Synergistic Effect of Pseudolaric Acid B with Fluconazole Against Resistant Isolates and Biofilm of Candida tropicalis

Pseudolaric acid B induces apoptosis associated with the mitochondrial and PI3K/AKT/mTOR pathways in triple‑negative breast cancer

Pseudolaric acid B (PAB), a diterpene acid isolated from the root bark of Pseudolarix kaempferi, has been shown to exert strong antitumor properties. The aim of the present study was to investigate the mechanisms underlying the proposed antitumor properties of PAB in the triple‑negative breast cancer cells, MDA‑MB‑231. The cell processes evaluated included cell proliferation by Cell Counting Kit‑8 assay, colony formation and EdU assay, apoptosis by Annexin V‑FITC/PI apoptosis assay, cell migration by Transwell migration assay and invasion by Transwell invasion assay. PAB significantly inhibited the proliferation of MDA‑MB‑231 cells through a mechanism that was considered to be associated with cell cycle arrest at the G2/M phase. There was decreased protein expression levels of CDK1 and cyclin B1 and increased protein expression levels of p53 and p21. However, there were no well‑defined inhibitory effects on the normal breast cell line MCF10A. PAB also triggered apoptosis in a concentration‑dependent manner through the mitochondrial apoptosis pathway. It caused collapse of mitochondrial membrane potential, accumulation of reactive oxygen species and release of cytochrome c, as well as upregulation of cleaved caspase‑3, cleaved caspase‑9, cleaved PARP and Bax, and downregulation of Bcl‑2 and Bcl‑xl. The migration and invasion ability of MDA‑MB‑231 cells were inhibited by decreasing the expression levels of the epithelial‑mesenchymal transition‑related markers N‑cadherin and vimentin and increasing the expression of E‑cadherin. Moreover, the expression levels of PI3K (p110β), phosphorylated (p)‑AKT (ser473) and p‑mTOR (ser2448) were downregulated and LY294002, a PI3K inhibitor, could interact additively with PAB to induce apoptosis of MDA‑MB‑231 cells. Overall, the present results demonstrated that PAB induced apoptosis via mitochondrial apoptosis and the PI3K/AKT/mTOR pathway in triple‑negative breast cancer. It also inhibited cellular proliferation, migration and invasion, suggesting that PAB may be a useful phytomedicine for the treatment of triple‑negative breast cancer.

Synergistic Effect of Plant Compounds in Combination with Conventional Antimicrobials against Biofilm of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida spp

Bacterial and fungal biofilm has increased antibiotic resistance and plays an essential role in many persistent diseases. Biofilm-associated chronic infections are difficult to treat and reduce the efficacy of medical devices. This global problem has prompted extensive research to find alternative strategies to fight microbial chronic infections. Plant bioactive metabolites with antibiofilm activity are known to be potential resources to alleviate this problem. The phytochemical screening of some medicinal plants showed different active groups, such as stilbenes, tannins, alkaloids, terpenes, polyphenolics, flavonoids, lignans, quinones, and coumarins. Synergistic effects can be observed in the interaction between plant compounds and conventional drugs. This review analyses and summarises the current knowledge on the synergistic effects of plant metabolites in combination with conventional antimicrobials against biofilms of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The synergism of conventional antimicrobials with plant compounds can modify and inhibit the mechanisms of acquired resistance, reduce undesirable effects, and obtain an appropriate therapeutic effect at lower doses. A deeper knowledge of these combinations and of their possible antibiofilm targets is needed to develop next-generation novel antimicrobials and/or improve current antimicrobials to fight drug-resistant infections attributed to biofilm.

Pseudolaric Acid B Ameliorates Fungal Keratitis Progression by Suppressing Inflammation and Reducing Fungal Load

This study aimed to determine the mechanisms of antifungal and anti-inflammation effects of pseudolaric acid B (PAB) on Aspergillus fumigatus (A. fumigatus) keratitis. In vitro MIC assay and crystal violet staining were conducted to evaluate the efficacy of PAB against A. fumigatus. PAB inhibited A. fumigatus growth and inhibited the formation of fungal biofilms in a dose-dependent manner. Molecular docking analysis revealed that PAB possesses strong binding properties with Rho1 of A. fumigatus, which is devoted to encoding (1,3)-β-d-glucan of A. fumigatus. RT-PCR results also showed that Rho1 was inhibited by PAB. In vivo, PAB treatment reduced clinical scores, fungal load, and macrophage infiltration, which were increased by A. fumigatus in mice corneas. In addition, PAB treatment suppressed the expression of Mincle, p-Syk, and cytokines (TNF-α, MIP2, iNOS, and CCL2) in infected corneas and in RAW264.7 cells, which were tested by RT-PCR, Western blot, and enzyme-linked Immunosorbent Assay. Notably, trehalose-6,6-dibehenate, an agonist of Mincle, pretreatment reversed the regulatory function of PAB in RAW 264.7 cells. Moreover, flow cytometry showed that PAB upregulated the ratio of M2/M1 macrophages in A. fumigatus-infected corneas and RAW264.7 cells. In conclusion, PAB produced antifungal activities against A. fumigatus and decreased the inflammatory response in mouse A. fumigatus keratitis.

