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Showing papers in "Journal of Natural Products in 1982"



Journal ArticleDOI
TL;DR: Fragments of a 62-year-old leaf of S. rebaudiana exhibited a potent and prolonged sensation of sweetness, thereby indicating the stability of its sweet ent-kaurene glycoside constituents to drying, preservation, mounting and storage.
Abstract: A total of 184 Stevia leaf samples taken from herbarium specimens, representing 110 species and 121 taxa, were screened organoleptically for their taste sensation. Fragments of a 62-year-old leaf of S. rebaudiana exhibited a potent and prolonged sensation of sweetness, thereby indicating the stability of its sweet ent-kaurene glycoside constituents to drying, preservation, mounting and storage. No other leaf samples exhibited an intensity of sweetness equivalent to that of S. rebaudiana, though 18 species and varieties were considered to exhibit a sweet taste. These taxa appear to be promising candidates for future phytochemical investigation for new and known ent-kaurene glycosides.

186 citations


Journal ArticleDOI
TL;DR: The extracts except that of leaves produced very significant antibacterial activity on Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Shigella flexneri.
Abstract: Ripe and unripe Carica papaya fruits (epicarp, endocarp, seeds and leaves) were extracted separately and purified. All the extracts except that of leaves produced very significant antibacterial activity on Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Shigella flexneri. The MIC of the substance was small (0.2-0.3 mg/ml) for gram-positive bacteria and large (1.5-4 mg/ml) for gram-negative bacteria. The substance was bactericidal and showed properties of a protein. Other proteins previously found in C. papaya did not show antibacterial activity.

176 citations


Journal ArticleDOI

143 citations


Journal ArticleDOI
TL;DR: The modified potato disc assay is a safe, simple, rapid, in-house, low cost, prescreen for 3PS antitumor activity; it detects some false positives, but few false negatives; it is statistically much more predictive of 3PS activity than either the 9KB or the 9PS cytotoxicity assays.
Abstract: Galsky et al. (10, 11) have reported that the inhibition and growth of crown gall tumors, initiated on potato discs by Agrobacterium tumefaciens, apparently has good agreement with 3PS in vivo antileukemic activity in mice. We have now modified and evaluated this assay for its potential use as a prescreen and fractionation monitor of plant extracts for 3PS activity. The modified assay was performed on a series of natural compounds and plant extracts (known to have 3PS activity) and on extracts of seeds of 41 Euphorbiaceae species. The results suggest that the potato disc assay is a safe, simple, rapid, in-house, low cost, prescreen for 3PS antitumor activity; it detects some false positives, but few false negatives; it is statistically much more predictive (p = 0.002) of 3PS activity than either the 9KB (p = 0.140) or the 9PS (p = 0.114) cytotoxicity assays. Its extended use could easily obviate the expense and extensive need for animals in the initial stages of antitumor screening and plant fractionation.

143 citations





Journal ArticleDOI
TL;DR: The isolation of two taxanes from Taxus brevifolia Nutt is described, together with the isolate of two acetylated taxol derivatives from an acetylation fraction from the same plant.
Abstract: The isolation of two taxanes from Taxus brevifolia Nutt. is described, together with the isolation of two acetylated taxol derivatives from an acetylated fraction from the same plant. The compounds were identified on the basis of their spectroscopic properties as taxa-4(20),11-diene-2 alpha, 5 alpha, 7 beta, 9 alpha, 10 beta, 13 alpha-hexaol 2,7,9,10,13-pentaacetate (1) (decinnamoyltaxinine J), 10-deacetylbaccatin III (2), taxol 2',7-diacetate (3), and 10-deacetyltaxol 2',7-diacetate (4).

106 citations




Journal ArticleDOI
TL;DR: The antiviral activity of an aqueous extract of Podophyllum peltatum was investigated, and podophyllotoxin was found to be the most active component in inhibiting the replication of measles and herpes simplex type I viruses.
Abstract: The antiviral activity of an aqueous extract of Podophyllum peltatum was investigated. The extract was fractionated by reversed-phase chromatography, and podophyllotoxin was found to be the most active component in inhibiting the replication of measles and herpes simplex type I viruses. beta-Peltatin and desoxypodophyllotoxin produced marginal antiviral effects, while alpha-peltatin and picropodophyllotoxin were inactive at the levels tested.

Journal ArticleDOI
TL;DR: It was shown that the inhibitory activity of lycorine on the cytopathogenic effect caused by a DNA and several RNA viruses on VERO cells was not virucidal, and Poliomyelitis virus inhibition occurred at lycorines as low as 1 microgram/ml, whereas concentrations exceeding 25 micrograms/ml were found to be cytotoxic.
Abstract: Lycorine (1), one of the main alkaloids of the Amaryllidaceae family, was found to be responsible for the pronounced antiviral activity of the crude extracts from the roots and leaves of Clivia miniata Regel. It was shown that the inhibitory activity of lycorine on the cytopathogenic effect caused by a DNA and several RNA viruses on VERO cells was not virucidal. Poliomyelitis virus inhibition occurred at lycorine concentrations as low as 1 microgram/ml, whereas concentrations exceeding 25 micrograms/ml were found to be cytotoxic. Clivimine (2), clivonine (3) and cliviamartine (4) were also isolated and characterized, but these alkaloids exhibited no antiviral properties.

Journal ArticleDOI
TL;DR: Reesterification of III with homovanillic acid showed that the previously proposed structure for resiniferatoxin has to be revised to resiniferonol-9, 13, 14-orthophenylacetate-20-(4-hydroxy-3-methoxyphenyl) acetate, and some aspects of structure-activity relations of irritancy of resinifer onol esters are established and discussed.
Abstract: Base catalyzed transesterifications of resiniferatoxin afforded the 9, 13, 14-orthophenylacetate (III), as well as (4-hydroxy-3-methyoxyphenyl) acetic acid methyl ester (II) Reesterification of III with homovanillic acid showed that the previously proposed structure for resiniferatoxin has to be revised to resiniferonol-9, 13, 14-orthophenylacetate-20-(4-hydroxy-3-methoxyphenyl) acetate (I) From III, different 20 esters (I, IV-IX) were prepared The orthophenylacetate III was cleaved by Acidic hydrolysis to yield the 14-phenylacetate X Subsequent alkaline transesterifications of X afforded the parent alcohol resiniferonol (XI), Starting from XI, the 14, 20-diesters XII and XV and the 9, 13, 20-diesters xii and XV and the 9, 13, 14-orthoesters XIII, XIV, XVI, XVII and XVIII were obtained All esters were tested for irritant activity on the mouse ear Some aspects of structure-activity relations of irritancy of resiniferonol esters are established and discussed