-NMR, FTIR, UV-Vis spectroscopy, and elemental analysis. Results: Among them, compound 4c, which exhibited notable anti-tumor activity, crystallized in a monoclinic system and was further analyzed via single-crystal X-ray diffraction. All synthesized compounds were evaluated in vitro on NCTC normal fibroblast cells and HEp-2 tumor epithelial cells. Compound 4c demonstrated significant anti-tumor activity while displaying no cytotoxic effects on normal cells. The antibacterial and anti-biofilm activities of the compounds were also assessed against four bacterial strains. Compounds 5a and 5c exhibited the highest antibacterial activity against Staphylococcus aureus ATCC 25923, both with a minimum inhibitory concentration (MIC) of 0.023 μg/mL. Additionally, compounds 4a, 5a, 6a, 6e, and 6f showed the strongest anti-biofilm effects, each presenting a minimum biofilm inhibition concentration (MBIC) of 0.023 μg/mL. ADME and ADMET in silico predictions indicated that all compounds exhibit generally favorable, drug-like physicochemical properties. Conclusions: The study reinforces the applicability of these compounds as promising anticancer, antibacterial, and anti-biofilm drugs. Full article

Background/Objectives: Dementia represents a growing public health challenge. The WHO Global Action Plan on the Public Health Response to Dementia emphasizes early detection, risk reduction, and innovation as key priorities. Mild Behavioral Impairment (MBI), defined as the emergence of persistent neuropsychiatric symptoms in older individuals, represents a potential marker of early neurodegeneration and possible window for early intervention. This review explores the role of MBI in dementia prevention, mapping current evidence within the WHO Global Action Plan framework. Methods: A comprehensive search was performed in PubMed, Scopus, and the official WHO website, during 1 September 2025–10 November 2025, without time restrictions. Eligible sources included original clinical studies, reviews, and policy documents addressing MBI, dementia prevention, and public health. Data were thematically synthesized according to the seven objectives of WHO: (1) dementia as a public health priority, (2) dementia awareness and friendliness, (3) dementia risk reduction, (4) dementia diagnosis, treatment, care and support, (5) support for dementia carers, (6) information systems for dementia, and (7) dementia research and innovation. Results: Accumulating evidence indicates that MBI assessment can capture early behavioral manifestations of neurodegenerative and other forms of dementia, correlating with fluid, neuroimaging and genetic biomarkers. Integrating MBI screening through the easy-to-administer MBI Checklist (MBI-C) into clinical and community-based care, including telemedicine pathways and research, may enhance early identification and personalized interventions, enrich the pool for clinical trials, and facilitate research in biomarker and therapy. MBI-related research further supports its integration in remote digital monitoring and population-based prevention. Conclusions: Embedding MBI-informed screening and interventions into national dementia strategies aligns with WHO objectives for early, equitable and scalable prevention and brain health. Full article

Staphylococcus aureus biofilms represent a critical healthcare challenge, driving chronic infections and antimicrobial resistance. This study investigates the anti-staphylococcal efficacy of two Lactiplantibacillus strains isolated from traditional Bulgarian pickled vegetables (turshiya): L. plantarum IZITR_24 and L. paraplantarum IZITR_13. Combining whole genome sequencing (WGS) with functional assays, we established a robust genotype-to-phenotype framework to characterize their antimicrobial arsenal. Based on WGS, we identified conserved plantaricin (plnJK, plnEF) clusters in both isolates, with IZITR_13 additionally carrying genes for pediocin and enterolysin A—alongside the confirmed absence of virulence factors. Reconstituted lyophilized cell-free supernatants (LCFSs) were evaluated in dose–response microtiter assays to determine the minimum biofilm inhibitory concentration (MBIC) and minimum inhibitory concentration (MIC). Both strains demonstrated clear, dose-dependent inhibitory activity against the S. aureus growth and biofilm formation. Microscopy (SEM/CLSM) confirmed significant biofilm disruption and cell membrane permeabilization. The observed consistency between genome-inferred capacity and phenotypes highlights the strong predictive value of a genome-first screening approach for selecting bacteriocin-producing lactic acid bacteria (LAB). These findings position IZITR_24 and IZITR_13 as promising postbiotic producers with potent antibiofilm activity against S. aureus. By utilizing their stable postbiotic products rather than relying on live colonization, this study proposes a targeted, antibiotic-sparing strategy to combat persistent staphylococcal biofilms. Full article

