Isolation and biological evaluation of chromone alkaloid dysoline,a new regioisomer of rohitukine from Dysoxylum binectariferum

The chromone alkaloid dysoline (1), a new regioisomer of rohitukine (2) along with rohitukine and rohitukine-N-oxide (3) were isolated from the stem barks of Dysoxylum binectariferum. The structure of dysoline (1) was determined by extensive 2D-NMR studies and the absolute configuration was established by NOESY and CD spectra. Dysoline (1) consisted of a 5,7-dihydroxy-2-methylchromone nucleus substituted with a 2′-hydroxylated N-Me piperidine ring at the C-6 position. Dysoline differs from rohitukine by the position of the piperidine ring on the chromone nucleus. Dysoline displayed promising cytotoxicity in HT1080 fibrosarcoma cells with an IC₅₀ of 0.21 μM, and also displayed significant inhibition of proinflammatory cytokines TNF-α and IL-6.     

Dysoxylentin A, the first 21-nortriterpenoid bearing a 2-(propan-2-ylidenyl)furan-3(2H)-one, from Dysoxylum lenticellatum

Dysoxylentin A (1), the first 21-nortriterpenoid bearing a 2-(propan-2-ylidenyl)furan-3(2H)-one functional group was isolated from the stem of Dysoxylum lenticellatum. Its structure was elucidated by extensive spectroscopic analysis. A plausible biosynthetic pathway was postulated. Dysoxylentin A exhibited selective cytotoxicity against HL-60 tumor cell line.     

Determination of the Absolute Configuration of Rohitukine

The absolute configuration of rohitukine, isolated from the stem-bark of Dysoxylum binectariferum, was determined to be 5,7-dihydroxy-2-methyl-8-[4-(3S, 4R-3-hydroxy-1-methyl)-piperidinyl]-4H-l-benzopyran-4-one by X-ray crystallographic analysis on the crystal of,4-bromobenzoyl derivatives of rohitukine. At the same time, the modified Mosher method was proved to be unsuitable for determining the absolute configuration of C-3‘ position in rohitukine.     

Open tubular supercritical fluid chromatography of triterpene acids from Dysoxylum pettigrewianum (Meliaceae)

Open tubular supercritical fluid chromatography (SFC) with carben dioxide as the mobile phase has been investigated for the separation of four triterpene acids, two of which were structural isomers. These compounds, isolated from Dysoxylum pettigrewianum (Meliaceae), were chromatographed on three stationary phases with different selectivities. 30%-biphenylmethylpolysiloxane and polyethylene glycol (Carbowax 20M) phases exhibited poor chromatographic selectivity for the compounds. The separation was improved by employing the shape selectivity of a liquid crystalline biphenylcarboxylate ester polysiloxane and utilizing simultaneous temperature and pressure programming. The elution order was explained on the basis of the molecular structures of the triterpene acids, and their interaction with the liquid crystal phase.     

Prenyleudesmanes,rare natural diterpenoids from Dysoxylum densiflorum

Prenyleudesmanes are rare natural diterpenoids and their structural features need further characterization. In this paper, twelve new prenyleudesmanes, dysoxydenones A–L (1–12), together with one known prenyleudesmane were isolated from Dysoxylum densiflorum. This is the first time the absolute configurations of prenyleudesmanes have been unambiguously confirmed by single-crystal X-ray diffraction with Cu Kα radiation. Moreover, the absolute configuration of dysokusone D was revised.     

Ergostane Steroids from Dysoxylum lukii

Phytochemical investigation of the 70% EtOH extract from the stem bark of Dysoxylum lukii led to the isolation of three new ergostane steroids, (3β)‐3,20‐dihydroxyergosta‐5,24(28)‐dien‐7‐one ( 1 ), (3β,4β,7α)‐ergosta‐5,24(28)‐diene‐3,4,7‐triol ( 2 ), and (3β,7α)‐3,20‐dihydroxyergosta‐5,24(28)‐dien‐7‐yl acetate ( 3 ), together with the known compound (3β,4β)‐ergosta‐5,24(28)‐diene‐3,4,20‐triol ( 4 ). Their structures were elucidated on the basis of extensive 1D‐ and 2D‐NMR (COSY, HMQC, HMBC, and NOESY) analyses.