http://colil.dbcls.jp:18052/sparql?query=define%20sql%3Adescribe-mode%20%22CBD%22%20%20DESCRIBE%20%3Chttp%3A%2F%2Fpurl.jp%2Fbio%2F10%2Fcolil%2Fid%2F25811596%3E&output=application%2Fatom%2Bxml2024-03-28T17:14:27.832352ZOData Service and Descriptor DocumentnodeID://b5759171232024-03-28T17:14:27.832352Z3nodeID://b5759171202024-03-28T17:14:27.832352Z3nodeID://b392037672024-03-28T17:14:27.832352ZCurcumin I is the most active component of turmeric that has been explored for its various biological and medicinal properties [1, 5, >>23<<]. In the present study, we focused upon the antibacterial activity of curcumin I against four genera of bacteria, including those that are Gram-positive (S.nodeID://b5759171172024-03-28T17:14:27.832352Z4nodeID://b392037412024-03-28T17:14:27.832352Zaureus) [>>10<<–12]. However, very few studies have demonstrated the mechanism of antibacterial activity of curcumin I which seems to differ depending on the strain being studied.nodeID://b392037362024-03-28T17:14:27.832352ZPrevious research has shown that it plays a therapeutic role in many diseases including diabetes, inflammatory disorders and different types of cancers [>>2<<–4]. Curcumin is a pleiotropic molecule that interacts with multiple targets involved in inflammatory reaction such as tumor necrosis factor-alpha (TNFα) and interleukins (ILs) [5]. Curcumin has also been shown to possess in vitronodeID://b392037742024-03-28T17:14:27.832352Zobservations are in agreement with previous studies, which showed an 80% decrease in E. coli cell growth on exposure of 100 μM curcumin [15], 100% inhibition of S. aureus and P. aeruginosa [8], and 80% inhibition in case of E. faecalis [>>8<<] due to the exposure of 200 μM of curcumin within 4h. The high concentrations required to kill the bacteria in this and other studies may be due to poor solubility of curcumin in aqueous media and the low bioavailability of curcumin [28].nodeID://b5759171342024-03-28T17:14:27.832352Z3nodeID://b5759171312024-03-28T17:14:27.832352Z3nodeID://b5759172012024-03-28T17:14:27.832352Z2nodeID://b5759171252024-03-28T17:14:27.832352Z3nodeID://b5759171282024-03-28T17:14:27.832352Z3nodeID://b5759171422024-03-28T17:14:27.832352Z3nodeID://b5759171192024-03-28T17:14:27.832352Z3nodeID://b5759171332024-03-28T17:14:27.832352Z3nodeID://b5759171362024-03-28T17:14:27.832352Z3nodeID://b5759171502024-03-28T17:14:27.832352Z3nodeID://b5759172032024-03-28T17:14:27.832352Z2nodeID://b5759172002024-03-28T17:14:27.832352Z2nodeID://b392037372024-03-28T17:14:27.832352ZCurcumin is a pleiotropic molecule that interacts with multiple targets involved in inflammatory reaction such as tumor necrosis factor-alpha (TNFα) and interleukins (ILs) [>>5<<]. Curcumin has also been shown to possess in vitro anti-microbial potential against a wide range of microorganisms including fungi [6] as well as several Gram-positive and Gram-negative bacteria [7–17]. Recently, Song et al. [9] showednodeID://b5759171442024-03-28T17:14:27.832352Z3nodeID://b5759171472024-03-28T17:14:27.832352Z3nodeID://b5759171412024-03-28T17:14:27.832352Z3nodeID://b392037752024-03-28T17:14:27.832352ZThe high concentrations required to kill the bacteria in this and other studies may be due to poor solubility of curcumin in aqueous media and the low bioavailability of curcumin [>>28<<]. To deal with this issue, several bio-conjugates and nanoparticles of curcumin have been synthesized by other groups and are under investigation [28–30].nodeID://b392037442024-03-28T17:14:27.832352Zaeruginosa) infection, curcumin was shown to have anti-infective activity through affecting virulence, quorum sensing and biofilm initiation [>>17<<]. Moreover, these mechanisms have not been confirmed in the case of other bacterial genera, hence could not be generalized for all bacteria. Therefore, a detailed study on antibacterial mechanism of curcumin, including a large number ofnodeID://b5759172142024-03-28T17:14:27.832352Z2nodeID://b5759172112024-03-28T17:14:27.832352Z2nodeID://b5759171382024-03-28T17:14:27.832352Z3nodeID://b5759171522024-03-28T17:14:27.832352Z3nodeID://b5759172082024-03-28T17:14:27.832352Z2nodeID://b5759172052024-03-28T17:14:27.832352Z2nodeID://b5759171552024-03-28T17:14:27.832352Z2nodeID://b5759172222024-03-28T17:14:27.832352Z2nodeID://b5759171462024-03-28T17:14:27.832352Z3nodeID://b5759171492024-03-28T17:14:27.832352Z3nodeID://b5759172162024-03-28T17:14:27.832352Z2nodeID://b5759172132024-03-28T17:14:27.832352Z2nodeID://b5759171632024-03-28T17:14:27.832352Z2nodeID://b5759171602024-03-28T17:14:27.832352Z2nodeID://b5759172302024-03-28T17:14:27.832352Z2nodeID://b5759171572024-03-28T17:14:27.832352Z2nodeID://b392037452024-03-28T17:14:27.832352ZCurcumin I showed no toxic effect on human health even when taken at doses as high as 8 g day−1 [>>18<<, 2]. Considering these factors, in the present study, we investigated the detailed antibacterial activity of curcumin I (the major component of commercial curcumin) against two Gram-positive bacteria, namely, S. aureus and EnterococcusnodeID://b392037782024-03-28T17:14:27.832352ZSuch a strategy could be immensely promising in the current scenario of continuous emergence of resistant microorganisms and antibiotic crisis [31, >>32<<]. Oxidative stress and inflammation often go together with bacterial infections [33, 34]. Therefore, curcumin I, an established anti-oxidant and anti-inflammatory natural herbal product, with easy availability, high efficacy, and lownodeID://b5759171742024-03-28T17:14:27.832352Z2nodeID://b5759172242024-03-28T17:14:27.832352Z2nodeID://b5759172272024-03-28T17:14:27.832352Z2nodeID://b5759171712024-03-28T17:14:27.832352Z2nodeID://b5759170982024-03-28T17:14:27.832352Z13nodeID://b392037522024-03-28T17:14:27.832352ZThe fluorescence emission can be detected by both spectrofluorimeter [19] and flow cytometer [>>21<<] equipped with an appropriate filter.nodeID://b5759172182024-03-28T17:14:27.832352Z2nodeID://b5759171682024-03-28T17:14:27.832352Z2nodeID://b5759171652024-03-28T17:14:27.832352Z2nodeID://b5759171822024-03-28T17:14:27.832352Z2nodeID://b5759172352024-03-28T17:14:27.832352Z2nodeID://b5759172322024-03-28T17:14:27.832352Z2nodeID://b5759171592024-03-28T17:14:27.832352Z2nodeID://b5759172262024-03-28T17:14:27.832352Z2nodeID://b5759172292024-03-28T17:14:27.832352Z2nodeID://b5759171732024-03-28T17:14:27.832352Z2nodeID://b5759171762024-03-28T17:14:27.832352Z2nodeID://b5759171902024-03-28T17:14:27.832352Z2nodeID://b5759172402024-03-28T17:14:27.832352Z2nodeID://b5759172432024-03-28T17:14:27.832352Z2nodeID://b392037792024-03-28T17:14:27.832352ZOxidative stress and inflammation often go together with bacterial infections [>>33<<, 34]. Therefore, curcumin I, an established anti-oxidant and anti-inflammatory natural herbal product, with easy availability, high efficacy, and low cytotoxicity, could be an ideal candidate to use in combination therapies againstnodeID://b5759172372024-03-28T17:14:27.832352Z2nodeID://b5759171872024-03-28T17:14:27.832352Z2nodeID://b5759171842024-03-28T17:14:27.832352Z2nodeID://b5759171812024-03-28T17:14:27.832352Z2nodeID://b392037532024-03-28T17:14:27.832352ZThe permeabilization of bacterial membrane due to curcumin I exposure was measured via calcein leakage by flow cytometry, as described in our previous reports [>>19<<, 20]. Calcein-AM (Calcein-Acetoxy Methyl Ester) is a membrane-permeating, non-fluorescent derivative of calcein whose excitation and emission wavelengths are 490 nm and 517 nm, respectively.nodeID://b392037482024-03-28T17:14:27.832352ZThe killing assay was performed according to the procedure mentioned in our previous publications [>>19<<, 20]. Bacterial cells were grown in BHI broth to mid logarithmic phase. Using spectrophotometer, the optical density (OD 600nm) of cells was adjusted to 0.5 (~108 CFU/ml) in 10 mM PBS buffer (pH 7.4).nodeID://b5759172542024-03-28T17:14:27.832352Z2nodeID://b5759172512024-03-28T17:14:27.832352Z2nodeID://b5759171782024-03-28T17:14:27.832352Z2nodeID://b392037602024-03-28T17:14:27.832352ZresultsnodeID://b5759172482024-03-28T17:14:27.832352Z2nodeID://b5759172452024-03-28T17:14:27.832352Z2nodeID://b5759171922024-03-28T17:14:27.832352Z2nodeID://b5759171952024-03-28T17:14:27.832352Z2nodeID://b5759172622024-03-28T17:14:27.832352Z2nodeID://b5759171862024-03-28T17:14:27.832352Z2nodeID://b5759171892024-03-28T17:14:27.832352Z2nodeID://b5759172392024-03-28T17:14:27.832352Z2nodeID://b5759172562024-03-28T17:14:27.832352Z2nodeID://b5759172532024-03-28T17:14:27.832352Z2nodeID://b5759172702024-03-28T17:14:27.832352Z2nodeID://b5759171972024-03-28T17:14:27.832352Z2nodeID://b5759171942024-03-28T17:14:27.832352Z2nodeID://b392037492024-03-28T17:14:27.832352ZThe killing assay was performed according to the procedure mentioned in our previous publications [19, >>20<<]. Bacterial cells were grown in BHI broth to mid logarithmic phase. Using spectrophotometer, the optical density (OD 600nm) of cells was adjusted to 0.5 (~108 CFU/ml) in 10 mM PBS buffer (pH 7.4).nodeID://b5759172612024-03-28T17:14:27.832352Z2nodeID://b5759172642024-03-28T17:14:27.832352Z2nodeID://b5759172672024-03-28T17:14:27.832352Z2nodeID://b392037562024-03-28T17:14:27.832352ZSEM was performed as described in our previous report [>>20<<]. In brief, 108 CFU/ml bacterial suspension was incubated with different doses of curcumin I (25 μM, 50 μM & 100 μM) in PBS for 60 min and centrifuged at 4,000 rpm for 10 min.nodeID://b392037612024-03-28T17:14:27.832352Zrepresent the number of S. aureus cells showing PI fluorescence on exposure of 25 μM, 50 μM and 100 μM curcumin I and two positive controls HNP-1 and nisin (well known antimicrobial peptides causing bacterial membrane permeabilization [>>22<<]) after 2h incubation, as quantified from a flow cytometry experiment repeated on three different days.nodeID://b5759172582024-03-28T17:14:27.832352Z2nodeID://b5759172752024-03-28T17:14:27.832352Z2nodeID://b5759172722024-03-28T17:14:27.832352Z2nodeID://b5759171992024-03-28T17:14:27.832352Z2nodeID://b5759172692024-03-28T17:14:27.832352Z2nodeID://b5759172662024-03-28T17:14:27.832352Z2nodeID://b5759172832024-03-28T17:14:27.832352Z2nodeID://b5759172802024-03-28T17:14:27.832352Z2nodeID://b5759172772024-03-28T17:14:27.832352Z2nodeID://b5759172742024-03-28T17:14:27.832352Z2nodeID://b392037572024-03-28T17:14:27.832352ZBacterial Viability Assay Kit for microscopy [L7007, from Invitrogen, this is a mixture of stains: SYTO 9 (for live cells) and PI (for dead cells) in two different ratios] according to the protocol as suggested by the manufacturer [>>19<<]. Briefly, 3 μl of the mixture was added to the bacterial cells previously treated with different concentrations of curcumin I (25 μM, 50 μM & 100 μM) for 2h, and untreated cells were kept as