Caffeoylquinic acids in leaves of selected Apocynaceae species: Their isolation and content

Background: Three compounds isolated from the methanol (MeOH) leaf extract of Vallaris glabra (Apocynaceae) were those of caffeoylquinic acids (CQAs). This prompted a quantitative analysis of their contents in leaves of V. glabra in comparison with those of five other Apocynaceae species (Alstonia angustiloba, Dyera costulata, Kopsia fruticosa, Nerium oleander, and Plumeria obtusa), including flowers of Lonicera japonica (Japanese honeysuckle), the commercial source of chlorogenic acid (CGA). Materials and Methods: Compound were isolated by column chromatography, and identified by NMR and MS analyses. CQA content of leaf extracts was determined using reversed-phase HPLC. Results: From the MeOH leaf extract of V. glabra, 3-CQA, 4-CQA, and 5-CQA or CGA were isolated. Content of 5-CQA of V. glabra was two times higher than flowers of L. japonica, while 3-CQA and 4-CQA content was 16 times higher. Conclusion: With much higher CQA content than the commercial source, leaves of V. glabra can serve as a promising alternative source.