The efficient expression of human fibroblast collagenase in Escherichia coli and the discovery of flavonoid inhibitors

Five New Tamarixetin Glycosides from Astragalus thracicus Griseb. Including Some Substituted with the Rare 3-Hydroxy-3-methylglutaric Acid and Their Collagenase Inhibitory Effects In Vitro

Along with the known kaempferol-3-O-α-l-rhamnopyranosyl-(1 → 2)-[6-O-(3-hydroxy-3-methylglutaryl)]-β-d-galactopyranoside (1), five new flavonoids, containing the rarely isolated aglycon tamarixetin, were isolated from a methanolic extract of the endemic Balkan species Astragalus thracicus Griseb. Three of the new compounds are substituted with 3-hydroxy-3-methylglutaryl residue (HMG), untypical for the genus Astragalus. The compounds were identified as tamarixetin-3-O-α-l-rhamnopyranosyl-(1 → 2)-[6-O-(3-hydroxy-3-methylglutaryl)]-β-d-galactopyranoside (2), tamarixetin-3-O-(2,6-di-O-α-l-rhamnopyranosyl)-β-d-galactopyranoside (3), tamarixetin 3-O-β-d-apiofuranosyl-(1 → 2)-β-d-galactopyranoside (4), tamarixetin-3-O-β-d-apiofuranosyl-(1 → 2)-[6-O-(3-hydroxy-3-methylglutaryl)]-β-d-galactopyranoside (5), and tamarixetin-3-O-β-d-apiofuranosyl-(1 → 2)-[α-l-rhamnopyranosyl-(1 → 6)]-β-d-galactopyranoside (6). Selected compounds from A. thracicus were tested to evaluate their anticollagenase activity. The greatest effect was observed for quercetin-3-O-β-d-apiofuranosyl-(1 → 2)-β-d-galactopyranoside, possibly due to the presence of an ortho-dihydroxy arrangement of flavonoid ring B. The effect on collagenase and elastase was further evaluated also by in silico study, and the test compounds showed some level of in silico interaction.

Fisetin in Cancer: Attributes, Developmental Aspects, and Nanotherapeutics

Cancer is one of the major causes of mortality, globally. Cancerous cells invade normal cells and metastasize to distant sites with the help of the lymphatic system. There are several mechanisms involved in the development and progression of cancer. Several treatment strategies including the use of phytoconstituents have evolved and been practiced for better therapeutic outcomes against cancer. Fisetin is one such naturally derived flavone that offers numerous pharmacological benefits, i.e., antioxidant, anti-inflammatory, antiangiogenic, and anticancer properties. It inhibits the rapid growth, invasiveness, and metastasis of tumors by hindering the multiplication of cancer cells, and prompts apoptosis by avoiding cell division related to actuation of caspase-9 and caspase-8. However, its poor bioavailability associated with its extreme hydrophobicity hampers its clinical utility. The issues related to fisetin delivery can be addressed by adapting to the developmental aspects of nanomedicines, such as formulating it into lipid or polymer-based systems, including nanocochleates and liposomes. This review aims to provide in-depth information regarding fisetin as a potential candidate for anticancer therapy, its properties and various formulation strategies.

Collagenase and Tyrosinase Inhibitory Effect of Isolated Constituents from the Moss Polytrichum formosum

Mosses from the genus Polytrichum have been shown to contain rare benzonaphthoxanthenones compounds, and many of these have been reported to have important biological activities. In this study, extracts from Polytrichum formosum were analyzed in vitro for their inhibitory properties on collagenase and tyrosinase activity, two important cosmetic target enzymes involved respectively in skin aging and pigmentation. The 70% ethanol extract showed a dose-dependent inhibitory effect against collagenase (IC₅₀ = 4.65 mg/mL). The methanol extract showed a mild inhibitory effect of 44% against tyrosinase at 5.33 mg/mL. Both extracts were investigated to find the constituents having a specific affinity to the enzyme targets collagenase and tyrosinase. The known compounds ohioensin A (1), ohioensin C (3), and communin B (4), together with nor-ohioensin D (2), a new benzonaphthoxanthenone, were isolated from P. formosum. Their structures were determined by mass spectrometry and NMR spectroscopy. Compounds 1 (IC₅₀ = 71.99 µM) and 2 (IC₅₀ = 167.33 µM) showed inhibitory activity against collagenase. Compound 1 also exhibited inhibition of 30% against tyrosinase activity at 200 µM. The binding mode of the active compounds was theoretically generated by an in-silico approach against the 3D structures of collagenase and tyrosinase. These current results present the potential application from the moss P. formosum as a new natural source of collagenase and tyrosinase inhibitors.