control.nodeID://b5759172912024-03-28T17:14:27.832352Z2nodeID://b392037642024-03-28T17:14:27.832352ZdiscussionnodeID://b5759172882024-03-28T17:14:27.832352Z2nodeID://b5759172852024-03-28T17:14:27.832352Z2nodeID://b5759171012024-03-28T17:14:27.832352Z7nodeID://b5759172792024-03-28T17:14:27.832352Z2nodeID://b5759171032024-03-28T17:14:27.832352Z7nodeID://b5759171002024-03-28T17:14:27.832352Z8nodeID://b392037652024-03-28T17:14:27.832352ZCurcumin I is the most active component of turmeric that has been explored for its various biological and medicinal properties [>>1<<, 5, 23]. In the present study, we focused upon the antibacterial activity of curcumin I against four genera of bacteria, including those that are Gram-positive (S.nodeID://b392037342024-03-28T17:14:27.832352ZintroductionnodeID://b392037722024-03-28T17:14:27.832352ZThese observations are in agreement with previous studies, which showed an 80% decrease in E. coli cell growth on exposure of 100 μM curcumin [>>15<<], 100% inhibition of S. aureus and P. aeruginosa [8], and 80% inhibition in case of E. faecalis [8] due to the exposure of 200 μM of curcumin within 4h.nodeID://b5759171142024-03-28T17:14:27.832352Z4nodeID://b5759171112024-03-28T17:14:27.832352Z4nodeID://b5759171052024-03-28T17:14:27.832352Z6nodeID://b5759171082024-03-28T17:14:27.832352Z5nodeID://b5759171222024-03-28T17:14:27.832352Z3nodeID://b5759171162024-03-28T17:14:27.832352Z4nodeID://b5759171132024-03-28T17:14:27.832352Z4nodeID://b5759171302024-03-28T17:14:27.832352Z3nodeID://b392037352024-03-28T17:14:27.832352ZIt is also commonly used for medicinal purposes, particularly to treat inflammatory conditions [>>1<<]. Over the years, curcumin has been explored for various clinical applications. Previous research has shown that it plays a therapeutic role in many diseases including diabetes, inflammatory disorders and different types of cancers [2–4].nodeID://b5759171272024-03-28T17:14:27.832352Z3nodeID://b392037682024-03-28T17:14:27.832352ZBeing an amphipathic and lipophilic molecule, curcumin inserts into liposome bilayers and enhances their permeability [>>24<<]. Besides, it has also been found that curcumin is involved in disordering the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) membranes [25]. All previous studies on curcumin have indicated its membrane altering properties such asnodeID://b392037732024-03-28T17:14:27.832352ZThese observations are in agreement with previous studies, which showed an 80% decrease in E. coli cell growth on exposure of 100 μM curcumin [15], 100% inhibition of S. aureus and P. aeruginosa [>>8<<], and 80% inhibition in case of E. faecalis [8] due to the exposure of 200 μM of curcumin within 4h.nodeID://b5759171242024-03-28T17:14:27.832352Z3nodeID://b392037422024-03-28T17:14:27.832352ZFor instance, studies have demonstrated that the antibacterial activity of curcumin against Bacillus subtilis occurs through the inhibition of bacterial cell proliferation by blocking the assembly dynamics of FtsZ in the Z ring [>>15<<, 16]. In the case of Pseudomonas aeruginosa (P. aeruginosa) infection, curcumin was shown to have anti-infective activity through affecting virulence, quorum sensing and biofilm initiation [17].nodeID://b392037802024-03-28T17:14:27.832352ZOxidative stress and inflammation often go together with bacterial infections [33, >>34<<]. Therefore, curcumin I, an established anti-oxidant and anti-inflammatory natural herbal product, with easy availability, high efficacy, and low cytotoxicity, could be an ideal candidate to use in combination therapies against bacterialnodeID://b5759171182024-03-28T17:14:27.832352Z4nodeID://b5759171352024-03-28T17:14:27.832352Z3nodeID://b5759171322024-03-28T17:14:27.832352Z3nodeID://b5759172022024-03-28T17:14:27.832352Z2nodeID://b5759171262024-03-28T17:14:27.832352Z3nodeID://b5759171292024-03-28T17:14:27.832352Z3nodeID://b5759171402024-03-28T17:14:27.832352Z3nodeID://b5759171432024-03-28T17:14:27.832352Z3nodeID://b5759172102024-03-28T17:14:27.832352Z2nodeID://b392037692024-03-28T17:14:27.832352ZBesides, it