New neuroprotective derivatives of cinnamic acid by biotransformation

Microbial transformation is extensively utilized to generate new metabolites in bulk amounts with more specificity and improved activity. As cinnamic acid was reported to exhibit several important pharmacological properties, microbial transformation was used to obtain its new derivatives with enhanced biological activities. By manipulating the 2-stage fermentation protocol of biotransformation, five metabolites were produced from cinnamic acid. Two of them were new derivatives; N-propyl cinnamamide 2̲ and 2-methyl heptyl benzoate 3̲ produced by Alternaria alternata. The other 3 metabolites, p-hydroxy benzoic acid 4̲, cinnamyl alcohol 5̲ and methyl cinnamate 6̲, were produced by Rhodotorula rubra, Rhizopus species and Penicillium chrysogeneum, respectively. Cinnamic acid and its metabolites were evaluated for their cyclooxygenase (COX) and acetylcholinesterase (AChE) inhibitory activities. Protection against H2O2 and Aβ1-42 induced-neurotoxicity in human neuroblastoma (SH-SY5Y) cells was also monitored. Metabolite 4̲ was more potent as a COX-2 inhibitor than the parent compound with an IC50 value of 1.85 ± 0.07 μM. Out of the tested compounds, only metabolite 2̲ showed AChE inhibitory activity with an IC50 value of 8.27 μM. These results were further correlated with an in silico study of the binding interactions of the active metabolites with the active sites of the studied enzymes. Metabolite 3̲ was more potent as a neuroprotective agent against H2O2 and Aβ1-42 induced-neurotoxicity than catechin and epigallocatechin-3-gallate as positive controls. This study suggested the two new metabolites 2̲ and 3̲ along with metabolite 4̲ as potential leads for neurodegenerative diseases associated with cholinergic deficiency, neurotoxicity or neuroinflammation.

Daidzein and Chicory Extract Arrest the Cell Cycle via Inhibition of Cyclin D/CDK4 and Cyclin A/CDK2 Gene Expression in Hepatocellular Carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common cancers, associated with a high rate of mortality. A disturbance between cell proliferation and cell death is one of the cancer hallmarks including HCC. Cell proliferation is mainly controlled by the cell cycle. The arrest of the cell cycle is one of the important targets of anticancer agents.

OBJECTIVES

The present study tries to clarify the exact role of some natural products such as daidzein (DAZ) and alcoholic chicory leaf extract (CE), as possible regulators of cell cycle and apoptosis.

METHODS

HCC in rats was induced using diethylnitrosamine (DENA). Ninety rats were allocated and divided equally into nine groups, treated with CE, DAZ, a combination of both, and sorafenib with non-treated control groups.

RESULTS

Treatment with CE, DAZ, and their combination significantly downregulated hepatic tissue expression of cyclin D1/CDK4 axis as well as cyclin A/CDK2 axis. The suggested therapeutic protocol inhibited the proliferation and dampened Bcl-2 expression. Furthermore, the efficiency of combining CE and DAZ demonstrated a potency comparable to sorafenib in terms of cyclin D/CDK4 axis expression, as well as; this combination protocol was more potent in revealing a potentiated inhibitory effect on cyclin A and Ki-67 expression.

CONCLUSION

Treatment with DAZ or CE alone, or in combination, could possess an inhibitory effect on hepatocarcinogenesis via cell cycle arrest, inhibition of proliferation through suppression of Ki-67 expression, and apoptosis induction, mediated by downregulation of Bcl-2.

Targeting the HIF-1α/Cav-1 Pathway with a Chicory Extract/Daidzein Combination Plays a Potential Role in Retarding Hepatocellular Carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most rapidly growing solid cancers, that is characterized by hypoxia. Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor that regulates tumor proliferation and metastasis. It induces caveolin-1 (Cav-1) expression, a glycoprotein found on the membrane surface, then Cav-1 triggers angiogenesis and metastasis in HCC.

OBJECTIVE

We hypothesize that targeting HIF-1α and consequently, Cav-1 using the antioxidant natural compound such as chicoric acid and a Cav-1 inhibitor daidzein (DAZ) could be a useful approach in the management of HCC. This study was conducted to investigate the possible therapeutic efficacy of standardized chicory leaf extract (SCLE) and DAZ via modulation of HIF-1α and Cav-1 in HCC rats.

METHODS

Diethyl nitrosamine (DENA) was used for HCC induction. After the induction period, four groups (10 rats for each) were treated with SCLE, DAZ, a combination of both, as well as sorafenib, all compared to the non-treated control. We assessed hepatic HIF-1α protein expression, Cav-1 gene expression, serum level of AFP, hepatic tissue content of VEGF, MMP-9, oxidative stress markers MDA and SOD.

