GC/MS and LC/MS analysis,and antioxidant and antimicrobial activities of various solvent extracts from Mirabilis jalapa tubers

The antioxidant and antimicrobial activities of various solvent extracts from Mirabilis jalapa tubers (MJT) were investigated using various in vitro assays. The total phenolic and flavonoid contents varied from 21.45 to 364.6 mg gallic acid equivalent (GAE)/g dried extract and 5.2 to 71.6 mg quercetin/g dried extract, respectively. Water extract of MJT was the most potent antioxidant in all assays used, followed by methanol extract. The five solvent extracts were screened for antibacterial and antifungal activities. Water extract was the most effective with minimum inhibitory concentration <200 μg/ml against Staphylococcus aureus, Micrococcus luteus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Bacillus cereus and Enterococcus faecalis. Only water extract showed antifungal activity against Aspergillus niger, Fusarium solani, Fusarium oxysporium and Fusarium granularium. GC/MS analysis of MJT dichloromethane and methanol extracts showed that oleic acid and β-sitosterol were, respectively, the major compounds. LC/MS analysis of the aqueous extract showed a high content of flavanol and flavonol compounds. Phenolic acids such as ferulic and caffeic acid were also detected.To our knowledge, this is the first report on the chemical composition, and antioxidant and antimicrobial activities of phenolic extracts from M. jalapa tubers (MJT). The results of the present work indicate that MJT extracts could be used as natural antioxidant and antimicrobial agents in the food preservation and human health.     

Investigation of the antimicrobial activity of soy peptides by developing a high throughput drug screening assay

BackgroundAntimicrobial resistance is a great concern in the medical community, as well as food industry. Soy peptides were tested against bacterial biofilms for their antimicrobial activity. A high throughput drug screening assay was developed using microfluidic technology, RAMAN spectroscopy, and optical microscopy for rapid screening of antimicrobials and rapid identification of pathogens.MethodsSynthesized PGTAVFK and IKAFKEATKVDKVVVLWTA soy peptides were tested against Pseudomonas aeruginosa and Listeria monocytogenes using a microdilution assay. Microfluidic technology in combination with Surface Enhanced RAMAN Spectroscopy (SERS) and optical microscopy was used for rapid screening of soy peptides, pathogen identification, and to visualize the impact of selected peptides.ResultsThe PGTAVFK peptide did not significantly affect P. aeruginosa, although it had an inhibitory effect on L. monocytogenes above a concentration of 625 µM. IKAFKEATKVDKVVVLWTA was effective against both P. aeruginosa and L. monocytogenes above a concentration of 37.2 µM. High throughput drug screening assays were able to reduce the screening and bacterial detection time to 4 h. SERS spectra was used to distinguish the two bacterial species.ConclusionsPGTAVFK and IKAFKEATKVDKVVVLWTA soy peptides showed antimicrobial activity against P. aeruginosa and L. monocytogenes. Development of high throughput assays could streamline the drug screening and bacterial detection process.General significanceThe results of this study show that the antimicrobial properties, biocompatibility, and biodegradability of soy peptides could possibly make them an alternative to the ineffective antimicrobials and antibiotics currently used in the food and medical fields. High throughput drug screening assays could help hasten pre-clinical trials in the medical field.     

Anti-quorum sensing and anti-biofilm activity of Amomum tsaoko (Amommum tsao-ko Crevost et Lemarie) on foodborne pathogens

Cell-to-cell communication or quorum sensing (QS) leads to biofilm formation and causing other virulence factors which are extreme problems for food safety, biofilm related infectious diseases etc. This study evaluated the anti-QS activity of the Amomum tsaoko extract (0.5–4 mg/ml) by using Chromobacterium violaceum a biosensor strain and biofilm formation by crystal violate assay. Experimental results demonstrated that the overall yield of Amomum tsao-ko extract was 11.33 ± 0.3% (w/w). MIC for Staphylococcus aureus (Gram positive), Salmonella Typhimurium and Pseudomonas aeruginosa (Gram negative) was 1, 2 and 2 mg/ml, respectively. A concentration of 4 mg/ml extract showed highest biofilm inhibition 51.96% on S. Typhimurium when 47.06%, 45.28% were shown by S. aureus, P. aeruginosa respectively. The damage of biofilm architecture was observed by Confocal Laser Scanning Microscopy (CLSM). A level of 44.59% inhibition of violacein production was demonstrated when the dose was 4 mg/ml. Swarming motility inhibition was observed in a dose dependent manner. Taken together, the treatment of A. tsaoko extract can deliver value to food product and medicine by controlling pathogenesis.     

