**Synthesis and Evaluation of the Lifespan-Extension Properties of Oleracones D–F, Antioxidative Flavonoids from** *Portulaca oleracea* **L.**

#### **Jeong A Yoon 1,**†**, Changjin Lim 2,**†**, Dong Seok Cha 3,\* and Young Taek Han 1,\***


Received: 10 September 2019; Accepted: 24 September 2019; Published: 25 September 2019

**Abstract:** Plant-derived antioxidants have been widely used as supplementary health foods, as well as having been regarded as drug candidates for aging and aging-associated diseases. Oleracones, a novel series of flavonoids isolated from *Portulaca oleracea* L., possess potent antioxidative activities and are expected to exhibit therapeutic potential on the aging process. The current paper describes the concise sequential synthesis of oleracones D–F. Oleracones D and F were efficiently synthesized via selective intramolecular oxa-Michael addition from oleracone E. In addition, we investigated their possible lifespan-extension properties using *Caenorhabditis elegans*, which is excellently suited as an experimental model to study aging. A significant longevity effect was observed when nematodes were grown with 20 μM of oleracone E.

**Keywords:** oleracone; flavonoid; anti-aging; longevity; *Portulaca oleracea* L.; *Caenorhabditis elegans*; total synthesis
