Kan Chantrapromma

Cassane diterpenoids from the stem of Caesalpinia pulcherrima.

Cassane diterpenoids: pulcherrin A, pulcherrin B, pulcherrin C, neocaesalpin P, neocaesalpin Q and neocaesalpin R, together with eight known compounds: isovouacapenol C, 6beta-cinnamoyl-7beta-hydroxy-vouacapen-5alpha-ol, pulcherrimin E, pulcherrimin C, alpha-cadinol, 7-hydroxycadalene, teucladiol and bonducellin were isolated from the stem of Caesalpinia pulcherrima. The chemical structures were elucidated by analysis of their spectroscopic data.

Antimalarial, antimycobacterial and cytotoxic limonoids from Chisocheton siamensis.

Five limonoids isolated from the seeds of Chisocheton siamensis were tested for their antimalarial activity against Plasmodium falciparum, antimycobacterial activity against Mycobacterium tuberculosis and cytotoxic activity against NCI-H187 (human small cell lung cancer), KB (oral human epidermal carcinoma) and MCF-7 (breast cancer) cancer cell lines. All limonoids (1-5) showed inhibitory effect against Plasmodium falciparum with IC(50) values ranging from 2.06 to 6.31 microg/ml. Only azadiradione (2) exhibited strong inhibitory effect against Mycobacterium tuberculosis with the MIC of 6.25 microg/ml. Compounds 1-4 also showed cytotoxic activity against NCI-H187, KB and MCF-7 cancer cell lines and dysobinine (1) had the highest activity with IC(50) of 1.67, 3.17 and 2.15 microg/ml, respectively.

Nitric Oxide Inhibitory Activity of Xanthones from the Green Fruits of Cratoxylum formosum ssp. pruniflorum

Three new xanthones, pruniflorone M-O (1–3), and a new xanthonolignoid, 3-methoxy-5′-demethoxycadensin G (4), were isolated from the green fruits of Cratoxylum formosum ssp. pruniflorum along with three known xanthones (5–7) and a known flavonoid (8). Their structures were elucidated by spectroscopic methods and the structure of 1 was also determined by X-ray crystallography. Compounds 2 and 7 showed potent nitric oxide inhibitory activity with IC50 values of 4.4 and 4.3 μM, respectively. Moreover, 7 also showed strong antibacterial activity against both Gram-positive and Gram-negative bacteria with an MIC value of 4.67 μg mL–1.

New cytotoxic steroids from the fruits of Syzygium siamense.

A new sterol, stigmast-5-ene-3β,17α-diol (1), together with six known compounds, stigmast-5-ene-3β-yl formate (2), stigmast-5-ene-3β,7α-diol (3), stigmast-5-ene-7α-methoxy-3β-ol (4), stigmast-5-ene-3-one (5), 3β-sitostanol (6), and 3β-sitosterol (7), was isolated from the fruits of Syzygium siamense, of which compound 2 is reported for the first time from a natural source. Their structures were elucidated by spectroscopic methods. The isolated compounds (1–7) were evaluated for their cytotoxic activities against human oral epidermoid carcinoma cancer (KB), human breast cancer (BC), and human small cell lung cancer (NCI-H187) cell lines.

Application of Residual Dipolar Couplings and Selective Quantitative NOE to Establish the Structures of Tetranortriterpenoids from Xylocarpus rumphii

Nine triterpenoid derivatives were isolated from the heartwood of Xylocarpus rumphii and were identified as xylorumphiins E (1), C (2), L (3), and M-R (4-9). Compounds 4-9 have a hemiacetal group in the triterpenoid side chain, making them impossible to purify. Purification was achieved after acetylation and subsequent separation of the epimeric mixtures of acetates; however differentiaition of the R and S epimers was not possible using standard NMR techniques. In one case, the relative configuration of a remotely located stereocenter with respect to the stereocenters in the main skeleton was unambiguously determined using residual dipolar couplings. Dipolar couplings were collected from the sample oriented in compressed poly(methyl methacrylate) gels swollen in CDCl3. In another case, the relative configuration was determined using 1D selective quantitative NOE experiments. Xylorumphiin K (10), xyloccensin E, taraxer-14-en-3β-ol, (22S)-hydroxytirucalla-7,24-diene-3,23-dione, and 25-hydroxy-(20S,24S)-epoxydammaran-3-one were isolated from the bark of the same plant. Compounds 3-10 are new compounds. Compounds 1-6 and xyloccensin E were tested at one concentration, 1 × 10-5 M, in the NCI59 cell one-dose screen but did not show significant activity.