Antibacterial metabolites from Australian macrofungi from the genus Cortinarius

In this study, ethyl acetate and aqueous fractions from 117 collections of Australian macrofungi belonging to the mushroom genus Cortinarius were screened for antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa. Overall, the lipophilic fractions were more active than the aqueous fractions. The ethyl acetate fractions of most or all collections of 13 species, namely Cortinarius ardesiacus, C. archeri, C. austrosaginus, C. austrovenetus, C. austroviolaceus, C. coelopus, C. [Dermocybe canaria]², C. clelandii, C. [D. kula], C. memoria-annae, C. persplendidus, C. sinapicolor, C. vinosipes and forty seven collections of un-described Cortinarius species exhibited IC₅₀ values of ?0.09 mg/mL against S. aureus. In contrast, most or all collections of only four species, namely C. abnormis, C. austroalbidus, C. [D. kula], C. persplendidus, and eleven un-described Cortinarius collections exhibited similar effects against P. aeruginosa (IC₅₀ ? 0.09 mg/mL). Anthraquinonoid pigments isolated from C. basirubescens together with emodin physcion and erythrogluacin were assessed for their antimicrobial activity. The fungal octaketides austrocortilutein, austrocortirubin, torosachrysone, physcion and emodin were found to strongly inhibit the growth of S. aureus (IC₅₀ 0.7–12 μg/mL) whereas only physcion and emodin exhibited potency against P. aeruginosa (IC₅₀ 1.5 and 2.0 μg/mL, respectively).     

Interactive efficacies of Elephantorrhiza elephantina and Pentanisia prunelloides extracts and isolated compounds against gastrointestinal bacteria

Elephantorrhiza elephantina (Burch.) Skeels (Fabaceae) and Pentanisia prunelloides (Klotzsch ex Eckl. & Zeyh.) Walp. (Rubiaceae) are two medicinal plants used extensively in southern Africa to treat various ailments. Often, decoctions and infusions from these two plants are used in combination specifically for stomach ailments. The antimicrobial activities of the methanol and aqueous extracts of the rhizomes of the two plants, as well as the two active ingredients from the plants [(−)-epicatechin and palmitic acid] have been determined apart and in combination against Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 8739) and Bacillus cereus (ATCC 11778). The minimum inhibitory concentration (MIC) values for the aqueous (0.50–16.00 mg/mL) and methanol (0.20–16.00 mg/mL) extracts independently demonstrated varied efficacies depending on the pathogen of study. When the two plants were combined in 1:1 ratios, synergistic to additive interactions (ΣFIC values 0.19–1.00) were noted. Efficacy for the two major compounds ranged between 0.13–0.63 mg/mL and mainly synergistic interactions were noted against E. faecalis and E. coli. The predominantly synergistic interactions noted between E. elephantina and P. prunelloides and major compounds, when tested in various ratios against these pathogens, provide some validation as to the traditional use of these two plants to treat bacterial gastrointestinal infections.     

γ-Alkylidene-γ-lactones and isobutylpyrrol-2(5H)-ones analogues to rubrolides as inhibitors of biofilm formation by Gram-positive and Gram-negative bacteria

Several molecules have been discovered that interfere with formation of bacterial biofilms, opening a new strategy for the development of more efficient treatments in case of antibiotic resistant bacteria. Amongst the most active compounds are some natural brominated furanones from marine algae Delisea pulchra that have proven to be able to control pathogenic biofilms. We have recently reported that some rubrolide analogues are able to inhibit biofilm formation of Enterococcus faecalis. In the present Letter we describe results of the biological evaluation of a small library of 28 compounds including brominated furanones and the corresponding lactams against biofilm formation of Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis and Streptococcus mutans. Our results showed that in general these compounds were more active against biofilms of S. epidermidis and P. aeruginosa, with little or no inhibition of planktonic bacterial growth. In some cases they were able to prevent biofilm formation of P. aeruginosa at concentrations as low as 0.6 μg/mL (1.3 μM, compound 3d) and 0.7 μg/mL (1.3 μM, 3f). Results also indicate that, in general, lactams are more active against biofilms than their precursors, thus designating this class of molecules as good candidates for the development of a new generation of antimicrobial drugs targeted to biofilm inhibition.     

