Neolignans and polyoxygenated seco-cyclohexenes from the stems and leaves of Piper suipigua Buch.-Ham. ex D. Don.

Five new compounds including, a neolignan, eupomatenoid-19 (1) and four polyoxygenated seco-cyclohexenes, artahongkongenes G-J (2-5), together with fifteen known compounds (6-20) were isolated from the stems and leaves of Piper suipigua Buch.-Ham. ex D. Don. Their structures were determined by spectroscopic evidence (IR, UV, 1H NMR, 13C NMR and 2 D NMR) as well as MS. The absolute configurations of polyoxygenated seco-cyclohexenes 2-8 were identified by NOESY data and by comparison of their experimental and calculated ECD spectral data. Neolignans, eupomatenoid-19 (1) and eupomatenoid-7 (10), displayed cytotoxicity against several cancer cell lines. In addition, eupomatenoid-7 (10) showed antibacterial activity against Bacillus cereus, Bacillus subtilis and Staphylococcus aureus.

Acrotrione B, a Prenylated and Highly Oxidized Xanthenoid with Antibacterial and Anti-proliferative Activities from the Roots of Acronychia pedunculata.

A new prenylated xanthenoid with a highly oxidized core, acrotrione B (1: ), together with six previously reported acetophenones (2:  - 7: ), were isolated from the roots of Acronychia pedunculata. The structures of the isolated compounds were elucidated by thorough analysis of their 1D and 2D NMR spectroscopic data. The relative and absolute configurations of acrotrione B were determined by electronic circular dichroism (ECD) calculations. Acrotrione B is an unusual, oxidized xanthenoid with a cyclohexadienone core that has not been previously reported. It thus represents a new skeletal type within the xanthenoid class. Acrotrione B (1: ) exhibited anti-proliferative activity against Hela (IC50 = 16.0 µM) and A549 (IC50 = 16.3 µM) cell lines. 5'-Prenylacrovestone (4: ) and acrovestone (5: ) were even more potent with IC50 values of 5.1 µM and 0.77 µM, respectively, against Hela cells and 11.8 µM and 1.13 µM, respectively, against A549 cells. Moreover, acrotrione B (1: ) displayed moderate antibacterial activities against Staphylococcus aureus, Bacillus cereus, and Bacillus subtilis, with MIC values in the range of 16 - 64 µg/mL. Finally, acropyrone (6: ) showed a significant suppression of lipopolysaccharide (LPS) induced NO production in murine macrophage J774.A1 cells (IC50 = 8.9 µM).

Cytotoxic and antibacterial xanthones from the roots of Maclura cochinchinensis.

Three new furanoxanthones, macochinxanthones A-C (1-3) and sixteen known xanthones (4-19) were isolated from the roots of Maclura cochinchinensis. Their structures were elucidated by spectroscopic analysis including NMR, UV and IR, as well as mass spectrometry. Chiral-phase HPLC analysis of 1-3 revealed that they were scalemic mixtures with an enantiomeric excess (ee) of 0.05%, 36.8% and 8%, respectively. Most of the isolated xanthones exhibited potent cytotoxicity against four cancer cell lines (KB, HelaS3, A549 and HepG2) with IC50 values in the range of 1.29-90.15 µM. In addition, many of them displayed antibacterial activity against Gram-positive bacteria and Methicillin resistant Stephylococus aureus (MRSA) with MIC values in the range of 4-128 µg/mL.

Derrisrobustones A-D, isoflavones from the twig extract of Derris robusta (DC.) Benth. and their α-glucosidase inhibitory activity.

Three previously undescribed isoflavones, derrisrobustones A-C, and a previously undescribed natural isoflavone, derrisrobustone D, along with eight known isoflavones, were isolated from the twig extract of Derris robusta (DC.) Benth. All structures were identified by extensive spectroscopic analysis. Derrisrobustones A-C were obtained as scalemic mixtures and were resolved by chiral HPLC. The (1″R, 2″R) absolute configuration of (+)-derrisrobustone B was established by single-crystal X-ray crystallography using Cu Kα radiation. The absolute configurations of derrisrobustones A and C were determined by analysis of experimental and calculated ECD data. All compounds were evaluated for their α-glucosidase inhibitory activity. Of these, derrubone displayed the best α-glucosidase inhibitory activity with an IC50 value of 64.2 µM.

