Search results for "natural product"

<strong>Artemisinin: Tentative Mechanism of Action and Resistance</strong>

2016

The sesquiterpene lactones constitute a large class of secondary plant metabolites, which carry a‑methylene‑g‑lactone groups as common structural element and display a number of bioactivities. Every year, 1–2 million people living in the tropics and subtropics die of malaria. Lactone artemisinin is the most effective treatment vs. malaria, the most infectious disease in the world today. Artemisinins are derived from extracts of sweet wormwood (Artemisia annua) and are well established for the treatment of malaria, e.g., highly drug-resistant strains. They resulted in one of the most significant advances in the treatment of malaria since the discovery and first use of quinine over 300 years …

SF002-96-1, a new drimane sesquiterpene lactone from an Aspergillus species, inhibits survivin expression

2013

Survivin, a member of the IAP (inhibitor of apoptosis) gene family, is overexpressed in virtually all human cancers and is functionally involved in the inhibition of apoptosis, regulation of cell proliferation, metastasis and resistance to therapy. Because of its upregulation in malignancy, survivin has currently attracting considerable interest as a new target for anticancer therapy. In a screening of approximately 200 strains of imperfect fungi for the production of inhibitors of survivin promoter activity, a new drimane sesquiterpene lactone, SF002-96-1, was isolated from fermentations of an Aspergillus species. The compound inhibited survivin promoter activity in transiently transfected…

Synthesis of elemane bis-lactones structurally related to vernolepin

1998

Abstract The chemical transformation of santonin into an elemane bis -lactone structurally related to the antitumour compound vernolepin is reported. The transformation of ring A of santonin into a hemiacetal δ-lactone was achieved in eleven steps. The spectroscopic characteristics of the synthetic product obtained in this way revealed that the proposed structure for the natural product should be revised.

High-Yield Formation of Arbutin from Hydroquinone by Cell-Suspension Cultures ofRauwolfia serpentina

1992

High-density cell-suspension cultures of Rauwolfia serpentina cultivated in a nutrition medium optimized for the production of the glucoalkaloid raucaffricine synthesize hydroquinone glycosides from continuously added hydroquinone with a total yield of 23.87 g/1 (18 g/1 of arbutin and 5.87 g/1 of a hydroquinone diglycoside) in 7 days. This arbutin production is by far the highest formation of a natural product by plant-cell-culture systems reported to date.

Total Synthesis of a Partial Structure from Arabinogalactan and Its Application for Allergy Prevention

2020

Abstract Arabinogalactan, a microheterogeneous polysaccharide occurring in plants, is known for its allergy‐protective activity, which could potentially be used for preventive allergy treatment. New treatment options are highly desirable, especially in a preventive manner, due to the constant rise of atopic diseases worldwide. The structural origin of the allergy‐protective activity of arabinogalactan is, however, still unclear and isolation of the polysaccharide is not feasible for pharmaceutical applications due to a variation of the activity of the natural product and contaminations with endotoxins. Therefore, a pentasaccharide partial structure was selected for total synthesis and subse…

Current Bioactive Azole-Containing Natural Products

2010

On the structure of passifloricin A: asymmetric synthesis of the delta-lactones of (2Z,5S,7R,9S,11S)- and (2Z,5R,7R,9S,11S)tetrahydroxyhexacos-2-enoi…

2003

Stereoselective syntheses of the delta-lactone of (2Z,5S,7R,9S,11S)-tetrahydroxyhexacos-2-enoic acid, the structure reported for passifloricin A, and of its (5R)-epimer are described. The creation of all stereogenic centers relied upon Brown's asymmetric allylation methodology. The lactone ring was created via ring-closing metathesis. The NMR data of both synthetic products, however, were different from those of the natural product. The published structure of passifloricin A is thus erroneous and will require further synthetic work to be unambiguously assigned. [structure: see text]

Synthesis of plagiochiline N from santonin.

2001

This article reports the transformation of O-acetylisophotosantonin, obtained by photochemical rearrangement of santonin, into plagiochiline N, an ent-2,3-secoaromadendrane isolated from Plagiochila ovalifolia. The synthesis was carried out in a sequence involving as the key steps (a) the substitution of the lactone moiety by a gem-dimethylcyclopropane ring through a synthetic intermediate having a C(6)-C(7) double bond and (b) the ozonolysis of the C(2)-C(3) bond followed by cyclization to the dihydropyran ring characteristic of plagiochiline N. Spectroscopic data of the synthetic product fully coincided with the reported data for the natural product.

Natural products and enzymes from plant cell cultures

1995

Plants represent an unlimited source of natural products. Many of the recently detected phytochemicals exhibit remarkable bioactivities, ranging from anticancer activity, phosphodiesterase inhibition to cytotoxicity against HIV-infected cells. Cultivated plant cells produce at their unorganized, dedifferentiated stage secondary metabolites, but in very different amounts in so far as new compounds are concerned. In fact, more than 140 novel natural products are presently known from plant cell cultures, which also include new metabolites formed by biotransformation. The biotransformation capacity of suspended cells is described and recent high yielding transformations, like the formation of a…

Preparation of 9a-Fluorinated Sesquiterpenic Drimanes and Evaluation of Their Antifeedant Activities

2010

19 pages, figures, and tables statistics.