| Juniperus rigida(J.rigida),an evergreen small tree or shrub of the Juniperus Cupressaceae,which is used as a traditional Mongolian medicine and Tibetan medicine.J.rigida needles are rich in essential oils and phenols,so they have good antibacterial and antioxidant properties.Current research status of Juniper at home and abroad shows that the research on Juniper mainly focuses on chemical constituents,however,there are few studies on the structural development and the change of chemical composition at different altitudes.In this study,chemical composition,anatomical structure and histochemistry were utilized to study the J.rigida needles at the same altitude in different leaf ages and at different altitudes in the same leaf ages in Helan Mountains.The relationship between structure and main chemical compositions was discussed.The changes of chemical composition and anatomical structure of J.rigida needles at different leaf ages and altitudes were revealed.The development stage and altitude area of maximum value of J.rigida needles was determined.The specific results are as follows:The main chemical compositions differences of J.rigida needles at different needle and different altitudes were significant.(1)A total of 43 terpenoids were detected in different leaf age J.rigida needles essential oil,the most varigied compositions were α-pinene,(-)-β-caryophyllene,(1E,4E,8E)-α-humulene,myrcene(0～5.85%)and β-myrcene(0～5.52%)in different leaf age needles.triennial needles owned the highest yield of essential oil(0.300～0.355%),biennial needles and triennial needles owned the highest contents of terpenoids(87.04%,88.38%).The content of phenolic compounds in different needle ages of J.rigida was significantly different.The triennial needles owned the highest total phenolic content(14.51±1.82～20.05±3.00 mmol equiv.GAE/100 g),the HPLC method detected 10 phenolic compounds in J.rigida needles,and the most varigied compounds were catechin,cumaric acid,chlorogenic acid and podophyllotoxin.The triennial needles was also owned the highest total content of 10 phenolic compounds(857.75mg/g).(2)A total of59 terpenoids were detected in J.rigida needles essential oil at different altitudes,the most varigied compositions were α-pinene,(-)-β-caryophyllene,(1E,6E,8S)-1-methyl-5-methylene-8-(1-methylethyl)-1,6-cyclodecadiene,β-myrcene and(1E,4E,8E)-α-humulene at different altitudes.2400 m owned the highest yield of essential oil(0.280～0.355%)and the highest contents of terpenoids(92.69%).The content of phenolic compounds of J.rigida at different altitudes was significantly different.The 2200 m needles owned the highest total phenolic content(14.05±1.82～20.05±3.00 mmol equiv.GAE/100 g),the HPLC method detected 10 phenolic compounds in J.rigida needles,and the most varigied compounds were catechin,cumaric acid,chlorogenic acid and podophyllotoxin.The 2400 m owned the highest total content of 10 phenolic compounds(857.75mg/g).(3)HCA and PCA of terpenoids and phenols were carried out.The results provided a basis for the quality evaluation and classification of J.rigida needles at different needle ages and altitudes.At the same time,3-methyl-4-methylidenebicyclo [3.2.1] oct-2-ene,myrcene,borneol,and(1R,3Z,7Z,11S)-1,5,5,8-tetramethyl-12-oxabicyclo[9.1.0]dodeca-3,7-diene were screened out as the indicating compounds of terpenoids affecting the quality evaluation;hyperoside,podophyllotoxin and galangal were screened out as the indicating phenolic compounds affecting the quality evaluationThe anatomical features differences of J.rigida needles at different needle ages and altitudes were significant.Some anatomical structures of J.rigida needles were different from other species of Juniper:(1)The cross-section of J.rigida needles is almost V-shaped,single vascular bundle,a marginal resin duct,a stomatal band in upper epidermis with paracitic stomata.At the same time,with the increase of needle age and altitude,it shows obvious xeromorphic properties of structure.(2)The results of HCA and PCA of 23 anatomical characteristic values provide a basis for the classification of different needle ages and altitudes.At the same time,cross-sectional perimeter,area of phloem,area of sponge tissue and cross-sectional area were picked as the indicating anatomical characteristic values affecting the classification The differences in histochemical analysis of terpenoids and phenols of J.rigida needles were significant.(1)The terpenoids is mostly in palisade tissue and edge of the resin duct,terpenoids was not found in xylem,phloem,mechanical tissue,stomatal band,stomata and epidermal cells.(2)The presence of phenolic compounds in the epidermal cells,sponge tissue and endothelial layer cells,at the same time,the accumulation in the center of the cell is greater than the edge.The phenols was not found in Xylem,phloem,mechanical tissue and resin duct.In summary,the utilization value of biennial needles and 2200-2400 m needles of J.rigida in Helan Mountains was the highest according to the yield,main chemical composition and anatomical structure. |
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