Isoflavones with unusually modified B-rings and their evaluation as antiproliferative agents

Anti-inflammation of hydrogenated isoflavones in LPS-stimulated RAW264.7 cells via inhibition of NF-κB and MAPK signaling pathways

Isoflavones are commonly found in diets, such as soybean and clover. Their anti-inflammatory effects are due to the inhibition of the transcriptional regulation of NF-κB. Hydrogenated isoflavones are metabolites of isoflavones with higher bioavailability, however, there have been few studies on their anti-inflammatory effects. In this work, by using the LPS-stimulated RAW264.7 cell model, we investigated the anti-inflammatory effect and the underlying mechanism of hydrogenated isoflavones. Hydrogenated isoflavones reduced the production of LPS-stimulated pro-inflammatory mediators and enzymes, including TNF-α, IL-6, NO, iNOS and COX-2. The level of ROS was also diminished in LPS-stimulated RAW264.7 cells. Further mechanistic studies showcase that hydrogenated isoflavones block NF-κB and MAPK pathways via attenuation of p65 nuclear translocation and JNK, ERK, and p38 phosphorylation, respectively. In addition, we found that hydrogenated isoflavones display anti-proliferation effect in human colon cancer cells with wild-type p53. Together, hydrogenated isoflavones could be used as an adjuvant for the treatment of inflammation and cancer.

Untargeted Metabolomics of Streptomyces Species Isolated from Soils of Nepal

Actinomycetes are natural architects of numerous secondary metabolites including antibiotics. With increased multidrug-resistant (MDR) pathogens, antibiotics that can combat such pathogens are urgently required to improve the health care system globally. The characterization of actinomycetes available in Nepal is still very much untouched which is the reason why this paper showcases the characterization of actinomycetes from Nepal based on their morphology, 16S rRNA gene sequencing, and metabolic profiling. Additionally, antimicrobial assays and liquid chromatography-high resolution mass spectrometry (LC-HRMS) of ethyl acetate extracts were performed. In this study, we employed a computational-based dereplication strategy for annotating molecules which is also time-efficient. Molecular annotation was performed through the GNPS server, the SIRIUS platform, and the available databases to predict the secondary metabolites. The sequencing of the 16S rRNA gene revealed that the isolates BN6 and BN14 are closely related to Streptomyces species. BN14 showed broad-spectrum antibacterial activity with the zone of inhibition up to 30 mm against Staphylococcus aureus (MIC: 0.3051 µg/mL and MBC: 9.7656 µg/mL) and Shigella sonnei (MIC: 0.3051 µg/mL and MBC: 4.882 µg/mL). Likewise, BN14 also displayed significant inhibition to Acinetobacter baumannii, Klebsiella pneumoniae, and Salmonella typhi. GNPS approach suggested that the extracts of BN6 and BN14 consisted of diketopiperazines ((cyclo(D-Trp-L-Pro), cyclo(L-Leu-L-4-hydroxy-Pro), cyclo(L-Phe-D-Pro), cyclo(L-Trp-L-Pro), cyclo(L-Val-L-Pro)), and polypeptide antibiotics (actinomycin D and X2). Additional chemical scaffolds such as bacterial alkaloids (bohemamine, venezueline B, and G), anthramycin-type antibiotics (abbeymycin), lipase inhibitor (ebelactone B), cytocidal (oxopropaline D), antifungal and antitumor antibiotics (reductiomycin, streptimidone, deoxynybomycin), alaremycin, fumaramidmycin, anisomycin, and others were also annotated, which were further confirmed by using the SIRIUS platform, and literature survey. Thus, the bioprospecting of natural products from Streptomyces species from Nepal could be a potential source for the discovery of clinically significant and new antimicrobial agents in the future.

Antimicrobial Prenylated Isoflavones from the Leaves of the Amazonian Medicinal Plant Vatairea guianensis Aubl

Vatairea guianenis Aubl. (Fabaceae) is an Amazonian medicinal plant species traditionally used for treating skin diseases. In an initial screening, a V. guianensis leaf extract and its subextracts showed antibacterial and antifungal activities. The EtOAc subextract was selected for chemical workup and afforded five known (1-4 and 8) and six undescribed isoflavones, vatairenones C-H (5-7 and 9-11). All isoflavones are prenylated in position C-8, displaying either chain-prenylated (1-7) or ring-closed forms (8-11). The most bioactive compound (3) exhibited in vitro activity against clinically relevant bacteria and fungi with IC₅₀ values ranging from 6.8 to 26.9 μM. Due to its broad antimicrobial activity and low general toxicity, compound 3 is a potential lead compound for structural modifications. The results of the present study support the ethnomedicinal use of V. guianensis in the treatment of dermatological disorders. ¹H NMR spectra of some of the isolated compounds showed intricate signal patterns, which might explain repeated errors in assigning the correct structure of the isoflavonoid B-ring in the literature and which we resolved by higher order spectra simulations.

