Characterization of HphA: The First Enzyme in the Homologation Pathway of l-Phenylalanine and l-Tyrosine.

Homologation of amino acids is the insertion or deletion of a methylene group to their side chain, which is a relatively uncommon chemical transformation observed in peptide natural product (NP) structure. Homologated amino acids can potentially make the NP more stable in a biological system, but its biosynthesis is yet to be understood. This study biochemically characterized the first of three unexplored enzymes in the homologation pathway of l-phenylalanine and l-tyrosine. Previously proposed reactions catalyzed by HphA were confirmed by reversed-phase high-performance liquid chromatography and tandem mass spectrometry analysis. The substrate profile and kinetic parameters showed high selectivity for the natural substrates and their close analogs. The comparability of HphA to homologous enzymes in primary metabolic pathways, 2-isopropylmate synthase and homocitrate synthase which are involved in l-leucine and l-lysine biosynthesis, respectively, was validated by bioinformatical and site-directed mutagenesis studies. The knowledge obtained from this study has deepened the understanding of the homologation of amino acids, which can lead to future combinatorial biosynthesis and metabolic engineering studies.

Natural Products That Contain Higher Homologated Amino Acids.

This review focuses on discussing natural products (NPs) that contain higher homologated amino acids (homoAAs) in the structure as well as the proposed and characterized biosynthesis of these non-proteinogenic amino acids. Homologation of amino acids includes the insertion of a methylene group into its side chain. It is not a very common modification found in NP biosynthesis as approximately 450 homoAA-containing NPs have been isolated from four bacterial phyla (Cyanobacteria, Actinomycetota, Myxococcota, and Pseudomonadota), two fungal phyla (Ascomycota and Basidiomycota), and one animal phylum (Porifera), except for a few examples. Amino acids that are found to be homologated and incorporated in the NP structures include the following ten amino acids: alanine, arginine, cysteine, isoleucine, glutamic acid, leucine, phenylalanine, proline, serine, and tyrosine, where isoleucine, leucine, phenylalanine, and tyrosine share the comparable enzymatic pathway. Other amino acids have their individual homologation pathway (arginine, proline, and glutamic acid for bacteria), likely utilize the primary metabolic pathway (alanine and glutamic acid for fungi), or have not been reported (cysteine and serine). Despite its possible high potential in the drug discovery field, the biosynthesis of homologated amino acids has a large room to explore for future combinatorial biosynthesis and metabolic engineering purpose.

Modified Curcumins as Potential Drug Candidates for Breast Cancer: An Overview.

Breast cancer (BC), the most common malignancy in women, results from significant alterations in genetic and epigenetic mechanisms that alter multiple signaling pathways in growth and malignant progression, leading to limited long-term survival. Current studies with numerous drug therapies have shown that BC is a complex disease with tumor heterogeneity, rapidity, and dynamics of the tumor microenvironment that result in resistance to existing therapy. Targeting a single cell-signaling pathway is unlikely to treat or prevent BC. Curcumin (a natural yellow pigment), the principal ingredient in the spice turmeric, is well-documented for its diverse pharmacological properties including anti-cancer activity. However, its clinical application has been limited because of its low solubility, stability, and bioavailability. To overcome the limitation of curcumin, several modified curcumin conjugates and curcumin mimics were developed and studied for their anti-cancer properties. In this review, we have focused on the application of curcumin mimics and their conjugates for breast cancer.

Plant-Based Natural Products and Extracts: Potential Source to Develop New Antiviral Drug Candidates.

Viral infections are among the most complex medical problems and have been a major threat to the economy and global health. Several epidemics and pandemics have occurred due to viruses, which has led to a significant increase in mortality and morbidity rates. Natural products have always been an inspiration and source for new drug development because of their various uses. Among all-natural sources, plant sources are the most dominant for the discovery of new therapeutic agents due to their chemical and structural diversity. Despite the traditional use and potential source for drug development, natural products have gained little attention from large pharmaceutical industries. Several plant extracts and isolated compounds have been extensively studied and explored for antiviral properties against different strains of viruses. In this review, we have compiled antiviral plant extracts and natural products isolated from plants reported since 2015.

Thermoanaerosceptrum fracticalcis gen. nov. sp. nov., a Novel Fumarate-Fermenting Microorganism From a Deep Fractured Carbonate Aquifer of the US Great Basin.

