Evaluation Of Antimicrobial Activity Research Articles

Wound Healing, Cell Viability and Antimicrobial Potency of Mucus from Pangasianodon hypophthalmus

Acute and chronic wounds are the major cause of death according to World Health Organization (WHO), in which, antimicrobial resistance is considered to be a major plight. In this regard, our study is aimed at developing an antimicrobial agent using the mucus of Pangasianodon hypophthalmus against the clinically resistant microbial pathogens and to evaluate the cell cytotoxicity and cell viability followed by an in vitro wound healing analysis. The evaluation of antimicrobial activity was performed through well diffusion method and micro dilution method. The cell cytotoxicity and cell viability were assessed using MTT assay. The cell migration and in vitro wound healing was performed using scratch assay. The acidic extracts of mucus showed antimicrobial activity against the eight different selected bacterial strains while the organic extract showed against seven bacterial strains. L929 showed a cell viability of 102.96% at a concentration of 75 µg/mL and did not show cell toxicity effect up to the concentration of 300 µg/mL. In the in vitro wound healing analysis, the cell migration rate was 99.27% in the treated cells while, the untreated showed only 94.68%. The current research work clearly shows that the mucus of P. hypophthalmus possesses antimicrobial activity and wound healing potency. Furthermore, gene expression analysis and in vivo trials have to be performed for a thorough understanding of the actual cellular mechanism of wound healing.

In Vitro Evaluation of Cytotoxicity and Antimicrobial Activity of Green Synthesized Silver Nanoparticles Based on Their Particle Size and Stability

In Vitro Evaluation of Cytotoxicity and Antimicrobial Activity of Green Synthesized Silver Nanoparticles Based on Their Particle Size and Stability

Potassium Phosphate-Mediated Synthesis of C4-Phosphorylated Quinolines via Cascade Cycloisomerization of Ynones.

A cascade phosphorylation cycloisomerization of readily accessible ynones and diphenylphosphine oxides facilitated by potassium phosphate is described, allowing for the straightforward synthesis of C4-phosphorylated quinoline scaffolds. The formation of a C-P bond and a C-N bond is achieved in a single procedure without the need for pre-assembled quinoline cores prior to phosphorylation. This transformation operates without the requirement for metals or oxidants and exhibits excellent compatibility with various functional groups. Furthermore, antimicrobial activity evaluation demonstrated that the synthesized C4 phosphorylated quinoline derivatives exhibited potent inhibitory activity against Staphylococcus aureus.

Phytochemical screening and evaluation of antiradical and antimicrobial activities of Annona senegalensis and Detarium microcarpum leaves used in Benin to treat urinary infections

The challenge of resistance to synthetic antimicrobials necessitates new alternative solutions. Medicinal plants are rich in active compounds with various medicinal properties that can be used in treatment of urinary infections. This work aims to highlight the value of Annona senegalensis and Detarium microcarpum by evaluating phytochemical and antimicrobial potentials of their leaf extracts. Qualitative and quantitative analyses were carried out using color and precipitation reactions and spectrophotometric assays. The antiradical activity was evaluated using the DPPH test, and the antimicrobial activity was assessed by the agar diffusion method. Phytochemical screening showed that both plants contain anthraquinones, catechic tannins, coumarins, flavonoids, reducing compounds, sterols and terpenes. Hydroethanolic extract of Detarium microcarpum and A. senegalensis showed IC50 inhibition percentages of 0.20 mg/mL and 0.22 mg/mL respectively. Regarding antimicrobial activity, the hydroethanolic leaf extracts of D. microcarpum and A. senegalensis were found to be bactericidal and fungicidal against the tested bacteria and molds. This extract showed more pronounced antimicrobial activity than amoxicillin and ciprofloxacin, which are synthetic antimicrobials. Diversity of secondary metabolites and notable antimicrobial activity of D. microcarpum and A. senegalensis may justify their use in traditional medicine for treating urinary infections in Benin.

