Medicinal plants have historically proven their value as a source of molecules with therapeutic potential, and nowadays still represent an important pool for the identification of novel drug leads. In the past decades, pharmaceutical industry focused mainly on libraries of synthetic compounds as drug discovery source. They are comparably easy to produce and resupply, and demonstrate good compatibility with established high throughput screening (HTS) platforms. However, at the same time there has been a declining trend in the number of new drugs reaching the market, raising renewed scientific interest in drug discovery from natural sources, despite of its known challenges. In this survey, a brief outline of historical development is provided together with a comprehensive overview of used approaches and recent developments relevant to plant-derived natural product drug discovery. Associated challenges and major strengths of natural product-based drug discovery are critically discussed. A snapshot of the advanced plant-derived natural products that are currently in actively recruiting clinical trials is also presented. Importantly, the transition of a natural compound from a “screening hit” through a “drug lead” to a “marketed drug” is associated with increasingly challenging demands for compound amount, which often cannot be met by re-isolation from the respective plant sources. In this regard, existing alternatives for resupply are also discussed, including different biotechnology approaches and total organic synthesis.While the intrinsic complexity of natural product-based drug discovery necessitates highly integrated interdisciplinary approaches, the reviewed scientific developments, recent technological advances, and research trends clearly indicate that natural products will be among the most important sources of new drugs also in the future.
The syntheses of extended thiadiazole, thiadiazole oxide, and thiadiazole dioxide heterocycles are described. The electron-accepting heterocycles were investigated by X-ray crystallography and optical as well as electrochemical measurements and supported by DFT calculations. The thiadiazole dioxide heterocycles have reduction potentials of -0.7 V vs ferrocene/ferrocenium, suggesting a viable building block for n-type organic materials.
The three new fluorinated anions BPFPA, PFTFSI, and PFNFSI for highly hydrophobic, hydrolytically stable ionic liquids are introduced, together with a strategy allowing a combinatorial approach for the synthesis of imidazolium and phosphonium based ionic liquids of these relatives of bistriflylimide (BTFSI).
Leoligin is a natural lignan found
in Edelweiss (Leontopodium nivale ssp. alpinum). The aim of this study was to examine its influence on cholesterol
efflux and to address the underlying mechanism of action. Leoligin
increases apo A1- as well as 1% human plasma-mediated cholesterol
efflux in THP-1 macrophages without affecting cell viability as determined
by resazurin conversion. Western blot analysis revealed that the protein
levels of the cholesterol efflux transporters ABCA1 and ABCG1 were
upregulated, whereas the SR-B1 protein level remained unchanged upon
treatment with leoligin (10 μM, 24 h). Quantitative reverse
transcription PCR further uncovered that leoligin also increased ABCA1
and ABCG1 mRNA levels without affecting the half-life of the two mRNAs
in the presence of actinomycin D, a transcription inhibitor. Proteome
analysis revealed the modulation of protein expression fingerprint
in the presence of leoligin. Taken together, these results suggest
that leoligin induces cholesterol efflux in THP-1-derived macrophages
by upregulating ABCA1 and ABCG1 expression. This novel activity suggests
leoligin as a promising candidate for further studies addressing a
possible preventive or therapeutic application in the context of atherosclerosis.
A series of novel, low‐valent germanium compounds 2a–2j based on four diethylenetriamines 1a–1d, (methyl)bis(pyrrol‐2‐ylmethyl)amine (1e), N,N′‐(sulfanediyldibenzene‐2,1‐diyl)bis(pentafluoroaniline) (1f), N,N′‐(oxydibenzene‐2,1‐diyl)bis(pentafluoroaniline) (1g), and (pentafluorophenyl)amines 1i and 1j have been obtained either by the reaction of Ge[N(SiMe3)2]2 with various diamines (1a–1e) or by the metathesis reaction of [GeCl2·dioxane] with lithium amides. The oxidative insertion (with halogenation reagents, MeI, disulfides), [1+4] cycloaddition, and oxidation reactions of the synthesized germylenes were investigated. The compositions and structures of the novel compounds were established by elemental analysis, 1H and 13C NMR spectroscopy, and X‐ray diffraction analysis (germylenes 2b, 2i, 2j, Ge4+ compounds 5b, 7a, 7b, 8, 10, 11). All the synthesized germylenes are monomeric.
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