A. D. Kinghorn

Bio: A. D. Kinghorn is an academic researcher from University of Illinois at Urbana–Champaign. The author has contributed to research in topics: Reverse transcriptase & Naringenin. The author has an hindex of 8, co-authored 13 publications receiving 1035 citations. Previous affiliations of A. D. Kinghorn include University of Illinois at Chicago.

Evaluation of natural products as inhibitors of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase.

Abstract: Inhibition of human immunodeficiency virus reverse transcriptase is currently considered a useful approach in the prophylaxis and intervention of acquired immunodeficiency syndrome (AIDS), and natural products have not been extensively explored as inhibitors of this enzyme. We currently report that the reverse transcriptase assay developed for the detection of the enzyme in virions involving polyadenylic acid.oligodeoxythymidylic acid (poly rA.oligo dT) and radiolabeled thymidine 5'-triphosphate (TTP), can be applied as a simple method for screening the human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) inhibitory potential of natural products. As reported herein, 156 pure natural products have been examined in this system. Benzophenanthridine alkaloids such as faragaronine chloride [1] and nitidine chloride, which are known inhibitors of avian myeloblastosis virus reverse transcriptase, demonstrated potent activity in the HIV-1 RT system, and 1 (IC50 10 micrograms/ml) was adopted as a positive-control substance. Additional inhibitors found were columbamine iodide [2] and other protoberberine alkaloids, the isoquinoline alkaloid O-methylpsychotrine sulfate [3], and the iridoid fulvoplumierin [4]. A number of indolizidine, pyrrolizidine, quinolizidine, indole, and other alkaloids, as well as compounds of many other structural classes, were tested and found to be inactive. A total of 100 plant extracts have also been evaluated, and 15 of these extracts showed significant inhibitory activity. Because tannins and other polyphenolic compounds are potent reverse transcriptase inhibitors, methods were evaluated for the removal of these from plant extracts prior to testing. Polyphenolic compounds were found to be responsible for the activity demonstrated by the majority of plant extracts. After appropriate tannin removal procedures were established, the bioassay system was shown to be generally applicable to both pure natural products and plant extracts. The method also proved useful in directing an isolation procedure with Plumeria rubra to yield fulvoplumierin [4] as an active compound (IC50 45 micrograms/ml).

Potential sweetening agents of plant origin. iii. organoleptic evaluation of stevia leaf herbarium samples for sweetness

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.

Potential sweetening agents of plant origin. II. field search for sweet-tasting Stevia species

Abstract: Field work in Paraguay, Peru, Colombia and Mexico, including field organoleptic tests and interviews, was carried out in search of sweet-tasting Stevia species. Results of such tests performed on at least 31 species, as well as ethnobotanical data on 9 species, are presented. The data obtained showed that leaves of no other Stevia species studied possessed a potent sweet taste comparable to that of S. rebaudiana leaves. Since only 15% of the approximately 200 known species in this genus were investigated in this study, it is quite possible that further research may reveal additional sweet-tasting Stevia species.

Aromatase inhibitors from Broussonetia papyrifera

Abstract: A composition and method of cancer treatment is disclosed. The composition and method utilize the extract of B. papyrifera, or compounds included therein having aromatase inhibition properties, as active cancer chemopreventative and treating agents in mammals, including humans.

Plant Products as Antimicrobial Agents

Abstract: The use of and search for drugs and dietary supplements derived from plants have accelerated in recent years. Ethnopharmacologists, botanists, microbiologists, and natural-products chemists are combing the Earth for phytochemicals and “leads” which could be developed for treatment of infectious diseases. While 25 to 50% of current pharmaceuticals are derived from plants, none are used as antimicrobials. Traditional healers have long used plants to prevent or cure infectious conditions; Western medicine is trying to duplicate their successes. Plants are rich in a wide variety of secondary metabolites, such as tannins, terpenoids, alkaloids, and flavonoids, which have been found in vitro to have antimicrobial properties. This review attempts to summarize the current status of botanical screening efforts, as well as in vivo studies of their effectiveness and toxicity. The structure and antimicrobial properties of phytochemicals are also addressed. Since many of these compounds are currently available as unregulated botanical preparations and their use by the public is increasing rapidly, clinicians need to consider the consequences of patients self-medicating with these preparations.

The value of plants used in traditional medicine for drug discovery.

Abstract: In this review we describe and discuss several approaches to selecting higher plants as candidates for drug development with the greatest possibility of success. We emphasize the role of information derived from various systems of traditional medicine (ethnomedicine) and its utility for drug discovery purposes. We have identified 122 compounds of defined structure, obtained from only 94 species of plants, that are used globally as drugs and demonstrate that 80% of these have had an ethnomedical use identical or related to the current use of the active elements of the plant. We identify and discuss advantages and disadvantages of using plants as starting points for drug development, specifically those used in traditional medicine.