Antibiotic resistance modulation by natural products obtained from Nasutitermes corniger (Motschulsky, 1855) and its nest

Insects and their products are included in the traditional pharmacopoeia of various ethnic groups worldwide. In the Brazilian semiarid region can be highlighted the use of the termite Nasutitermes corniger for the treatment of various diseases. This study evaluated the ethanol extract of N. corniger and its nest as an antimicrobial agent and as a modulator of bacterial resistance against multidrug strains. The Minimum Inhibitory Concentration (MIC) of the extract on Staphylococcus aureus and Escherichia coli by microdilution was determined, as well as MIC of antibiotics in the presence and absence of extract. Despite having no significant antimicrobial activity (MIC ⩾ 1000 μg mL⁻¹), the extract showed additive activity to the antibiotic efficacy, significantly reducing its MIC. These results suggest that N. corniger and its nest are promising natural products for use in antimicrobial therapy.     

Volatile constituents and antimicrobial activities of nine South African liverwort species

The volatile constituents of nine liverworts species (Asterella marginata, Dumortiera hirsuta, Fossombronia swaziensis, Marchantia pappeana, Marchantia polymorpha subsp. ruderalis, Pallavicinia lyellii, Plagiochasma rupestre, Riccia albolimbata and Symphyogyna podophylla) from South Africa were determined by gas chromatography. Where possible the volatile constituents identified were compared to those reported for the same species from other countries. Among the analysed liverworts, the chemical compositions of A. marginata, F. swaziensis, M. pappeana, and R. albolimbata are reported for the first time. Each of the analysed liverwort species produced its own characteristic components. Thujopsanes, chamigranes and cuparanes were found to be the most characteristic components of M. polymorpha subsp. ruderalis. The presence of dumortane-type sesquiterpenoids in D. hirsuta indicated that this species is similar in chemistry to an Argentinean sample. This is one of only a handful of reports on the presence of this sesquiterpene-type in liverworts. Simple thallose liverworts, S. podophylla and P. lyellii, were characterized by the presence of labdane-type diterpenoids. In addition, the antimicrobial activities of chloroform:methanol (1:1) extracts of the liverworts were evaluated against several important human pathogens using the serial dilution assay. Four of the liverwort species were active against Pseudomonas aeruginosa with MIC values ranging from 0.50 to 1.0 mg/mL. Some activity (MIC value of 1.0 mg/mL) was also recorded for the crude extracts of P. lyellii and M. pappeana against Escherichia coli. The extract of S. podophylla displayed the best activity towards the yeast Cryptococcus neoformans (MIC = 1.0 mg/mL). Although approximately 300 liverwort species occur in southern Africa, a Scopus search confirmed that this is the first report of the volatile profiles and biological properties of species from the region.     

Inhibition and destruction of Pseudomonas aeruginosa biofilms by antibiotics and antimicrobial peptides

Pseudomonas aeruginosa is one of the major nosocomial pathogen that can causes a wide variety of acute and chronic infections P. aeruginosa is a dreaded bacteria not just because of the high intrinsic and acquired antibiotic resistance rates but also the biofilm formation and production of multiple virulence factors. We investigated the in vitro activities of antibiotics (ceftazidime, tobramycin, ciprofloxacin, doripenem, piperacillin and colistin) and antimicrobial cationic peptides (AMPs; LL-37, CAMA: cecropin(1–7)-melittin A(2–9) amide, melittin, defensin and magainin-II) alone or in combination against biofilms of laboratory strain ATCC 27853 and 4 clinical strains of P. aeruginosa. The minimum inhibitory concentrations (MIC), minimum bactericidal concentration (MBC) and minimum biofilm eradication concentrations (MBEC) were determined by microbroth dilution technique. The MBEC values of antibiotics and AMPs were 80–>5120 and 640–>640 mg/L, respectively. When combined with the LL-37 or CAMA at 1/10× MBEC, the MBEC values of antibiotics that active against biofilms, were decreased up to 8-fold. All of the antibiotics, and AMPs were able to inhibit the attachment of bacteria at the 1/10× MIC and biofilm formation at 1× or 1/10× MIC concentrations. Time killing curve studies showed 3-log₁₀ killing against biofilms in 24 h with almost all studied antibiotics and AMPs. Synergism were seen in most of the studied combinations especially CAMA/LL-37 + ciprofloxacin against at least one or two strains’ biofilms. Since biofilms are not affected the antibiotics at therapeutic concentrations, using a combination of antimicrobial agents including AMPs, or inhibition of biofilm formation by blocking the attachment of bacteria to surfaces might be alternative methods to fight with biofilm associated infections.     