Evaluation of antimicrobial activity of plant extracts and column fractions of hexane extract against Mycobacterium kansaii

The aim of this study is to assess the antibacterial efficacy of aerial parts of the Ageratum conyzoides plant extracts and column fractions against Mycobacterium kansaii. The antimicrobial experiments were performed using five doses (0.1 µg/ml, 1 µg/ml, 10 µg/ml, 100 µg/ml, 1000 µg/ml) of plant extracts and column fractions. The results showed notable inhibitory effects on Mycobacterium kansaii. The results indicated that the extract of A. conyzoides exhibited action against all the tested bacterial isolates, with the level of activity varying depending on the concentration. The hexane extract exhibited antibacterial activity, with mean zones of inhibition measuring 97.88±9.46 and 27.1±3.33, while the ethanol extract showed a mean zone of inhibition of 100.6±3.42 and 36.77±1.74 against M.kansaii, respectively. Nevertheless, the hexane extract's three column fractions exhibited average inhibition zones of 98.60±1.0 and 23.11±4.35, 90.02±10.22 and 21.94±6.77, 99.32±3.04 and 17.23±5.26 for the third, fourth, and fifth (last sample) respectively. The findings of this study provide evidence for the conventional utilization of the Ageratum plant and emphasize the necessity for further comprehensive research to explore potential alternatives to current antibacterial medications.

Validation of ethnopharmacological findings of Aegle marmelos (L.) Correa through phytochemical screening and bioactivity assay

For centuries, medicinal plants have been integral to human health and well-being across the world. Aegle marmelos (Rutaceae), a medicinal plant indigenous to Nepal, holds substantial ethnomedicinal use among indigenous communities in South Asian countries. Present study aimed to explore the integration of contemporary scientific analysis of the phytochemical composition and bioactivity of A. marmelos leaf extracts harvested from Nepal with traditional ethnopharmacological knowledge. Leaf extracts of A. marmelos were subjected to phytochemical analysis utilizing mass spectrometry. The extracts underwent in vitro evaluation for antimicrobial, antidiabetic, antioxidant, and toxicity activities. Hexane fraction was found to possess volatile oils, polyphenols, and tannins, while other fractions were found to have alkaloids, terpenoids, coumarins, flavonoids, glycosides, saponins, and reducing sugars. Further analysis of the hexane fraction identified 21 compounds with over 90 % accuracy. The main phytoconstituents were 9,12,15-octadecatrienoic acid methyl ester (24.25 %), hexadecanoic acid (10.89 %), methylcyclohexane (8.39 %), methyl ester (4.26 %), and caryophyllene (4.10 %). The methanol extract exhibited significant antibacterial activity against Staphylococcus aureus and Escherichia coli. Additionally, the methanol extract demonstrated pronounced cytotoxic effects against brine shrimp, with an LC50 value of 50.11 µg/mL. The 1,1-diphenyl-2-picryl hydrazyl assay revealed both methanol and acetone extract to have notable antioxidant activity, with IC50 values of 90.63 ± 1.47 µg/mL and 89.93 ± 2.52 µg/mL, respectively. Remarkably, the acetone extract displayed superior antidiabetic activity compared to acarbose, with an IC50 value of 13.50 ± 0.79 µg/mL. Our findings proves A. marmelos leaf extracts to harbor significant bioactive constituents, suggesting their potential as sources of natural compounds for applications in medicine and healthcare.

Evaluation of Antimicrobial Activity of Selected Plant Extracts against Staphylococcus Strains Isolated from Wound Infections.

