A Hot Water Extract of Sideritis scardica Prolongs Life Span and Enhances Heat Shock Resistance in Caenorhabditis elegans

Abstract

Sideritis scardica is a Lamiaceae plant that is endemic to the alpine zone of the Balkan Peninsula. The tea of S. scardica has been handed down as a “tea of longevity” in the Rhodope region of Bulgaria for an unknown amount of time. In this study, we prepared a hot water extract of S. scardica (SHWE) and examined its effects on both life span and stress response in living tissue using Caenorhabditis elegans and its transgenic mutants. The life span of wild-type N2 worms was prolonged by approximately 15% at the SHWE concentration of 5 µg/mL and approximately 22% at the SHWE concentration of 50 µg/mL, as compared with the control group. The effect of SHWE on the expression of heat shock protein 16.2 (HSP-16.2) under heat stress was investigated using TJ375 worms, a transgenic mutant of C. elegans. In the TJ375 worms pretreated with SHWE, the fluorescence intensity of green fluorescent protein fluorescence, which indicates the expression of HSP-16.2, was significantly increased. In the assay using TJ356 worms, the worms pretreated with SHWE did not show the translocation of DAF-16, a forkhead transcription factor class O homolog, from the cytoplasm to nucleus under heat stress. Additionally, under heat stress, the pretreatment of SHWE improved the survival rate of GR1307 worms, a knockout mutant of daf-16. These results indicate that SHWE enhances HSP-16.2 expression through a stress-response pathway (eg, HSF-1 pathway) other than the DAF-16 pathway, resulting in a prolonged life span of C. elegans under heat stress.