Modulation of the antibiotic activity against multidrug resistant strains of 4-(phenylsulfonyl) morpholine

The compound 4-(Phenylsulfonyl) morpholine belongs to the class of sulfonamides, which are widely used in the treatment of a large number of diseases caused by microorganisms. This compound has a morpholine group, which is also known for its antimicrobial properties. The aim of the present study was to investigate the antimicrobial and modulating activity of 4-(Phenylsulfonyl) morpholine against standard and multi-resistant strains of Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and strains of the fungi Candida albicans, C. tropicalis and C. krusei. Antimicrobial activity was assessed based on the minimum inhibitory concentration (MIC) using the microdilution method. MIC was ⩾1024 μg/mL for all microorganisms. Regarding modulating activity, the most representative effect occurred with the combination of 4-(Phenylsulfonyl) morpholine at a concentration of 128 μg/mL (MIC 1/8) and amikacin against P. aeruginosa 03, with a reduction in MIC from 312.5 to 39.06 μg/mL.     

Design,synthesis and antibacterial activity studies of thiazole derivatives as potent ecKAS III inhibitors

Two series of thiazole derivatives containing amide skeleton were synthesized and developed as potent Escherichia coli β-ketoacyl-(acyl-carrier-protein) synthase III (ecKAS III) inhibitors. All the 24 new synthesized compounds were assayed for antibacterial activity against the respective Gram-negative and Gram-positive bacterial strains, including E. coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus. In which, 10 compounds with broad-spectrum antibacterial activities were further tested for their ecKAS III inhibitory activity. Last, we have successfully found that compound 4e showed both the promising broad antibacterial activity with MIC of 1.56–6.25 μg/mL against the representative bacterial stains, and also processed the most potent ecKAS III inhibitory activity with IC₅₀ of 5.3 μM. In addition, docking simulation also carried out in this study to give a potent prediction binding mode between the small molecule and ecKAS III (PDB code: 1hnj) protein.     

Chemistry,antioxidant and antimicrobial potential of nutmeg (Myristica fragrans Houtt)

Antioxidant and antimicrobial activities of nutmeg (Myristica fragrans Houtt) seed extracts were evaluated. Seeds were extracted with acetone, ethanol, methanol, butanol and water. All the extracts have shown significant antioxidant and antimicrobial activities against the tested microorganisms. Among all extracts, acetone extract has shown the highest antioxidant activity. The acetone extract showed 93.12 ± 1.48 mg gallic acid equivalents (GAE)/100 g dry weight total phenolic content, DPPH scavenging activity of 63.04 ± 1.56%, chelating activity of 64.11 ± 2.21% and 74.36 ± 1.94% inhibition of β-carotene bleaching, at 1 mg/mL extract concentration. Out of all extracts, acetone extract was able to exert antimicrobial activity against all tested bacteria and fungi. Acetone extract has shown the strongest antibacterial and antifungal activity with Staphylococcus aureus (13.8 ± 0.42 mm) and Aspergillus niger (14.4 ± 0.37 mm), respectively. GC–MS analysis of acetone extract has revealed the presence of 32 compounds of extract representing 99.49%. Sabinene (28.61%) has shown the highest occurrence in the extract. β-Pinene (10.26), α-pinene (9.72), myristicin (4.30%), isoeugenol (2.72%), p-cymene (1.81%), carvacrol (1.54%), eugenol (0.89%) and β-caryophellene (0.82%) were reported as possible contributor for antioxidant and antimicrobial activity of nutmeg.     

