Antioxidant and anti-melanogenic activities of ultrasonic extract from Stichopus japonicus

Objective:To investigate the antioxidant and anti-melanogenesis activities of an ultrasonic extract of red sea cucumber,Stichopus japonicus,collected from Jeju Island.Methods:Antioxidant activity experiments were assessed by an electron spin resonance system and a cellular model of immortalized human keratinocytes(HaCaT)to determine its radical scavenging activity and protective effects against 2,2’-azobis(2-amidinopropane)dihydrochloride(AAPH)-induced oxidative stress.Antimelanogenic activity of the ultrasonic extract of red sea cucumber was also examined using the melanoma cell model B16F10 and mushroom tyrosinase.Following the induction byα-melanocytestimulating hormone,the effects of the ultrasonic extract of red sea cucumber on intracellular tyrosinase activity,melanin content and the melanogenic protein expression of microphthalmia-associated transcription factor,tyrosinase,and tyrosinase-related proteins(TRP-1,and TRP-2)were examined.Results:The ultrasonic extract of red sea cucumber significantly scavenged 2,2-diphenyl-1-picrylhydrazyl and alkyl radicals[IC50:(0.924±0.035)and(0.327±0.006)mg/mL,respectively],as well as showed a protective effect against oxidative stress and attenuated generation of intracellular reactive oxygen species on AAPHinduced HaCaT cells,with no cytotoxicity(12.5-400μg/mL).The ultrasonic extract of red sea cucumber also exhibited a tyrosinase inhibitory effect[IC50:(2.750±0.006)mg/mL].Onα-melanocytestimulating hormone-stimulated B16F10 melanoma cells,the ultrasonic extract of red sea cucumber(25-200μg/mL)significantly inhibited not only melanin synthesis and tyrosinase activity,but also protein expressions of microphthalmia-associated transcriptional factor,tyrosinase,TRP-1,and TRP-2.Conclusions:The ultrasonic extract of red sea cucumber shows antioxidant and anti-melanogenic potential and may be a natural candidate for anti-aging as well as a whitening agent in the cosmeceuticals industry.

Transient shuttle for a widespread neural probe with minimal perturbation

Bioelectronic implants in the deep brain provide the opportunity to monitor deep brain activity with potential applications in disease diagnostics and treatment.However,mechanical mismatch between a probe and brain tissue can cause surgical trauma in the brain and limit chronic probe-based monitoring,leading to performance degradation.Here,we report a transient shuttle-based probe consisting of a PVA and a mesh-type probe.A rigid shuttle based on PVA implants an ultrathin mesh probe in the target deep brain without a tangle,while creating both a sharp edge for facile penetration into the brain and an anti-friction layer between the probe and brain tissue through dissolving its surface.The capability to shuttle dissolved materials can exclude the retracted process of the shuttle in the brain.Complete dissolution of the shuttle provides a dramatic decrease(~1078-fold)in the stiffness of the probe,which can therefore chronically monitor a wide area of the brain.These results indicate the ability to use a simplistic design for implantation of wide and deep brain probes while preventing unnecessary damage to the brain and probe degradation during long-term use.