| Viola yedoensis Makino is a perennial herb of Violaceae（Viola L.）and the dried whole plant is a traditional Chinese medicine.It has the functions of clearing heat,detoxifying,cooling blood and eliminating swelling.At present,most studies on Viola yedoensis Makino are from the perspective of gardens and pharmacology.However,there are few reports on the effects of light intensity on the growth,physiological characteristics,chemical composition,cold and heat properties and pharmacological activities of Viola yedoensis Makino.Therefore,this study studied the differences of growth,physiological characteristics,effective chemical components,cold-heat medicinal properties and pharmacological activities of Viola yedoensis Makino under different light intensities in order to provide reference for the cultivation of Viola yedoensis Makino and lay a foundation for further study of the hypothesis of "light-cold-heat medicinal properties".The main results and conclusions are as follows:（1）Five levels of light intensity were set,100%,80%,50%,35%and 5%full sunlight respectively.The morphological indexes,biomass,chlorophyll fluorescence parameters,photosynthetic parameters,antioxidant enzymes and total flavonoids and coumarin contents were measured at harvest time.The results showed that the biomass of 50%full-sunlight treatment was the highest,and the apparent biomass of 5%full-sunlight treatment was significantly lower than that of the other four groups（P<0.05）,but there was no significant difference between 35%and 100%full-sunlight treatment.Photosynthetic parameters and chlorophyll fluorescence parameters increased first and then decreased with the decrease of light intensity.There was no obvious abnormality in chloroplast structure under 50%to 100%full-sunlight;chloroplast matrix lamella concentration decreased and starch grains decreased under 35%full-sunlight;chloroplast matrix lamella edge and matrix lamella were blurred under 5%full-sunlight,and starch grains were small and decreased significantly.With the decrease of light intensity,the activities of SOD and POD increased first and then decreased,while the activities of CAT increased.MDA content in 5%full light was significantly higher than that in the other four groups（P<0.05）.The content of total coumarin and total flavone decreased with the decrease of light intensity.To sum up,Viola yedoensis Makino grew better under 50%-100%full-sunlight,and the contents of flavonoids and coumarins were positively correlated with light intensity.（2）Carrageenan was used to induce acute inflammation in ICR mice.The local body temperature,heat radiation,foot swelling and liver energy metabolism-related enzymes activities were compared before and after the injection of Viola yedoensis Makino with different light intensity.Human lung cancer cell A549 was treated with Viola yedoensis Makino planted in different light intensities,and the effects of Viola yedoensis Makino on cell proliferation were compared.The results showed that except for 5%full-light group,the body temperature of mice in the other four groups was significantly lower than that in the blank group（P<0.05）,and the degree of decrease in body temperature was positively correlated with light intensity;SDH activity in liver tissue of all groups was decreased,and the inhibition degree of 100%full-light group and 80%full-light group was significantly lower than that of model group（P<0.05）,but there was a positive correlation between light intensity and inhibition degree in liver group.The activity of Na+-k+-ATPase and Ca2+-Mg2+ATPase in tissues did not change significantly.With the decrease of light intensity,the inhibition of Viola yedoensis Makino on foot swelling showed a downward trend.The inhibitory effect of Viola yedoensis Makino extract on A549 cells was positively correlated with the planting light intensity.The stronger the light intensity,the stronger the inhibitory effect on the proliferation of A549 cells.In conclusion,the ability of Viola yedoensis Makino to reduce foot temperature and swelling,SDH activity in liver and its inhibition on A549 cells were positively correlated with light intensity,suggesting that light intensity was positively correlated with cold properties of Viola yedoensis Makino,which accorded with the hypothesis of "light-cold-heat medicinal properties".Viola yedoensis Makino used as the base of traditional Chinese medicine should be planted under 100%full-sunlight.（3）Carrageenan was used to induce acute inflammation in ICR mice,and the content of inflammatory factors in foot tissues of mice in different Viola yedoensis Makino groups was detected by ELISA;RAW264.7 macrophages were induced by LPS,and the secretion of inflammatory factors in RAW264.7 cells in different Viola yedoensis Makino groups was detected by ELISA.The results showed that the levels of IL-1β,IL-6,TNF-α and PGE2 in foot tissue of mice in Viola yedoensis Makino group were significantly lower than those in model group.The contents of IL-1β,IL-6 and PGE2 in 80%full-sunlight group were the lowest,and there was no significant difference in TNF-α among different light groups.The secretion of IL-1β,IL-6,TNF-α and PGE2 in Violayedoensis Makino group was significantly lower than that in model group（P<0.05）.The contents of IL-1β,IL-6 and NO in Viola yedoensis Makino group were the lowest in 80%full-light group,while the contents of TNFa in Viola yedoensis Makino group were not significantly different.The activity of SOD and GSH-PX in 100%full-sunlight group were significantly higher than those in model group（P<0.05）,and the activity of GSH-PX was significantly higher than that in the other four groups（P<0.05）,and the total antioxidant capacity（T-AOC）was higher in model group.In conclusion,the anti-inflammatory effect of Viola yedoensis Makino is related to its ability to inhibit the secretion of IL-1β,IL-6,TNF-α,PGE2,NO,inhibit the proliferation of inflammatory cells and improve the antioxidant capacity of the body.80%full-sunlight Viola yedoensis Makino had the strongest inhibitory effect on the secretion of IL-1β,IL-6,TNF-α,PGE2 and NO in inflammatory cells,and 100%full-sunlight Viola yedoensis Makino had the strongest antioxidant activity.In order to improve the anti-inflammatory and anti-oxidative activities,medicinal Viola yedoensis Makino should be planted in 80%to 100%full-sunlight environment.（4）DPPH method,salicylic acid method,TBARS method and FRAP method were used to detect the in vitro antioxidant capacity of Viola yedoensis Makino planted under different light intensities,and the in vitro bacteriostasis ability of Viola yedoensis Makino planted under different light intensities was investigated by filter paper dipping method and Microdouble dilution method.The results showed that the inhibition rate of lipid oxidation and iron reduction ability decreased with the decrease of light intensity;DPPH free radical scavenging ability was 50%full-sunlight>100%full-sunlight>5%full-sunlight>35%full-sunlight>80%full-sunlight;hydroxyl radical scavenging ability was significantly lower in 5%fullsunlight treatment than in the other four groups（P<0.05）.The minimal inhibitory concentration of water extract of Viola yedoensis Makino on Staphylococcus aureus was 50,100,100,100 mg/mL-1 under 100%full-sunlight,80%full-sunlight and 50%full-sunlight,respectively.The water extract of Viola yedoensis Makino under 5%and 35%full-sunlight showed that there non inhibitory effect on Staphylococcus aureus.In conclusion,the antioxidant capacity and in vitro bacteriostasis ability of Viola yedoensis Makino decreased with the decrease of light intensity.In order to improve the antioxidant capacity and in vitro bacteriostasis ability,Viola yedoensis Makino should be planted in 100%full light environment. |
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