Inhibition of Candida glabrata Biofilm by Combined Effect of Dendritic Compounds and Amphotericin

In the last decade, Candida glabrata has become an important emerging opportunistic pathogen not only because of the increase in nosocomial infections frequency but also because of its ability to form biofilms and its innate resistance to commercial antifungals. These characteristics make this pathogen a major problem in hospital settings, including problems regarding equipment, and in immunosuppressed patients, who are at high risk for candidemia. Therefore, there is an urgent need for the development of and search for new antifungal drugs. In this study, the efficacy of two dendritic wedges with 4-phenyl butyric acid (PBA) at the focal point and cationic charges on the surface ArCO₂G₂(SNMe₃I)₄ (1) and ArCO₂G₃(SNMe₃I)₈ (2) was studied against C. glabrata strain to inhibit the formation of biofilms and eliminate established biofilm. For this, MBIC (minimum biofilm inhibitory concentration), MBDC (minimum biofilm damaging concentrations), as well as MFCB (minimum fungicidal concentration in biofilm) and MBEC (minimum biofilm eradicating concentration) were determined. In addition, different combinations of dendrons and amphotericin B were tested to study possible synergistic effects. On the other hand, cytotoxicity studies were performed. C. glabrata cells and biofilm structure were visualized by confocal microscopy. ArCO₂G₂(SNMe₃I)₄ (1) and ArCO₂G₃(SNMe₃I)₈ (2) dendrons showed both an MBIC of 8 mg/L and a MBDC of 32 mg/L and 64 mg/L, respectively. These dendrons managed to eradicate the entirety of an established biofilm. In combination with the antifungal amphotericin, it was possible to prevent the generation of biofilms and eradicate established biofilms at lower concentrations than those required individually for each compound at these conditions.

Evaluation of the effect of Jaftex herbal mouthwash on the growth of Candida albicans and Candida tropicalis

Background

Increased resistance of Candida albicans to standard antifungal agents has caused special attention to medicinal plants. The aim of this study was to evaluate the effect of Jaftex mouthwash on the growth of C. albicans and Candida tropicalis.

Methods and Material

In this in vitro study, standard strains of C. albicans and C. tropicalis were used. Jaftex mouthwash was prepared with the active ingredient (10g/100cc) of aqueous extract of oak fruit hull (Jaft), Zataria multiflora, and Satureja bachtiarica. The mouthwash was diluted in half, 8 different concentrations were obtained. 10 μl volume of each dilution was poured on discs mounted linearly on the culture medium inoculated with the target fungus. After 24 h, due to the slow growth rate of these fungi, the Petri dishes were incubated at 37°C and the mean minimum inhibitory concentration (MIC) was determined for each fungus. The modified E. test method was used to measure the MIC of Jaftex mouthwash for the two fungi. The experiment was repeated three times for each fungus and the mean value was measured.

Results

The mean value of MIC for C. albicans and C. tropicalis was 0.0625 (mg/mL) and 0.0833 (mg/mL), respectively. Candida albicans appeared to be more sensitive to Jaftex, but no statistically significant difference was observed.

Conclusion

Jaftex mouthwash inhibits the growth of C. albicans and C. tropicalis. The use of this mouthwash is recommended for treatment of oral candidiasis.

Transcriptomic Analysis of Drug-Resistance Acinetobacter baumannii under the Stress Condition Caused by Litsea cubeba L. Essential Oil via RNA Sequencing

Litsea cubeba L. essential oil(LCEO) can affect the growth of drug-resistance bacteria. However, research on stress response of drug-resistant A. baumannii under sub-lethal LCEO concentrations had been limited so far. Therefore, transcriptomic analysisof A. baumannii under 1/2 minimum inhibitory concentration (MIC, 0.54 mg/mL) of LCEO was performed. Results of transcriptomic analysis showed that 320/352 genes were significantly up/down-regulated, respectively, in LCEO-treated A. baumannii. Both up and down-regulated genes were significantly enriched in three GO terms (oxidation-reduction process; oxidoreductase activity; oxidoreductase activity, acting on the CH-CH group of donors), which indicated that the redox state of A. baumannii was significantly affected by LCEO. LCEO may also inhibit aerobic respiration, synthesis of ketone bodies and the metabolism of some amino acids while, meanwhile, promoting fatty acid degradation of A. baumannii according to Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. The permeability and the stress of cell membrane of A. baumannii were significantly affected by LCEO. After crystal violet dyeing, the biofilm formation of A. baumannii was promoted/inhibited by extremely low/relatively high concentration of LCEO, respectively. LCEO and chloramphenicol have synergistic growth inhibitory effect against A. baumannii according to the Fractional Inhibitory Concentration Index (FICI) value = 0.375. Our results indicate that the growth of A. baumannii was inhibited by LCEO, and give insights into the stress response of A. baumannii under sub-lethal concentrations of LCEO. These results provided evidence that A. baumannii was inhibited by LCEO, and expanded knowledges of stress response of A. baumannii under sub-lethal concentration of LCEO.

Herbal Products and Their Active Constituents Used Alone and in Combination with Antifungal Drugs against Drug-Resistant Candida sp

Clinical isolates of Candida yeast are the most common cause of opportunistic fungal infections resistant to certain antifungal drugs. Therefore, it is necessary to detect more effective antifungal agents that would be successful in overcoming such infections. Among them are some herbal products and their active constituents.The purpose of this review is to summarize the current state of knowledge onherbal products and their active constituents havingantifungal activity against drug-resistant Candida sp. used alone and in combination with antifungal drugs.The possible mechanisms of their action on drug-resistant Candida sp. including (1) inhibition of budding yeast transformation into hyphae; (2) inhibition of biofilm formation; (3) inhibition of cell wall or cytoplasmic membrane biosynthesis; (4) ROS production; and (5) over-expression of membrane transporters will be also described.