Effect of storage on antibacterial and COX-1 anti-inflammatory activity of three plants used as traditional medicines in Lesotho

Traditional healers in Lesotho often stored air-dried material indoors for up to five years before use. The effect of storage on antibacterial and COX-1 antiinflammatory activity of three plants (Malva parviflora, Eriocephalus tenuifolius and Asparagus microraphis) commonly used in traditional medicine in Lesotho were monitored. Dried, ground leaf and/or root material of these plants were stored at 10°C, room temperature (23 ± 2°C) and outside where the material was exposed to both low and high as well as large fluctuations in temperature. Antibacterial activity of M. parviflora (leaves and roots) and E. tenuifolius (leaves) initially increased with storage with the highest inhibitory activity being measured after three-to-six months storage after which activity gradually decreased. COX-1 anti-inflammatory activity of M. parviflora (leaves and roots), E. tenuifolius (leaves) and A. microraphis (leaves and roots) also increased after three-to-six months storage. Inhibitory activity of the hexane and methanol extracts decreased with prolonged storage except for A. microraphis roots where high inhibitory activity was detected throughout the twelve month experiment. COX-1 anti-inflammatory activity gradually increased in the water extracts of M. parviflora (leaves and roots) and A. microraphis (leaves) with storage. Generally, the material stored at room temperature had the highest inhibitory activity. These results suggest that the three plants may not have a long shelf-life and further investigation, including in vivo studies, is needed to ensure effective treatment of bacterial and inflammatory complaints