Phyllostachys edulis leaf extract reduces TNFα-induced release of VEGF and IL-8 in immortalized HaCaT cells

Abstract

Phyllostachys edulis Carriere (Poaceae) has received considerable attention in pharmacological research due to their potent antitumor, anti-inflammatory, antimicrobial, and antiulcerogenic activities. In this study, we investigated the antiinflammatory effects of two leaf extracts (young versus old harvested leaves) prepared from Phyllostachys edulis on TNFα-induced overproduction of IL-8, VEGF and IL-6 in immortalized human keratinocytes (HaCaT). These cytokines play important roles in various inflammatory skin diseases, such as psoriasis. Bamboo leaves of different maturity and age levels were used since we expected a different phytochemical profile and therefore a different pharmacological activity. Both leaf extracts were prepared by Soxhlet extraction using water as extraction solvent. The amounts of major flavonoids were quantified using a LC-MS/MS method. Isoorientin was detected as the main flavonoid in both extracts with amounts of 1590 mg/kg (old leaves) and 1440 mg/kg (young leaves). The Soxhlet extract prepared from the young bamboo leaves (SEYL) dose dependently (25 – 250 µg/ml) inhibited the release of TNFα-induced IL-8, and VEGF, but not IL-6, in HaCaT cells while the extract prepared from the old leaves (SEOL) had no effect. In addition, isoorientin (ISO; 10 – 100µM) dose dependently reduced the levels of VEGF, IL-8 and IL-6 in TNFα-treated HaCaT cells, comparable to the positive control hydrocortisone (HC; 10µM). Cell viability was determined by the MTT (3-[4,5-dimethylthiazol-2yl]-diphenyl tetrazolium bromide) colorimetric assay. SEYL and SEOL up to a concentration of 250 µg/ml as well as ISO and HC (10 – 100µM, respectively) did not have any toxic effects on HaCaT cells. Taken together, an extract prepared from the young leaves of Phyllostachys edulis as well as isoorientin exerted anti-inflammatory effects in TNFα-treated HaCaT cells, suggesting interesting cosmetical and pharmacological applications.