Wound infections are a significant medical problem, with Staphylococcus species being one of the most common etiological factors. Treatment is complex due to bacterial antibiotic resistance and the ability to form a biofilm. The aim of this study was to determine the drug susceptibility of the clinical isolates of Staphylococcus species obtained from wound infections, assess their ability to form a biofilm in vitro, evaluate the level of extracellular slime synthesis, and test the antistaphylococcal properties of selected plant extracts against plate-cultured bacteria and activity against mature biofilms. A total of 20 Staphylococcus strains were evaluated. The antibiotic susceptibility and sensitivity of the strains to the tested extracts were determined using the disc diffusion method. The production of extracellular bacterial slime was assessed using Congo Red agar plates. The biofilm formation and the effect of plant extracts on the biofilm layer were examined using the MTT method on polystyrene microtiter plates. Diverse drug susceptibility profiles, slime production ability, and in vitro biofilm formation were observed among the tested strains. It was found that aqueous extracts from the Serpylli herba, Arctii lappae folium, Taraxaci folium, and Galii aparini herba showed antibacterial activity against some of the tested strains. In contrast, their antibiofilm activity was not confirmed. Among all tested preparations, the most promising antimicrobial extracts in both planktonic cultures and biofilm were Thymus serpyllum herb and Taraxacum officinale leaf extracts. These results allowed us to conclude their potential application in medicine to support the treatment of challenging wound conditions.

Fabrication of functionalized bio synthetic hydrogels using poly vinyl alcohol and Fucoidan

Abstract Background: Animal bodies are mostly made up of hydrogels, which are networks of hydrophilic polymers that have been permeated with water. These hydrogels make up the bulk of the cells and tissues in animals. Polyvinyl alcohol (PVA) hydrogels are of particular interest due to their various benefits such as biocompatibility, non-immunogenicity, and low biodegradability. Fucoidan is a sulfated polysaccharide molecule found in brown algae cell walls. They are nontoxic, non-irritating and bioactive. Rutin trihydrate is an antioxidant flavonoid and nitric oxide scavenger. The current study aimed to fabricate a functional biosynthetic polymer by combining fucoidan, PVA and Rutin trihydrate. This study also involves characterization and evaluation of antimicrobial activity of the obtained material. Commercial fucoidan(1g), PVA(0.5g) and Rutin (0.5g) was added to distilled water(50ml). The sample was kept in a magnetic stirrer for at 60°C,430 rpm for 30 min and dried in the hot air oven for 24hrs. The dried sample was studied by SEM and FTIR. Contact angle of the sample was also evaluated. Antimicrobial activity of the fabricated hydrogel was determined by agar diffusion method. The synthesized hydrogel is found to be hydrophilic in nature since the contact angle is 31.1°. The surface area of the synthesized hydrogel is found to be rough, irregular, porous and crystalline. Functional groups and compatibility between the polymers were determined by FTIR. Acceptable antimicrobial activity was demonstrated by the synthesized hydrogel against S.aureus and S.mutans (Zone of inhibition 12 mm and 12mm respectively). From the current study, it is concluded that the (Fucoidan- PVA) - Rutin, hydrogel fabricated is hydrophilic in nature and exhibits acceptable antimicrobial activity. Physical properties show that the hydrogel is suitable for drug delivery, tissue engineering and wound dressing.

Evaluation of fatty acid composition and antimicrobial activity of supercritical fluid extract of Rubus ulmifolius Schott fruits

In this study, we continue our research on Rubus ulmifolius Schott extracts obtained by supercritical fluid extraction (SFE) using CO2 as solvent. Extraction experiments were carried out at pressures of 300 bar and a temperature of 40 °C, SFE [300:40], on mature fruits of R. ulmifolius. The fatty acid (FA) profile of extracts was assessed by reversed-phase HPLC-DAD/ELSD analysis. The most represented fatty acids in the extract were linoleic acid (386 mg/g), oleic acid (210 mg/g), linolenic acid (112 mg/g), palmitic acid (48 mg/g), and stearic acid (40 mg/g). SFE extraction showed a total FA amount of 795.8 mg/g of dry weight. The chemical and biological characteristics of this extract were compared with those obtained with different extraction methods. Following the diffusion-susceptibility test, three fruit extracts, SFE [300:40], Sx, and MEtOH, didn’t show an inhibition profile against Streptococcus mutans. Kirby-Bauer analysis showed only the methanolic extract demonstrated antimicrobial activity with 11-mm inhibition diameter.