Myricetin is a novel inhibitor of human inosine 5'-monophosphate dehydrogenase with anti-leukemia activity

Human inosine 5'-monophosphate dehydrogenase (hIMPDH) is a rate-limiting enzyme in the de novo biosynthetic pathway of purine nucleotides, playing crucial roles in cellular proliferation, differentiation, and transformation. Dysregulation of hIMPDH expression and activity have been found in a variety of human cancers including leukemia. In this study, we found that myricetin, a naturally occurring phytochemical existed in berries, wine and tea, was a novel inhibitor of human type 1 and type 2 IMPDH (hIMPDH1/2) with IC50 values of 6.98 ± 0.22 μM and 4.10 ± 0.14 μM, respectively. Enzyme kinetic analysis using Lineweaver-Burk plot revealed that myricetin is a mix-type inhibitor for hIMPDH1/2. Differential scanning fluorimetry and molecular docking simulation data demonstrate that myricetin is capable of binding with hIMPDH1/2. Myricetin treatment exerts potent anti-proliferative and pro-apoptotic effects on K562 human leukemia cells in a dose-dependent manner. Importantly, cytotoxicity of myricetin on K562 cells were markedly attenuated by exogenous addition of guanosine, a salvage pathway of maintaining intracellular pool of guanine nucleotides. Taking together, these results indicate that natural product myricetin exhibits potent anti-leukemia activity by interfering with purine nucleotides biosynthetic pathway through the suppression of hIMPDH1/2 catalytic activity.

Soluble Expression of Bladder Cancer Biomarker Matrix Metalloproteinase 1

BACKGROUND

Matrix metalloproteinase 1 (MMP1) has been shown as a novel unique biomarker of bladder cancer in urine. MMP1 can only be detected using conventional and time-consuming methods, such as ELISA and Western. Refolded MMP1 has been achieved and used in probe screen for many years, while there is no clinical application for MMP1 detection until now. Soluble expression of MMP1 is necessary in urine detection.

METHODS

cDNA of MMP1 has been isolated from human embryonic kidney 293(HEK293) cells. The catalytic domain of MMP1 is expressed as fusion protein with Escherichia coli thioredoxin (TrxA). The 30 kDa recombinant proteins were purified by Ni-chelating chromatography. The activity of soluble MMP1 was determined and compared with refolded MMP1 by zymography.

RESULTS

Compared with refolded MMP1, TrxA can increase the solubility of MMP1. The soluble MMP1 has the same protein sequences with refolded MMP1 and increased 1.54-fold of gelatin-degradation activities than refolded MMP1.

CONCLUSION

Successfully soluble expression of MMP1 has been achieved by fusion expression and will make progress in discovering specific molecular probes against MMP1.

Fisetin: a dietary antioxidant for health promotion

SIGNIFICANCE

Diet-derived antioxidants are now being increasingly investigated for their health-promoting effects, including their role in the chemoprevention of cancer. In general, botanical antioxidants have received much attention, as they can be consumed for longer periods of time without any adverse effects. Flavonoids are a broadly distributed class of plant pigments that are regularly consumed in the human diet due to their abundance. One such flavonoid, fisetin (3,3',4',7-tetrahydroxyflavone), is found in various fruits and vegetables, such as strawberry, apple, persimmon, grape, onion, and cucumber.

RECENT ADVANCES

Several studies have demonstrated the effects of fisetin against numerous diseases. It is reported to have neurotrophic, anticarcinogenic, anti-inflammatory, and other health beneficial effects.

CRITICAL ISSUES

Although fisetin has been reported as an anticarcinogenic agent, further in-depth in vitro and in vivo studies are required to delineate the mechanistic basis of its observed effects. In this review article, we describe the multiple effects of fisetin with special emphasis on its anticancer activity as investigated in cell culture and animal models.

FUTURE DIRECTIONS

Additional research focused toward the identification of molecular targets could lead to the development of fisetin as a chemopreventive/chemotherapeutic agent against cancer and other diseases.