The influence of temperature, pH value, and solvent on the degradation behavior of astilbin was studied by HPLC. Results showed that the degradation of astilbin was pH and temperature dependent, and the isomerization of astilbin to its three stereoisomers was found. The degradation process followed the first-order kinetics model, and the degradation rate k values increased, whereas half-life (t1/2) values declined with the rise of pH and temperature. The stability of astilbin was related to its B-ring substitution. Engeletin with a 4'-hydroxy-substituted B-ring was more stable than astilbin with a 3',4'-dihydroxy-substituted B-ring. The stability of astilbin differed depending on the solvent and followed the order 50% ethanol > ethanol > methanol > 50% methanol > water. In cultural media, astilbin was less stable than in water, which may be related to the presence of metal ions. The stability results of astilbin were confirmed in the extraction of dihydroflavonols from Rhizoma Smilacis Glabrae and may have a guiding function in turtle jelly production.

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Rhizoma Smilacis Glabrae (RSG) and Rhizoma Smilacis Chinae (RSC) are two herbal materials that belong to the same genera and are both listed in the Chinese Pharmacopoeia. Chemical constituents in the two species were compared by HPLC-DAD-MS/MS. Many common constituents were found in both species, including shikimic acid, 5-O-caffeoylshikimic acid, trans-resveratrol, taxifolin, astilbin and its three stereoisomers, engeletin and isoengeletin. However, syringic acid was found only in RSG, while chlorogenic acid was found only in RSC.

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Spin relaxation properties of π-conjugated organic semiconductors are key indicators of the performance of organic spintronic devices. However, reliable determination of spin relaxation parameters in organic materials is hindered by complex interfacial phenomena at organic/ferromagnetic metal interfaces that couple spin injection with charge injection. Here, we study the spin pumping induced pure spin transport in Permalloy/rubrene/Pt trilayers and determine the spin diffusion length λs = 132 ± 9 nm and the spin relaxation time τs = 3.8 ± 0.5 ms in rubrene films at room temperature by using the inverse spin Hall effect. The determined spin diffusion length λs is found to be almost two times larger than that of ∼46.3 nm at 100 K extracted from rubrene spin valve devices in which charge carrier injection/detection occurs at organic/ferromagnetic metal interfaces. Our results demonstrate experimentally that the efficiency and the rate of spin polarized charge transport through the organic/ferromagnetic metal interface play a dominant role in determining the spin relaxation process of spin valve devices in which charge and spin currents are coupled.