Kanda Panthong

Antioxidative and Free Radical Scavenging Activities of Some Plants Used in Thai Folk Medicine

Abstract Ten methanol extracts from various parts of seven medicinal plants, Angiopteris evecta Hoffm.., (Marattiaceae) Citrus hystrix DC.., (Rutaceae) Laurentia longiflora (L.). Peterm.., (Campanulaceae) Nelumbo nucifera Gaertn.., (Nelumbonaceae), Piper sarmentosum Roxb.., (Piperaceae), Portulaca oleracea Linn.., (Portulacaceae) and Stachytarphera indica (L.). Vahl. (Verbenaceae), commonly used in Thai traditional medicine, were evaluated for their antioxidative and free radical scavenging activities. Among them, only that prepared from sacred lotus (N. nucifera) leaves exhibited a pronounced activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay with an IC50 of 90 µg/ml, compared with an IC50 of 30 µg/ml for the butylated hydroxytoluene (BHT) control. The same extract was also found to be the most potent in removing the superoxide anion () radical and in inhibiting the 2,2′-azo-bis.-(2-amidinopropane) dihydrochloride (AAPH)-induced erythrocyte hemolysis and lipid peroxidation in a rat brain homogenate. The extract from leaves and peels of the Kaffir lime (C. hystrix.) exerted the strongest effect on production of the hydroxyl radical (OH·). They conferred a twice greater protection of deoxyribose from OH· than did tannin. However, none of the extracts examined in this study showed a significant pro-oxidant action in the bleomycin-dependent DNA oxidation system.

Cowaxanthone F, a new tetraoxygenated xanthone, and other anti-inflammatory and antioxidant compounds from Garcinia cowa

A new tetraoxygenated xanthone, cowaxanthone F (1), as well as four known compounds, morelloflavone (2), volkensiflavone (3), morelloflavone-7″-O-glucoside (fukugiside, 4), and 1,6-dihydroxyxanthon...

Benzene, coumarin and quinolinone derivatives from roots of Citrus hystrix

Two coumarins, hystrixarin (1) and (+)-hopeyhopin (2); a benzenoid derivative, hystroxene-I (3) and a quinolinone alkaloid, hystrolinone (4), along with 33 known compounds were isolated from the crude acetone extract of the roots of Citrus hystrix. Their structures were determined by analysis of 1D and 2D NMR spectroscopic data. The antioxidant, anti-HIV and antibacterial activities of the isolated compounds were also evaluated.

Terpenoid constituents and antifungal activity of Aglaia forbesii seed against phytopathogens

Two new trisnortriterpenoids possessing a g-lactone ring linked to the D-ring of a 3,4-secodammarane skeleton in a 20R configuration, named isoeichlerialactone (1) and methyl isoeichlerialactone (2), were isolated from the seed of Aglaia forbesii, along with the three dammarane triterpenes, isocabralealactone (3), isoeichlerianic acid (4), and aglinin A (5), the sesquiterpene spathulenol (6), and the widespread sterols b-sitosterol and stigmasterol. Their structures were estab- lished based on detailed spectroscopic analysis. Antifungal activity of A. forbesii seed against three phytopathogens, Phy- tophthora botryosa, P. palmivora, and Rigidoporus microporus, was carried out using the mycelium inhibition test and broth microdilution technique. Superior activity was exhibited by hexane and dichloromethane fractions containing the compounds 1, 4, and 5 as the main components. Subsequent antiphytopathogenic fungi tests proved that compounds 1, 4, and 5 possessed good antifungal activity.

Studies toward the total synthesis of naturally occurring pyranonaphthoquinones from Ventilago harmandiana

The enantioselective synthesis of a naturally occurring pyranonaphthoquinone isolated from a Thai endemic plant, Ventilago harmandiana, has been achieved. L-Rhamnose and gallic acid were used as the starting materials. A new C-1-glycosidation of L-rhamnal with trimethyl aluminum in the presence of a catalytic amount of ytterbium(III) triflate was developed. A new reagent, PhSCF2H/SnCl4, for the formylation of partially deactivated and hindered aromatic compounds has been introduced. Phenylthiophthalide was used efficiently as a cycloannulating agent in the Hauser cycloannulation reaction, employing slightly excess lithium t-butoxide as a base with a catalytic amount of lithium chloride. The synthetic route developed is applicable for the synthesis of other analogues with substituents at the aromatic and pyran rings.

Prenylated flavone from roots of a hybrid between Artocarpus heterophyllus and Artocarpus integer and its biological activities

Uma nova flavona prenilada, 2,8-dihodroxi-3,10-dimetoxi-6-(2-metil-1-propeno-1-il)6H,7H-[1]benzopirano[4,3-b][1]-benzopirano-7-ona, juntamente com 24 compostos conhecidos foram isolados do extrato bruto em acetona das raizes de um hibrido entre Artocarpus heterophyllus e Artocarpus integer. Suas estruturas foram determinadas pelos dados de espectroscopia da ressonância magnetica nuclear (NMR) 1D e 2D. Avaliaram-se as atividades antioxidante e bactericida dos compostos isolados. O novo composto mostrou atividade antioxidante potente com relacao a DPPH • e superoxido com valores de IC50 de 0,033 e 0,125 mg mL -1 , respectivamente. One new prenylated flavone, 2,8-dihydroxy-3,10-dimethoxy-6-(2-methyl-1-propen-1-yl)6H,7H-[1]benzopyrano[4,3-b][1]-benzopyran-7-one, together with 24 known compounds were isolated from crude acetone extract from the roots of a hybrid between Artocarpus heterophyllus and Artocarpus integer. Their structures were determined by 1D and 2D nuclear magnetic resonance (NMR) spectroscopic data. The antioxidant and antibacterial activities of the isolated compounds were evaluated. The new compound showed potent antioxidant activity against DPPH

1,3-Dimethylisoguanine

The structure of 1,3-dimethylisoguanine [ or 6-amino-1,3-dimethyl-1H-purin- 2(3H)- one], C7H9N5O, has been redetermined and the correct assignment of H atoms on the heterocycle is now reported. Intermolecular hydrogen-bonding interactions confirm that this form is the correct molecular structure; this form is also in agreement with an earlier reported structure of the trihydrate form.