Deep fractured rock ecosystems across most of North America have not been studied extensively. However, the US Great Basin, in particular the Nevada National Security Site (NNSS, formerly the Nevada Test Site), has hosted a number of influential subsurface investigations over the years. This investigation focuses on resident microbiota recovered from a hydrogeologically confined aquifer in fractured Paleozoic carbonate rocks at 863 - 923 meters below land surface. Analysis of the microorganisms living in this oligotrophic environment provides a perspective into microbial metabolic strategies required to endure prolonged hydrogeological isolation deep underground. Here we present a microbiological and physicochemical characterization of a deep continental carbonate ecosystem and describe a bacterial genus isolated from the ecosystem. Strain DRI-13T is a strictly anaerobic, moderately thermophilic, fumarate-respiring member of the phylum Firmicutes. This bacterium grows optimally at 55°C and pH 8.0, can tolerate a concentration of 100 mM NaCl, and appears to obligately metabolize fumarate to acetate and succinate. Culture-independent 16S rRNA gene sequencing indicates a global subsurface distribution, while the closest cultured relatives of DRI-13T are Pelotomaculum thermopropionicum (90.0% similarity) and Desulfotomaculum gibsoniae (88.0% similarity). The predominant fatty acid profile is iso-C15 : 0, C15 : 0, C16 : 0 and C14 : 0. The percentage of the straight-chain fatty acid C15 : 0 is a defining characteristic not present in the other closely related species. The genome is estimated to be 3,649,665 bp, composed of 87.3% coding regions with an overall average of 45.1% G + C content. Strain DRI-13T represents a novel genus of subsurface bacterium isolated from a previously uncharacterized rock-hosted geothermal habitat. The characterization of the bacterium combined with the sequenced genome provides insights into metabolism strategies of the deep subsurface biosphere. Based on our characterization analysis we propose the name Thermoanaerosceptrum fracticalcis (DRI-13T = DSM 100382T = ATCC TSD-12T).

The importance of total number of sentinel lymph nodes in patients with stage N0 cutaneous melanoma.

Staging of malignant melanoma now relies routinely on the sentinel node (SN) technique. On average, 2.1 SNs are removed per patient. Nevertheless, despite the success of the SN technique, approximately 10% of patients with negative SNs experience metastatic recurrence. Because a prior theoretical analysis using Poisson and Bayes probability models suggested that limited sampling of SNs could cause false-negative results, we undertook this study to see whether the subset of patients with negative SN and only 1 or 2 nodes examined have a shorter time to recurrence than patients with 3 or more nodes examined and found to be negative. Our study cases comprised 178 melanoma cases with SN biopsy: positive SN, 47; negative SN and fewer than 3 nodes examined, 68; and negative SN and more than 2 nodes examined, 63. Patients with negative SNs and fewer than 3 examined had disease-free survival intermediate between patients with positive SNs and those with negative SNs and more than 2 examined (P = .013). These results suggest that among patients with negative SNs, those with fewer than 3 nodes examined have greater risk for recurrence.

Evaluation of thyroid fine-needle aspirations: can ThinPrep be used exclusively to appropriately triage patients having a thyroid nodule?

Thyroid fine-needle aspiration (FNA) represents an ideal management tool for thyroid nodules. ThinPrep is routinely used in preparation of a variety of nongynecologic cytology specimens, including FNA. The authors investigated ThinPrep to determine if its diagnostic accuracy is sufficient to triage patients presenting with a thyroid nodule. ThinPrep (TP) slides from four separate study categories were reviewed in a blind fashion. Twenty-five cases of papillary carcinoma, follicular lesion, Hashimoto's thyroiditis and multinodular goiter were examined retrospectively. Diagnostic accuracy of TP for each diagnostic category was determined relative to the final FNA diagnosis. Of 100 total study cases, 46 (46%) had noncorrelation. Twenty five (25%) of the study cases had noncorrelation as a result of insufficient cellularity. The diagnostic accuracy of TP for papillary carcinoma was 64%, for follicular lesion 24%, for Hashimoto's thyroiditis 72% and for multinodular goiter 56%. Cytologic features of papillary carcinoma, Hashimoto's thryoiditis, and multinodular goiter are preserved in TP slides. Cytologic features of follicular lesion are less predictable in TP slides. When all cases of noncorrelation were examined, we concluded that insufficient or marginal cellularity most often accounts for the discrepancy between TP and CS diagnoses in each study category. If techniques can be established to improve cellularity of TP slides, particularly in follicular lesions, we believe that sufficient diagnostic accuracy can be achieved to result in appropriate patient triage. Additional studies exploring methods to improve TP cellularity are needed before TP can be used as the sole diagnostic test for thyroid FNA.