Akkharawit Kanjana-Opas

Synthesis, structure and in vitro antibacterial activities of new hybrid disinfectants quaternary ammonium compounds: pyridinium and quinolinium stilbene benzenesulfonates.

The series of pyridinium (1-10) and quinolinium (11-20) stilbene benzenesulfonates have been synthesized and their structures were investigated by UV-vis, FT-IR and (1)H NMR spectroscopy. In addition, compound 5 was also determined by single crystal X-ray diffraction technique. The antibacterial activity of the synthesized compounds against both gram-positive and gram-negative bacteria has been determined. The quinolinium derivatives exhibited two very potent characteristic activities, namely, (i) specific activity to Methicillin-Resistant Staphylococcus aureus and (ii) with broad band spectrum activity. Compounds 11, 13 and 14 are the most active showing broad spectrum antibacterial activity against gram-positive (Methicillin-Resistant S. aureus, S. aureus, Bacillus subtilis, Vancomycin-Resistant Enterococcus faecalis and E. faecalis) and gram-negative bacterium (Shigella sonnei). The MICs of these compounds were found to be better than that of Benzalkonium chloride (BZK), the commercially used disinfectant.

Acetylcholinesterase-inhibiting activity of pyrrole derivatives from a novel marine gliding bacterium, Rapidithrix thailandica.

Acetylcholinesterase-inhibiting activity of marinoquinoline A (1), a new pyrroloquinoline from a novel species of a marine gliding bacterium Rapidithrix thailandica, was assessed (IC50 4.9 μM). Two related pyrrole derivatives, 3-(2′-aminophenyl)-pyrrole (3) and 2,2-dimethyl-pyrrolo-1,2-dihydroquinoline (4), were also isolated from two other strains of R. thailandica. The isolation of 3 from a natural source is reported here for the first time. Compound 4 was proposed to be an isolation artifact derived from 3. The two isolated compounds were virtually inactive in the acetylcholinesterase-inhibitory assay (enzyme inhibition < 30% at 0.1 g L−1).

Cytotoxic and antibacterial sesquiterpenes from Thespesia populnea.

Eight new sesquiterpenoids, named populene A-H (1-8), were isolated from dichloromethane extracts of the wood and dark heartwood of Thespesia populnea, together with 11 known compounds (9-19). Their structures were determined on the basis of spectroscopic analyses. The cytotoxic activity of isolated compounds was evaluated against four cancer cell lines: MCF-7, HeLa, HT-29, and KB. Mansonone E (11) and (+)-gossypol (18) showed significant activities. Their antibacterial properties against Bacillus subtilis, Staphylococcus aureus, and Enterococcus faecalis are also presented.

Phanginin A-K, diterpenoids from the seeds of Caesalpinia sappan Linn.

The first chemical study on the seeds of Caesalpinia sappan Linn. led to isolation of 11 cassane-type diterpenes, named phanginin A-K (1-11). The skeleton present in compounds 1-8 is rather unusual, consisting of a cassane-type diterpene with an ether bridge between C-19/C-20 in compounds 1-6 and C-11/C-20 in compounds 7 and 8. Their structures were elucidated on the basis of spectroscopic techniques. In addition, the X-ray structure of phanginin A (1) is reported. Only phanginin I (9) exhibited cytotoxic effect against KB cell line with IC50 value of 4.4 microg/ml.

Alkaloid and coumarins from the green fruits of Aegle marmelos

Five (1-5) and 15 known compounds were isolated from the acetone extract of the green fruits of Aegle marmelos. The structure of compounds 1-5, marmesiline (1), 6-(4-acetoxy-3-methyl-2-butenyl)-7-hydroxycoumarin (2), 6-(2-hydroxy-3-hydroxymethyl-3-butenyl)-7-hydroxycoumarin (3), marmelonine (4) and 8-hydroxysmyrindiol (5), were determined on the basis of spectroscopic analyses. Antifungal and antibacterial activities of selected compounds were also evaluated.

Candenatenins A−F, Phenolic Compounds from the Heartwood of Dalbergia candenatensis

Chemical investigation of the CH2Cl2 extract of the heartwood of Dalbergia candenatensis affored six new phenolic compounds, designated candenatenins A-F (1-6), as well as four known compounds, (2R,3R)-3,5-dihydroxy-7-methoxyflavanone (7), 4-hydroxy-3-methoxy-8,9-methylenedioxypterocarpan (8), nutiducol (9), and sophoraflavanone A (10). The structures of the new compounds were determined by 1D- and 2D-NMR spectroscopic studies as well as by MS analysis. The cytotoxic activities of the isolated compounds are also reported.

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.

Diversity of marine gliding bacteria in Thailand and their cytotoxicity

Eighty-four marine gliding bacteria were isolated from specimens collected in the Gulf of Thailand and the Andaman Sea. All exhibited gliding motility and swarm colonies on cultivation plates and they were purified by subculturing and micromanipulator techniques. Their 16S rRNA genes were amplified by the polymerase chain reaction (PCR) technique. The phylogenetic analysis indicated that the represented isolates can be separated into six different clads (gr 1 - gr 6) within the Cytophaga-Flavobacterium-Bacteriodes (CFB) group. Group 1 formed a remote linear, with only 90% sequence similarity, from Flavobacteriaceae bacterium which indicated a potentially novel taxonomic group. Groups 2 and 3 were identified as the recently proposed Tenacibaculum mesophilum and Fulvivirga kasyanovii respectively. Groups 4, 5 and 6, consisting of the largest number of the members, were identified as Rapidithrix thailandica , Aureispira marina and Aureispira maritima respectively. The isolates were cultivated in four different cultivation media (Vy/2, RL 1, CY and SK) and the crude extracts were submitted to screen cytotoxicity using a sulphorodamine B (SRB) assay. The results from cytotoxic screening showed that groups 2, 4 and 6 were capable of producing the cytotoxic metabolites against selected human cell lines (breast adenocarcinoma (MCF-7), colon cancer (HT-29), cervical cancer (HeLa) and oral cancer (KB)). However, groups 1, 3 and 5 did not produce metabolites with cytotoxicity when cultivated in the same cultivation media as the previous groups. CY medium was the only cultivation medium which could yield the cytotoxic metabolites against MCF-7.

Coumarins and xanthones from the seeds of Mammea siamensis

A new coumarin, mammea E/BB cyclo D (1), together with five known compounds, mammea E/BA cyclo D (2), suragin C (3), therapin B (4), 1,7-dihydroxyxanthone (5) and 1-hydroxy-5-methoxyxanthone (6), were isolated from the seeds of Mammea siamensis. Their structures were characterized using 1D and 2D NMR spectral data. Suragin C and therapin B showed cytotoxic activity against breast adenocarcinoma (MCF-7), human cervical cancer (HeLa), colon cancer (HT-29) and human oral cancer (KB).

Naphthalene derivatives from Diospyros wallichii

Three new naphthalene derivatives, 2-hydroxymethyl-1,5-dimethoxynaphthalen-4-ol (1), 2,2′-bis-hydroxymethyl-1,1′,5,5′-tetramethoxy-3,3′-binaphthalen-4,4′-diol (2), and 5,5′-dihydroxy-2,2′-dimethyl-...