Redetermination and absolute configuration of pruniflorone M monohydrate

The title xanthone known as pruniflorone M (systematic name: (2R)-5,10-dihydroxy-2-hydroxymethyl-1,1-dimethyl-1H-furo[2,3-c]xanthen-6-one), crystallized in a monohydrate form, C18H16O6·H2O. It was isolated from the green fruits of Cratoxylum formosum ssp. pruniflorum. The structure of the title compound has been reported previously [Boonnak et al. (2010 ▶). Aust. J. Chem. 63, 1550–1556], but we report here the absolute configuration determined using Cu Kα radiation. There are two crystallograpically independent molecules in the asymmetric unit, which differ slightly in the bond angles. The hydroxymethyl substituents at position 2 of the furan rings of both pruniflorone M molecules adopt R configurations. In both molecules, the three rings of the xanthone skeleton are approximately coplanar, with an r.m.s. deviation of 0.0124 (2) Å for one molecule and 0.0289 (2) Å for the other, and the furan ring adopts an envelope conformation. In the crystal, molecules of pruniflorone M and water are linked into a two-dimensional network by O—H⋯O hydrogen bonds and weak C—H⋯O interactions. The crystal structure is further consolidated by π–π interactions with centroid–centroid distances in the range 3.5987 (13)–3.7498 (14) Å. Short C⋯C [3.378 (3) Å] and O⋯O [2.918 (3) Å] contacts are also observed.

1‐[4‐(3,5‐Di­methoxy‐2‐methyl­phenoxy)‐2,6‐di­hydroxy‐3‐methyl­phenyl]­ethanone

The benzene rings of the title compound, C18H20O6, are nearly perpendicular to each other [dihedral angle 75.2 (1)°]. The two methoxy groups and the acetyl group are almost coplanar to their attached benzene rings. One hydroxyl group is involved in an intramolecular O—H⋯O hydrogen bond with the adjacent acetyl O atom. The crystal structure is stabilized by intermolecular O—H⋯O contacts.

Synthesis, antityrosinase activity of curcumin analogues, and crystal structure of (1E,4E)-1,5-bis(4-ethoxyphenyl)penta-1,4-dien-3-one

Five derivatives of curcumin analogue (R = OCH2CH3 (1), R = N(CH3)2 (2), R = 2,4,5-OCH3 (3), R = 2,4,6-OCH3 (4), and R = 3,4,5-OCH3 (5)) were synthesized and characterized by 1H NMR, FT-IR and UV–Vis spectroscopy. The synthesized derivatives were screened for antityrosinase activity, and found that 4 and 5 possess such activity. The crystal structure of 1 was determined by single crystal X-ray diffraction: monoclinic, sp. gr. P21/c, a = 17.5728(15) Å, b = 5.9121(5) Å, c = 19.8269(13) Å, β = 121.155(5)°, Z = 4. The molecule 1 is twisted with the dihedral angle between two phenyl rings being 15.68(10)°. In the crystal packing, the molecules 1 are linked into chains by C−H···π interactions and further stacked by π···π interactions with the centroid–centroid distance of 3.9311(13) Å.

ent-(15S)-Pimar-8(14)-ene-15,16-diol

The title compound {systematic name: (S)-1-[(2S,4aR,8aR)-2,4b,8,8-tetramethyl-2,3,4,4a,4b,5,6,7,8,8a,9,10-dodecahydrophenanthren-2-yl]ethane-1,2-diol}, C20H34O2, is an ent-pimarane diterpenoid which was isolated from the stem bark of Ceriops tagal. In the asymmetric unit, there are two crystallographically independent molecules, which are conformationally almost identical. In each molecule, the two cyclohexane rings of the fused three-ring system adopt chair conformations, while the cyclohexene ring is in an envelope conformation, with the methylene C atom next to the side chain as the flap atom. In the crystal, molecules are stacked in columns along the b axis through O—H⋯O hydrogen bonds.

Atomic charges of cerbinal

The molecule of the title compound, methyl 1-formyl-6-oxa-6H-indene-4-carboxylate, C(11)H(8)O(4), is planar. There are weak C--H...O intramolecular interactions and an intermolecular hydrogen bond in the structure, and these influence the crystal packing.