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Medicinal plants are rich sources of bioactive compounds with diverse pharmacological properties, including antimicrobial activities. This study aimed to assess the antibiofilm potential of methanol and ethanol extracts from nine selected medicinal plants, as well as their synergistic effects with doxycycline against Bacillus strains. Standard procedures were employed to determine the phytochemical composition, total phenolic, and flavonoid contents of the extracts. The antibacterial activity was evaluated using the broth microdilution method, while biofilm formation was assessed via the microtiter plate method. Antibiofilm activity was determined using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium-bromide (MTT) assay. Combination studies were conducted using the checkerboard microdilution method. All extracts contained phenols, flavonoids, steroids, triterpenes, and anthraquinones. The methanolic extract of Psidium guajava exhibited the highest total phenolic and flavonoid contents (90.48 ± 0.55 mg GAE/g), while the ethanolic extract of Olax subscorpioidea showed the highest flavonoid content (6.48 ± 0.33 mg QE/g). Ethanol extracts of Eucalyptus globulus and Psidium guajava and methanolic extract of Syzygium jambos demonstrated significant antibacterial activity against Bacillus anthracis 34F2 Sterne strains, with a MIC value of 64 μg/mL. Biofilm formation in Bacillus strains was notably enhanced in the presence of glucose. The methanolic extract of O. subscorpioides exhibited the highest biofilm imbibition (85%), while Picralima nitida methanolic extract showed the most effective biofilm eradication (79%). The combination of Solanum torvum ethanol extract with doxycycline displayed synergistic effects against biofilm formation inhibition and eradication in all tested Bacillus strains. Taken together, Solanum torvum ethanol extract shows promise for developing new combination antibacterial therapies.

Pseudomonas aeruginosa is one of the most frequently resistant and dangerous bacteria isolated from infected wounds of patients. This study aimed to determine the prevalence of P. aeruginosa from infected wounds of patients in the Dschang District Hospital to evaluate their antibiotic susceptibility profiles and their ability to swarm and swim and correlate pyocyanin production with biofilm formation. Wound swab samples were collected and the identification of P. aeruginosa was performed using microbiological and biochemical tests. Their antimicrobial susceptibility was determined by the broth microdilution method. Swarming and swimming were determined by measuring the diameters of motility in semisolid/low-viscosity media. Furthermore, pyocyanin production and biofilm formation were evaluated spectrophotometrically using a microtiter plate. The prevalence of P. aeruginosa from infected wounds in our study population was 26%. All P. aeruginosa isolates were resistant to streptomycin and paromomycin, and the frequency of multidrug resistance (MDR) was 65.8%. All P. aeruginosa isolates showed the ability to produce biofilm and pyocyanin. Out of the 37 isolates screened, 19 including the reference strains (51.4%) were strong biofilm producers. A significant positive correlation was observed among biofilm formation, pyocyanin production, and the antibiotic resistance profile of the isolates. Findings from this study suggest that infected wounds could act as a reservoir for MDR and virulent P. aeruginosa. The presence of strong biofilm producers of P. aeruginosa in infected wounds is a serious public health concern. Therefore, surveillance programs to monitor and control MDR P. aeruginosa in these patients are required to prevent their dissemination in hospital settings.

Background. Candidiasis is the common name for diseases caused by yeast of the genus Candida. Candida albicans is one of the most implicated species in superficial and invasive candidiasis. Antifungals, polyenes, and azoles have been used to treat candidiasis. However, due to the development of antifungal resistance, research of natural substances with potential antifungal effects at low concentrations or combined is also a possibility. Methods. The broth microdilution method was used to evaluate the antifungal activity. The biofilm formation was assessed using the microtiter plate method. The antibiofilm activities were assessed using micro plaque tetrazolium salt assay (MTT). The combination effect of antifungal with natural substances was made using the checkerboard method. Results. Among our isolates, clotrimazole was the most resistant, but amphotericin B was the most effective antifungal. The biofilm was formed by all isolates of C. albicans. Curcumin and piperine displayed antibiofilm activity with minimum biofilm inhibitory concentration (MBIC) and minimum eradicating concentration (MBEC) ranging from 64 to 1024 μg/mL and 256 to 2048 μg/mL. In combination, piperine presented double synergistic effects compared to curcumin with all antifungals tested. Curcumin shows more synergistic effect when combined with polyenes than with azoles. However, piperine shows a more synergistic effect when combined with azoles compared to polyenes. Conclusion. C. albicans was susceptible to curcumin and piperine both on planktonic cells and biofilm. The combination of curcumin and piperine with antifungals has shown synergistic effects against multiresistant clinical isolates of Candida albicans representing an alternative drug research for the treatment of clinical candidiasis.

