High Plasticity of the Amicetin Biosynthetic Pathway in Streptomyces sp. SHP 22-7 Led to the Discovery of Streptcytosine P and Cytosaminomycins F and G and Facilitated the Production of 12F-Plicacetin

Mavintramycin A is a promising antibiotic for treating Mycobacterium avium complex infectious disease

Mycobacterium avium complex (MAC) is a serious disease that is mainly caused by infection with the non-tuberculous mycobacteria (NTM), Mycobacterium avium and Mycobacterium intracellulare. Seven new compounds, designated mavintramycins A-G (1-7), were isolated along with structurally related compounds, including amicetin (9) and plicacetin (10), from the culture broth of Streptomyces sp. OPMA40551 as anti-MAC compounds that were active against M. avium and M. intracellulare. Among them, mavintramycin A showed the most potent and selective inhibition of M. avium and M. intracellulare. Furthermore, mavintramycin A was active against more than 40 clinically isolated M. avium, including multidrug-resistant strains, and inhibited the growth of M. avium in a persistent infection cell model using THP-1 macrophages. Mavintramycin A also exhibited in vivo efficacy in silkworm and mouse infection assays with NTM. An experiment to elucidate its mechanism of action revealed that mavintramycin A inhibits protein synthesis by binding to 23S ribosomal RNA in NTM. Mavintramycin A, with a different chemical structure from those of clinically used agents, is a promising drug candidate for the treatment of MAC infectious disease.

Marine natural products

Covering: January to the end of December 2022This review covers the literature published in 2022 for marine natural products (MNPs), with 645 citations (633 for the period January to December 2022) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, the submerged parts of mangroves and other intertidal plants. The emphasis is on new compounds (1417 in 384 papers for 2022), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. An analysis of NP structure class diversity in relation to biota source and biome is discussed.

Purification and biological analysis of antimicrobial compound produced by an endophytic Streptomyces sp

Fungal phytopathogens and drug-resistant bacteria are two significant challenges in agriculture and public health, respectively. As a result, new sources of antimicrobial compounds are urgently needed. Taking into consideration these aspects, the present study was carried out to explore the antimicrobial activity of Streptomyces sp. SP5 against drug-resistant bacteria, especially methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococcus  and fungal phytopathogens. MRSA and VRE are both types of antibiotic-resistant bacteria that pose significant challenges to public health. In vitro analysis of the metabolites of Streptomyces sp. SP5 exhibited broad-spectrum antimicrobial activity against drug-resistant bacteria and phytopathogenic fungi. Further chemical investigation of the diethyl ether extract led to the isolation and purification of an antimicrobial compound. The structure of the purified compound was elucidated by performing detailed spectroscopic analysis including MS, IR, and NMR. The compound was identified as plicacetin. Plicacetin is a nucleoside antibiotic that has been reported for antibacterial activity against Gram-positive bacterium Mycobacterium tuberculosis. According to our knowledge, the present study is the first to demonstrate the antimicrobial properties of plicacetin against Fusarium oxysporum, Alternaria brassicicola, Fusarium solani, VRE and Bacillus subtilis. The outcome of the current study endorses that compound produced by Streptomyces sp. SP5 can be used as an antimicrobial agent against fungal phytopathogens and drug-resistant bacteria.

Metabolome Mining of Curcuma longa L. Using HPLC-MS/MS and Molecular Networking

Turmeric, Curcuma longa L., is a type of medicinal plant characterized by its perennial nature and rhizomatous growth. It is a member of the Zingiberaceae family and is distributed across the world's tropical and subtropical climates, especially in South Asia. Its rhizomes have been highly valued for food supplements, spices, flavoring agents, and yellow dye in South Asia since ancient times. It exhibits a diverse array of therapeutic qualities that encompass its ability to combat diabetes, reduce inflammation, act as an antioxidant, exhibit anticancer properties, and promote anti-aging effects. In this study, organic extracts of C. longa rhizomes were subjected to HPLC separation followed by ESI-MS and low-energy tandem mass spectrometry analyses. The Global Natural Product Social Molecular Networking (GNPS) approach was utilized for the first time in this ethnobotanically important species to conduct an in-depth analysis of its metabolomes based on their fragments. To sum it up, a total of 30 metabolites including 16 diarylheptanoids, 1 diarylpentanoid, 3 bisabolocurcumin ethers, 4 sesquiterpenoids, 4 cinnamic acid derivatives, and 2 fatty acid derivatives were identified. Among the 16 diarylheptanoids identified in this study, 5 of them are reported for the first time in this species.

Generation of Aurachin Derivatives by Whole-Cell Biotransformation and Evaluation of Their Antiprotozoal Properties

The natural product aurachin D is a farnesylated quinolone alkaloid, which is known to possess activity against the causative agent of malaria, Plasmodium spp. In this study, we show that aurachin D inhibits other parasitic protozoa as well. While aurachin D had only a modest effect on Trypanosoma brucei rhodesiense, two other trypanosomatids, T. cruzi and Leishmania donovani, were killed at low micromolar and nanomolar concentrations, respectively, in an in vitro assay. The determined IC₅₀ values of aurachin D were even lower than those of the reference drugs benznidazole and miltefosine. Due to these promising results, we set out to explore the impact of structural modifications on the bioactivity of this natural product. In order to generate aurachin D derivatives with varying substituents at the C-2, C-6 and C-7 position of the quinolone ring system, we resorted to whole-cell biotransformation using a recombinant Escherichia coli strain capable of aurachin-type prenylations. Quinolone precursor molecules featuring methyl, methoxy and halogen groups were fed to this E. coli strain, which converted the substrates into the desired analogs. None of the generated derivatives exhibited improved antiprotozoal properties in comparison to aurachin D. Obviously, the naturally occurring aurachin D features already a privileged structure, especially for the inhibition of the causative agent of visceral leishmaniasis.

Discovery of Ircinianin Lactones B and C-Two New Cyclic Sesterterpenes from the Marine Sponge Ircinia wistarii

Two new ircinianin-type sesterterpenoids, ircinianin lactone B and ircinianin lactone C (7 and 8), together with five known entities from the ircinianin compound family (1, 3–6) were isolated from the marine sponge Ircinia wistarii. Ircinianin lactones B and C (7 and 8) represent new ircinianin terpenoids with a modified oxidation pattern. Despite their labile nature, the structures could be established using a combination of spectroscopic data, including HRESIMS and 1D/2D NMR techniques, as well as computational chemistry and quantum-mechanical calculations. In a broad screening approach for biological activity, the class-defining compound ircinianin (1) showed moderate antiprotozoal activity against Plasmodium falciparum (IC₅₀ 25.4 μM) and Leishmania donovani (IC₅₀ 16.6 μM).