scholarly journals Structure–Activity Relationships of the Antimalarial Agent Artemisinin 10. Synthesis and Antimalarial Activity of Enantiomers of rac-5β-Hydroxy-d-Secoartemisinin and Analogs: Implications Regarding the Mechanism of Action

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4163
Author(s):  
Mohamed Jahan ◽  
Francisco Leon ◽  
Frank R. Fronczek ◽  
Khaled M. Elokely ◽  
John Rimoldi ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Antimalarial Activity ◽  
Crystallographic Analysis ◽  
Hydroxyl Group ◽  
Moderate Activity ◽  
Ether Oxygen ◽  
Tricyclic Analog ◽  
Intramolecular Hydrogen ◽  
New Compounds

An efficient synthesis of rac-6-desmethyl-5β–hydroxy-d-secoartemisinin 2, a tricyclic analog of R-(+)-artemisinin 1, was accomplished and the racemate was resolved into the (+)-2b and (−)-2a enantiomers via their Mosher Ester diastereomers. Antimalarial activity resided with only the artemisinin-like enantiomer R-(−)-2a. Several new compounds 9–16, 19a, 19b, 22 and 29 were synthesized from rac-2 but the C-5 secondary hydroxyl group was surprisingly unreactive. For example, the formation of carbamates and Mitsunobu reactions were unsuccessful. In order to assess the unusual reactivity of 2, a single crystal X-ray crystallographic analysis revealed a close intramolecular hydrogen bond from the C-5 alcohol to the oxepane ether oxygen (O-11). All products were tested in vitro against the W-2 and D-6 strains of Plasmodium falciparum. Several of the analogs had moderate activity in comparison to the natural product 1. Iron (II) bromide-promoted rearrangement of 2 gave, in 50% yield, the ring-contracted tetrahydrofuran 22, while the 5-ketone 15 provided a monocyclic methyl ketone 29 (50%). Neither 22 nor 29 possessed in vitro antimalarial activity. These results have implications in regard to the antimalarial mechanism of action of artemisinin.

From classical antimalarial drugs to new compounds based on the mechanism of action of artemisinin

2001 ◽  
Vol 73 (7) ◽  
pp. 1173-1188 ◽  
Author(s):  
Anne Robert ◽  
Françoise Benoit-Vical ◽  
Odile Dechy-Cabaret ◽  
Bernard Meunier
Keyword(s):  
Mechanism Of Action ◽  
Antimalarial Activity ◽  
Short Review ◽  
Mechanisms Of Action ◽  
Antimalarial Drugs ◽  
Molecular Aspect ◽  
New Compounds

A short review of the antimalarial drugs currently used in human clinics is reported. The molecular aspect of the different possible mechanisms of action of artemisinin is documented, including recent data on heme alkylation. The preparation and the in vitro antimalarial activity of new modular molecules named "trioxaquines" are also presented.

scholarly journals In vitro activities of novel catecholate siderophores against Plasmodium falciparum.

1996 ◽  
Vol 40 (9) ◽  
pp. 2094-2098 ◽  
Author(s):  
B Pradines ◽  
F Ramiandrasoa ◽  
L K Basco ◽  
L Bricard ◽  
G Kunesch ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Mechanism Of Action ◽  
Ribonucleotide Reductase ◽  
Antimalarial Activity ◽  
Iron Chelators ◽  
Resistant Clone ◽  
Iron Deprivation ◽  
Level Of Activity ◽  
Susceptible Clone

The activities of novel iron chelators, alone and in combination with chloroquine, quinine, or artemether, were evaluated in vitro against susceptible and resistant clones of Plasmodium falciparum with a semimicroassay system. N4-nonyl,N1,N8-bis(2,3-dihydroxybenzoyl) spermidine hydrobromide (compound 7) demonstrated the highest level of activity: 170 nM against a chloroquine-susceptible clone and 1 microM against a chloroquine-resistant clone (50% inhibitory concentrations). Compounds 6, 8, and 10 showed antimalarial activity with 50% inhibitory concentrations of about 1 microM. Compound 7 had no effect on the activities of chloroquine, quinine, and artemether against either clone, and compound 8 did not enhance the schizontocidal action of either chloroquine or quinine against the chloroquine-resistant clone. The incubation of compound 7 with FeCI3 suppressed or decreased the in vitro antimalarial activity of compound 7, while no effect was observed with incubation of compound 7 with CuSO4 and ZnSO4. These results suggest that iron deprivation may be the main mechanism of action of compound 7 against the malarial parasites. Chelator compounds 7 and 8 primarily affected trophozoite stages, probably by influencing the activity of ribonucleotide reductase, and thus inhibiting DNA synthesis.

