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Biomedical subjects

L A Mitscher

Publications and source records attributed to L A Mitscher.

At least 109 records · Page 6Linked to original sources
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Comprehensive survey of indigenous Iraqi plants for potential economic value. 1. Screening results of 327 species for alkaloids and antimicrobial agents.

Three hundred and twenty-seven indigenous Iraqi plant species were screened for their antimicrobial activities and for the presence of alkaloids. The plants represent 221 genera and 49 families. Ethanolic extracts were tested for the presence of alkaloids with both Mayer's and Dragendorff's reagents. Of these, 146 species, belonging to 109 genera distributed among 32 families, showed positive alkaloid tests to both reagents. Of these, 26 genera have not been previously reported in the literature as containing alkaloid-bearing plants. The extracts were also tested for their in vitro antimicrobial activity by an agar dilution-streak method against six economically significant microbes. Five species were highly active, while another 90 species showed weak activity against one or more microorganisms.

Alkaloids↗
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Antimicrobial agents from higher plants. Antimicrobial isoflavanoids and related substances from Glycyrrhiza glabra L. var. typica.

Bioassay-directed fractionation of Glycyrrhiza glabra L. var. typica resulted in the isolation and characterization of glabridin (I), glabrol (2), glabrene (3), 3-hydroxyglabrol (4), 4'-O-methylglabridin (5), 3'-methoxyglabridin (6), formononetin (7), phaseollinisoflavan (8), hispaglabridin A (9), hispaglabridin B (13), salicylic acid and O-acetyl salicylic acid. Of these, hispaglabridin A, hispaglabridin B, 4'-O-methylglabridin, glabridin, glabrol and 3-hydroxyglabrol possess significant antimicrobial activity in vitro; hispaglabridin A, hispaglabridin B, 3'-methoxyglabridin, 4'-O-methylglabridin 3-hydroxyglabrol, phaseollinisoflavan, salicylic acid, and O, acetyl salicylic acid are newly found in Glycyrrhiza sp.; and hispaglabridin A, hispaglabridin B, 3'-methoxyglabridin, 4'-O-methylglabridin, and 3-hydroxyglabrol are new to the literature and their structures are proposed herein.

Anti-Infective Agents↗
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A modern look at folkloric use of anti-infective agents.

Infectious diseases are of ancient origin, and mankind has a venerable history of use of higher plant extracts for the therapy of such infections. Some such agents survive in use from earlier times--quinine, emetine, and sanguinarine, for example--but the modern use of fermentation-based antibiotics has greatly overshadowed work on agents from other sources. After a brief review of the present status of the field of antibiotics, this review focuses upon the present status of antimicrobial agents from higher plants with particular reference to agents from plants with a folkloric reputation for treatment of infections. In particular, recent work on the tropical genus Erythrina is emphasized. The use of modern microbiological techniques demonstrates that higher plants frequently exhibit significant potency against human bacterial and fungal pathogens, that many genera are involved, that many folkloric uses can be rationalized on this basis, that the active constituents are readily isolated by bioassay-directed techniques, that their chemical structures are types uncommon amongst fermentation-based agents but are familiar to natural product chemists, that their antimicrobial spectra are comparatively narrow but that their potency is often reasonable, that they are comparatively easy to synthesize and the unnatural analogues so produced can possess enhanced therapeutic potential and, thus, it is concluded that such work generates a gratifying number of novel lead structures and that the possibility of finding additional agents for human or agricultural use based upon higher plant agents is realistic.

Anti-Bacterial Agents↗
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Antimicrobial agents from higher plants. The quaternary alkaloids of Ptelea trifoliata.

Quaternary alkaloid extracts of Ptelea trifoliata showed potentially interesting antimicrobial activity. Chromatographic examination showed the presence of six components. Of these, choline and O-4-methyl ptelefolinium were known compounds. Rational structures are proposed for the new alkaloids, O-4-methylhydroxyluninium, neohydroxylunine and pteleatinium salts. Pteleatinium salt is responsible for the antimicrobial activity of the extracts of the plant.

Alkaloids↗