O,O-Silyl Group Migrations in Quinic Acid Derivatives: An Opportunity for Divergent Synthesis

The O,O-silyl group migrations on a quinic acid-derived cyclitol have been studied, and the ease of migration was observed to be dependent on the silicon substituents and reaction conditions. Conditions were found to improve the formation of a main isomer during the O,O-silyl group migrations that could be integrated into the formal synthesis of vitamin D receptor modulator VS-105 and in the first total synthesis of a metabolite from the African ant Crematogaster nigriceps.

Comprehensive LC-MS/MS-based phytochemical perspectives and osteogenic effects of Uraria crinita

Osteogenesis plays a vital role in the maintenance of bone health. Imbalances in osteogenesis influence the onset of several bone loss-associated diseases. The intake of Uraria crinita (Fabaceae) through dietary supplements is advised for childhood bone dysplasia. This botanical provides edible tonics and detoxifiers, and is also used as a folk beverage. We evaluated the osteogenic effects of a 50% ethanol extract of the root of U. crinita on primary human osteoblasts (HObs) and initiated a novel comprehensive phytochemical strategy using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for quality control of this functional food. Two isoflavones, genistein (5) and 5,7-dihydroxy-3',5'-dihydroxyisoflavone (6), increased the alkaline phosphatase activity (differentiation stage); the flavone glycoside vitexin (1), and the phenolic acid salicylic acid (2) enhanced the mineralization (mature stage). The isoflavone 2'-hydroxygenistein (4) possessed high osteogenic potential among the isolated compounds in HObs. It promoted osteogenesis-related stages and upregulated the gene expressions in a dose-dependent manner. The major compounds in the active fraction were quantitatively analyzed via phytochemical fingerprint detection. These LC-MS/MS-based phytochemical perspectives can act as reference standards in developing food supplements from U. crinita.

Three New Isoflavonoid Glycosides from the Mangrove-Derived Actinomycete Micromonospora aurantiaca 110B

The mangrove ecosystem is a rich resource for the discovery of actinomycetes with potential applications in pharmaceutical science. Besides the genus Streptomyces, Micromonospora is also a source of new bioactive agents. We screened Micromonospora from the rhizosphere soil of mangrove plants in Fujian province, China, and 51 strains were obtained. Among them, the extracts of 12 isolates inhibited the growth of human lung carcinoma A549 cells. Strain 110B exhibited better cytotoxic activity, and its bioactive constituents were investigated. Consequently, three new isoflavonoid glycosides, daidzein-4'-(2-deoxy-α-l-fucopyranoside) (1), daidzein-7-(2-deoxy-α-l-fucopyranoside) (2), and daidzein-4',7-di-(2-deoxy-α-l-fucopyranoside) (3) were isolated from the fermentation broth of strain 110B. The structures of the new compounds were determined by spectroscopic methods, including 1D and 2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry (HR-ESIMS). The result of medium-changing experiments implicated that these new compounds were microbial biotransformation products of strain M. aurantiaca 110B. The three compounds displayed moderate cytotoxic activity to the human lung carcinoma cell line A549, hepatocellular liver carcinoma cell line HepG2, and the human colon tumor cell line HCT116, whereas none of them showed antifungal or antibacterial activities.

Isolation of naturally occurring novel isoflavonoids: an update

This review covers the literature concerning the isolation and identification of new naturally occurring isoflavonoids from Leguminosae and non-Leguminous species between 2012–2017.

