Development and assessment of tyrosinase inhibitory activity of liposomes of Asparagus racemosus extracts

The purpose of this study was to develop liposomal formulations of Asparagus racemosus root extract(AR1-6)as well as evaluate the physicochemical properties and in vitro tyrosinase inhibitory activity.Liposomes composed of AR1-6 to lipid weight ratio of 1:10 and lecithin(LEC)or Phospholipon
90G(PC90G)as structural phospholipid at 7:3 molar ratio to CHOL were prepared by various methods,i.e.chloroform-film(CF),reverse-phase evaporation(REV),polyol dilution(PD),and freeze-drying of monophase solution(MFD)methods.The results revealed that vesicles prepared by CF and MFD were multilamellar whereas those prepared by REV and PD were oligolamellar in nature with particle sizes ranging from 0.26 to 13.83 mm.The zeta potentials were in the range of
1.5 to
39.3 mV.AR1-6 liposomes with LEC possessed significantly higher entrapment than those with PC90G.The highest entrapment efficiency and in vitro tyrosinase inhibitory activity of 69.08%and 25%,respectively,were obtained from liposomes having LEC and prepared by PD method.The tyrosinase inhibitory activity were in the rank order of LEC>PC90G,and PD>CF>REV>MFD.It could be concluded that the mechanism of vesicle forming in each method of preparation was the key factor influencing physicochemical properties,particularly vesicle type,size,surface charge,and entrapment,which were well correlated with the biological activity.

In vitro anti-melanoma effect of polyphenolic compounds

Objective:To evaluate the effects of phenolic acids(caffeic,ferulic,and coumaric acids)and flavones(luteolin and apigenin)on the proliferation and melanogenesis in murine melanoma B16-F10 cells.Methods:Cell proliferation was determined after 24 and 48 hours of incubation using MTT assay.The effects of these tested compounds on cell cycle progression were analyzed by flow cytometry.Moreover,the melanin content and tyrosinase activity were measured spectrophotometrically at 475 nm.Results:Luteolin and apigenin exhibited significant anti-proliferative activity against B16-F10 cells,while caffeic,ferulic,and coumaric acids induced slight inhibition after 24 and 48 hours of incubation.The tested compounds disturbed cell cycle progression of B16-F10,by a subsequent decrease in G1 and arrested cycle progression in either G1/S or G2/M phase.Furthermore,apigenin provoked an increase in melanin content of B16-F10 cells.In contrast,luteolin,caffeic,ferulic and coumaric acids induced a decrease in melanin content of B16-F10 cells by inhibiting tyrosinase activity.Conclusions:These active polyphenols may be used as skin whitening agents or natural tanning agents to treat skin pigmentation disorders.

Tyrosinase Inhibitory Activity of Total Triterpenes and Poricoic Acid A Isolated from Poria cocos

Objective With the improvement of people＇s living standards, people＇s requests for beauty are increasing. Skin whitening and lightening have become the pursuit of many women, and whitening and removing freckles have become the focus of scientific research. At present, widely used whitening agents, such as kojic acid, vitamin C, and its derivatives, have shortcomings such as poor stability and retarded effect. Therefore, safer and more effective whitening products from herbs are urgently needed. To explore the possibility of triterpenes as whitening active substance, the effects of total triterpenes of Poria（TTP） and poricoic acid A（PAA） on mushroom tyrosinase activities and B16 cells were investigated, and their mechanisms on mushroom tyrosinase were also studied. Methods Using arbutin and nicotinamide as reference substances, we determinated the inhibitory effects of TTP and PAA on mushroom tyrosinase and tyrosinase in B16 cells and then studied the inhibitory mechanism on mushroom tyrosinase. Results TTP and PAA exhibited good inhibitory effects on the activities of monophenolase and diphenolase in mushroom tyrosinase, as well as a certain inhibitory effect on tyrosinase in B16 cells. Conclusion TTP and PAA are potential whitening active ingredients.

Design,synthesis and bioactivity of chalcones and its analogues

The Vernohia anthelmintica L.＇s extract is one of the most popular Uygur medicines used for vitiligo. It is believed that the chalcone compounds of the plant play an important role in the treatment since they may activate tyrosinase and improve melanin production. In this study, twenty-one chalcones and nine analogues were synthesized in view of three different components of chalcone（A, B ring and a,b-unsaturated carbonyl）. After biological evaluation of their activity on tyrosinase in cell-free systems,the result showed that most compounds（except polyhydroxy chalcones） possess activator effect on the tyrosinase, especially for 13a–15a, 20 a and 1b, which bearing a comparable activity to the positive control8-MOP. SAR of these tyrosinase activator was summed up for the first time as well. Finally, compound 13 a was found to increase melanin contents and tyrosinase activity 1.75 and 1.3 fold, respectively, compared with that of untreated murine B16 cells at the concentration of 40 mg/m L.

Effect of kappa elastin on melanogenesis in A375 human melanoma cells and its related mechanism

Background Elastin derived peptides can regulate melanocyte precursor development. Ultraviolet irradiation, infrared radiation and heat can increase the synthesis of tropoelastin in human skin epidermis. The aim of this study was to investigate whether the over expressed tropoelastin in epidermis has some role in melanogenesis of melanocytes. Methods A375 human melanoma cells were treated with different concentrations of kappa elastin for 24 hours. A375 human melanoma cells were randomly assigned to control, kappa elastin, and lactose pre-incubated groups. The cell viabilities were detected by the methyl thiazoleterazolium assay. Melanin content and tyrosinase activity in A375 melanoma cells were measured. The expressions of endothelin B receptor （ETBR） mRNA and c-kit mRNA in A375 melanoma cells were measured by quantative reverse transcription polymerase chain reaction. Results Fifty pg/ml of kappa elastin significantly increased the melanin content by 56.64% compared with the control （P 〈0.05）. Kappa elastin increased cellular tyrosinase activity by 46.73% compared with the control at 24 hours （P 〈0.05）. Kappa elastin increased the expressions of ETBR and c-kit mRNA levels by 2.13-fold and 2.47-fold compared with the controls, respectively. When pre-incubating cells with a lactose solution （10 mmol/L）, the inhibition on melanin production was 34.96% compared with the kappa elastin group （P 〈0.05）, tyrosinase activity was inhibited by 29.93% compared with kappa elastin group （P 〈0.05）, and the expressions of ETBR mRNA and c-kit mRNA were decreased by 1.56-fold and 0.82-fold compared with kappa elastin group, respectively. Conclusion Kappa elastin increased the melanogenesis in A375 melanoma cells via the stimulation of tyrosinase activity and the expression of ETBR and c-kit. The over expressed tropoelastin produced by keratinocytes might play a role in melanogenesis of epidermal melanocytes.