5-Hydroxy-3,3′,4′,5′,7-pentamethoxyflavone (combretol)

Abstract

The structure of the title compound, C20H20O8, which was extracted from Rhodomyrtus tomentosa, confirms the connectivity and is consistent with the results from spectroscopy. The structure, notable for the crowded sequence of (3′,4′,5′) tri­methoxy substituents, is compared with that of its previously recorded analogue lacking the methyl at the 4′‐oxy­gen (two polymorphs), and with myricetin which lacks all O‐methyl­ation (cocrystallized with tri­phenyl­phosphine oxide). The latter, interestingly, has a dihedral angle of 36.4 (3)° between its planar aromatic components, but the overall cyclic framework of the title mol­ecule is essentially planar. In the crystal structure, the mol­ecules stack obliquely along the short [4.244 (2) Å] c axis of the orthogonal cell.

5,3′-Dihydroxy-3,6,7,4′-tetramethoxyflavone

“…The bond lengths and angles of the flavone ring system in (I) ( Fig. 1) are comparable to those of 5,3 0 -dihydroxy-3,7,4 0 ,5 0tetramethoxyflavone (Etti et al, 2005) and 5-hydroxy-3,7,3 0 ,4 0 ,5 0 ,-pentamethoxyflavone (Dachriyanus et al, 2004). As expected, rings A (C4a/C5-C8/C8a), B (O1/O2/C3/C4/C4a/ C8a) and C (C1 0 -C6 0 ) are planar, the dihedral angles between them being A/B = 2.37 (4) , A/C = 9.49 (3) and B/C = 7.20 (4) .…”

Polymethylated Myricetin in Trichomes of the Wild Tomato Species Solanum habrochaites and Characterization of Trichome-Specific 3′/5′- and 7/4′-Myricetin O-Methyltransferases

“…Our metabolic profiling of trichome glands from S. habrochaites leaf identified three forms of O-methylated myricetin species: 3,7,3#-MeM, 3,7,3#,5#-MeM, and 3,7,3#,4#,5#-MeM. These three compounds have previously been shown to accumulate in tissues of several other plants (Stevens et al, 1995;Dachriyanus et al, 2004;Ariyanathan et al, 2010), but they have not yet been reported to be present in trichomes. By isolating individual types of glands, we were able to show that these compounds are found in three types of glandular trichomes, types 1, 4, and 6 (Fig.…”

Cycloartane Triterpenes Isolated from Combretum quadrangulare in a Screening Program for Death-Receptor Expression Enhancing Activity

“…Compounds 10 − 17 were revealed to be arjunolic acid ( 10 ), asiatic acid ( 11 ), 5,7,3′,5′-tetrahydroxy-3,4′-dimethyoxyflavone ( 12 ), combretol ( 13 ), 3′,5-dihydroxy-3,4,′5′,7-tetramethoxyflavone ( 14 ), pachypodol (5,4′-dihydroxy-3,7,3′-trimethoxyflavone) ( 15 ), quercetin 3,4′-dimethyl ether (5,7,3′-trihydroxy-3,4′-dimethoxyflavone) ( 16 ), and myricetin 3,3′,4′-trimethyl ether ( 17 ) by comparison of their NMR and MS data with those in the literature.…”