Background. Cryptococcosis is one of the most common fungal infections in immunocompromised patients, which is caused by Cryptococcus neoformans. However, relatively little is known about the virulence factors of C. neoformans and the incidence of antifungal drug resistance in C. neoformans is rapidly increasing. This study was undertaken to investigate the virulence factors in C. neoformans, thymol, curcumin, piperine, gallic acid, eugenol, and plumbagin for their potential antimicrobial activity against C. neoformans. Methods. The production of phospholipase and proteinase was detected using standard methods. Biofilm formation was determined using the microtiter plate method. The broth microdilution method was used to determine the antifungal activity. The antibiofilm activity was assessed using the safranin staining method. Results. All isolates of C. neoformans produced biofilms with optical density values ranging from 0.16 to 0.89. A majority of C. neoformans isolates that were tested exhibited strong phospholipase (7/8) and proteinase (5/8) production. Plumbagin (with minimum inhibitory concentration values ranging from 4 to 16 μg/mL) showed the highest antifungal activity followed by thymol (with minimum biofilm inhibitory concentration values ranging from 8 to 64 μg/mL). In addition, plumbagin showed the highest antibiofilm activity with minimum biofilm inhibitory concentration and minimum biofilm eradication concentration values ranging from 4 to 16 μg/mL and 32 to 256 μg/mL, respectively. Conclusion. Plumbagin, compared to other natural products studied, was the most efficient in terms of antifungal and antibiofilm activities. Hence, plumbagin could be used in combination with antifungals for the development of new anticryptococcal drugs.

Eriobotrya japonica (loquat) has been used in African traditional medicine with numerous beneficial health effects. The extracts from loquat contain several bioactive compounds with a plethora of pharmacological properties. However, a scientific study on the activity against the aetiological agent of cryptococcosis has not yet been reported. Therefore, this study aimed to investigate the antifungal potential of various extracts from Eriobotrya japonica against clinical isolates of Cryptococcus neoformans. Quantitative and qualitative phytochemical analyses of extracts were made by following standard procedures. The broth microdilution method and the checkerboard methods were used to determine the antifungal activity and the combination of extracts with antifungals drugs. The methanol extract of seeds and the hexane extract of leaves exhibited the best significant antifungal activity with MIC values of 32 µg/mL. Furthermore, the combination of both extracts with nystatin and clotrimazole showed synergistic interactions with a 32-fold reduction in the MIC values of nystatin. Our findings indicate that Eriobotrya japonica extracts are a potential source of new antifungals that could be developed for use in the treatment of cryptococcosis. The anticryptococcal and antifungal activities potentiating activity of the studied extracts indicate their potential in the management of cryptococcosis. Further study should be considered to identify the bioactive principles against Cryptococcus neoformans.

Background. Plants are a rich source of therapeutic compounds that have tremendous applications in the pharmaceutical industry. This study aimed to identify the phytochemicals present in the seven selected medicinal plants as well as their antioxidant and antimicrobial activities. Methods. Phytochemical screening, total phenolic, and flavonoid contents were determined using standard methods. The antioxidant activity of plant extracts was determined using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl (OH), and nitric oxide (NO) radical scavenging assays. The antimicrobial activity of the plant extracts was determined by the broth microdilution method. Results. The results of phytochemical analysis showed the presence of phenols, flavonoids, and steroids in all plant extracts. The extract of Psychotria peduncularis showed the highest total phenolic and flavonoid contents (5.57 ± 0.22 mg GAE/g and 1.38 ± 0.06 mg QE/g, respectively). All plant extracts showed very strong antioxidant activity against DPPH and NO radical scavenging with IC50 values ranging from 0.55 to 49.43 µg/mL and 0.65 to 13.7 µg/mL, respectively. The extracts of Tristemma mauritianum and P. peduncularis displayed significant antibacterial activity with MIC values ranging from 16 to 1024 µg/mL. T. mauritianum extract showed bactericidal activity against all tested species. The extracts of Alsophila manianna and P. peduncularis showed significant antifungal activity (MIC = 64 µg/mL) against Candida albicans strain. Conclusion. The screened extracts of medicinal plants used in our study can be used as potential antioxidant and antimicrobial agents, and resources for the development of new drugs.