Viridicatol

A pair of new quinolone alkaloid enantiomers, (Ra)-(-)-viridicatol (1) and (Sa)-(+)-viridicatol (4), and seven known compounds, namely,2,3and5-9, were isolated fromPenicillium christenseniaeSD.84. The structures of1and4were determined using NMR and HRESIMS data. Theoretical calculations through CD and ECD confirmed1and4as a pair of enantiomers. The MIC values of4againstStaphylococcus aureusand methicillin-resistantS. aureuswere 12.4 and 24.7 μM, respectively, compound1had no inhibitory activity. Antimicrobial assays of2,3, and5-7showed a moderate activity againstS. aureusand methicillin-resistantS. aureus. This study demonstrated the remarkable potential ofPenicilliumsp. to produce new drug-resistant leading compounds, thereby advancing the mining for new sources of antimicrobial agents.

In the title compound, also known as viridicatol monohydrate, C(15)H(11)NO(3)·H(2)O, the dihedral angle between the benzene ring and quinoline ring system is 64.76 (5)°. An intra-molecular O-H⋯O hydrogen bond occurs. The crystal structure is stabilized by classical inter-molecular N-H⋯O and O-H⋯O hydrogen bonds and weak π-π inter-actions with a centroid-centroid distance of 3.8158 (10) Å.

A systematic chemical investigation of the deep-sea-derived fungusPenicillium solitumMCCC 3A00215 resulted in the isolation of one novel polyketide (1), two new alkaloids (2and3), and 22 known (4-25) compounds. The structures of the new compounds were established mainly on the basis of exhaustive analysis of 1D and 2D NMR data. Viridicatol (13) displayed moderate anti-tumor activities against PANC-1, Hela, and A549 cells with IC50values of around 20 μM. Moreover,13displayed potent in vitro anti-food allergic activity with an IC50value of 13 μM, compared to that of 92 μM for the positive control, loratadine, while indole-3-acetic acid methyl ester (9) and penicopeptide A (10) showed moderate effects (IC50= 50 and 58 μM, respectively).