scholarly journals Unusual derivatives from Hypericum scabrum

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sara Soroury ◽  
Mostafa Alilou ◽  
Thomas Gelbrich ◽  
Marzieh Tabefam ◽  
Ombeline Danton ◽  
...  
Keyword(s):  
Trypanosoma Brucei ◽  
2D Nmr ◽  
Moderate Activity ◽  
Trypanosoma Brucei Rhodesiense ◽  
L6 Cells ◽  
Aerial Parts ◽  
Hypericum Scabrum ◽  
New Compounds ◽  
Absolute Structure

AbstractThree new compounds (1–3) with unusual skeletons were isolated from the n-hexane extract of the air-dried aerial parts of Hypericum scabrum. Compound 1 represents the first example of an esterified polycyclic polyprenylated acylphloroglucinol that features a unique tricyclo-[4.3.1.11,4]-undecane skeleton. Compound 2 is a fairly simple MPAP, but with an unexpected cycloheptane ring decorated with prenyl substituents, and compound 3 has an unusual 5,5-spiroketal lactone core. Their structures were determined by extensive spectroscopic and spectrometric techniques (1D and 2D NMR, HRESI-TOFMS). Absolute configurations were established by ECD calculations, and the absolute structure of 2 was confirmed by a single crystal determination. Plausible biogenetic pathways of compounds 1–3 were also proposed. The in vitro antiprotozoal activity of the compounds against Trypanosoma brucei rhodesiense and Plasmodium falciparum and cytotoxicity against rat myoblast (L6) cells were determined. Compound 1 showed a moderate activity against T. brucei and P. falciparum, with IC50 values of 3.07 and 2.25 μM, respectively.

scholarly journals Assessment of Antimalarial Activity againstPlasmodium falciparumand Phytochemical Screening of Some Yemeni Medicinal Plants

2009 ◽  
Vol 6 (4) ◽  
pp. 453-456 ◽  
Author(s):  
Mohammed A. Alshawsh ◽  
Ramzi A. Mothana ◽  
Hassan A. Al-shamahy ◽  
Salah F. Alsllami ◽  
Ulrike Lindequist
Keyword(s):  
Medicinal Plants ◽  
Antimalarial Activity ◽  
Traditional Healers ◽  
Antiplasmodial Activity ◽  
World Health ◽  
Moderate Activity ◽  
Phytochemical Screening ◽  
Cissus Rotundifolia ◽  
Health Organization

Developing countries, where malaria is one of the most prevalent diseases, still rely on traditional medicine as a source for the treatment of this disease. In the present study, six selected plants (Acalypha fruticosa,Azadirachta indica,Cissus rotundifolia,Echium rauwalfii,Dendrosicyos socotranaandBoswellia elongata) commonly used in Yemen by traditional healers for the treatment of malaria as well as other diseases, were collected from different localities of Yemen, dried and extracted with methanol and water successfully. The antiplasmodial activity of the extracts was evaluated against fresh clinical isolates ofPlasmodium falciparum. The selectivity parameters to evaluate the efficacy of these medicinal plants were measured byin vitromicro test (Mark III) according to World Health Organization (WHO) 1996 & WHO 2001 protocols of antimalarial drug tests. Among the investigated 12 extracts, three were found to have significant antiplasmodial activity with IC50values less than 4 µg/ml, namely the water extracts ofA. fruticosa,A. indicaandD. socotrana. Six extracts showed moderate activity with IC50values ranging from 10 to 30 µg/ml and three appeared to be inactive with IC50values more than 30 µg/ml. In addition, preliminary phytochemical screening of the methanolic and aqueous extracts indicated the presence of saponins, tannins, flavonoids, terpenoids, polysaccharides and peptides.

Anti-inflammatory and Anti-HIV Compounds from Swertia bimaculata

Planta Medica ◽  
2017 ◽  
Vol 83 (17) ◽  
pp. 1368-1373 ◽  
Author(s):  
Miao Dong ◽  
Li-Qiu Quan ◽  
Wei-Feng Dai ◽  
Shi-Li Yan ◽  
Chin-Ho Chen ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Ethanol Extract ◽  
Moderate Activity ◽  
Nitric Oxide Production ◽  
X Ray Diffraction ◽  
Oxide Production ◽  
New Compounds ◽  
Anti Hiv ◽  
Hiv 1