Anti-inflammatory and cytotoxic agents from Xylaria sp. SWUF09-62 fungus.

The ongoing search for anti-cancer agents from microorganisms led to the isolation of four new compounds including 6-ethyl-8-hydroxy-4H-chromen-4-one (1), 6-ethyl-7,8-dihydroxy-4H-chromen-4-one (2), (3S)-3,4-dihydro-8-hydroxy-7-methoxy-3-methylisocoumarin (3) and (3S)-3,4-dihydro-5,7,8-trihydroxy-3-methylisocoumarin (4), together with eleven known compounds (5-15) from Xylaria sp. SWUF09-62 fungus. The chemical structures were deduced from IR, 1D and 2D NMR, and MS data. The absolute configurations of 3 and 4 were determined by ECD experiment. Compounds 2 and 4 indicated possible chemo-prevention and chemo-therapeutic properties, exhibited anti-inflammatory properties by reducing nitric oxide production in LPS-stimulated RAW264.7 cells (IC50 = 1.57 ± 0.25 and 3.02 ± 0.27 µg/mL) and cytotoxicity against HT29 cells (IC50 = 16.46 ± 0.48 and 97.78 ± 7.14 µg/mL).

Types A and D Trichothecene Mycotoxins from the Fungus Myrothecium roridum.

Chromatographic separation of extracts from the fungal biomass of a plant pathogenic fungus, Myrothecium roridum, yielded 8 trichothecene toxins including 6 type D trichothecenes (1: -6: ) and 2 type A trichothecenes (7: -8: ). 6',12'-Epoxymyrotoxin A (1: ) and 7'-hydroxymytoxin B (2: ) were new macrocyclic trichothecenes, while the other trichothecenes were identified as myrotoxin B (3: ), myrotoxin D hydrate (4: ), 2',3'-epoxymyrothecine A (5: ), miotoxin A (6: ), and 2 trichothecenes lacking the macrocyclic lactone system, roridin L-2 (7: ) and trichoverritone (8: ). The structures of these mycotoxins were characterized using spectroscopic methods. The absolute configurations of 1: and 2: were determined by NOESY and a comparison of their experimental and calculated ECD spectra. Most of these mycotoxins (1: -4: and 6: ) exhibited highly potent antimalarial activity against Plasmodium falciparum. They also showed strong cytotoxicity towards KB and NCI-H187 cell lines (IC50 0.60 - 112.28 nM), as well as the Vero cell line (IC50 1.50 - 46.51 nM).

Bioactive homogentisic acid derivatives from fruits and flowers of Miliusa velutina.

Chromatographic separation of fruits and flowers of the Thai medicinal plant, Miliusa velutina, resulted in the isolation of five new rare homogentisic acid derivatives, miliusanal (1) and miliusanones A-D (2-5), together with fifteen known secondary metabolites (6-20). Their structures were determined through the use of extensive spectroscopic data. The absolute configurations of homogentisic acid derivatives 2-7 were identified using NOESY data and a comparison of experimental and calculated ECD spectral data. Compounds 2, 3, 6, and 7 showed antimalarial activity with IC50 values in the range of 3.3-5.2 µg/mL. Compound 6 also showed activity against Mycobacterium tuberculosis with an MIC value of 50 µg/mL. Compounds 1-3, 6 and 7 exhibited cytotoxicity againt KB, MCF-7, NCI-H187 and Vero cell lines with IC50 values in the range of 5.8-40.4 µg/mL. In addition, compounds 1, 2 and 6 showed moderate antibacterial activities against three Gram-positive bacteria (Bacillus cereus, Staphylococcus aureus, and Methicillin resistant S. aureus) with MICs in the range of 32-64 µg/mL.