Molecular Weight Determination of Component Polypeptides of Glutenin after Fractionation by Gel Filtration

Reduced and cyanoethylated glutenin was fractionated into three fractions (F I, F II and F III) by gel filtration on Sephadex G–100 in 0.1 m acetic acid. The molecular weight determination was made with these three fractions by sedimentation equilibrium in 6.5 m guanidine hydrochloride containing 0.01 m acetic acid. The molecular weight obtained was 44,000 for F II, and 32,000 for F III. F I showed a distribution of molecular weight due to the aggregation. The average molecular weight of F I was 52,000, being 27,000 at the meniscus and 98,000 at the bottom. The estimation of molecular weight by SDS–PAGE* gave overestimated values for glutenin polypeptides, as was already reported for gliadin.     

Polyphenol Characterization,Antioxidant and Skin Whitening Properties of Alnus cordata Stem Bark

In this study, we investigated the phenolic composition of the crude extract (MeOH 80 %) of Alnus cordata (Loisel .) Duby stem bark (ACE) and its antioxidant and skin whitening properties. RP‐LC‐DAD analysis showed a high content of hydroxycinnamic acids (47.64 %), flavanones (26.74 %) and diarylheptanoids (17.69 %). Furthermore, ACE exhibited a dose‐dependent antioxidant and free‐radical scavenging activity, expressed as half‐maximal inhibitory concentration (IC₅₀): Oxygen radical absorbance capacity (ORAC, IC₅₀ 1.78 μg mL^?1)>Trolox equivalent antioxidant capacity (TEAC, IC₅₀ 3.47 μg mL^?1)>2,2‐Diphenyl‐1‐picrylhydrazyl (DPPH, IC₅₀ 5.83 μg mL^?1)>β‐carotene bleaching (IC₅₀ 11.58 μg mL^?1)>Ferric reducing antioxidant power (FRAP, IC₅₀ 17.28 μg mL^?1). Moreover, ACE was able to inhibit in vitro tyrosinase activity (IC₅₀ 77.44 μg mL^?1), l ‐DOPA auto‐oxidation (IC₅₀ 39.58 μg mL^?1) and in an in vivo model it exhibited bleaching effects on the pigmentation of zebrafish embryos (72 h post fertilization) without affecting their development and survival. In conclusion, results show that A. cordata stem bark may be considered a potential source of agents for the treatment of skin disorders due to its bleaching properties and favorable safety profiles, associated to a good antioxidant power.     

Studies on Extracellular Ribonuclease from Yeast

An extracellular ribonuclease of Rhodotorula glutinis was purified about 50-fold from the culture broth, by a procedure involving ammonium sulfate fractionation, DEAE-Sephadex column chromatography, acetone fractionation and Sephadex G-100 gel filtration. The purified enzyme was homogeneous when examined by the ultracentrifuge and disc electrophoresis. The molecular weight was calculated to be 58,900 and 56,000 by the sedimentation-diffusion method and the sedimentation equilibrium method, respectively.     

Prunus mume extract exerts antioxidant activities and suppressive effect of melanogenesis under the stimulation by alpha-melanocyte stimulating hormone in B16-F10 melanoma cells

In the current study, we examined the antioxidant and skin-whitening properties of Prunus mume extract (PME). The ability of PME to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals was investigated in vitro. At a concentration of 1000 μg/mL, PME neutralized >45% free radical activity. Cell viability assessment with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that at concentrations <1500 μg/mL, PME does not exert cytotoxic effects on murine B16 melanoma (B16) cells. Morphological analysis disclosed that melanin production is inhibited in B16 cells treated with 250 nM α-melanocyte-stimulating hormone (α-MSH) and PME. We conclude that fruit extracts of P. mume exert a skin-whitening effect by inhibiting melanin production via regulation of melanogenesis-associated protein expression in melanocytes.     

Antimelanogenic Activity of Ocotillol‐Type Saponins from Panax vietnamensis

The ocotillol (OCT)‐type saponins have been known as a tetracyclic triterpenoid, possessing five‐ or six‐membered epoxy ring in the side chain. Interestingly, this type saponin was mostly found in Panax vietnamensis Ha et Grushv ., Araliaceae (VG), hence making VG unique from the other Panax spp. Five OCT‐type saponins, majonoside R2, vina‐ginsenoside R2, majonoside R1, pseudoginsenoside RT4, vina‐ginsenoside R11, together with three protopanaxadiol (PPD)‐type saponins and four protopanaxatriol (PPT)‐type saponins from VG were evaluated for their antimelanogenic activity. All of isolates were found to be active. More importantly, the five OCT‐type saponins inhibited melanin production in B16‐F10 mouse melanoma cells, without showing any cytotoxicity. Besides ginsenoside Rd and ginsenoside Rg3 in PPD and notoginsenoside R1 in PPT‐type saponins, majonoside R2 was the most potent melanogenesis inhibitory activity in OCT‐type saponins. In this article, we highlighted antimelanogenic activity of OCT‐type saponins and potential structure–activity relationship (SAR) of ginsenosides. Our results suggested that OCT‐type saponins could be used as a depigmentation agent.