Antimicrobial activity of some plant extracts against bacterial strains causing food poisoning diseases

Prevention of food spoilage and food poisoning pathogens is usually achieved by use of chemical preservatives which have negative impacts including: human health hazards of the chemical applications, chemical residues in food & feed chains and acquisition of microbial resistance to the used chemicals. Because of such concerns, the necessity to find a potentially effective, healthy safer and natural alternative preservatives is increased. Within these texts, Plant extracts have been used to control food poisoning diseases and preserve foodstuff. Antimicrobial activity of five plant extracts were investigated against Bacillus cereus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi using agar disc diffusion technique. Ethanolic extracts of Punica granatum, Syzygium aromaticum, Zingiber officinales and Thymus vulgaris were potentially effective with variable efficiency against the tested bacterial strains at concentration of 10 mg/ml while extract of Cuminum cyminum was only effective against S. aureus respectively. P. granatum and S. aromaticum ethanolic extracts were the most effective plant extracts and showed bacteriostatic and bactericidal activities against the highly susceptible strains of food borne pathogenic bacteria (S. aureus and P. aeruginosa) with MIC's ranged from 2.5 to 5.0 mg/ml and MBC of 5.0 and 10 mg/ml except P. aeruginosa which was less sensitive and its MBC reached to 12.5 mg/ml of S. aromaticum respectively. These plant extracts which proved to be potentially effective can be used as natural alternative preventives to control food poisoning diseases and preserve food stuff avoiding healthy hazards of chemically antimicrobial agent applications.     

Screening of some Australian Flacourtiaceae species for in vitro antioxidant,cytotoxic and antimicrobial activity

A total of 27 methanol extracts obtained from different plant parts of 10 species of rain forest trees belonging to four genera of the Flacourtiaceae and originating from Australia were investigated. In vitro cytotoxicity was measured by an ATP Lite-M assay method against the mouse P388 lymphocytic leukemia cell line. The total antioxidant activity has been assessed based on scavenging activity of stable ABTS free radicals. The minimum inhibition concentration (MIC) was determined by the dilution method performed in 96 well plates against four different microbes. The leaf extract of Casearia sp. (RB 3051), mature stem extract of Casearia grayi and stem extract of Scolopia braunii were found to have most antioxidant activity (IC₅₀=2.9 μg/ml), cytotoxic activity (LC₅₀=0.89 μg/ml) and antimicrobial activity against all four different microbes, respectively. The results obtained suggested that among the four genera studied Casearia is the most promising in respect of finding significant antioxidant, cytotoxic and also antimicrobial activity.     

Expression and characterization of antimicrobial peptide CecropinAD in the methylotrophic yeast Pichia pastoris

Hybrid antibacterial peptide CecropinAD (CAD) is a linear cationic peptide that has potent antimicrobial properties without hemolytic activity. To explore a new approach to express the hybrid peptide CAD in the methylotrophic yeast Pichia pastoris, the cDNA sequence encoding CAD was obtained by recursive PCR (rPCR) and cloned into the vector pPICZα-A. The Sac I-linearized recombinant plasmid pPICZα-CAD was transformed into P. pastoris GS115 by electroporation. Expression of recombinant CAD was induced for 96 h with 1.0% methanol at 28 °C, pH 5.0. The recombinant CAD was purified by two steps of reversed-phase HPLC and 1.8 mg pure active CAD was obtained from 100 ml culture. Tricine-SDS-PAGE and mass spectrometry analyses demonstrated that the molecular weight of the purified CAD was 3.8 kDa. Analysis of circular dichroism (CD) revealed that CAD mainly has α-helixes in the presence of 10 mM phosphate buffer (pH 7.2), 50% TFE/water solution (pH 2.0), or 30 mM SDS (pH 10.8). FACScan analysis showed that the antibacterial mechanism of CAD is to act on the cell membrane to disrupt bacterial cell structure. Antimicrobial assays demonstrated that recombinant CAD has a broad spectrum of anti-microbial property against fungi, as well as Gram-positive and Gram-negative bacteria, but does not have hemolytic activity against human erythrocytes. Our results suggest that recombinant antimicrobial peptide CAD may serve as an attractive candidate for the development of therapeutic antimicrobial drugs.     

Synthesis and structural characterization of silver nanoparticles using bacterial exopolysaccharide and its antimicrobial activity against food and multidrug resistant pathogens

A green, simple, and effective approach was performed to synthesize potent silver nanoparticles (SNPs) using bacterial exopolysaccharide as both a reducing and stabilizing agent. The synthesized SNPs were characterized using UV-vis spectroscopy, transmission electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, and Fourier-transform-infrared spectra analyses. The SNPs varied in shape and were multidispersed with a mean diameter of 10 nm ranging from 2 to 15 nm and were stable up to 2 months at room temperature. The antimicrobial activity of the SNPs was analyzed against bacterial and fungal pathogens using the agar well diffusion method. Dose dependent inhibition was observed for all bacterial pathogens. The multidrug resistant pathogens P. aeruginosa and K. pneumonia were found to be more susceptible to the SNPs than the food borne pathogen L. monocytogenes. The fungi Aspergillus spp. exhibited a maximum zone of inhibition compared to that of Penicillum spp. These results suggest that exopolysaccharide-stabilized SNPs can be used as an antimicrobial agent for various biomedical applications.     

