*Article* **Talaromarins A–F: Six New Isocoumarins from Mangrove-Derived Fungus** *Talaromyces flavus* **TGGP35**

**Jin Cai 1,2,†, Xiao-Chen Zhu 3,†, Wei-Nv Zeng 1,2, Bin Wang 1,2, You-Ping Luo 1,2, Jing Liu 1,2, Min-Jing Chen 1,2, Gao-Yu Li 1,2, Guo-Lei Huang 1,2, Guang-Ying Chen 1,2, Jing Xu 3,\* and Cai-Juan Zheng 1,2,\***


**Abstract:** Six new isocoumarin derivative talaromarins A-F (**1**–**6**), along with 17 known analogues (**<sup>7</sup>**–**23**), were isolated from the mangrove-derived fungus *Talaromyces flavus* (Eurotiales: Trichocomaceae) TGGP35. Their structures were identified by detailed IR, UV, 1D/2D NMR and HR-ESI-MS spectra. The absolute configurations of new compounds were determined by the modified Mosher's method and a comparison of their CD spectra with dihydroisocoumarins described in the literature. The antioxidant, antibacterial, anti-phytopathogenic and inhibitory activity against α-glucosidase of all the isolated compounds were tested. Compounds **6**–**11**, **17**–**19** and **21**–**22** showed similar or better antioxidant activity than the IC50 values ranging from 0.009 to 0.27 mM, compared with the positive control trolox (IC50 = 0.29 mM). Compounds **10**, **18**, **21** and **23** exhibited strong inhibitory activities against α-glucosidase with IC50 values ranging from 0.10 to 0.62 mM, while the positive control acarbose had an IC50 value of 0.5 mM. All compounds showed no antibacterial or anti-phytopathogenic activity at the concentrations of 50 μg/mL and 1 mg/mL, respectively. These results indicated that isocoumarins will be useful to developing antioxidants and as diabetes control agents.

**Keywords:** *Talaromyces flavus*; isocoumarins; antioxidant; antibacterial; *α*-glucosidase inhibitory activity; anti-phytopathogenic
