Potent, non-peptidic oxytocin receptor antagonists from a natural source

Divergent cyclodimerizations of styrylnaphthols under aerobic visible-light irradiation and Brønsted acid catalysis

Dimeric cyclization reactions show great potential to rapidly form highly substituted complex cyclic molecules from simple starting materials. However, such an appealing process is often hampered by the lack of selectivity. Herein we report two divergent cyclodimerization reactions of 1-styrylnaphthalen-2-ol derivatives under simple and very mild reaction conditions. A stereoselective visible light-induced oxidative (1 + 1 + 4 + 4) homodimerization gave rise to highly substituted 1,5-dioxocanes in moderate yields. This transformation harnessed singlet oxygen as a safe and mild oxidant under photocatalyst-free reaction conditions. Additionally, we demonstrated that the same substrates undergo a (4 + 2) heterodimerization under Brønsted-acid catalysis to produce chromane derivatives featuring 3 contiguous tertiary stereocenters in good to high yields with excellent diastereoselectivities.

Triton B-promoted regioselective intramolecular addition of enolates to tethered ynamides for the construction of 8-membered O-heterocycles

Benzo-1,5 dioxocines have been synthesized via unique ynamides tethered to propargylic ethers. Triton B allowed a proximal enol addition on the N-allenamide creating shelf-stable 8-membered-O-heterocycles with a broad functional group tolerance.

A fungus-derived purpactin A as an inhibitor of TMEM16A chloride channels and mucin secretion in airway epithelial cells

TMEM16A is a Ca2+-activated Cl- channel involved in mucus secretion in inflamed airways and proposed as a drug target for diseases associated with mucus hypersecretion including asthma. This study aimed to identify novel inhibitors of TMEM16A-mediated Cl- secretion in airway epithelial cells from a collection of compounds isolated from fungi indigenous in Thailand and examine its potential utility in mitigating airway mucus secretion using Calu-3 cells as a study model. Screening of > 400 fungal metabolites revealed purpactin A isolated from a soil-derived fungus Penicillium aculeatum PSU-RSPG105 as an inhibitor of TMEM16A-mediated Cl- transport with an IC50 value of ~2 µM. A consistent inhibitory effect of purpactin A on TMEM16A were observed regardless of TMEM16A activators or in the presence of an inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMKII), a negative regulator of TMEM16A. In addition, purpactin A did not affect cell viability, epithelial barrier integrity and activities of membrane transport proteins essential for maintaining airway hydration including CFTR Cl- channels and apical BK K+ channels. Intriguingly, purpactin A prevented a Ca2+-induced mucin release in cytokine-treated airway cells. Taken together, purpactin A represents the first class of TMEM16A inhibitor derived from fungus, which may be beneficial for the treatment of diseases associated with mucus hypersecretion.

Antibacterial Secondary Metabolites from Marine-Derived Fungus Aspergillus sp. IMCASMF180035

Four new secondary metabolites, including one spiro[anthracenone-xanthene] derivative aspergiloxathene A (1), one penicillide analogue, Δ^2′-1′-dehydropenicillide (2), and two new phthalide derivatives, 5-methyl-3-methoxyepicoccone (3) and 7-carboxy-4-hydroxy-6-methoxy-5-methylphthalide (4), together with four known compounds, yicathin C (5), dehydropenicillide (6), 3-methoxyepicoccone (7), 4-hydroxy-6-methoxy-5-methylphthalide (8), were identified from the marine-derived fungus Aspergillus sp. IMCASMF180035. Their structures were determined by spectroscopic data, including high-resolution electrospray ionization mass spectrometry (HRESIMS), 1D and 2D nuclear magnetic resonance (NMR) techniques. Compound 1 was identified as the first jointed molecule by xanthene and anthracenone moieties possessing an unprecedented carbon skeleton with spiro-ring system. All compounds were evaluated activities against Staphylococcus aureus, methicillin resistant S. aureus (MRSA), Escherichia coli, Escherichia faecium, Pseudomonas aeruginosa, and Helicobacter pylori. Compound 1 showed significant inhibitory effects against S. aureus and MRSA, with minimum inhibitory concentration (MIC) values of 5.60 and 22.40 µM. Compounds 2 and 6 exhibited potent antibacterial activities against H. pylori, with MIC values of 21.73 and 21.61 µM, respectively.

