Bioactive polyketides from the fungus Astrocystis sp. BCC 22166

Five new compounds, phthalide 1, dihydroisocoumarin 2, and 3, pyrone 4, and benzophenone 5, together with nine known compounds, 3,4-dihydro-4,5,8-trihydroxy-3-methylisocoumarin, sclerotinin A, methyl-8-hydroxy-6-methylxanthone-1-carboxylate, sydowinin A, conioxanthone A, 1,3,8-trihydroxy-6-methylxanthone, 1,8-dihydroxy-3-methoxy-6-methylxanthone, coniochaetone B, and xylaranol B, were isolated from the fungus Astrocystis sp. BCC 22166. Structures of these compounds were elucidated using NMR spectroscopic and MS spectrometric analyses. Compound 1 exhibited antibacterial activity against Bacillus cereus (IC₅₀=12.5 μg/mL) while compound 2 showed cytotoxicity to KB and Vero cells (IC₅₀=22.6 and 48.2 μg/mL).     

Cytotoxic tropolones from the fungus Nemania sp. BCC 30850

Twelve new compounds, including nine tropolones, nemanolones A?I (1–9), three 7-isochromenones, nemanecins A?C (10–12), and a new naturally isolated 4-isochromanone (13), along with two known compounds, 7,8-dihydroxy-3-methyl isochroman-4-one (XJP), and chaetoquadrin F, were isolated from culture broth of the fungus Nemania sp. BCC 30850. Structures of these compounds were elucidated by NMR and MS spectroscopic analyses. Nemanolones exhibited cytotoxic activities and two of them, compounds 1 and 2, also showed antibacterial activity against Bacillus cereus and antifungal activity against Candida albicans.     

Cytotoxic sesquiterpenes from luminescent mushroom Neonothopanus nambi

Four new aristolane sesquiterpenes named nambinones A–C (1–3) and 1-epi-nambinone B (4), a new sesquiterpene, nambinone D (5), a known compound, aurisin A (6) as well as a new dimeric sesquiterpene, aurisin K (7), were isolated from two isolates of luminescent mushroom, Neonothopanus nambi, PW1 and PW2. These structures were established on the basis of spectroscopic evidence. The relative configuration of 6 was determined by X-ray crystallographic analysis. Compounds 6 and 7 exhibited antimalarial activity against Plasmodium falciparum and antimycobacterial activity against Mycobacterium tuberculosis. Compounds 3, 6, and 7 showed cytotoxicity against NCI-H187 cancer cell lines. In addition, 6 and 7 showed cytotoxicity against the cholangiocarcinoma cell lines.     

(+)-Bornyl piperate, a new monoterpene ester from Piper aff. pedicellatum roots

A new monoterpene ester, (+)-bornyl piperate was isolated from the underground roots of Piper aff. pedicellatum and its structure was elucidated on the basis of spectroscopic evidence and confirmed by X-ray analysis. The compound crystallizes in the triclinic space group P1 with a=7.3232(4) A, b=11.4705(7) A, c=23.2520(14) A, V=1943.6(2) A(3). This compound showed an antituberculosis activity against Mycobacterium tuberculosis (H(37)Ra strain) with the minimum inhibitor concentration (MIC) of 25 microg/ml.     

Dihydronaphthalenones from endophytic fungus Fusarium sp. BCC14842

Eleven new dihydronaphthalenones 1-11, together with five known compounds; 5-hydroxydihydrofusarubin C (12), javanicin, bostrycoidin, anhydrofusarubin, and 3-O-methylfusarubin, were isolated from the endophytic fungus Fusarium sp. BCC14842. Structures were elucidated by analyses of the NMR spectroscopic and mass spectrometry data. Javanicin, 3-O-methylfusarubin, compounds 3 and 7 exhibited antimycobacterial and cytotoxic activities. Javanicin also displayed antifungal activity with IC₅₀ of 6.16 μg/mL, while compounds 2, 4, 5, 8, and 12 showed only cytotoxic activity.     

