Pannorin B, a new naphthopyrone from an endophytic fungal isolate of Penicillium sp

The herbal remedy, milk thistle (Silybum marianum), has been used in traditional medicine for various liver, kidney, and gall bladder ailments. For over a decade, our research group has been investigating\udthe flavonolignans obtained from this medicinal herb for cancer chemoprevention and hepatoprotection.[1–6] Recently, we\udextended our studies toward examining the diversity as well as distribution\udpatterns of fungal endophytes in leaves, stem, and roots of milk thistle.[7] These fungi inhabit the internal living tissues of\udthe host plants asymptomatically, though they may also cause disease over time.[8] In addition to the phylogenetic profiling of these endophytes, a series of fungal extracts were also examined for chemical composition. Although the plant–endophyte relationship\udmay ormay not be mutualistic, the compounds produced by some endophytes could play a role in the growth and survival of the host.\udIn a previous study, Penicillium restrictum, isolated from milk thistle, yielded promising secondary metabolites.[9] Hence, in pursuit\udof interesting chemistry, a related monoverticillate endophytic Penicillium sp. was explored