A new lignan, (+)-nortrachelogenin (I), and a known compound, daphnoretin were isolated from Wikstroemia indica C.A. Meyer (Thymelaeaceae). The structure of (+)-nortrachelogenin was established as 8(R)8'-4,4',8'-trihydroxy-3,3'-dimethoxylignan-olid, (9,9') on the basis of spectroscopic evidence and comparison with its enantiomer, (-)-nortrachelogenin. +-nortrachelogenin(I) showed effects on the central nervous system producing depression in rabbits.
Benzophenanthridine alkaloids, fagaronine 4, O-methylfagaronine 5,nitidine 1, allonitidine 3 and methoxydihydronitidine 2 have been shown to possess inhibitory activity against reverse transcriptase of RNA tumor viruses. The enzyme inhibition (50%) by these alkaloids was found in the range of 6-60 microgram per milliliter of the reaction mixture when polynucleotide-oligodeoxynucleotide complexes were used as template primers. The results suggested that the benzophenanthridine alkaloids interacted with the template primers (particularly of the A:T base pairs) and not with the enzyme proteins. Kinetics reaction of the reverse transciptase inhibition showed that the alkaloids stopped the DNA polymerase synthesis instantly, probably by interacting with the template primer.
Fractionation of Simaba multiflora A. Juss. guided by bioassay has resulted in the isolation of a new antileukemic quassinoid 6alpha-senecioyloxychaparrinone (2) and the previously reported quassinoid chaparrinone (3). The structure of the former has been established by spectral and chemical methods. Compound 2 has high anti-neoplastic activity against several mouse leukemia systems (P-388, L-1210 and in solid-tumor B-16 melanoma). This demonstrates for the first time that the presence of a C-15 ester function is not required for antineoplastic activity in the quassinoids.
Chaparrinone (1) and 6alpha-tigloyoxychaparrinone (2) were shown to be responsible for the antitumor and cytotoxic activities of the root bark of Ailanthus integrifolia ssp. calycina. The structure of the latter compound was established by analysis of spectral data. Compound 2 exhibited a more pronounced biological activity than chaparrinone (1) and demonstrates, for the first time, anticancer activity of a simaroubolide ester substituted at only the 6-position.
The preparation, characterization and chemistry of alkaloid N-oxides is reviewed. Because the literature on amine N-oxides is more extensive for animals than for plants, a brief resumé of the pharmacology, metabolism, and toxicity of N-oxides is given. Some 64 naturally occuring N-oxides representing pyrrolidine-piperidine-, pyrrolizidine-, quinolizidine-, tropane-, isoquinoline-, morphinane-, indole- and miscellaneous-type alkaloids are reviewed. These alkaloid N-oxides are additional to and, in the main, have been isolated since those described in a 1971 review. The earlier review dealt with some 56 naturally occurring N-oxides which represented mainly pyrrolizidine and indole types. The role of N-oxides in plants is discussed.
The stem bark and stem wood of Cinchona pubescens were found to owe their weak cytotoxic activity to the presence of quinovic acid. This acid and its 3-rhamnoside were isolated and characterized through several derivatives, all of which were assayed for their cytotoxicity.
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