Beta2-amino acids in the design of conformationally homogeneous cyclo-peptide scaffolds

Herein, we report studies on the influence of chiral beta(2)-amino acids in the design of conformationally homogeneous cyclic tetrapeptide scaffolds. The cyclic alpha-tetrapeptide cyclo(-Phe-D-Pro-Lys-Phe-) (1) and its four mixed analogues, having one of the alpha-Phe replaced by either an (S)- or an (R)-beta(2)hPhe residue (i.e., cyclo(-(R)-beta(2)hPhe-D-Pro-Lys-Phe) (2a), cyclo(-(S)-beta(2)hPhe-D-Pro-Lys-Phe-) (2b), cyclo(-Phe-D-Pro-Lys-(R)-beta(2)hPhe-) (3a), and cyclo(-Phe-D-Pro-Lys-(R)-beta(2)hPhe-) (3b)), were all synthesized through solid-phase procedures followed by solution-phase cyclization. Initially, all five cyclo-peptides were analyzed by (1)H NMR spectroscopic studies in different solvents and at variable temperatures. Subsequently, a detailed 2D NMR spectroscopic analysis of three of the mixed peptides in water was performed, and the information thus extracted was used as restraints in a computational study on the peptides' conformational preference. An X-ray crystallographic study on the side chain-protected (Boc) 2a revealed the solid-state structure of this peptide. The results presented herein, together with previous literature data on beta(3)-amino acid residues, conclusively demonstrate the potential of beta-amino acids in the design of conformationally homogeneous cyclic peptides that are homologous to peptides with known applications in biomedicinal chemistry and as molecular receptors.     

Tetrahydro-1,4-epoxynaphthalene-1-carboxylic acid: a chiral derivatizing agent for the determination of the absolute configuration of secondary alcohols

A new chiral derivatizing agent, tetrahydro-1,4-epoxynaphthalene-1-carboxylic acid (THENA), with a represented syn-periplanar disposition of O-C_α-CO as a part of the bicyclic system to lock the aromatic residue conformation and the availability of an internal reference proton for ¹H NMR spectral alignment, is introduced. In the determination of the absolute configuration of chiral secondary alcohols, THENA offered good uniformity of Δδ with high reliability, resulting in unambiguous assignment of the absolute configuration.     

Highly Conjugated Ergostane‐Type Steroids and Aranotin‐Type Diketopiperazines from the Fungus Aspergillus terreus BCC 4651

Two new ergostane derivatives, 12β,15α,25,26‐tetrahydroxyergosta‐4,6,8(14),22‐tetraen‐3‐one ( 1 ) and 12β,15α,25,28‐tetrahydroxyergosta‐4,6,8(14),22‐tetraen‐3‐one ( 2 ), and a new aranotin‐type diketopiperazine, bisdethiobis(methylsulfanyl)apoaranotin ( 3 ), were isolated from the fungus Aspergillus terreus BCC 4651. The structures of the new compounds were elucidated by means of NMR spectroscopic and MS analyses.     

Intramolecular acylation of α-sulfinyl carbanion: A new general route to 5-substituted Δ2 cyclopentenones

A general method for the preparation of 5-substituted Δ²-cyclopentenones $\text{via}$ the intramolecular acylation of $\text{αot}$-sulfinyl carbanions has been demonstrated.     

Terpenoids with potent antimycobacterial activity against Mycobacterium tuberculosis from Trigonostemon reidioides roots

Phytochemical investigation of Trigonostemon reidioides roots led to the isolation of fourteen compounds. These included six new diterpenoids, trigonoreidons A?F (1?6), together with eight known diterpenoids 7?14. The structures of the new compounds were elucidated by spectroscopic techniques and the absolute configuration at the asymmetric carbon was determined by the modified Mosher's method. The structure of trigonoreidon B (2) was confirmed by X-ray crystallographic analysis. The known compounds were identified by comparison of the spectroscopic and physical data with those of reported values. The isolated compounds were evaluated for antimycobacterial activity against Mycobacterium tuberculosis. Among the compounds that exhibited antimycobacterial activity, the diterpenoids rediocide C (12) and rediocide G (14) were the most active compounds, with the MIC value of 3.84 μM.