Structural Analogues of the Calanolide Anti-HIV Agents. Modification of the trans-10,11-Dimethyldihydropyran-12-ol Ring (Ring C)

• Published in: Journal of medicinal chemistry Vol. 40; no. 6; pp. 1005 - 1017
• Main Authors: Zembower, David E, Liao, Shuyuan, Flavin, Michael T, Xu, Ze-Qi, Stup, Tracy L, Buckheit, Robert W, Khilevich, Albert, Mar, Aye Aye, Sheinkman, Abram K
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 14-03-1997
• Subjects: AIDS/HIV; Anti-HIV Agents - chemical synthesis; Anti-HIV Agents - chemistry; Anti-HIV Agents - pharmacology; Antibiotics. Antiinfectious agents. Antiparasitic agents; Antiviral agents; Biological and medical sciences; Cell Survival - drug effects; Coumarins - chemical synthesis; Coumarins - chemistry; Coumarins - metabolism; Coumarins - pharmacology; HIV Reverse Transcriptase - metabolism; HIV-1 - drug effects; HIV-1 - enzymology; Human immunodeficiency virus; Humans; Magnetic Resonance Spectroscopy; Medical sciences; Molecular Structure; Pharmacology. Drug treatments; Pyranocoumarins; Reverse Transcriptase Inhibitors - chemical synthesis; Reverse Transcriptase Inhibitors - chemistry; Reverse Transcriptase Inhibitors - pharmacology; Tumor Cells, Cultured; RNA-directed DNA polymerase; Enzyme; Transferases; Retroviridae; Enzyme inhibitor; Lactone; Tetracyclic compound; Oxygen heterocycle; Ketone; In vitro; Cis stereoisomer; Virus; Nucleotidyltransferases; Structure activity relation; Racemate; Lentivirinae; Antiviral; Aromatic compound; Human immunodeficiency virus; Chemical synthesis
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/jm960355m

(+)-Calanolide A is a potent inhibitor of reverse transcriptase from human immunodeficiency virus type 1 (HIV-1), which was isolated from an extract of Calophyllum lanigerum, along with seven related compounds. In order to examine the structure−activity relationships of the trans-10,11-dimethyldihydropyran-12-ol ring (designated ring C), a series of structural analogues were prepared and evaluated using a whole cell cytopathicity assay (XTT). Removal of the 10-methyl group resulted in decreased activity, with only one epimer exhibiting anti-HIV activity. Substituting the 10-methyl group with an ethyl chain maintained anti-HIV activity, with only a 4-fold reduction in potency relative to racemic calanolide A. Substitution of the 10-methyl group with an isopropyl moiety completely eliminated the anti-HIV activity. Addition of an extra methyl group at either the 10- or 11-position maintained the basic stereochemical features of the parent calanolide system while removing the chirality at the respective carbon, but resulted in decreased activity relative to calanolide A. In all the above examples, analogues containing a cis relationship between the 10- and 11-alkyl moieties were completely devoid of activity. Synthetic intermediates in which the 12-hydroxyl group was in the ketone oxidation state exhibited surprising anti-HIV activity, with EC50 values only 5-fold less potent than that of calanolide A for both the 10,11-cis (6) and -trans (5) series. These ketones represent the first derivatives in the calanolide series to exhibit anti-HIV activity while not containing a 12-hydroxyl group. Likewise, ketone derivative 6 was the first example of a compound in the calanolide series having a cis relationship between the 10- and 11-methyl groups found to exhibit anti-HIV activity. Analogues which showed anti-HIV activity in the CEM-SS cytoprotection assay were further confirmed to be inhibitors of HIV-1 reverse transcriptase.