Identification and characterization of an anti-pseudomonal dichlorocarbazol derivative displaying anti-biofilm activity

Pseudomonas aeruginosa strains resistant towards all currently available antibiotics are increasingly encountered, raising the need for new anti-pseudomonal drugs. We therefore conducted a medium-throughput screen of a small-molecule collection resulting in the identification of the N-alkylated 3,6-dihalogenocarbazol 1-(sec-butylamino)-3-(3,6-dichloro-9H-carbazol-9-yl)propan-2-ol (MIC = 18.5 μg mL⁻¹). This compound, compound 1, is bacteriostatic towards a broad spectrum of Gram-positive and Gram-negative pathogens, including P. aeruginosa. Importantly, 1 also eradicates mature biofilms of P. aeruginosa. 1 displays no cytotoxicity against various human cell types, pointing to its potential for further development as a novel antibacterial drug.     

Antimicrobial activities of Dilobeia thouarsii Roemer and Schulte,a traditional medicinal plant from Madagascar

The leaves of Dilobeia thouarsii (Roemer and Schulte), a tree that is endemic to Madagascar (Proteaceae), are used in traditional Malagasy medicine to treat bacterial skin infections and wounds. This study investigated the in vitro antibacterial activities of D. thouarsii leaf extracts and identified the bioactive compounds with the aim of providing a scientific basis for its use against skin diseases. Using broth microdilution method for leaf crude extract and its compounds, we investigated inhibition of the growth of Bacillus cereus, Bacillus megaterium, Staphylococcus aureus, Enterococcus faecalis, Vibrio harveyi, Vibrio fisheri, Salmonella Typhimurium, Salmonella antarctica, Escherichia coli, and Klebsiella pneumoniae. The two purified phenolic compounds from leaf ethyl acetate extracts (1, 2) were found to be more active than the crude extract itself. The structure of the two compounds was elucidated by NMR and mass spectrometry: compound 1 was identified as 4-aminophenol and compound 2 as 4-hydroxybenzaldehyde. A marked inhibitory effect (MIC < 0.1 mg/ml) was found against S. aureus, which is a major agent in skin infections. We observed moderate activities (MIC values of between 0.1 and 0.5 mg/ml) for E. faecalis, Vibrio spp., and Bacillus spp. Neither compound was active against Salmonella spp., E. coli and K. pneumoniae (MICs > 1 mg/ml). To conclude, the high antimicrobial activity of D. thouarsii leaf extracts against S. aureus supports its traditional use to treat skin infections.     

Antimicrobial and cytotoxic activities of the crude extracts of Dietes bicolor leaves,flowers and rhizomes

The crude extracts of Dietes bicolor leaves, flowers and rhizomes were subjected to comparative antimicrobial screening against two Gram-positive, two Gram-negative bacteria and four fungal strains using the agar well diffusion method. The minimum inhibitory concentrations (MIC) of the tested extracts were also determined. Furthermore, the cytotoxic activity was evaluated. D. bicolor extracts generally demonstrated notable broad spectrum antimicrobial activities (MIC values ≤ 500 μg/mL) against all tested pathogens. D. bicolor leaf extract showed potent broad spectrum antimicrobial activity with MIC values ranging between 0.24 and 31.25 μg/mL against all tested pathogens. Moreover, the flowers extract exhibited promising antimicrobial activities, displaying MIC values ranging between 1.95 and 125 μg/mL against the tested bacteria and fungi. However, the rhizomes extract showed moderate antimicrobial activity with MIC values ranging between 31.25 and 500 μg/mL. Despite the potent antimicrobial activity of D. bicolor extracts, they were ineffective as cytotoxic agents against nine tested cancer cell lines, displaying 50% inhibitory concentration (IC₅₀) values above 100 μg/mL. The reported potent antimicrobial activity along with the lack of measurable cytotoxic activity indicated that the antimicrobial activity of D. bicolor crude extracts is mediated through a mechanism other than cytotoxicity. These results suggest that D. bicolor can act as a potential source for natural antibacterial and antifungal agents with a good safety profile at a preliminary level.