Chemical analysis of the Alphaproteobacterium strain MOLA1416 associated with the marine lichen Lichina pygmaea

Alphaproteobacterium strain MOLA1416, related to Mycoplana ramosa DSM 7292 and Chelativorans intermedius CC-MHSW-5 (93.6% 16S rRNA sequence identity) was isolated from the marine lichen, Lichina pygmaea and its chemical composition was characterized by a metabolomic network analysis using LC-MS/MS data. Twenty-five putative different compounds were revealed using a dereplication workflow based on MS/MS signatures available through GNPS (https://gnps.ucsd.edu/). In total, ten chemical families were highlighted including isocoumarins, macrolactones, erythrinan alkaloids, prodiginines, isoflavones, cyclohexane-diones, sterols, diketopiperazines, amino-acids and most likely glucocorticoids. Among those compounds, two known metabolites (13 and 26) were isolated and structurally identified and metabolite 26 showed a high cytotoxic activity against B16 melanoma cell lines with an IC₅₀ 0.6 ± 0.07 μg/mL.

A comprehensive review of glycosylated bacterial natural products

A systematic analysis of all naturally-occurring glycosylated bacterial secondary metabolites reported in the scientific literature up through early 2013 is presented. This comprehensive analysis of 15 940 bacterial natural products revealed 3426 glycosides containing 344 distinct appended carbohydrates and highlights a range of unique opportunities for future biosynthetic study and glycodiversification efforts.

NMR spectroscopic method for the assignment of 3,5-dioxygenated aromatic rings in natural products

In recent years, certain "new" naturally occurring compounds (1-28) with 3,5-dioxygenated aromatic rings have been reported. A comparison of the NMR data of these compounds with the data of four model compounds (A-D) indicated that the structures of these "new" compounds were erroneous. The reason for the incorrect elucidation of the structures of 1-28 was attributed to "deceptively simple" (1)H NMR spectra, which displayed two broad singlets with integrations of 1:2 for H-2 and H-5, H-6, respectively. To expose the misleading results from the spectra, serial (1)H NMR experiments on compounds A-D were performed using various deuterated solvents and temperatures. The results revealed separated proton signals for the ABX system in certain deuterated solvents. Additionally, the characteristic differences between 3,4- and 3,5-dioxygenated aromatic rings in their (13)C NMR spectra are summarized based on our experiment and data reported. This approach is useful for analyzing the patterns of dioxygenated aromatic rings in natural products, especially when "deceptively simple" (1)H NMR spectra are displayed.

Novel genistein derivatives induce cell death and cell cycle arrest through different mechanisms

Genistein is a natural compound belonging to isoflavone family of secondary plant metabolites, characterized by pleiotropic biological activity. Here we present the results of a study on new analogs and polysaccharide complexes of genistein as potent antiproliferative and cell death-inducing agents. Most potent were 2 analogs (i.e., IFG-027 and IFG-043) and 2 complexes (i.e., SPG-G and XG-G), which had higher or similar antiproliferative activity in comparison to genistein. However, these 2 analogs decreased the number of cells in G2/M phase in contrast to genistein and SPG-G complex. Genistein analogs, IFG-027 and IFG-043, and also SPG-G complex decreased mitochondrial membrane potential and induced the externalization of phosphatidylserine to the extracellular membrane site, which indicates the induction of apoptosis. Interestingly, genistein and its analogs induced caspase 3-activation supporting apoptotic mechanism of cell death but SPG-G supported caspase 3-independent apoptosis. XG-G complex probably did not induce cell death through the apoptotic pathway, as we did not find the externalization of phosphatidylserine and activation of caspase-3. After the treatment of HL-60 cells with genistein, SPG-G and XG-G formation of acidic vesicular organelle (AVO) was detected. In contrast, in the cells that were treated with genistein analogs IFG-027 and IFG-043, AVO formation was not observed.

Metallomics: lessons for metalliferous soil remediation

The term metallomics has been established for the investigation of transcriptome, proteome, and metabolome changes induced by metals. The mechanisms allowing the organisms to cope with metals in the environment, metal resistance factors, will in turn change biogeochemical cycles of metals in soil, coupling the metal pool with the root system of plants. This makes microorganisms key players in introducing metals into food webs, as well as for bioremediation strategies. Research on physiological and metabolic responses of microorganisms on metal stress in soil is thus essential for the selection of optimized consortia applicable in bioremediation strategies such as bioaugmentation or microbially enhanced phytoextraction. The results of metallomics studies will help to develop applications including identification of biomarkers for ecotoxicological studies, bioleaching, in situ soil regeneration, and microbially assisted phytoremediation of contaminated land. This review will therefore focus on the molecular understanding of metal resistance in bacteria and fungi, as can be derived from metallomics studies.