Antioxidant and cytotoxic activities of compounds isolated from stem bark of Garcinia oblongifolia (Clusiaceae), a vietnamese medicinal plant

The stem bark of Garcinia oblongifolia is used in Vietnamese traditional medicine for treatment of allergy, rash, itching, ulcer, hepatitis, laryngitis and hemoptysis [1]. Our primary screening results showed that the dichloromethane fraction from 50% ethanol extract of stem bark of G. oblongifolia showed significant antioxidant and cytotoxic activities in vitro assay system. We tried to isolate bioactive compounds with antioxidant and cytotoxic activities and obtained five single compounds (1˜5) from the dichloromethane fraction. We identified the chemical structures as guttiferone F (1), oblongifolin A (2) and benzoic acid (5) containing oblongixanthonone (3) and 30-epi-cambogin (4), new compounds in nature [2,3]. The antioxidant activities of compound 1, 2, 4 were stronger than that of α-tocopherol (IC₅₀=14.8µM) used as positive control. The compound 1, 2, 4 also showed cytotoxic activities against cancer cells, A549 and A431. Compound 4 showed the strongest activity in these assays: antioxidant activity in DPPH assay with IC₅₀=9.1±0.78µM, cytotoxic activity with IC₅₀ of 14.8±0.8µM and 14.3±0.5µM in A549 and A431 cells, respectively. The antioxidant and cytotoxic activities of guttiferone F (1), oblongifolin A (2) and 30-epi-cambogin (4) are reported for the first time.

Acknowledgements: This study was supported by a grant from the Ministry of Knowledge Economy (MKE) and the Korea Institute of Industrial Technology Evaluation & Planning (ITEP) through the Biohealth Products Research Center (BPRC) of Inje University and in part Brain Korea 21 (BK21) of Korea Research Foundation.

References: 1. Bich, D.H. et al. (2004) Medicinal plants and animals in Vietnam 1. NXB KHKT. Hanoi. 273–274.

2. Fuller, R.W. et al. (1999)J Nat Prod 62:130–132.

3. Hamed, W. et al. (2006)J Nat Prod 69:774–777.