AbstractThree new compounds (1 – 3), including a sesterterpenoid, aspterpenacid C (1), with an unusual 5/3/7/6/5 pentacyclic skeleton, together with seven known ones (4 – 10), were isolated from the ethanol extract of the traditional Chinese medicinal plant Swertia bimaculata. Their structures were elucidated on the basis of the methods of spectroscopic NMR, MS, and computational chemistry. The structure of 1 was further confirmed by single-crystal X-ray diffraction analysis. Compounds 1 – 10 were tested for activities on the inhibition of nitric oxide production and HIV-1 replication in vitro. Compound 1 exhibited moderate activity in inhibiting nitric oxide production (IC50 = 16.1 µM) and HIV-1 replication (EC50 = 1.35 µM).

scholarly journals Specific 12β-Hydroxylation of Cinobufagin by Filamentous Fungi

2004 ◽  
Vol 70 (6) ◽  
pp. 3521-3527 ◽  
Author(s):  
Min Ye ◽  
Guiqin Qu ◽  
Hongzhu Guo ◽  
Dean Guo
Keyword(s):  
Microbial Transformation ◽  
Reversed Phase ◽  
In Vitro Models ◽  
In Vitro Cytotoxicity ◽  
New Drugs ◽  
Hydroxyl Group ◽  
Cytotoxic Activities ◽  
Phase Liquid ◽  
New Compounds

ABSTRACT Biotransformation of natural products has great potential for producing new drugs and could provide in vitro models of mammalian metabolism. Microbial transformation of the cytotoxic steroid cinobufagin was investigated. Cinobufagin could be specifically hydroxylated at the 12β-position by the fungus Alternaria alternata. Six products from a scaled-up fermentation were obtained by silica gel column chromatography and reversed-phase liquid chromatography and were identified as 12β-hydroxyl cinobufagin, 12β-hydroxyl desacetylcinobufagin, 3-oxo-12β-hydroxyl cinobufagin, 3-oxo-12β-hydroxyl desacetylcinobufagin, 12-oxo-cinobufagin, and 3-oxo-12α-hydroxyl cinobufagin. The last five products are new compounds. 12β-Hydroxylation of cinobufagin by A. alternata is a fast catalytic reaction and was complete within 8 h of growth with the substrate. This reaction was followed by dehydrogenation of the 3-hydroxyl group and then deacetylation at C-16. Hydroxylation at C-12β also was the first step in the metabolism of cinobufagin by a variety of fungal strains. In vitro cytotoxicity assays suggest that 12β-hydroxyl cinobufagin and 3-oxo-12α-hydroxyl cinobufagin exhibit somewhat decreased but still significant cytotoxic activities. The 12β-hydroxylated bufadienolides produced by microbial transformation are difficult to obtain by chemical synthesis.

Blood schizontocidal activity of azithromycin and its combination with α/β arteether against multi-drug resistant Plasmodium yoelii nigeriensis, a novel MDR parasite model for antimalarial screening

Parasitology ◽  
2005 ◽  
Vol 131 (3) ◽  
pp. 295-301 ◽  
Author(s):  
R. TRIPATHI ◽  
S. DHAWAN ◽  
G. P. DUTTA
Keyword(s):  
Antimalarial Activity ◽  
Wide Spectrum ◽  
Oral Route ◽  
Plasmodium Yoelii ◽  
Drug Resistant ◽  
Curative Effect ◽  
Resistant Lines ◽  
High Doses ◽  
New Compounds

Many different drug-resistant lines of rodent malaria are available as screening models. It is obligatory to screen new compounds for antimalarial activity against a series of resistant lines in order to identify a compound with potential for the treatment of multi-drug resistant (MDR) malaria infections. Instead of using a battery of resistant lines, a single MDR Plasmodium yoelii nigeriensis strain that shows a wide spectrum of drug resistance to high doses of chloroquine, mepacrine, amodiaquine, mefloquine, quinine, quinidine, halofantrine as well as tetracyclines, fluoroquinolines and erythromycin, was used to assess the blood schizontocidal efficacy of a new macrolide azithromycin and other antibiotics. The present study shows that only azithromycin has the potential to control an MDR P. y. nigeriensis infection in Swiss mice, provided the treatment with a dose of 50–100 mg/kg/day by oral route is continued for a period of 7 days. Tetracycline, oxytetracycline, doxycyline, erythromycin, ciprofloxacin and norfloxacin, although active in vitro, failed to protect the mice. Tetracycline, ciprofloxacin and norfloxacin combinations with chloroquine did not control the infection. Additionally, the antimalarial efficacy of azithromycin can be potentiated with the addition of arteether, which is an ethyl ether derivative of artemisinin. A total (100%) curative effect has been obtained with a shorter regimen of 4 days only.

