Planta Med 2010; 76 - P430
DOI: 10.1055/s-0030-1264728

Antimicrobial acylphloroglucinol derivatives from Hypericum linarioides (Hypericaceae)

S Crockett 1, O Kunert 1, M Jacob 2, R Bauer 1, P Nedialkov 3
  • 1Institute for Pharmaceutical Chemistry, Pharmacognosy, Universitaetsplatz 4, 8010 Graz, Austria
  • 2Natural Center for Natural Products Research, University of Mississippi, 38677 University, United States
  • 3Faculty of Pharmacy, Pharmacognosy, Medical University of Sofia, 1000 Sofia, Bulgaria

Hypericum linarioides Bosse (taxonomic section Taeniocarpium) has one center of distribution in western and southern Transcaucasia, adjacent parts of Russia and northern Iran and Turkey, and a second center in southern Serbia, northern Greece and western Bulgaria. Naphthodianthrones, simple anthrones, flavonoids, flavonol glycosides, caffeic acid derivatives and the xanthone-C-glycoside mangiferin have been previously reported from this species [1, 2]. TLC and HPLC screening of an extract of this species collected in western Bulgaria revealed the presence of a rich diversity of acylphloroglucinol derivatives. Correspondingly, bioassay-guided fractionation of the dichloromethane extract of dried, ground aerial parts of H. linarioides was performed, testing extracts against a range of bacterial and fungal pathogens. Upon observation of promising activity against Candida glabrata (IC50=16.91–21.86µg/mL), Cryptococcus neoformans (IC50=2.48–8.43µg/mL), Staphylococcus aureus (IC50=2.98–24.90µg/mL) and MRSA (IC50=2.72–18.99µg/mL), extracts were further fractionated, resulting in the isolation of several structurally related acylphloroglucinol derivatives. Extracts were analyzed by chromatographic means (TLC, OC, HPLC) and structure elucidation performed using data from NMR and MS. This work resulted in the isolation of 3-geranyl-1-(2′-methylbutanoyl)phloroglucinol (1) and 3-geranyl-1-(2′-methylpropanoyl)phloroglucinol (2) as main constituents, as well as several minor derivatives. 1 has been previously reported from H. empetrifolium (sect. Coridium) [3] and 2 has been previously reported from H. empetrifolium, H. jovis (sect. Coridium) [4] and H. styphelioides (sect. Brathys) [5]. Implications of this chemical convergence are discussed.

Fig.1: Major phloroglucinol derivatives of Hypericum linarioides

Acknowledgements: This research was supported in part by a grant from the Austrian Science Foundation (FWF, Project T345).

References: 1. Šmelcerovic et al. (2006) Phytochemistry 67: 171–77.

2. Ayan and (Ccedil))irak (2008) Pharmaceutical Biology 46: 288–91.

3. Crockett et al. (2008) Phytochemical Letters 1: 37–43.

4. Athanas et al. (2004) Journal of Natural Products 67: 973–77.

5. Gamiotea-Turro et al. (2004) Journal of Natural Products 67: 869–71.