| Summary: | <i>Monascus</i> species are asexually or sexually reproduced homothallic fungi that can produce a red colorant, specifically the so-called red yeast rice or Anka, which is used as a food ingredient in Asia. Traditional experiences of using <i>Monascus</i> for treating indigestion, enhancing blood circulation, and health remedies motivate us to investigate and repurpose <i>Monascus</i>-fermented products. Here, two new 5<i>H</i>-cyclopenta[<i>c</i>]pyridine type azaphilones, 5<i>S</i>,6<i>S</i>-monaspurpyridine A (<b>1</b>) and 5<i>R</i>,6<i>R</i>-monaspurpyridine A (<b>2</b>), two new xanthonoids, monasxanthones A and B (<b>3</b> and <b>4</b>), one new naphthalenone, monasnaphthalenone (<b>5</b>), and one new azaphilone, monapurpurin (<b>6</b>), along with two known compounds were isolated from the 70% EtOH extract of a citrinin-free domesticated strain <i>M. purpureus</i> BCRC 38110. The phytochemical properties of the xanthonoid and naphthalenone components were first identified from <i>Monascus</i> sp. differently from the representative ingredients of polyketide-derived azaphilones. UVB-induced cell viability loss and reactive oxygen species (ROS) overproduction in human keratinocytes were attenuated by monascuspirolide B (<b>7</b>) and ergosterol peroxide (<b>8</b>), indicating their photoprotective potentials. Ergosterol peroxide (<b>8</b>) decreased the melanin contents and tyrosinase activities of mouse melanocytes, depending on the concentration, suggesting their anti-melanogenic effects. In conclusion, six new and two known compounds were isolated from <i>M. purpureus</i> BCRC 38110, and two of them exhibited dermal protective activities. The results revealed the novel potential of <i>M. purpureus</i> for developing natural cosmeceutics against skin photoaging.
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