Two new phthalide derivatives (1-2) and four known phthalide compounds (3-6) were purified from the culture of a mangrove endophytic fungus Pestalotiopsis sp. SAS4. Their chemical structures were established by analyses of 1D and 2D nuclear magnetic resonance (NMR) and high resolution mass spectrometry (HR-MS) spectroscopic data. All of these compounds were evaluated in vitro for antibacterial, cytotoxicity, and resistance to hypoxic-ischemic injury activities. 1 | INTRODUCTION Endophytic fungi are widely distributed in nature. Endophytic fungi live on the health tissue of the host plants without causing any infection [1, 2]. Mangrove trees Jiayin Peng and Peiwen Chen contributed equally.

C17H15NO, monoclinic, C2/c (no. 15), a = 19.197(2) Å, b = 8.0719(8) Å, c = 16.6511(18) Å, α = 90°, β = 100.171(10)°, γ = 90°,V = 2539.6(5) Å3, Z = 8, Rgt(F) = 0.0416, wRref(F2) = 0.1107, T = 100(1) K.CCDC no.: 2020262

hydrogen bonds system (intra-and intermolecular ones) and crystal packing are also discussed. The crystal packing are stabilized by -interactions between benzene rings and/or triazole heterocycles. The packing coefficient and solvent accessible potential area in crystal were also analyzed.