Surk-Sik Moon

Structure and reactivity of illudins

Abstract An X-ray crystallographic analysis of illudin S, an anitumor sesquiterpene from Omphalotusilludens, has been carried out. Crystal data: C15H20O4, orthorhombic, space group P21212, a = 15.103(5), b = 10.574(5), c = 8.917(3) A, Z = 4, F(000) = 568, λ (Cu) = 1.54184 A. Final residual index R = 0.037. Interatomic distances indicate nonbonded repulsive interactions between the methylenes of the cyclopropane ring and the adjacent tertiary hydroxyl and methyl groups. Relief of this interaction may explain the ready isomerization of illudins to isoilludins. Molecular mechanics calculations show isoilludin M to be ∼5 kcal/mol more stable than illudin M in agreement with this postulate. Reaction of illudin M with dilute HCl gives two chloroindantriols by nucleophilic attack of chloride on the cyclopropane ring leading to a quinoid intermediate which is trapped by solvent. mudins can thus act as bifunctional alkylating agents.

Synthesis of dehydro-oogoniol and oogoniol: the adrenosterone route

Abstract Dehydro-oogoniol(3β,11α,15β,29-tetrahydroxystigmasta-5,24(28)(E)-dien-7-one), a female-activating hormone of the water mold Achlya, has been synthesized from 4-androstene-3,11,17-trione by a series of highly stereoselective reactions. One of these involved 1,4-addition of the magnesium cyanocuprate derivative of 3-(1,3-dioxolan-2-yl)-4-methylpentyl bromide to 3β-hydroxy-15β,16β-epoxy-11-oxo-(17E)-pregna -5, 17(20)-diene 3-tert -butyidimethylsilyl ether. The structure of an intermediate, 3β,11β,15β-triacetoxy-5-cholesten-24-one, was confirmed by X-ray crystallographic analysis. Oogoniol [(24R)-3β,11α,15β,29-tetrahydroxy-stigmast-5-en-7-one] was synthesized in a similar manner by reaction of the magnesium cyanocuprate of (S)-3-(1-methylethyl)-5-[(tert-butyldimethylsilyl)oxy]pentyl bromide with the above epoxy pregnadiene

Cytotoxic Grifolin Derivatives Isolated from the Wild Mushroom Boletus pseudocalopus (Basidiomycetes)

Activity‐guided purification of a MeOH extract of the Korean wild mushroom Boletus pseudocalopus afforded three new grifolin derivatives, 1–3, along with four known phenolic compounds 4–7. Their structures were established by a combination of 1H‐ and 13C‐NMR, NOESY, and extensive two‐dimensional NMR spectroscopic experiments such as gCOSY, gHSQC, gHMBC, and ROESY. The major metabolites 4 and 5 were subjected to reduction to provide the side chain‐reduced compounds 8 and 9 for biological testing. All of the compounds except compound 6 showed anticancer activities in the range of IC50 3.5–11.0 μg/ml against human lung carcinoma A549 and mouse melanoma B16F1 cell lines. In addition, all compounds showed moderate radical‐scavenging activities determined by DPPH assay.

Tea triterpenoidal saponins from the roots of Camellia sinensis have inhibitory effects against alcohol dehydrogenase.

Ten new polyhydroxyolean-12-ene pentacyclic triterpenoidal saponins, named rogchaponins 1-10, were isolated from the methanolic extract of the roots of Camellia sinensis by a series of chromatographic methods (silica gel flash column and C18 MPLC followed by C18 HPLC). Their structures were established by 1D and 2D-NMR techniques along with IR and HR-TOF-MS. Rogchaponins R4 ( 4) and R5 (5) showed inhibitory activities against yeast alcohol dehydrogenase (ADH) with IC (50) values of 16.1 ± 3.2 and 15.4 ± 3.3 µM, respectively. A 4-methylpyrazole positive control exhibited an IC (50) of 2750 ± 50 µM. However, the saponins showed no inhibitory activity against yeast aldehyde dehydrogenase (ALDH).

Cyclic Dipeptides from Bacillus vallismortis BS07 Require Key Components of Plant Immunity to Induce Disease Resistance in Arabidopsis against Pseudomonas Infection

Cyclic dipeptides (CDPs) are one of the simplest compounds produced by living organisms. Plant-growth promoting rhizobacteria (PGPRs) also produce CDPs that can induce disease resistance. Bacillus vallismortis strain BS07 producing various CDPs has been evaluated as a potential biocontrol agent against multiple plant pathogens in chili pepper. However, plant signal pathway triggered by CDPs has not been fully elucidated yet. Here we introduce four CDPs, cyclo(Gly-L-Pro) previously identified from Aspergillus sp., and cyclo(L-Ala-L-Ile), cyclo(L-Ala-L-Leu), and cyclo(LLeu-L-Pro) identified from B. vallismortis BS07, which induce disease resistance in Arabidopsis against Pseudomonas syringae infection. The CDPs do not directly inhibit fungal and oomycete growth in vitro. These CDPs require PHYTOALEXIN DEFICIENT4, SALICYLIC ACID INDUCTION DEFICIENT2, and NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 important for salicylic acid-dependent defense to induce resistance. On the other hand, regulators involved in jasmonate-dependent event, such as ETHYLENE RECEPTOR1, JASMONATE RESPONSE1, and JASMONATE INSENSITIVE1, are necessary to the CDP-induced resistance. Furthermore, treatment of these CDPs primes Arabidopsis plants to rapidly express PATHOGENESIS-RELATED PROTEIN4 at early infection phase. Taken together, we propose that these CDPs from PGPR strains accelerate activation of jasmonate-related signaling pathway during infection.