Purple corn silk: A potential anti-obesity agent with inhibition on adipogenesis and induction on lipolysis and apoptosis in adipocytes

Ethnopharmacological relevance: Corn silk or the stigma of Zea mays L. has traditionally been used in weight loss stimulation and treatment of cystitis, urinary infections and obesity. Purple corn silk, rich of polyphenolic substances, was reported on anti-diabetic and anti-obesity effect in animal studies. However, scientific evidence on mechanisms and targets of action of purple corn silk related to adipocyte life cycle has been limited. Aim of study: To determine phytochemical compositions and investigate anti-obesity potential of the purple corn silk focusing on interruption of adipocyte life cycle; effect on pre-adipocyte proliferation, adipogenesis, adipocyte lipolysis, and apoptosis. Materials and methods: The ethanolic purple corn silk extract (PCS) was prepared and investigated for phytochemical compositions by LC/MS/MS technique and anti-obesity potential using murine 3T3-L1 cell line. Using methyl thiazole tetrazolium (MTT) assay, the effects on pre-adipocytes and adipocyte viability and on preadipocytes proliferation at 24-, 48-, and 72-h incubation period were evaluated. In addition, anti-adipogenesis via inhibition on adipocyte differentiation and reduction of total lipid accumulation was evaluated using Oil Red O staining and spectrophotometric methods, respectively. The lipolysis effect was determined by measurement of glycerol released content using glycerol test kit after 48-h treatment of PCS to adipocytes. Apoptosis inductive effect was done by using 2-(4-Amidinophenyl)-6-indolecarbamidine dihydrochloride (DAPI) staining method. Results: The polyphenols including anthocyanins, quercetin and phenolic acids and derivatives were found as the major chemical compositions of the PCS. With multiple-stages interruption on the adipocyte life cycle, anti obesity effect of PCS was interestingly demonstrated. When compared to the control, the PCS at concentration range between 250-1000 pg/mL showed anti-adipogenesis effect as expressing of significant inhibition on preadipocyte proliferation at all incubation period (43.52 +/- 5.28 - 75.51 +/- 9.09%) and significant decreasing of total lipid accumulation at concentration of 500 mu g/mL (80.22 +/- 6.58%) and 1000 mu g/mL (69.62 +/- 5.42%). Moreover, the PCS exhibited lipolysis and apoptosis inductive effect with dose dependent manner and significance at concentration of 1000 mu g/mL by increase of released glycerol content (173.88 +/- 6.13% of the control) and of nuclei condensing and apoptotic bodies (with relative apoptosis induction as 131.74 +/- 1.64% of the control). Conclusion: Our data has evidenced the anti-obesity potential of PCS related interruption at multiple stages of adipocyte life cycle. Its potency was attributed to inhibition on adipocyte proliferation and adipogenesis as well as induction on lipolysis and apoptosis at high concentration. However, further in vivo investigation should be considered to insist the possibility in applications of PCS in prevention and treatment of obesity.