Structures of flavone and flavonol glycosides
SummaryLiterature information on the structures of O-glycosides of flavones and flavonols has been generalized. Using the methods of combinatorial mathematics, the possibility of a great diversity of the structure of the glycosides has been shown without taking into account their acylation, the dimensions of the oxide rings of the sugars, and the nature of the glycosidic bonds.
Isolation and structural determination of 13 flavonoid glycosides in Hibiscus esculentus (okra).
A B S T R A C T Eleven flavonol glycosides and two anthocyaninis, only one of which was previously identified, were isolated from the flower petals of okra, Hibiscus esculentus L. On the basis of chromatographic, spectral, anid degradative evidence, the following structural assignments were made: quercetin 4'-glucoside, quercetin 7-glucoside, quercetin 5-glucoside, quercetin 3-diglucoside, quercetini 4'-diglucoside, quercetin 3-triglucoside, quercetin 5-rhamnoglucoside, gossypetin 8glucoside, gossypetiin 8-rhamnoglucoside, gossypetin 3-glucosido-8-rhamnoglucoside, cyanidin 4'-glucoside, and cyaniidin 3-glucosido-4' glucoside. Some evidence was obtained of a pentahydroxy, monomethoxy-flavone glycoside. The total flavonoid content in the red portion of the petal was 0.48% of fresh weight; that in the white portion was 2.51%. The two anthocyanins comprised 28.5% of the flavonoid content of the red flower but only a trace of the content of the white. HIBISCUS ESCULENTUS L., commonly known as okra or gumbo, is a tropical annual of both
Feeding and Oviposition of the Boll Weevil, Anthonomus grandis (Coleoptera: Curculionidae), on the Rose-of-Sharon, an Alternate Host
The calyx that enclosed the developing bud of the Rose-of-Sharon ( Hibiscus syriacus L.) until the prebloom stage deterred feeding and oviposition of the boll weevil, Anthonomus grandis Boheman, on this alternate host. When the calyxes were removed, weevils fed on and oviposited in the buds at about the same rate as on flower buds (squares) of cotton. Although the calyxes were not a morphological barrier, they contained a substance that discouraged weevil feeding and oviposition during the bud stage of development and contributed to Rose-of-Sharon's undesirability as a host. Field observations showed that infestation of Rose-of-Sharon by the boll weevil occurs only when the plant grows near cotton.