The growing global threat of antimicrobial resistance (AMR), particularly in cutaneous wound infections, represents a significant clinical and economic challenge. Biofilm formation by multidrug-resistant pathogens, such as Acinetobacter baumannii, often complicates healing and leads to therapeutic failure. Antimicrobial peptides (AMPs) are a promising alternative to conventional antibiotics due to their potent membrane-disrupting mechanism of action and lower propensity to induce resistance. Background/Objectives: This study aimed to evaluate the antibacterial, antibiofilm, and in vivo efficacy of four snake venom-derived cathelicidin-like peptides—Btn (15-34) and BotrAMP14 from Bothrops atrox, and Ctn (15-34) and CrotAMP14 from Crotalus durissus—against multidrug-resistant A. baumannii, Escherichia coli, and Pseudomonas aeruginosa clinical isolates from skin infections, with emphasis on A. baumannii, a WHO priority pathogen. Methods: Minimal Inhibitory Concentration (MIC), Minimal Bactericidal Concentration (MBC), and Minimal Biofilm Inhibitory Concentration (MBIC) were determined against A. baumannii, Escherichia coli, and Pseudomonas aeruginosa. Time-kill kinetics, hemolytic activity, and cytotoxicity assays were performed. A murine skin wound infection model was established to evaluate in vivo antibacterial efficacy and safety. Results: MIC/MBC values ranged from 0.78 to 25 µM against planktonic cells. In comparison, MBIC ranged from 1.56 to 12.5 µM against biofilms. BotrAMP14 eradicated A. baumannii within 4 min, while CrotAMP14 achieved bactericidal action in 20 min at 1.56 µM. Both peptides exhibited no hemolytic activity up to 128 µM and low cytotoxicity (IC₅₀ > 128 µM). In vivo, BotrAMP14 and CrotAMP14 demonstrated significant antibacterial activity at 24 h and 48 h post-infection, respectively, surpassing that of meropenem. Conclusions: These findings suggest that BotrAMP14 and CrotAMP14 are promising topical antimicrobial agents for managing multidrug-resistant skin infections and may help address the urgent need for alternative therapies against antibiotic-resistant pathogens. Full article

Background: Commercial oral care products commonly incorporate synthetic antimicrobials such as cetylpyridinium chloride (Cetyl Cl.), L-Arginine (L-arg.), and stannous fluoride (SnF₂). Although effective against oral pathogens, these agents are often associated with adverse effects including mucosal irritation, taste alteration, and disruption of the oral microbiome. These limitations have spurred growing interest in safer, plant-based alternatives. In this study, we present a two-pronged in vitro oral care testing model that integrates cell assays with machine-guided quantitative microscopy analyses to assess both antibacterial efficacy and host biocompatibility of botanical extracts. Methods: Using Miswak (Salvadora persica) and Neem (Azadirachta indica) as representative natural products, we conducted antibacterial and antibiofilm testing including the evaluation of the minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC), alongside biocompatibility assessments via MTT cell viability assays on probiotic bacteria and mammalian oral cells. To evaluate biofilm structure and disruption, we employed scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), augmented with machine-guided Weka segmentation and automated image analysis. Results: Our findings show that Miswak and Neem extracts exhibited 75–100% antibacterial and antibiofilm efficacy against all tested bacteria, as demonstrated by cell assays and microscopy analyses, comparable to synthetic oral care agents. They also maintained ~100% viability toward commensal microbes and mammalian oral cells, whereas Cetyl Cl. and SnF₂ showed dose-dependent cytotoxicity. Conclusions: This dual-assessment oral care testing model provides a comprehensive and biologically relevant framework for the discovery and screening of safe and effective natural herbal extracts in oral care applications. Full article

Background: Oral infections such as dental caries and candidiasis are mediated by resilient biofilms, which are increasingly tolerant to conventional antimicrobials. This study investigated the antimicrobial and antibiofilm effects of Salvia officinalis and Nigella sativa CO₂ extracts against Streptococcus mutans and Candida albicans, with emphasis on synergistic interactions. Methods: Extracts were analyzed using gas chromatography–mass spectrometry analysis (GC–MS) and evaluated through planktonic MIC/MBC assays, time–kill kinetics, and biofilm models (MBIC/MBEC, biomass, metabolic activity). A novel three-dimensional checkerboard (3D-CB) and fractional inhibitory concentration index (FICI) approach was applied to optimize extract ratios, concentrations, and exposure times. Results: S. officinalis extract showed greater activity against S. mutans (MIC 256 mg/L; MBC 512 mg/L), while N. sativa was more effective against C. albicans (MIC 256 mg/L; MFC 512 mg/L). Both extracts reduced biofilm biomass and metabolic activity by over 70% at higher doses. Synergy was confirmed at ratios of 70:30 (S. officinalis: N. sativa) for S. mutans (FICI 0.38) and 40:60 for C. albicans (FICI 0.42). The achieved synergistic effect further decreased MBEC values fourfold and prolonged post-antibiotic effects. Conclusions: Synergistic S. officinalis–N. sativa formulations enhanced antimicrobial activity against oral pathogens in both planktonic and biofilm states, supporting their potential as next-generation dental antimicrobials. Full article