has also been found that curcumin is involved in disordering the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) membranes [>>25<<]. All previous studies on curcumin have indicated its membrane altering properties such as thinning and disruption of the membrane at high concentrations using artificial membranes only [26]. However, curcumin induced membranenodeID://b5759171372024-03-28T17:14:27.832352Z3nodeID://b392037382024-03-28T17:14:27.832352ZCurcumin has also been shown to possess in vitro anti-microbial potential against a wide range of microorganisms including fungi [>>6<<] as well as several Gram-positive and Gram-negative bacteria [7–17].nodeID://b392037432024-03-28T17:14:27.832352ZFor instance, studies have demonstrated that the antibacterial activity of curcumin against Bacillus subtilis occurs through the inhibition of bacterial cell proliferation by blocking the assembly dynamics of FtsZ in the Z ring [15, >>16<<]. In the case of Pseudomonas aeruginosa (P. aeruginosa) infection, curcumin was shown to have anti-infective activity through affecting virulence, quorum sensing and biofilm initiation [17].nodeID://b5759172072024-03-28T17:14:27.832352Z2nodeID://b5759171512024-03-28T17:14:27.832352Z3nodeID://b392037762024-03-28T17:14:27.832352ZTo deal with this issue, several bio-conjugates and nanoparticles of curcumin have been synthesized by other groups and are under investigation [>>28<<–30].nodeID://b5759171542024-03-28T17:14:27.832352Z3nodeID://b5759172042024-03-28T17:14:27.832352Z2nodeID://b392037502024-03-28T17:14:27.832352ZA final inoculum of 106 and 104 CFU/ml was exposed to various concentrations of curcumin I (25 μM, 50 μM & 100 μM) in the presence of PBS [>>19<<]. At the chosen time points (30 min, 60 min & 120 min), aliquots were taken, placed on BHI agar plate in triplicates and incubated overnight at 37°C. Next day, the bacterial colonies were counted and bacterial survival was expressed asnodeID://b5759172212024-03-28T17:14:27.832352Z2nodeID://b5759171482024-03-28T17:14:27.832352Z3nodeID://b5759171452024-03-28T17:14:27.832352Z3nodeID://b5759172152024-03-28T17:14:27.832352Z2nodeID://b5759171622024-03-28T17:14:27.832352Z2nodeID://b5759172122024-03-28T17:14:27.832352Z2nodeID://b5759171392024-03-28T17:14:27.832352Z3nodeID://b5759171562024-03-28T17:14:27.832352Z2nodeID://b5759172092024-03-28T17:14:27.832352Z2nodeID://b5759172062024-03-28T17:14:27.832352Z2nodeID://b5759171532024-03-28T17:14:27.832352Z3nodeID://b5759171702024-03-28T17:14:27.832352Z2nodeID://b5759172232024-03-28T17:14:27.832352Z2nodeID://b5759172202024-03-28T17:14:27.832352Z2nodeID://b5759170972024-03-28T17:14:27.832352Z13nodeID://b392037392024-03-28T17:14:27.832352ZCurcumin has also been shown to possess in vitro anti-microbial potential against a wide range of microorganisms including fungi [6] as well as several Gram-positive and Gram-negative bacteria [>>7<<–17]. Recently, Song et al. [9] showed that curcumin suppresses adherence of Streptococcus mutants to human tooth surfaces and extra-cellular matrix protein. Research has further highlighted that curcumin possesses a synergistic effectnodeID://b5759171642024-03-28T17:14:27.832352Z2nodeID://b5759172172024-03-28T17:14:27.832352Z2nodeID://b5759171612024-03-28T17:14:27.832352Z2nodeID://b5759171672024-03-28T17:14:27.832352Z2nodeID://b392037772024-03-28T17:14:27.832352ZSuch a strategy could be immensely promising in the current scenario of continuous emergence of