Comparative Evaluation of Antimicrobial Activity and Minimum Inhibitory Concentration of Commercially Available Pediatric Dentifrices: An In Vitro Study.

The aim of this study was to evaluate the antimicrobial efficacy and minimum inhibitory concentration (MIC) of commercially available pediatric dentifrices containing different compositions against Streptococcus mutans and Lactobacillus activity. Four different commercially available brands of pediatric dentifrices, designated as sample I-fluoride, sample II-herbal, sample III-xylitol with nanosilver particles, and sample IV-xylitol with fluoride, along with two control groups (a positive control-ciprofloxacin and a negative control-distilled water), were tested for their antibacterial activity by measuring the zone of inhibition, followed by MIC against two dental bacterial pathogens, S. mutans strain and Lactobacillus acidophilus (LB) strain, at five different twofold dilutions of 100, 50, 25%, 12.5, and 6.25% concentrations. All four dentifrices were found to have wide variations in their effectiveness against the two tested microorganisms at 100% (pure) and 50% concentrations, with sample I having the highest activity, followed by sample IV and sample II. At 25% concentration, only sample I and sample IV showed antibacterial activity, while at 12.5 and 6.25% concentrations, none of the tested toothpastes exhibited any antibacterial activity. Sample III failed to show antibacterial activity even in pure form against the two microorganisms. In our present study, the fluoride-containing pediatric dentifrice with a lower fluoride concentration (458 ppm) exhibited the highest zone of inhibition, followed by the xylitol with fluoride dentifrice and the herbal dentifrice. No zone of inhibition was observed in the nanosilver with xylitol dentifrice. Dureha R, Navit S, Khan SA, et al. Comparative Evaluation of Antimicrobial Activity and Minimum Inhibitory Concentration of Commercially Available Pediatric Dentifrices: An In Vitro Study. Int J Clin Pediatr Dent 2024;17(8):938-944.

Phytochemical Screening and Evaluation of Antimicrobial Activity of Desmostachya bipinnata Roots

This study was conducted for preliminary phytochemical study of different extracts and to study antimicrobial effects of methanolic extract of Desmostachya bipinnata roots. Desmostachya bipinnata Stapf is an official drug of ayurvedic pharmacopoeia, belongs to the family of Poaceae/Gramineae. Phytochemical screening was done to identify the main groups of chemical constituents present in different extract of Desmostachya bipinnata by their colour reactions with different reagents. Four extracts viz: Petroleum, chloroform, ethyl acetate and methanolic, were subjected for carbohydrates, flavonoids, glycosides, alkaloids, saponins, proteins and amino acids using a test procedure. Preliminary antimicrobial test of D. bipinnata extract was carried out by well diffusion method. The extract was subjected for antimicrobial screening using reference standard, Gentamicin (10µg). The antimicrobial screening of the plant extract revealed the antimicrobial activity against Staphylococcus aureus (Gram positive microorganism) and Escherichia coli (Gram negative microorganism).

Antimicrobial activity of edaphic microorganisms against clinically relevant bacteria

In recent decades, the emergence of bacterial resistance to antimicrobial agents has raised a significant challenge in the medical field. The search for new therapeutic alternatives has become a challenging task. With an estimated diversity ranging from 100 million to 1 billion different bacterial types with unique functions and roles, it is critical to find antimicrobial solutions Recent studies have focused on bacterial species in soil as a source of antimicrobial compounds that can be used as potential therapeutics for the treatment of infectious diseases. This study focused on isolating, culturing, and characterizing the bacteria present in the soil of the Universidad de Investigación de Tecnología Experimental Yachay campus. To assess their potential therapeutic impact, antagonistic tests were carried out between the bacterial isolates and three strains of the most prevalent pathogens: Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The results showed that according to antimicrobial activity evaluations, the metabolites produced by two soil strains, UITEY-030 and UITEY-055, exhibited partially inhibitory effects on the growth of S. aureus and E. coli. These results highlight the capability of soil-derived compounds as candidates for developing novel antimicrobials. .Keywords: Antimicrobial metabolites; antimicrobial resistance, soil microorganisms.