Selective synthesis and biological activity of triazine-porphyrins as potential anti-cancer agents

2010 ◽  
Vol 14 (02) ◽  
pp. 123-127 ◽  
Author(s):  
Shen-Chu Xiao ◽  
Chao-Zhou Liu ◽  
Wu-Kun Liu ◽  
Wen-Zhong Xie ◽  
Wei-Ying Lin ◽  
...  
Keyword(s):  
Hydroxyl Group ◽  
Selective Synthesis ◽  
One Pot ◽  
Similar Activity ◽  
H Nmr ◽  
Porphyrin Derivatives ◽  
Anti Cancer ◽  
New Compounds ◽  
Mcf 7

Ten new triazine-porphyrin derivatives were synthesized using a simple one-pot procedure from the reaction of tetraphenylporphyrin bearing a hydroxyl group with 2,4,6-trichloro-1,3,5-triazine, and then with amines or alcohols. The structures of the products were characterized by 1H NMR, LC/MS, UV-vis and elemental analysis. The cytotoxic activity of the triazine-porphyrin derivatives was evaluated in vitro against MCF-7 cell. All new compounds showed similar activity against MCF-7 cells in the absence of light when compared to 5-fluorouracil and hematoporphyrin.

scholarly journals Relationship between Antimalarial Activity and Heme Alkylation for Spiro- and Dispiro-1,2,4-Trioxolane Antimalarials

2008 ◽  
Vol 52 (4) ◽  
pp. 1291-1296 ◽  
Author(s):  
Darren J. Creek ◽  
William N. Charman ◽  
Francis C. K. Chiu ◽  
Richard J. Prankerd ◽  
Yuxiang Dong ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Antimalarial Activity ◽  
Biologically Active ◽  
Radical Intermediate ◽  
Reaction Conditions ◽  
Artemisinin Derivatives ◽  
Major Reaction Product ◽  
Major Reaction ◽  
Insight Into

ABSTRACT The reaction of spiro- and dispiro-1,2,4-trioxolane antimalarials with heme has been investigated to provide further insight into the mechanism of action for this important class of antimalarials. A series of trioxolanes with various antimalarial potencies was found to be unreactive in the presence of Fe(III) hemin, but all were rapidly degraded by reduced Fe(II) heme. The major reaction product from the heme-mediated degradation of biologically active trioxolanes was an alkylated heme adduct resulting from addition of a radical intermediate. Under standardized reaction conditions, a correlation (R 2 = 0.88) was found between the extent of heme alkylation and in vitro antimalarial activity, suggesting that heme alkylation may be related to the mechanism of action for these trioxolanes. Significantly less heme alkylation was observed for the clinically utilized artemisinin derivatives compared to the equipotent trioxolanes included in this study.

scholarly journals 1α,24(S)-dihydroxyvitamin D2: a biologically active product of 1α-hydroxyvitamin D2 made in the human hepatoma, Hep3B

1995 ◽  
Vol 310 (1) ◽  
pp. 233-241 ◽  
Author(s):  
S Strugnell ◽  
V Byford ◽  
H L J Makin ◽  
R M Moriarty ◽  
R Gilardi ◽  
...  
Keyword(s):  
Vitamin D ◽  
Biological Properties ◽  
Crystallographic Analysis ◽  
Biologically Active ◽  
Hydroxyl Group ◽  
X Ray ◽  
Metabolic Bone ◽  
Vitamin D Analogue ◽  
Made In

A major metabolite of the vitamin D analogue 1 alpha-hydroxyvitamin D2 in human liver cells in culture has been identified as 1 alpha,24(S)-dihydroxyvitamin D2 [1 alpha,24(S)-(OH)2D2]. 1 alpha-Hydroxyvitamin D3 incubated with the same cells gives rise to predominantly 25- and 27-hydroxylated products. Our identification of 1 alpha,24(S)-dihydroxyvitamin D2 is based on comparisons of the liver cell metabolite with chemically synthesized 1 alpha,24(S)-(OH)2D2 and 1 alpha,24(R)-(OH)2D2 by using HPLC, GC and GC-MS techniques. The stereochemical orientation of the 24-hydroxyl group was inferred after X-ray-crystallographic analysis of the 24(R)-OH epimer. 1 alpha,24(S)-Dihydroxyvitamin D2 binds strongly to the vitamin D receptor and is biologically active in growth hormone and chloramphenicol acetyltransferase reporter gene expression systems in vitro, but binds poorly to rat vitamin D-binding globulin, DBP. We suggest that this metabolite, 1 alpha,24(S)-(OH)2D2, possesses the spectrum of biological properties to be useful as a drug in the treatment of psoriasis, metabolic bone disease and cancer.

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