resistant microorganisms and antibiotic crisis [>>31<<, 32]. Oxidative stress and inflammation often go together with bacterial infections [33, 34]. Therefore, curcumin I, an established anti-oxidant and anti-inflammatory natural herbal product, with easy availability, high efficacy, and lownodeID://b392037512024-03-28T17:14:27.832352ZThe fluorescence emission can be detected by both spectrofluorimeter [>>19<<] and flow cytometer [21] equipped with an appropriate filter.nodeID://b392037462024-03-28T17:14:27.832352ZCurcumin I showed no toxic effect on human health even when taken at doses as high as 8 g day−1 [18, >>2<<]. Considering these factors, in the present study, we investigated the detailed antibacterial activity of curcumin I (the major component of commercial curcumin) against two Gram-positive bacteria, namely, S. aureus and EnterococcusnodeID://b5759172342024-03-28T17:14:27.832352Z2nodeID://b5759172312024-03-28T17:14:27.832352Z2nodeID://b5759171582024-03-28T17:14:27.832352Z2nodeID://b5759172252024-03-28T17:14:27.832352Z2nodeID://b5759171752024-03-28T17:14:27.832352Z2nodeID://b5759171722024-03-28T17:14:27.832352Z2nodeID://b5759172282024-03-28T17:14:27.832352Z2nodeID://b5759170992024-03-28T17:14:27.832352Z10nodeID://b5759172422024-03-28T17:14:27.832352Z2nodeID://b5759171662024-03-28T17:14:27.832352Z2nodeID://b5759172192024-03-28T17:14:27.832352Z2nodeID://b5759171692024-03-28T17:14:27.832352Z2nodeID://b5759172362024-03-28T17:14:27.832352Z2nodeID://b5759171832024-03-28T17:14:27.832352Z2nodeID://b5759171802024-03-28T17:14:27.832352Z2nodeID://b5759172332024-03-28T17:14:27.832352Z2nodeID://b5759172502024-03-28T17:14:27.832352Z2nodeID://b5759171772024-03-28T17:14:27.832352Z2nodeID://b392037472024-03-28T17:14:27.832352Zmaterials and methodsnodeID://b5759172412024-03-28T17:14:27.832352Z2nodeID://b5759172442024-03-28T17:14:27.832352Z2nodeID://b5759172472024-03-28T17:14:27.832352Z2nodeID://b5759171912024-03-28T17:14:27.832352Z2nodeID://b392037542024-03-28T17:14:27.832352ZThe permeabilization of bacterial membrane due to curcumin I exposure was measured via calcein leakage by flow cytometry, as described in our previous reports [19, >>20<<]. Calcein-AM (Calcein-Acetoxy Methyl Ester) is a membrane-permeating, non-fluorescent derivative of calcein whose excitation and emission wavelengths are 490 nm and 517 nm, respectively.nodeID://b5759172382024-03-28T17:14:27.832352Z2nodeID://b5759171852024-03-28T17:14:27.832352Z2nodeID://b5759171882024-03-28T17:14:27.832352Z2http://purl.jp/bio/10/colil/id/258115962024-03-28T17:14:27.832352ZPMC010.1371%2Fjournal.pone.0121313nodeID://b5759172552024-03-28T17:14:27.832352Z2nodeID://b5759172522024-03-28T17:14:27.832352Z2nodeID://b5759171792024-03-28T17:14:27.832352Z2nodeID://b5759172492024-03-28T17:14:27.832352Z2nodeID://b5759171932024-03-28T17:14:27.832352Z2nodeID://b5759171962024-03-28T17:14:27.832352Z2nodeID://b5759172462024-03-28T17:14:27.832352Z2nodeID://b5759172632024-03-28T17:14:27.832352Z2nodeID://b5759172602024-03-28T17:14:27.832352Z2nodeID://b5759172572024-03-28T17:14:27.832352Z2nodeID://b392037552024-03-28T17:14:27.832352ZThe S. aureus cells loaded with calcein were diluted 100-fold (106 CFU/ml), treated with different concentrations of curcumin I (i.e., 25 μM, 50 μM & 100 μM) and gramicidin D, a well known pore forming antimicrobial peptide [>>20<<] for 2h at 37°C.nodeID://b5759172712024-03-28T17:14:27.832352Z2nodeID://b5759171982024-03-28T17:14:27.832352Z2nodeID://b392037622024-03-28T17:14:27.832352ZGramicidin D was incorporated as a positive control in this assay, which caused loss of calcein from 94% of cells as a result of membrane pore formation [>>19<<, 20]. Furthermore, the percentage of calcein leakage was quantified from the flow cytometry data repeated on different days (Fig. 5B). The exposure of S. aureus cells to 25 μM, 50 μM and 100 μM curcumin I for 2h led to 65.5 ± 5.2%, 70.3 ±nodeID://b5759172652024-03-28T17:14:27.832352Z2nodeID://b5759172682024-03-28T17:14:27.832352Z2nodeID://b5759172822024-03-28T17:14:27.832352Z2nodeID://b5759172592024-03-28T17:14:27.832352Z2nodeID://b5759172762024-03-28T17:14:27.832352Z2nodeID://b5759172732024-03-28T17:14:27.832352Z2nodeID://b5759172902024-03-28T17:14:27.832352Z2nodeID://b5759172872024-03-28T17:14:27.832352Z2nodeID://b5759172812024-03-28T17:14:27.832352Z2nodeID://b5759172842024-03-28T17:14:27.832352Z2nodeID://b392037632024-03-28T17:14:27.832352ZGramicidin D was incorporated as a positive control in this assay, which caused loss of calcein from 94% of cells as a result of membrane pore formation [19, >>20<<]. Furthermore, the percentage of calcein leakage was quantified from the flow cytometry data repeated on different days (Fig. 5B). The exposure of S. aureus cells to 25 μM, 50 μM and 100 μM curcumin I for 2h led to 65.5 ± 5.2%, 70.3 ±nodeID://b392037582024-03-28T17:14:27.832352ZStatistical analysis (multiple comparison among data sets) was performed using one-way analysis of variance (ANOVA) using Minitab [>>19<<, 20]. A p value ≤ 0.05 was considered significant.nodeID://b5759172782024-03-28T17:14:27.832352Z2nodeID://b392037702024-03-28T17:14:27.832352ZAll previous studies on curcumin have indicated its membrane altering properties such as thinning and disruption of the membrane at high concentrations using artificial membranes only [>>26<<]. However, curcumin induced membrane permeabilization was never studied exclusively using live bacteria from either Gram-positive or Gram-negative groups, which is the main focus of our study. The level of bacterial infection is directlynodeID://b5759172892024-03-28T17:14:27.832352Z2nodeID://b5759172862024-03-28T17:14:27.832352Z2nodeID://b5759171022024-03-28T17:14:27.832352Z7nodeID://b5759171102024-03-28T17:14:27.832352Z4nodeID://b392037592024-03-28T17:14:27.832352ZStatistical analysis (multiple comparison among data sets) was performed using one-way analysis of variance (ANOVA) using Minitab [19, >>20<<]. A p value ≤ 0.05 was considered significant.nodeID://b392037712024-03-28T17:14:27.832352ZThe level of bacterial infection is directly related to the level of inoculum size of the bacterium and infections with high densities of bacteria are resistant to antibiotics [>>27<<]. Therefore, in order to critically evaluate the antibacterial efficacy of curcumin I, the killing assay was performed using both low (104 CFU/ml) and high (106 CFU/ml) cell densities of S. aureus and E. coli. Moreover, all of thenodeID://b5759171042024-03-28T17:14:27.832352Z6nodeID://b5759171072024-03-28T17:14:27.832352Z5nodeID://b392037662024-03-28T17:14:27.832352ZCurcumin I is the most active component of turmeric that has been explored for its various biological and medicinal properties [1, >>5<<, 23]. In the present study, we focused upon the antibacterial activity of curcumin I against four genera of bacteria, including those that are Gram-positive (S.nodeID://b392037402024-03-28T17:14:27.832352ZRecently, Song et al. [>>9<<] showed that curcumin suppresses adherence of Streptococcus mutants to human tooth surfaces and extra-cellular matrix protein.nodeID://b5759171212024-03-28T17:14:27.832352Z3nodeID://b5759171152024-03-28T17:14:27.832352Z4nodeID://b5759171122024-03-28T17:14:27.832352Z4nodeID://b5759171092024-03-28T17:14:27.832352Z4nodeID://b5759171062024-03-28T17:14:27.832352Z5