The comparative evaluation of cell viability, inflammatory response, and antimicrobial activity of calcium hydroxide-bovine dentin grain

Abstract Objectives Dentin tissue can act as a reservoir for bioactive molecules that create signals for cellular proliferation and differentiation to initiate tissue regeneration. Therefore, the aim of this study is to compare the cell viability, inflammatory response, and antimicrobial activity of bovine dentin grain-added calcium-hydroxide (CH-BDG) with different pulp-capping materials. Methods ProRoot MTA, Biodentine, Dycal, TheraCal-LC, and an experimental material, CH-BDG, were examined. Cell viability was determined via the WST-1 assay. The inflammatory response was analysed by the monocyte chemoattractant protein-1 (MCP-1/CCL2) and macrophage inflammatory protein-1α (MIP-1α/CCL3) levels. The antimicrobial activity was evaluated by agar-diffusion. Results The cell viability of CH-BDG was analogous with Biodentine and control at 24 h. The cell viability of CH-BDG decreased at 48 h, but the rate was higher than ProRoot MTA and Dycal (p<0.05). For MCP-1 and MIP-1α values, there was no significant difference between the control and CH-BDG. The MCP-1 level of CH-BDG was lower compared to other pulp-capping materials (p<0.05). The MIP-1α level of CH-BDG was lower compared to ProRoot MTA, Biodentine, and TheraCal-LC (p<0.05). No inhibition zone was detected against oral microorganisms for CH-BDG. Conclusions The experimentally developed CH-BDG showed competing properties and additional advantages compared to the existing pulp-capping materials.

Antimicrobial activity evaluation of combinations of essential oils, thymol and R-limonene against food-borne pathogens and spoilage agents

The application of essential oils has been shown to be an effective and sustainable alternative against the multiplication of spoilage and pathogenic microorganisms in food. The aim of this work was to study the antimicrobial activity effect of Cerrado Rosemary (Baccharis dracunculifolia DC.), Pepper Rosemary (Lippia sidoides Cham.), Mandarin (Citrus nobilis Lour.), Mexican Lime (Citrus aurantifolia Swingle) essential oils, and the thymol and R-limonene compounds against strains of Penicillium expansum, Pichia kudriavzevii, Salmonella Thypimurium and Staphylococcus aureus. The essential oils were characterized in terms of their chemical composition, the Minimum Inhibitory Concentration, and Minimum Bactericidal and Fungicidal Concentration; using the microdilution method in 96-well plates. In addition, effects from mixtures of the essential oils, and the isolated compounds in sub-inhibitory concentrations were performed. The Pepper Rosemary essential oil and thymol, separately, showed the lowest Minimum Inhibitory Concentration values against all the microorganisms evaluated, with the lowest ranging from 0.03 to 1.25 mg. mL−1 for P. expansum and 0.31–1.25 mg. mL−1 for S. Thypimurium. Mandarin and Mexican lime, have an enhanced antimicrobial effect when used in mixture. The R-limonene compound showed a synergistic additive effect when combined with the essential oils, against S. aureus strains only. The application of thymol and Lippia was able to reduce growth by 3 log10 for S. aureus and S. Typhimurium in 24 h. Therefore, the Pepper Rosemary essential oil, applied freely or in combination with the thymol compound, has greater potential for use as an antifungal and bactericidal agent, against the microorganisms evaluated.

Conventional and microwave-assisted synthesis, antimicrobial and antioxidant activity evaluation with in silico studies of carbazole-thiazole-Schiff base hybrids

Conventional and microwave irradiation (MWI) methods were applied to synthesize a series of thirteen carbazole-thiazole-Schiff base hybrids (2a-2m). MWI assisted synthesis was a benign approach to green synthesis on account of its miniscule reaction time and use of solvent. The structures of the synthesized derivatives were confirmed by means of spectral analytical data. All the compounds were evaluated for dual biological potency i.e., antimicrobial and antioxidant activity. The tested analogues had shown some modest antimicrobial activity and compounds 2f and 2i exhibited higher antioxidant activity compared to standard ascorbic acid. Oral bioavailability and adverse effects of the new entities were considered from druglikeness descriptors, having no violation of Lipinski's rule of five and Veber's rule for the synthesized compounds except for 2i, 2l, and 2m. The compounds which exhibited relatively high activity were explored further for molecular docking studies to understand the mode of binding interactions with the receptor protein. Molecular dynamics (MD) simulation was further studied to predict the stability of selective compounds inside the receptors which was well agreed with in vitro results and antioxidant value.

