Prodigiosin is a red pigment with a pyrrolylpyrromethane skeleton. It is mainly produced by bacterial strains belonging to the Serratia genus, but also by some other genera, including Streptomyces and Vibrio. Within the genus Serratia, the pigment is generally produced as a virulence factor. However, it also has many important beneficial biological activities such as immunosuppressive and anti- proliferative activities. Moreover, the pigment has many industrial applications in textile and cosmetics. In this mini-review, we discuss the genetic and molecular mechanisms supporting prodigiosin synthesis and production from the Serratia genus, as well as its potential applications.

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Objective: To characterize the antifungal activity of methanolic leaf extract of Calotropis gigantea alone or in combination with amphotericin B against invasive pulmonary aspergillosis in mice. Methods: GC/MS was used for analysis of active constituents of Calotropis gigantea extract. Spore germination assay and broth micro-dilution method were used to determine antifungal potential of Calotropis gigantea/amphotericin B against Aspergillus fumigatus. Neutropenic mice were randomly assigned into 5 groups: group 1 was neutropenic (control); group 2 was infected with Aspergillus fumigatus; group 3 was infected with Aspergillus fumigatus, and treated with Calotropis gigantea extract; group 4 was infected with Aspergillus fumigatus and treated with amphotericin B; group 5 was infected with Aspergillus fumigatus and treated with both Calotropis gigantea extract and amphotericin B. Fresh lung tissues were histopathologically examined. Fungal burden and gliotoxin concentration were evaluated in lung tissues. Catalase, superoxide dismutase, and malondialdehyde content were determined in lung tissues. Myeloperoxidase, tumor necrosis factor-alpha, interleukin-1, and interleukin-17 were also estimated by the sandwich enzyme-linked immuno-sorbent assay. Results: Calotropis gigantea/amphotericin B had a minimum inhibitory concentration and minimum fungicidal concentration of 80 and 160 μg/mL, respectively, for Aspergillus fumigatus. Additionally, Calotropis gigantea/amphotericin B significantly reduced lung fungal burden by 72.95% and inhibited production of gliotoxin in lung tissues from 6 320 to 1 350 μg/g lung. Calotropis gigantea/amphotericin B reduced the oxidative stress of the lung via elevating the activity of antioxidant enzymes and decreasing the levels of lipid peroxidation. Myeloperoxidase activity and the production of pro-inflammatory cytokines were also significantly reduced. Scanning electron microscopy revealed deteriorations in the hyphae ultrastructure in Calotropis gigantea/amphotericin B treated Aspergillus fumigatus and leak of cellular components after damage of the cell wall. In vivo study revealed the suppression of lung tissue damage in mice of invasive pulmonary aspergillosis, which was improved with Calotropis gigantea/amphotericin B compared to the control group. Conclusions: Calotropis gigantea/amphotericin B is a promising treatment to reduce lung fungal burden and to improve the drugs’ therapeutic effect against invasive pulmonary aspergillosis.

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Objective: To investigate the effect and its underlying molecular mechanisms of essential oil from Saussurea costus in esophageal cancer cell line Eca109. Methods: The chemical composition of essential oil from Saussurea costus was investigated by gas chromatography-mass spectrometry (GC-MS). The anti-proliferative, anti-migrative, and apoptotic effects of essential oil from Saussurea costus against Eca109 cells were analyzed. Moreover, the expression of proteins associated with cell cycle, metastasis, and apoptosis was determined. Results: GC-MS analysis showed that essential oil from Saussurea costus was predominantly comprised of sesquiterpenes. Saussurea costus essential oil inhibited the viability of Eca109 cells in a dose-and time-dependent manner with IC₅₀ values of (24.29±1.49), (19.16±2.27) and (6.97±0.86) μg/mL at 12, 24, and 48 h, respectively. The expression levels of target proteins in the cell cycle (phase G₁/S), including cyclin D1, p21, and p53, were affected by Saussurea costus essential oil. The essential oil also downregulated the expression of metastasis-related proteins MMP-9 and MMP-2. Moreover, it induced apoptosis of Eca109 cells through the mitochondrial pathway, as well as inhibition of STAT3 phosphorylation. Conclusions: The essential oil from Saussurea costus exhibited anti-proliferative, anti-migrative, and apoptotic effects on Eca109 cells, and could be further explored as a potential anti-esophageal cancer agent.

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Objective: To demonstrate the effect of dieckol from Eisenia bicyclis on osteoclastogenesis using RAW 264.7 cells. Methods: Murine macrophage RAW 264.7 cells were subjected to dieckol treatment, followed by treatment with receptor activator of nuclear factor kappa-B ligand (RANKL) to induce osteoclastogenesis. Tartrate-resistant acid phosphatase (TRAP) activity was examined using a TRAP activity kit. Western blotting analysis was conducted to examine the level of osteoclast- related factors, including TRAP and calcitonin receptor (CTR), transcriptional factors, including c-Fos, c-Jun, and nuclear factor of activated T cells cytoplasmic 1 (NFATc1), nuclear factor kappa-B (NF-κB), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK). Immunofluorescence staining was conducted to examine the expression of c-Fos, c-Jun, and NFATc1. Results: Among the four phlorotannin compounds present in Eisenia bicyclis, dieckol significantly hindered osteoclast differentiation and expression of RANKL-induced TRAP and CTR. In addition, dieckol downregulated the expression levels of c-Fos, c-Jun, NFATc1, ERK, and JNK, and suppressed NF-κB signaling. Conclusions: Dieckol can suppress RANKL-induced osteoclastogenesis. Therefore, it has therapeutic potential in treating osteoclastogenesis- associated diseases.

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Objective: To investigate the effects of syringic acid on HEK 293 and HepG2 cells in the absence and presence of exogenous Cu (II) and Fe (II) ions. Methods: The antiproliferative effects of syringic acid on HEK 293 and HepG2 cells in the absence and presence of exogenous Cu (II) and Fe (II) ions were examined by MTT assay. Additionally, colony-forming, reactive oxidative species (ROS) generation, apoptosis induction, autophagy, mitochondrial membrane potential, and mitochondrial mass were investigated. Results: At 24 and 72 h, no significant differences were observed in the viability of HepG2 cells between the control and syringic acid + Fe (II) groups. However, exposure of HepG2 cells to syringic acid + Cu (II) for 72 h reduced the cell viability significantly. Furthermore, ROS formation, induction of apoptosis, and autophagic vacuoles were significantly increased in HepG2 cells without marked changes in mitochondrial membrane potential and mitochondrial mass. Moreover, syringic acid + Cu (II) reduced the plating efficiency and surviving fraction significantly. Conclusions: The combination of syringic acid with Cu (II) was toxic to cancer cells and showed pro-oxidant activity. In addition, this combination induced autophagy in cancer cells with less cytotoxic effects on normal cells, which is a potential candidate for the development of novel therapeutics towards cancer.

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