The Petroleum Ether Extract from Hypericum perforatum Root Cultures Exhibits Potent Antiproliferative Activity in Human Keratinocytes and Fibroblasts.

The hyperforin content of Hypericum perforatum herb was repeatedly reported to be responsible for a multitude of pharmacological activities. Our recent report about the hyperforin accumulation in in vitro root cultures of H. perforatum provides an alternative perspective to achieve constant product quality and to serve the rapidly growing market. In this study, the antiproliferative effect of a petroleum ether extract from the in vitro root cultures was investigated. When normalized to 1 µM hyperforin content, the extract reduced the viability of human keratinocytes (HaCaT) and human dermal fibroblast monolayers to 33 and 36%, respectively, after 72 h of incubation. A cytotoxicity assay and live-dead cell staining confirmed that the extract lacked a cytotoxic effect and that the reduction in cell viability was mainly due to the antiproliferative activity. Application of the 1 µM hyperforin-normalized extract to a 3D artificial skin construct significantly reduced the proliferation of HaCaT in the presence of fibroblasts. This effect was proved by the reduction in thickness of the epidermal construct from 100 µm (control) to 17 µm (treated). Notably, 1 µM pure hyperforin lacked effectiveness in both monolayer cultures and 3D artificial skin constructs. Nor were fractions of the extract containing colupulone and xanthones active. The combination of these constituents also failed to reassemble the antiproliferative activity, which indicates a synergistic role of yet unidentified components present in the extract. Our findings may introduce H. perforatum root cultures as a novel lead system for the treatment of hypertrophic scars.