Antioxidant, antityrosinase and antitumor activity comparison: the potential utilization of fibrous root part of Bletilla striata (Thunb.) Reichb.f.

This study was carried out to evaluate the utilization probability of the fibrous root part (FRP) of Bletilla striata, which was usually discarded and harvesting pseudobulb part (PSP). The chemical composition, total phenolic content, DPPH radical scavenging activity, Ferric-reducing antioxidant power and tyrosinase inhibition activity were compared between FRP and PSP. Antioxidant and pro-oxidant effect as well as antitumor effect of the extract of FRP and PSP were analyzed by in vitro cell system as well. Thin layer chromatography and high performance liquid chromatography analysis indicated that the chemical compositions in the two parts were similar, but the content in FRP was much higher than PSP. Meanwhile, the FRP extracts showed higher phenolic content, stronger DPPH scavenging activity, Ferric-reducing antioxidant capacity and tyrosinase inhibition activity. Sub-fraction analysis revealed that the distribution characteristic of phenolic components and other active constituents in FRP and PSP were consistent, and mainly deposited in chloroform and acetoacetate fractions. Especially, the chloroform sub-fraction (sch) of FRP showed extraordinary DPPH scavenging activity and tyrosinase inhibition activity, with IC50 0.848 mg/L and 4.3 mg/L, respectively. Besides, tyrosinase inhibition activity was even stronger than the positive compound arbutin (31.8 mg/L). Moreover, In vitro cell system analysis confirmed that FRP extract exerts comparable activity with PSP, especially, the sub-fraction sch of FRP showed better antioxidant activity at low dosage and stronger per-oxidant activity at high dosage, and both sch of FRP and PSP can dose-dependent induce HepG2 cells apoptosis, which implied tumor therapeutic effect. Considering that an additional 0.3 kg FRP would be obtained when producing 1.0 kg PSP, our work demonstrated that FRP is very potential to be used together with PSP.