Oxygenated Cyclohexene Derivatives and Other Constituents from the Roots of Monanthotaxis trichocarpa

Abstract

Three new oxygenated cyclohexene derivatives, trichocarpeols A (1), B (2), and C (3), along with nine known secondary metabolites, were isolated from the methanolic root extract of Monanthotaxis trichocarpa. They were identified by NMR spectroscopic and mass spectrometric analyses, and the structure of trichocarpeol A (1) was confirmed by single-crystal X-ray diffraction. Out of the 12 isolated natural products, uvaretin (4) showed activity against the Gram-positive bacterium Bacillus subtilis with a MIC value of 18 μM. None of the isolated metabolites was active against the Gram-negative Escherichia coli at a ∼5 mM (2000 μg/mL) concentration. Whereas 4 showed cytotoxicity at EC50 10.2 μM against the MCF-7 human breast cancer cell line, the other compounds were inactive or not tested.

Biflavanones, Chalconoids, and Flavonoid Analogues from the Stem Bark of Ochna holstii

“…The UV spectrum showed absorption maxima at 258 and 340 nm, conforming the presence of a flavanone-type structure. 26,29 The NMR spectroscopic data of 2 (Table 1, Figures S9−S15, Supporting Information) are closely related to those of compound 1. Compound 2 contained two additional methoxy groups with protons resonating at δ H 3.76 (δ C 55.8) and 3.78 (δ C 55.8) and attached to C-7 (δ C 165.1) and C-4‴ (δ C 155.7), respectively.…”

“…IR absorptions at 1631 and 1506 cm –1 are typical of CC stretches. The UV spectrum with absorption maxima centered at λ max 264, 320, and 346 nm indicated the presence of a chalconoid skeleton. , The 1 H NMR spectrum (Table , Figure S33, Supporting Information) displayed signals of a p -disubstituted aromatic ring resonating at δ H 7.23 (H-3′″″/5′″″) and 6.89 (H-2″″′/6″″′), three sets of ABX spin systems at 7.73 (H-6″″), 6.24 (H-3″″), and 6.26 (H-5″″) for ring A, at δ H 7.31 (H-2″), 7.00 (H-5″), and 7.46 (H-6″) for ring B 2 , and at 7.91 (H-6′), 6.38 (H-5′), and 6.27 (H-3′) for ring A 2 . The 1 H NMR spectrum consisted also of signals corresponding to trans -olefinic protons at δ H 7.72 (H-3) and 7.57 (H-2) and ethylene protons at δ H 3.24 (H-2‴) and 3.00 (H-3‴), which are common features of chalcone and dihydrochalcone moieties, respectively.…”

Oxygenated Cyclohexene Derivatives from the Stem and Root Barks of Uvaria pandensis

“…Our recent findings of the bioactive oxygenated cyclohexene derivatives including their chlorinated counterparts from Cleistochlamys kirkii ( 13 ) and Monathotaxis trichocarpa ( 11 ) inspired a reinvestigation of Uvaria pandensis Verdc., a plant species previously reported to contain similar compounds. 6 , 36 The species is used in some parts of Tanzania in traditional medicine to treat stomach disorders and fever.…”

“… 6 , 36 The species is used in some parts of Tanzania in traditional medicine to treat stomach disorders and fever. 11 Reported herein are the isolation and structure determination of five hitherto unreported oxygenated cyclohexene derivatives ( 1 – 5 ), which were obtained with 16 known compounds ( 6 – 21 ) from the CH 3 OH extracts of stem and root bark samples. The isolated metabolites were evaluated for antibacterial activity against the Gram-positive bacteria Bacillus subtilis and Staphylococcus epidermidis and the Gram-negative bacteria Enterococcus raffinosus , Escherichia coli, Paraburkholderia caledonica , Pectobacterium carotovorum , and Pseudomonas putida .…”

“…Members of the genus Uvaria host a vast number of secondary metabolites with varied chemical structures and biological activities . The phytochemical constituents of the genus Uvaria include flavonoids and oxygenated cyclohexene derivatives, with the latter being restricted to the genus and its closely related genera within the Uvariae tribe, − albeit with very few plant families other than Annonaceae. − Thus, oxygenated cyclohexene derivatives have so far been reported from about 20 species of Uvaria ,− ,,− and other genera of the Uvariae tribe such as Monanthotaxis , ,, Ellipeiopsis , , Dasymaschalon , Cleistochlamys , , and Artabotrys . , These compounds exhibit diverse bioactivities including antiproliferative, ,,, antimalarial, ,, antibacterial, and cytotoxic ,, activities.…”