Dihydroisocoumarins and Dihydroisoflavones from the Rhizomes of Dioscorea collettii with Cytotoxic Activity and Structural Revision of 2,2′-Oxybis(1,4-di-tert-butylbenzene)

Abstract

The investigation of the constituents of the rhizomes of Dioscorea collettii afforded one new dihydroisocoumarin, named (−)-montroumarin (1a), along with five known compounds—montroumarin (1b), 1,1’-oxybis(2,4-di-tert-butylbenzene) (2), (3R)-3′-O-methylviolanone (3a), (3S)-3′-O-methylviolanone (3b), and (RS)-sativanone (4). Their structures were elucidated using extensive spectroscopic methods. To the best of our knowledge, compound 1a is a new enantiomer of compound 1b. The NMR data of compound 2 had been reported but its structure was erroneous. The structure of compound 2 was revised on the basis of a reinterpretation of its NMR data (1D and 2D) and the assignment of the 1H and 13C NMR data was given rightly for the first time. Compounds 3a–4, three dihydroisoflavones, were reported from the Dioscoreaceae family for the first time. The cytotoxic activities of all the compounds were tested against the NCI-H460 cell line. Two dihydroisocoumarins, compounds 1a and 1b, displayed moderate cytotoxic activities, while the other compounds showed no cytotoxicity.

Cytotoxic and Anti-Inflammatory Activities of Dihydroisocoumarin and Xanthone Derivatives from Garcinia picrorhiza

“…Compound 3 was identified to be levorotary ([α] 20 D = −40.2) and showed a negative ECD Cotton effect (CE) at 276 nm followed by lowamplitude positive and negative CEs at 256 and 232 nm, respectively (See Supplementary Materials Figure S20). The two chiroptical data were in good agreement with previous results and thus implied that 3 favored 3R configuration [13,26,27]. The similar pattern of experimental ECD spectra of 1 and 2 with those of 3 indicated that they shared the same configuration at C-3 (Figure S20).…”

“…The CH 2 Cl 2 -soluble fraction from the stem bark of Garcinia picrorhiza was subjected to a combination of chromatographic methods using silica gel, Sephadex LH-20, and chromatotron to give 15 compounds, including a new dihydroisocoumarin derivative, 2 -hydroxyannulatomarin (3), and two new furanoxanthones, gerontoxanthone C hydrate (4) and 3 -hydroxycalothorexanthone (5). The structures of the known compounds were determined as (−)-montroumarin (1) [13], (−)-annulatomarin (2) [14,15], pancixanthone B (6) [16], 2-deprenylrheediaxanthone B (7) [17], formoxanthone C (8) [18], 1,2,5trihydroxyxanthone (9) [19], subelliptenone G (10) [20], 1,5-dihydroxy-2-methoxyxanthone (11) [21], 1,6-dihydroxy-5-methoxyxanthone (12) [22], 1,3,6-trihydroxy-5-methoxyxanthone (13) [23], 1,6-dihydroxy-3,5-dimethoxyxanthone (14) [24], and 1,3-dihydroxy-5,6,7-trimethoxyxanthone (15) [25] by comparison of their spectroscopic data with the literature (Figure 1). Compound 3 was obtained as a pale yellow amorphous solid with a molecular formula of C 16 H 14 O 6 based on its molecular ion peak at m/z 325.0693 [M + Na] + in HRESIMS, indicative of ten degrees of unsaturation.…”

“…Compound 4 was isolated as a pale yellow amorphous solid and its molecular formula was determined as C 23 H 26 O 7 from the molecular ion peak at m/z 437.1663 [M + Na] + in HRESIMS analysis, which in turn assigned 11 degrees of unsaturation. The 1 H-and 13 C-NMR spectra (Table 1) indicated 4 to feature a xanthone skeleton, especially the typical resonances for hydrogen-bonded hydroxy proton at δ H 13.26 (s, OH-1) and carbonyl carbon at δ C 182.0 [28]. Detailed analysis of 1D NMR data suggested that 4 had a scaffold similar to gerontoxanthone C [29], except that signals corresponding to a double bond of prenyl unit were missing in 4.…”

“…1 H-(400 MHz) and13 C-(100 MHz) NMR spectroscopic data of compounds 3-5 recorded in acetone-d 6 (δ in ppm).…”

Indonesian Euphorbiaceae: Ethnobotanical Survey, In Vitro Antibacterial, Antitumour Screening and Phytochemical Analysis of Euphorbia atoto

“…Despite its "unnatural" structure, it was previously isolated from nature twice. Specifically, tetra-tert-butyl-diphenyl ether (3) was obtained from the marine mollusc Onchidium struma [54] and Dioscorea collettii rhizomes [55]. Jing et al supposed that this unique structure is most likely attributed to the environmental stresses of plants (e.g., salinity, water supply).…”