Extraction, characterization and evaluation of antimicrobial activity of chitosan from adult Zophobas morio (Fabricius, 1776) (Coleoptera: Tenebrionidae)

The increasing demand for chitosan has led to the exploration of alternative sources, including insects. In this study, chitosan was extracted from Zophobas morio beetles with 19.17 % yield. FTIR and Raman Spectroscopy showed similar peaks in Z. morio chitosan (ZC) and commercial chitosan (CC). ZC showed low crystallinity (40.96 %) and high thermal residual mass (42.7 %) than CC. SEM imaging of ZC displayed pores ranging from 10 μm to 0.3 μm. EDX mapping revealed the homogenous presence of C, N and O elements. ZC exhibited low molecular weight (435.95 kDa) and low intrinsic viscosity (317.95 cm3/g) than CC (680.20 kDa and 480.87 cm3/g, respectively). Degree of deacetylation of ZC and CC was 96.24 % and 78.26 %, respectively. ZC showed antimicrobial activity against Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 13883), Proteus mirabilis (ATCC 29906), Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 29212) and Candida albicans (ATCC 90028) with zones of inhibition ranging from 5 mm to 11 mm. The minimum bactericidal concentration of ZC against K. pneumoniae and P. mirabilis was lower than CC. This study suggests the applicability of insect chitosan as an antimicrobial agent in the food and pharmaceutical industries.

Evaluation of Antimicrobial Activity and Phytoconstituents of Stem Bark Extract and Vacuum Liquid Chromatographic Fractions of Spondias mombin (Linn)

Evaluation of Antimicrobial Activity and Phytoconstituents of Stem Bark Extract and Vacuum Liquid Chromatographic Fractions of Spondias mombin (Linn)

Monitoring, antimicrobial activity evaluation, and molecular docking studies of chemical composition of various plant species to identify an inhibitory drug for Clostridium perfringens bacteria isolated from drinking water resources in Ardabil province

In this study, both the in vitro antimicrobial activity of plant essential oils and their active ingredients and their molecular docking properties are evaluated and a comprehensive understanding of their potential as therapeutic agents is provided. The study findings revealed that the bacterium C. perfringens was detected in 32.5 % of the drinking water sources. Regarding MIC, the essential oils of thymus, hypericum perforatum, zingiber officinale, foeniculum vulgare, and malva were identified at concentrations of 20 %, 35 %, 25 %, 20 %, and 30 %, respectively, for combating C. perfringens. In terms of MBC, the essential oils of thymus, hypericum perforatum, zingiber officinale, foeniculum vulgare, and malva at concentrations of 25 %, 45 %, 35 %, 30 %, and 40 % respectively, were found to deactivate the bacterium. Based on the results of the antimicrobial activity assessment, molecular docking studies, and evaluation of physicochemical properties, it can be inferred that the compounds from the essential oils of thymus (including linalool and thymol), foeniculum vulgare (including anethole), and zingiber officinale (including zingerone) could be promising candidates for inhibiting C. perfringens compared to the reference drugs metronidazole and ciprofloxacin. On the other hand, molecular docking studies show that the active ingredients anethole, zingerone, thymol and linalool with more potent binding energy than the reference drug metronidazole show better activity against C. perfringens bacteria, which is consistent with the results of antimicrobial activity.

