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DOI: 10.1055/s-2007-986974
Antioxidant and antimicrobial potential of Garcinia hombroniana Pierre bark
The crude methanolic extract from the bark of Garcinia hombroniana (Clusiaceae), a tree which is native to tropical areas in Southeast Asia, showed a promising antioxidant activity tested by the DPPH assay (EC50 2.11µg/ml) [1]. After partitioning between chloroform/water and subsequently bioassay-guided fractionation by chromatographic methods the antioxidant effect could be further increased. The red brown aqueous phase which was further separated by a Sephadex LH-20 column resulted in an antioxidant activity of EC50 0.61µg/ml in fraction 6. The activity could be referred to the high content of tannins. Additional phytochemical investigations elucidated the occurrence of flavonoids, saponins, terpenoids, essential oils and coumarins [2,3]. The methanolic extract (1mg/disc; disc diameter 9mm) as well as the fractions were tested [4] against 8 gram-positive and 6 gram-negative bacterial strains including the causative peptic-ulcer bacteria Helicobacter pylori and against two Candida strains. The plant extract demonstrated an inhibiting effect on the growth of Bac. cereus (inhibition zone diameter (IHD) 15mm), Bac. subtilis (IHD 12mm), E. faecalis (IHD 12mm), Helicobacter pylori (IHD 13mm), Staph. aureus (IHD 13mm) and Staph. epidermidis (IHD 12mm). The strongest effect was found against Bac. cereus. An interesting activity against Helicobacter pylori was detected.
Acknowledgements: ASEA-UNINET grants to H.H. and M.K. and the Pharmacy PSU grants are acknowledged.
References: [1] Hatano, T et al. (1988) Chem. Pharm. Bull. 36(6): 2090–2097 [2] Rukachaisirikul, V. et al. (2000) 55: 183–188. [3] Rukachaisirikul, V. et al. (2005) 68: 1222–1225. [4] Pharmacopoeia Europaea, ed. 5 (2005).