Kaempulchraols A–H, Diterpenoids from the Rhizomes of <i>Kaempferia pulchra</i> Collected in Myanmar

Eight new diterpenoids, kaempulchraols A–H (<b>1</b>–<b>8</b>), along with five known analogues were isolated from the CHCl₃-soluble extract of rhizomes of <i>Kaempferia pulchra</i> of Myanmar. The structures of these compounds were elucidated using extensive spectroscopic techniques including X-ray diffraction analysis. All the isolates were tested for their antiproliferative activity against a panel of five human cancer cell lines (A549, human lung cancer; HeLa, human cervix cancer; PANC-1 and PSN-1, human pancreatic cancer; MDA-MB-231, human breast cancer) and TIG-3, normal human primary fibroblast cells. Kaempulchraol F (<b>6</b>) exhibited weak activity against the human pancreatic PSN-1 cell line with an IC₅₀ value of 12.3 μM

Phenanthrene Derivatives from <i>Cymbidium</i> Great Flower Marie Laurencin and Their Biological Activities

A new phenanthrendione, ephemeranthoquinone B (<b>1</b>), two phenanthrenes, marylaurencinols A (<b>2</b>) and B (<b>3</b>), and a phenanthrene glucoside, marylaurencinoside A (<b>4</b>), were isolated from the roots of <i>Cymbidium</i> Great Flower Marie Laurencin, along with six known phenanthrenes, <b>5</b>–<b>10</b>. The structures of these compounds were established by a combination of extensive NMR spectroscopy and/or X-ray crystallographic analysis and chemical degradation. The compounds were tested for antibacterial activities against <i>Bacillus subtilis</i> and <i>Klebsiella pneumoniae</i> and for cytotoxic activity against the human promyelocytic leukemia (HL-60) cell line. Compounds <b>1</b>, <b>3</b>, and <b>6</b> showed antibacterial activities with minimum inhibitory concentration (MIC) values in the range of 4.88 to 65.10 μM. Notably, ephemeranthoquinone B (<b>1</b>) had a strong antibacterial effect on <i>B. subtilis</i>. Furthermore, <b>1</b> exhibited moderate cytotoxic activity (IC₅₀ 2.8 μM) against HL-60 cells. Compounds <b>4</b>–<b>9</b> also showed weak cytotoxic activity against the HL-60 cell line with IC₅₀ values of 19.3–52.4 μM

Aryl–Allene Cyclization via a Hg(OTf)₂‑Catalytic Pathway

Hg­(OTf)₂-catalyzed aryl–allene cyclization accompanied by formation of a quaternary carbon center has been realized. Deuterium-labeling experiments and computational modeling were used to propose a novel catalytic pathway involving direct H-transfer from the aromatic ring to the vinyl mercury moiety followed by mercury 1,2-migration

Total Synthesis of (−)-Thallusin: Utilization of Enzymatic Hydrolysis Resolution

(−)-Thallusin, isolated from a marine bacterium, is the only known natural product to act as an algal morphogenesis inducer. Because (−)-thallusin can only be obtained in exceedingly limited amounts from microbial cultivation, a synthetic supply of this compound is highly desirable. Here, we describe a novel synthetic pathway to (±)-thallusin and the first asymmetric synthesis of (−)-thallusin utilizing the enzymatic hydrolysis resolution with the combination of lipase PS-30 and lipase M Amamo-10

Opaliferin, a New Polyketide from Cultures of Entomopathogenic Fungus <i>Cordyceps</i> sp. NBRC 106954

Opaliferin, a polyketide with a unique partial structure in which a cyclopentanone and tetrahydrofuran were connected with an external double bond, was isolated from the insect pathogenic fungus <i>Cordyceps</i> sp. NBRC 106954. The structure and relative configuration of opaliferin were determined by spectroscopic analysis and X-ray crystallography. The absolute configuration was established by anomalous dispersion effects in X-ray diffraction measurements on the crystal of di­(<i>p</i>-bromobenzoyl) ester of opaliferin. A plausible biosynthetic pathway for opaliferin is proposed

Opaliferin, a New Polyketide from Cultures of Entomopathogenic Fungus <i>Cordyceps</i> sp. NBRC 106954

Opaliferin, a polyketide with a unique partial structure in which a cyclopentanone and tetrahydrofuran were connected with an external double bond, was isolated from the insect pathogenic fungus <i>Cordyceps</i> sp. NBRC 106954. The structure and relative configuration of opaliferin were determined by spectroscopic analysis and X-ray crystallography. The absolute configuration was established by anomalous dispersion effects in X-ray diffraction measurements on the crystal of di­(<i>p</i>-bromobenzoyl) ester of opaliferin. A plausible biosynthetic pathway for opaliferin is proposed

Development of Vizantin, a Safe Immunostimulant, Based on the Structure–Activity Relationship of Trehalose-6,6′-dicorynomycolate

Vizantin, 6,6′-bis-<i>O</i>-(3-nonyldodecanoyl)-α,α′-trehalose, was developed as a safe immunostimulator on the basis of a structure–activity relationship (SAR) study with trehalose 6,6′-dicorynomycolate (TDCM). It was possible to synthesize vizantin on a large scale more easily than in the case of TDCM, and the compound exhibited more potent prophylactic effect on experimental lung metastasis of B16–F0 melanoma cells. Because vizantin stimulated human macrophages, it is a promising candidate for clinical application