Phytochemicals and regulation of the adipocyte life cycle

Mesenchymal stem cells are the precursors of several different types of cells, including myoblasts, chondroblasts, osteoblasts and preadipocytes. Once preadipocytes are triggered to mature, they begin to change shape and undergo a round of cell division known as clonal expansion, followed by initiation of the genetic program that allows them to synthesize and store triglycerides. Mature adipocytes can continue storing lipid when energy intake exceeds output, and they can mobilize and oxidize lipid when energy output exceeds input. Mature adipocytes can also undergo apoptotic cell death under certain conditions.

Examples of individual natural compounds and combinations of compounds that affect specific stages of the adipocyte life cycle. Genistein inhibits preadipocyte proliferation and suppresses lipid accumulation in maturing preadipocytes. It also triggers lipolysis and induces apoptosis in mature adipocytes, and in combination with 1,25(OH)₂D₃, it can induce apoptosis in maturing preadipocytes. EGCG induces apoptosis in both preadipocytes and mature adipocytes, and it can inhibit lipid accumulation in maturing preadipocytes. Quercetin also has multiple effects — it can inhibit preadipocyte proliferation, induce preadipocyte apoptosis and stimulate lipolysis in mature adipocytes. Ajoene+CLA are especially potent in inducing apoptosis in mature adipocytes.