Location: Food Quality LaboratoryTitle: Antioxidant glucosylated caffeoylquinic acid derivatives in the invasive tropical soda apple, Solanum viarum Author
Submitted to: Journal of Natural Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2012
Publication Date: 12/13/2012
Citation: Wu, S., Meyers, R.S., Whitaker, B.D., Litt, A., Kennelly, E.J. 2012. Antioxidant glucosylated caffeoylquinic acid derivatives in the invasive tropical soda apple, Solanum viarum. Journal of Natural Products. 75:2246-2250. Interpretive Summary: The tropical soda apple, Solanum viarum, is a noxious invasive weed species from South America that is now widely distributed in the southeastern U.S. There is evidence that the success of this plant as an invasive weed is at least partly based on its ability to produce unique or unusual chemicals that combat feeding insects and disease. It has already been recognized that the fruit of S. viarum are a rich source of steroidal compounds that are useful for synthesis of corticosteroid drugs. In this study, two totally new compounds were isolated from S. viarum fruit which are members of a class of compounds known to have health-beneficial bioactivity in humans. The discovery that fruit of tropical soda apple include an array of abundant bioactive chemicals is information useful to the pharmaceutical industry and could incentivize widespread harvesting of this weed, contributing to its control and thus benefiting farmers and ranchers. In addition, breeders will find this information useful because S. viarum is closely related to crop species including eggplant, tomato, and potato, and thus there is a potential for its use in breeding programs to introduce new health-beneficial compounds into these crops and/or confer greater resistance to certain insect pests and diseases.
Technical Abstract: The eggplant (Solanum melongena) and other species within the “spiny solanums” (Solanum subgenus Leptostemonum) contain diverse and abundant antioxidant caffeoylquinic acid (CQA) derivatives. The fruit of an aggressive invasive species in the spiny solanums, Solanum viarum, contain numerous CQA derivatives, but only a few of these have been structurally elucidated. Two novel compounds were isolated from methanolic extracts of S. viarum fruit by C18-HPLC-DAD and their structures determined using 2D NMR and mass spectrometry. Both include a pair of 5-caffeoylquinic acid molecules joined by a glucose moiety via ester and glycosidic linkages. Structures of the new compounds, viarumacids A and B, are as follows: 5-caffeoyl-[4-(1ß-[6-(5-caffeoyl)quinate]-glucopyranosyl)]quinic acid and 3-malonyl-5-caffeoyl-[4-(1ß-[6-(5-caffeoyl)quinate]-glucopyranosyl)]quinic acid, respectively. Their antioxidant activities determined by ABTS•+ and DPPH• assays were found to be similar to that of 5-CQA.