A pungent diarylheptanoid from Alpinia oxyphylla

From the neutral fraction of the methanolic extract of the fruit of Alpinia oxyphylla, a new pungent compound has been isolated, and is shown to be 1-(4′-hydroxy-3′-methoxyphenyl)-7-phenyl-3-heptanone. This compound is 125 times more pungent than zingerone.     

Omphamurin-a new coumarin from Murraya omphalocarpa

A new coumarin, omphamurin, isolated from the n-hexane extract of the leaves of Murraya omphalocarpa, was characterized as 5,7-dimethoxy-8-(2′-hydroxy-3′-methyl-3′-butenyl) coumarin by chemical evidence and spectral data.     

SYNTHETIC STUDY OF 3′-α-FLUORO-2′,3′-DIDEOXYGUANOSINE

A synthetic method was established for 3′-α-fluoro-2′,3′-dideoxyguanosine 1 from guanosine 2 in 27% overall yield and 6 steps. A byproduct 6a of fluorination was identified by NMR studies, its presence strongly supporting our supposition that the fluorination itself proceeded via a bromonium cation.     

4-(2′-Carboxyphenyl)-4-oxobutyrate: An obligatory intermediate in lawsone biosynthesis

4-(2′-Carboxyphenyl)-4-oxobutyric acid (6) has been detected in cuttings of Impatiens balsamina. It is labelled under conditions where activity from U-¹⁴C-glutamate is incorporated effectively into lawsone (1). 3-(2′-Carboxyphenyl)-3-oxopropionic acid (7) has also been encountered in the cuttings.     

A substituted 1,2-diarylethane from Cymbidium giganteum

In addition to sitosterol and taraxerone, a new substituted 1,2-diarylethane, gigantol has been isolated from Cymbidium giganteum and characterized as 1-(3′-hydroxy-5′-methoxyphenyl-2-(4″-hydroxy-5″-methoxyphenyl)ethane on the basis of physicochemical data and through synthesis of its derivative.     

Pyrenocine C,A phytotoxin-related metabolite produced by onion pink root fungus,Pyrenochaeta terrestris

The structure of pyrenocine C, a new metabolite isolated from onion pink root fungus, Pyrenochaeta terrestris (Hansen) has been elucidated as (±)-(2′E)-5-(1′-hydroxybut-2′-enyl)-4-methoxy-6-methyl-2-pyrone by spectroscopic methods and chemical correlation with pyrenocine A.     

Synthesis of dihydrochalcones of Myrica gale

4,4,6-Trimethyl-2-(3-phenylpropionyl)cyclohexane-1,3,5-trione, 2′-hydroxy-4′,6′-dimethoxy-3′-methyldihydrochalcone, 2′,6′-dihydroxy-4′-methoxy-3′,5′-dimethyldihydrochalcone and 2,2,5-trimethyl-4(3-phenylpropionyl)cyclopent-4-ene-1,3-dione, constituents of Myrica gale, have been synthesized.     

Two antibacterial biphenyls from rhynchosia suaveolens

Two new biphenyls characterized as 4-(3-methyl-but-2-enyl)-5-methoxy-[1,1′-biphenyl]-3-ol 1 and 2-carboxy-4-(3-methyl-but-2-enyl)-5-methoxy- [1,1′-biphenyl]-3-ol 5 have been isolated from Rhynchosia suaveolens. Both compounds displayed antibacterial activity.     

Isoflavonoids from Myroxylon balsamum

Myroxylon balsamum (Leguminosae-Lotoideae) trunk wood contains a series of biogenetically related flavonoids, including the novel (±) -7-hydroxy-4′-methoxyisoflavanone, (±)-7,3′-dihydroxy-4′-methoxyisoflavanone and 2-(2′,4′-dihydroxyphenyl)-5,6-dimethoxybenzofuran.     

Neolignans from Nectandra miranda

Seven neolignans, isolated from a C₆H₆ extract of Nectandra miranda (Lauraceae) trunk wood, included the hitherto undescribed (2S, 3S, 3aS)- and (2S, 3S, 3aR)-5-allyl-3a-methoxy-2-(3′, 4′, 5′-trimethoxyphenyl)-3-methyl-2, 3, 3a, 6-tetrahydro-6-oxobenzofurans (respectively mirandin-A and mirandin -B), 7-allyl-6-hydroxy-5-methoxy-2-(3′, 4′, 5′-trimethoxyphenyl)-3-methylbenzofuran and (2R, 3R)-7-methoxy-2-(3′, 4′, 5′-trimethoxyphenyl)-3-methyl-5 -(E)-propenyl-2, 3-dihydrobenzofuran (licarin C).     

Algal carotenoids with novel end groups

The structures of three previously unidentified carotenoids from Eutreptiella gymnastica are reported. These include siphonein with defined n-2-trans-2-dodecenoic esterifying acid and assigned 3R(?), 3′R,6′R chirality, (3R)-3′,4′-anhydrodiatoxanthin and eutreptiellanone (3,6-epoxy-3′,4′,7′,8′-tetradehydro-5,6-dihydro-β,β-caroten-4-one) with probable 3S,5R,6S chirality.     

