Anti-Inflammatory Principles from Tamarix aphylla L.: A Bioassay-Guided Fractionation Study

Natural products have served as primary remedies since ancient times due to their cultural acceptance and outstanding biodiversity. To investigate whetherTamarix aphyllaL. modulates an inflammatory process, we carried out bioassay-guided isolation where the extracts and isolated compounds were tested for their modulatory effects on several inflammatory indicators, such as nitric oxide (NO), reactive oxygen species (ROS), proinflammatory cytokine; tumour necrosis factor (TNF-alpha), as well as the proliferation of the lymphocyte T-cells. The aqueous ethanolic extract of the plant inhibited the intracellular ROS production, NO generation, and T-cell proliferation. The aqueous ethanolic crude extract was partitioned by liquid-liquid fractionation usingn-hexane (n-C6H6), dichloromethane (DCM), ethyl acetate (EtOAc),n-butanol (n-BuOH), and water (H2O). The DCM andn-BuOH extracts showed the highest activity against most inflammatory indicators and were further purified to obtain compounds1-4. The structures of 3,5-dihydroxy-4',7-dimethoxyflavone (1) and 3,5-dihydroxy-4-methoxybenzoic acid methyl ester (2) from the DCM extracts; and kaempferol (3), and 3-hydroxy-4-methoxy-(E)-cinnamic acid (4) from then-BuOH extract were elucidated by different spectroscopic tools, including MS, NMR, UV, and IR. Compound2inhibited the production of ROS and TNF-alpha, whereas compound3showed inhibitory activity against all the tested mediators. A better understanding of the potential aspect ofTamarix aphyllaL. derivatives as anti-inflammatory agents could open the door for the development of advanced anti-inflammatory entities.