Antioxidant and antibacterial activities of the extract of Aquilaria crassna leaves

Aquilaria crassna Pierre ex Lecomte (Thymelaeaceae) or Krisana agarwood has long been used for the production of high valued incense, cosmetic and pharmaceutical products in Asia [1]. In Thailand, leaves of young Aquilaria crassna are used to produce commercial herbal teas. In addition to its aroma, it is believed that Krisana leaves possess many interesting medicinal properties, such as antidiarrheal, antidiabetic and antibacterial activities. However, scientific study on its pharmacological activity is very limited. The aims of this study were to investigate the safety and antibacterial activity of the aqueous extract of Aquilaria crassna leaves. Acute toxicity test showed that even at high dose (15,000mg/kg) the extract did not cause death or overt signs of toxicity when observed for 14 consecutive days in mice. It was found that the extract exhibited antibacterial activities against Staphylococcus aureus and Staphylococcus epidermidis with MIC of 12.0 and 4.0mg/ml, respectively. Since the correlation between antioxidant and antibacterial activities of plants has been reported [2], the total phenolic compound (TPC) and antioxidant property were also examined. The TPC of the extract was 162.4±0.3mg gallic acid equivalent/g. The extract showed strong antioxidant activity against DPPH radical with IC₅₀ of 6.04±0.18µg/ml. It is concluded that the aqueous extract of Aquilaria crassna leaves may be beneficial for treatment of diarrhea caused by Staphylococcus aureus and skin infection associated with Staphylococcus epidermidis.

Keywords: Aquilaria crassna, Acute toxicity, Antibacterial, Antioxidant

Acknowledgement: This study is funded by the Office of the Higher Education Commission, Thailand.

References: 1. Eurlings MCM et al. (2010) Forensic Sci Int 197: 30–34.

2. Bajpai VK et al. (2009) Food Chem Toxicol 47: 1876–1883.