RESULTS

DAZ, SCLE, and their combination, significantly down-regulated the expression of HIF-1α, Cav-1, and consequently dampened MMP-9, VEGF, hepatic content. It has been observed that the combination treatment showed a synergistic effect compared to either treatment alone. Importantly, the combination treatment exhibited a significantly more potent effect than sorafenib.

CONCLUSION

This study showed the potential role of the HIF-1α/Cav-1 pathway in HCC progression, moreover, SCLE and DAZ showed a potent efficacy in retarding HCC via modulation of this pathway.

The Shigella ProU system is required for osmotic tolerance and virulence

To cope with hyperosmotic stress encountered in the environments and in the host, the pathogenic as well as non-pathogenic microbes use diverse transport systems to obtain osmoprotectants. To study the role of Shigella sonnei ProU system in response to hyperosmotic stress and virulence, we constructed deletion and complementation strains of proV and used an RNAi approach to silence the whole ProU operon. We compared the response between wild type and the mutants to the hyperosmotic pressure in vitro, and assessed virulence properties of the mutants using gentamicin protection assay as well as Galleria mellonella moth larvae model. In response to osmotic stress by either NaCl or KCl, S. sonnei highly up-regulates transcription of proVWX genes. Supplementation of betaine greatly elevates the growth of the wild type S. sonnei but not the proV mutants in M9 medium containing 0.2 M NaCl or 0.2 M KCl. The proV mutants are also defective in intracellular growth compared with the wild type. The moth larvae model of G. mellonella shows that either deletion of proV gene or knockdown of proVWX transcripts by RNAi significantly attenuates virulence. ProU system in S. sonnei is required to cope with osmotic stress for survival and multiplication in vitro, and for infection.

Inflammasome priming is similar for francisella species that differentially induce inflammasome activation

Inflammasome activation is a two-step process where step one, priming, prepares the inflammasome for its subsequent activation, by step two. Classically step one can be induced by LPS priming followed by step two, high dose ATP. Furthermore, when IL-18 processing is used as the inflammasome readout, priming occurs before new protein synthesis. In this context, how intracellular pathogens such as Francisella activate the inflammasome is incompletely understood, particularly regarding the relative importance of priming versus activation steps. To better understand these events we compared Francisella strains that differ in virulence and ability to induce inflammasome activation for their relative effects on step one vs. step two. When using the rapid priming model, i.e., 30 min priming by live or heat killed Francisella strains (step 1), followed by ATP (step 2), we found no difference in IL-18 release, p20 caspase-1 release and ASC oligomerization between Francisella strains (F. novicida, F. holarctica -LVS and F. tularensis Schu S4). This priming is fast, independent of bacteria viability, internalization and phagosome escape, but requires TLR2-mediated ERK phosphorylation. In contrast to their efficient priming capacity, Francisella strains LVS and Schu S4 were impaired in inflammasome triggering compared to F. novicida. Thus, observed differences in inflammasome activation by F. novicida, LVS and Schu S4 depend not on differences in priming but rather on their propensity to trigger the primed inflammasome.

Inflammasome priming by lipopolysaccharide is dependent upon ERK signaling and proteasome function

Caspase-1 activation is a central event in innate immune responses to many pathogenic infections and tissue damage. The NLRP3 inflammasome, a multiprotein scaffolding complex that assembles in response to two distinct steps, priming and activation, is required for caspase-1 activation. However, the detailed mechanisms of these steps remain poorly characterized. To investigate the process of LPS-mediated NLRP3 inflammasome priming, we used constitutively present pro-IL-18 as the caspase-1-specific substrate to allow study of the early events. We analyzed human monocyte caspase-1 activity in response to LPS priming, followed by activation with ATP. Within minutes of endotoxin priming, the NLRP3 inflammasome is licensed for ATP-induced release of processed IL-18, apoptosis-associated speck-forming complex containing CARD, and active caspase-1, independent of new mRNA or protein synthesis. Moreover, extracellular signal-regulated kinase 1 (ERK1) phosphorylation is central to the priming process. ERK inhibition and small interfering RNA-mediated ERK1 knockdown profoundly impair priming. In addition, proteasome inhibition prevents ERK phosphorylation and blocks priming. Scavenging reactive oxygen species with diphenylene iodonium also blocks both priming and ERK phosphorylation. These findings suggest that ERK1-mediated posttranslational modifications license the NLRP3 inflammasome to respond to the second signal ATP by inducing posttranslational events that are independent of new production of pro-IL-1β and NOD-like receptor components.