Three new polyketides from the endophytic fungus Penicillium purpurogenum

Three new polyketides including two benzophenone derivatives, penibenzones A and B (1 and 2), and a new phthalide derivative, penibenzone C (3), along with six known compounds, were isolated from the solid-substrate cultures of the endophytic fungus Penicillium purpurogenum IMM003. Their structures were elucidated on the basis of spectroscopic data (UV, IR, HRESIMS, 1D and 2D NMR). All compounds were evaluated for inhibitory activity against pancreatic lipase, but none of them displayed activity.[Formula: see text].

A Brief Overview of Two Major Strategies in Diversity-Oriented Synthesis: Build/Couple/Pair and Ring-Distortion

In the interdisciplinary research field of chemical biology and drug discovery, diversity-oriented synthesis (DOS) has become indispensable in the construction of novel small-molecule libraries rich in skeletal and stereochemical diversity. DOS aims to populate the unexplored chemical space with new potential bioactive molecules via forward synthetic analysis. Since the introduction of this concept by Schreiber, DOS has evolved along with many significant breakthroughs. It is therefore important to understand the key DOS strategies to build molecular diversity with maximized biological relevancy. Due to the length limitations of this mini review, we briefly discuss the recent DOS plans using build/couple/pair (B/C/P) and ring-distortion strategies for the synthesis of major biologically relevant target molecules like natural products and their related compounds, macrocycles, and privileged structures.

Marine-Derived Penicillium Species as Producers of Cytotoxic Metabolites

Since the discovery of penicillin, Penicillium has become one of the most attractive fungal genera for the production of bioactive molecules. Marine-derived Penicillium has provided numerous excellent pharmaceutical leads over the past decades. In this review, we focused on the cytotoxic metabolites * (* Cytotoxic potency was referred to five different levels in this review, extraordinary (IC₅₀/LD₅₀: <1 μM or 0.5 μg/mL); significant (IC₅₀/LD₅₀: 1~10 μM or 0.5~5 μg/mL); moderate (IC₅₀/LD₅₀: 10~30 μM or 5~15 μg/mL); mild (IC₅₀/LD₅₀: 30~50 μM or 15~25 μg/mL); weak (IC₅₀/LD₅₀: 50~100 μM or 25~50 μg/mL). The comparative potencies of positive controls were referred when they were available). produced by marine-derived Penicillium species, and on their cytotoxicity mechanisms, biosyntheses, and chemical syntheses.

Improved pestalotiollide B production by deleting competing polyketide synthase genes in Pestalotiopsis microspora

Pestalotiollide B, an analog of dibenzodioxocinones which are inhibitors of cholesterol ester transfer proteins, is produced by Pestalotiopsis microspora NK17. To increase the production of pestalotiollide B, we attempted to eliminate competing polyketide products by deleting the genes responsible for their biosynthesis. We successfully deleted 41 out of 48 putative polyketide synthases (PKSs) in the genome of NK17. Nine of the 41 PKS deleted strains had significant increased production of pestalotiollide B (P &lt; 0.05). For instance, deletion of pks35, led to an increase of pestalotiollide B by 887%. We inferred that these nine PKSs possibly lead to branch pathways that compete for precursors with pestalotiollide B, or that convert the product. Deletion of some other PKS genes such as pks8 led to a significant decrease of pestalotiollide B, suggesting they are responsible for its biosynthesis. Our data demonstrated that improvement of pestalotiollide B production can be achieved by eliminating competing polyketides.

Importance and synthesis of benzannulated medium-sized and macrocyclic rings (BMRs)

Cyclic molecular frameworks, especially the benzannulated medium-sized and macrocyclic ring (BMR) systems, constitute an integral component of a large number of biologically significant natural or synthetic molecules.

Dibenzodioxocinones—A new class of CETP inhibitors

Derivatives of the natural product 11-hydroxy-3-[(S)-1-hydroxy-3-methylbutyl]-4-methoxy-9-methyl-5H,7H-dibenzo[b,g][1,5]dioxocin-5-one 1 were studied as novel CETP inhibitors. Compound 2 was identified from HTS as a micromolar inhibitor. The compound suffered from very low stability in plasma. Optimisation by partial synthesis started from 1 and led to low-nanomolar inhibitors with good stability in rat plasma.