Flavonoids from the Leaves of Chromolaena subscandens

Abstract

Phytochemical analysis of the leaves from Chromolaena subscandens afforded ß-sitosterol, umbelliferone, /-methoxybenzoic acid, and several known flavonoids, as well as a new one, 5,7-dihydroxy-8,4'-dimethoxyflavanone, which we have named subscandenin [1]. The structure of this new flavanone was established by spectral methods.

New reports on surface flavonoids from Chamaebatiaria (Rosaceae), Dodonaea (Sapindaceae), Elsholtzia (Lamiaceae), and Silphium (Asteraceae)

“…The NMR data we recorded for 5,7-diOH-8,4´-diOMe flavanone are in excellent agreement with those reported previously [4,3], except that in [3] the assignments for C-6 and C-8 are reversed. 104.5 (C10), 120.5 (C1'), 129.5 (C2'), 127.8 (C3'), 157.9 (C4'), 115.0 (C5'), 127.4 (C6'), 59.5 (C3-OMe), 59.9 (C6-OMe), 27.7 (C1''), 122.1 (C2"), 132.1 (C3"), 17.5 (C4"), 25.4 (C5").…”

A New Flavanone as a Potent Antioxidant Isolated from Chromolaena odorata L. Leaves

“…Furthermore, a leaf water extract is widely used as a diarrhea, malaria, and diabetes drug [6]. In the past 40 years, this plant has been reported in phytochemical studies in the United States [14, 15]. Recently, C. odorata was described for its beneficial attributes in some Asia-Africa countries, especially the pharmacological effects of this plant.…”

“…They have hydrogen-to-carbon correlations between H-6/C-4, C-7, C-9, C-10; H-8/C-6, C-7, C-9, C-10; H-2'/C-2, C-1', C-4'; H-4'/C-1'; H-5'/C-2, C-2', C-3', C-6' which were also confirmed by HMQC spectrum as Figure 4(b). Accordingly, both hydroxyl and methoxy substituents were assigned as 3'-hydroxy [9, 13] and 8-methoxy [14] at C-3' and C-8. Interestingly, although more than 79 flavonoid compounds have been isolated from the genus Chromolaena [8], the methoxy substituent at C-6' has not been reported yet before.…”

Complete 13C and 1H NMR spectral assignments of two isoflavones from the roots of Dalbergia horrida

“…We report here the complete 1 H NMR and 13 C NMR spectra of dalspinin (1) and dalspinosin (2). In the case of 5,7-dihydroxyflavonoids, a few reported techniques have been useful in determining the positions of the substituents at C-6 or C-8 of flavonoids, including the Gibb's test, 5 aluminium chloride-induced UV shift, 6,7 chemical shift of the 5-OH signal 8 -10 and the chemical shift of the lone A-ring proton. 11 In the present study, the complete assignments of the protonated and non-protonated carbons and the position of the methoxyl group at C-6 in both 1 and 2 were assigned by interpretation of data from 2D NMR experiments such as HMQC and HMBC.…”