Cleavage of ring A and formation of an unusual nor-triterpene skeleton via the Baeyer–Villiger reaction

Tag̀, Özgür; Çağır, Ali; Khan, Ikhlas A.; Bedir, Erdal

doi:10.1016/j.tetlet.2012.08.068

Cited by 7 publications

(3 citation statements)

References 19 publications

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“…Compound 2a was obtained from an oxidation reaction of AG. At 0°C, Jones oxidation resulted in 2a in 64% yield as previously described [21].…”

Section: Structure Elucidation Of the New Compounds (2 And 3)mentioning

confidence: 91%

“…The combined organic layers were washed with brine solution, dried over Na 2 SO 4 , and filtered. The filtrate was evaporated, and chromatographic separation of the crude product on a silica gel column was performed by using n-hexanes:EtOAc (8:2) as eluent to give 2a (74.7 mg lyophilized white powder, 74.7% yield) [21]. 2a (3,6,16-trioxo-astragenol) (120 mg) was dissolved in 8 mL THF and was added NaOMe (135 mg) at room temperature.…”

Section: Compoundmentioning

confidence: 99%

“…In the 13 C-NMR spectrum, the characteristic signals of C-20 and C-24 are supposed to resonate ca. at δ 88.0 and 82.5, respectively for CG, AG and 2a possessing 20R,24S absolute stereochemistry [20,21]. When 13 C-NMR and HMQC spectra of 2 were examined together, an oxymethine carbon was located at δ 82.5, whereas a quaternary carbon resonated at δ 84.5.…”

Section: Structure Elucidation Of the New Compounds (2 And 3)mentioning

confidence: 99%

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Cycloartane-type sapogenol derivatives inhibit NFκB activation as chemopreventive strategy for inflammation-induced prostate carcinogenesis

et al. 2018

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Chronic inflammation is associated to 25% of cancer cases according to epidemiological data. Therefore, inhibition of inflammation-induced carcinogenesis can be an efficient therapeutic approach for cancer chemoprevention in drug development studies. It is also determined that anti-inflammatory drugs reduce cancer incidence. Cell culture-based in vitro screening methods are used as a fast and efficient method to investigate the biological activities of the biomolecules. In addition, saponins are molecules that are isolated from natural sources and are known to have potential for tumor inhibition. Studies on the preparation of analogues of cycloartane-type sapogenols (9,19-cyclolanostanes) have so far been limited. Therefore we have decided to direct our efforts toward the exploration of new anti-tumor agents prepared from cycloastragenol and its production artifact astragenol. The semi-synthetic derivatives were prepared mainly by oxidation, condensation, alkylation, acylation, and elimination reactions. After preliminary studies, five sapogenol analogues, two of which were new compounds (2 and 3), were selected and screened for their inhibitory activity on cell viability and NFκB signaling pathway activity in LNCaP prostate cancer cells. We found that the astragenol derivatives 1 and 2 as well as cycloastragenol derivatives 3, 4, and 5 exhibited strong inhibitory activity on NFκB signaling leading the repression of NFκB transcriptional activation and suppressed cell proliferation. The results suggested that these molecules might have significant potential for chemoprevention of prostate carcinogenesis induced by inflammatory NFκB signaling pathway.

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“…Compound 2a was obtained from an oxidation reaction of AG. At 0°C, Jones oxidation resulted in 2a in 64% yield as previously described [21].…”

Section: Structure Elucidation Of the New Compounds (2 And 3)mentioning

confidence: 91%

Section: Compoundmentioning

confidence: 99%

Section: Structure Elucidation Of the New Compounds (2 And 3)mentioning

confidence: 99%

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