Evaluation of anti-microbial activity of biotite and biotite composite based on crystallographic parameters: Estimation of crystallite size employing X-ray diffraction data

This study dealt with naturally occurring biotite from the river sediment to synthesize biotite based composite to evaluate antimicrobial activities against gram positive bacteria, negative bacteria and fungi. Biotite mineral, and synthesized carbon aerogel –biotite (CBt) composite and carbon aerogel-biotite –ZnO (CBtZ) composites were considered for the antimicrobial study. The samples were characterized by X-ray diffraction technique and different crystallographic parameters were computed applying X-ray diffraction data. Also, FESEM was performed to understand the surface morphology of the samples. Crystal size of the biotite, CBt and CBtZ were computed 103.215, 57.567, and 36.496 nm respectively. Tabulated microstrain are 0.175, 0.499 and 0.935 for the biotite, CBt and CBtZ respectively. Various models and equations were used to justify crystallite size, including the Williamson-Hall plot, linear straight line model, Scherrer equation, Monshi-Scherrer model, Size-strain plot (SSP) model, Halder-Wagner method and Sahadat-Scherrer model. For the both composite samples, following models confirmrd the presence of nanocrystal with a range of 50.789–97.777 nm (CBt) and 36.496–105.843 nm(CBtZ). However, for the biotite, all mentioned models were proved invalid except scherrer equation, SSP model and Monshi-Scherrer model. Linear straight line model was found invalid to calculate crystallite size of the three samples. Moreover, different crystal parameters like dislocation density, volume of the unit cell, lattice parameters were computed. Zone of inhabitation estimation method was employed to estimate antimicrobial activity against Listeria monocytogenes, Staphylococcus aureus, Salmonella abony, Escherichia coli and Candida albicans. Required minimum inhibitory concentration (MIC) together with minimum bactericidal concentration (MBC) also estimated in this study. Crystal size effect on the antimicrobial activities of the samples were evaluated in this study.

Bioactivity-Guided Isolation of Secondary Metabolites with Antioxidant and Antimicrobial Activities from Camellia fascicularis.

Camellia fascicularis has important ornamental, medicinal, and food values, which also have tremendous potential for exploiting bioactivities. We performed the bioactivity-guided (antioxidant and antimicrobial) screening of eight fractions obtained from the ethyl acetate phase of C. fascicularis. The antioxidant activity was measured by DPPH, ABTS, and FRAP, and the antibacterial activity was measured by the minimum inhibitory concentration (MIC) of Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus. The results of bioactivity-guided isolation indicated that the major antioxidant compounds in the ethanolic extracts of C. fascicularis may be present in fractions (Fr.) (A-G, obtained after silica gel column chromatography). Fr. (D-I, obtained after silica gel column chromatography) is a fraction of C. fascicularis with antimicrobial activity. The structures of compounds were determined by spectral analysis and nuclear magnetic resonance (NMR) combined with the available literature on secondary metabolites of C. fascicularis leaves. In this study, 17 compounds were identified, including four phenolics (1, 3-4, and 14), a phenylpropane (2), five terpenoids (5-7, 12, and 15), four flavonoids and flavonoid glycosides (8-10 and 16), and two lignins (13 and 17). Compounds 4-7, 13-15, and 17 were isolated from the genus Camellia for first time. The remaining compounds were also isolated from C. fascicularis for first time. The evaluation of antioxidant and antimicrobial activities revealed that compounds 1, 3, 9, 11, and 17 exhibited higher antioxidant activity than the positive control drug (ascorbic acid), and compounds 4, 8, 10, and 13 showed similar activity to ascorbic acid. The other compounds had weaker or no significant antioxidant activities. The MIC of antibacterial activity for compounds 4, 7, and 11-13 against P. aeruginosa was comparable to that of the positive control drug tetracycline at 125 µg/mL, and other secondary metabolites inhibited E. coli and S. aureus at 250-500 µg/mL. This is also the first report of antioxidant and antimicrobial activities of compounds 5-7, 13-15, and 17. The results of the study enriched the variety of secondary metabolites of C. fascicularis and laid the foundation for further research on the pharmacological efficacy and biological activity of this plant.