Oligonucleotides Containing an Acridine Group Covalently Bonded to the Nucleotide Flanking the 3′-3′ Phosphodiester Junction for Alternate Strand Triple Helix Formation

Abstract

Oligonucleotides with a 3′-3′ inversion of polarity and containing an acridine group attached to nucleotide base flanking the 3′-3′ phosphodiester bon have been synthesized, characterized and used as third strand in alternate triple helix formation. CD melting studies and molecular mechanics calculations have been carried out to investigate these triplex structures.     

Chirality of plectaniaxanthin

The chirality of plectaniaxanthin, a carotenoid vic. glycol from Plectania coccinea, could not be determined by the modified Horeau method. Chiroptical correlation of plectaniaxanthin acetonide and (2′S)-16′, 17′-dinorplectaniaxanthin acetonide was taken as proof of 2′R chirality for natural plectaniaxanthin and its mono- and diesters. The synthesis of the chiral model carotenoid was effected from d-mannitol via 2, 3-O-isopropylidene-d-glyceraldehyde as key synthon.     

Flavonoids from the exudate of Acacia neovernicosa

2′,4′-Dihydroxychalcone, 4′-hydroxy-2′-methoxychalcone and 2′,4′-dihydroxy-3′-methoxychalcone were isolated and characterized from the resinous exudate produced by Acacia neovernicosa. Smaller amounts of isoliquiritigenin, pinocembrin and chrysin were also found and identified by their chromatographic properties and UV spectra. The material of one collection contained galangin, 3-methylkaempferol and 3,3′ -dimethylquercetin.     

Ultraviolet-mediated antibiotic activity of thiophene compounds of Tagetes

Two intensely mauve UV fluorescent compounds isolated from Tagetes root were found to be phototoxic to Candida albicans. By chromatography on alumina followed by gel filtration on Sephadex LH-20, the compounds were identified as 5-(3-buten-1-ynyl)-2,2′-bithienyl and α-terthienyl.     

Reactions of adenosine 5′-phosphorimidazolide with adenosine analogs on a polyuridylic acid template: The uniqueness of the 2′-3′-unsubstituted β-ribosyl system

We have studied the reactions between adenosine 5′-phosphorimidazolide and various adenosine analogs on a poly(U) template. The nucleosides were adenosine (I), 2′-deoxyadenosine (II), 3′-deoxyadenosine (III), 2′-O-methyladenosine (IV), 3′-O-methyladenosine (V), 9-β-d-xylofuranosyladenine (VI), and 9-β-d-arabinofuranosyladenine (VII). We find that the various analogs form triple helices with poly(U) which are of comparable stability, but that only the β-riboside takes part in an efficient template-directed condensation.     

Thiolytic cleavage of the anti-tumour compound 4′-(9-acridinylamino)-methanesulphon-m-anisidine (m-AMSA,NSC 156 303) in blood

4′-(9-acridinylamino)methanesulphon-m-anisidide (m-AMSA), a compound with a broad spectrum of experimental anti-tumour activity, was found to have a short biological half-life in mice bearing L1210 leukaemia. The fate of m-AMSA [³H]-labelled in the acridine nucleus, was determined following injection into mice. There was rapid formation of covalent adducts with plasma proteins. Adducts were also formed in freshly isolated blood samples following incubation at 37°C, and were found to be highly fluorescent. The formation of adducts was accompanied by a decrease in the free thiol concentration in plasma, and the concomitant addition of radioactivity from [³H]acridine nuclei. Acid or alkaline hydrolysis of the plasma protein adduct liberated acridone, while digestion with a protease produced unstable fluorescent compounds. A comparison of the rates of acid hydrolysis of the adducts and of model compounds suggested that the adducts were produced as a result of nucleophilic attack at the C-9 position of m-AMSA by protein thiol groups. The side chain of m-AMSA was liberated as 4-amino-3-methoxymethanesulphonanilide. Several congeners of m-AMSA were shown to form similar or identical adducts both in vivo and in vitro, and at rates which correlated with their reactivity towards simple organic thiols.     

Plasmodium falciparum: Antimalarial activity in culture of sinefungin and other methylation inhibitors

A culture line of Plasmodium falciparum (FCR-3/Gambia) was exposed in vitro for a 2-day period to several analogs of adenosylhomocysteine. Minimal concentrations giving complete inhibition of growth were 0.2 mM for 3-deazaadenosine, 0.2 mM for 5′-deoxy-5′-(isobutylthio)-3-deazaadenosine, and 0.3 μM for sinefungin. The effects of the first two of these compounds were potentiated by homocysteine-thiolactone, suggesting that they were inhibiting methylation reaction(s) indirectly via adenosylhomocysteine hydrolase (EC 3.3.1.1).