Showing papers by "Min Xu published in 2015"
TL;DR: 18 new compounds were found to feature a diversity of highly oxygenated side chains, formed by hydrolysis of the C-20 sugar moiety followed by dehydration, dehydrogenation, epoxidation, hydroxylation, or methoxylation of the main saponins in the raw roots.
Abstract: The roots of Panax notoginseng, an important Chinese medicinal plant, have been used traditionally in both the raw and processed forms, due to the different chemical constituents and bioactivities found. Thirty-eight dammarane-type triterpenoid saponins were isolated from the steam-processed roots of P. notoginseng, including 18 new substances, namely, notoginsenosides SP1-SP18 (1-18). The structures of 1-18 were determined on the basis of spectroscopic analysis and acidic hydrolysis. The absolute configuration of the hydroxy group at C-24 in 1-4, 19, and 20 was determined in each case by Mo-2(AcO)(4)-induced circular dichroism. The new compounds were found to feature a diversity of highly oxygenated side chains, formed by hydrolysis of the C-20 sugar moiety followed by dehydration, dehydrogenation, epoxidation, hydroxylation, or methoxylation of the main saponins in the raw roots. The new saponins 1, 2, 6-8, 14, and 17 and the known compounds 20-27 showed promoting effects on the differentiation of PC12 cells, at a concentration of 10 mu M.
40 citations
TL;DR: It is demonstrated that lignans, phenylpropanoid and biphenyl found in Piper wallichii may be responsible for antithrombotic effect of the titled plant.
35 citations
TL;DR: In an effort to identify anti-viral and cytotoxic compounds from Phyllanthus spp.
27 citations
TL;DR: Fifteen known compounds including four triterpenoids, one sterol, one diketopiperazine alkaloid and nine phenolics were isolated from the stems of Piper wallichii and the structure of compound 1 was fully assigned by 1D and 2D NMR experiments for the first time.
22 citations
TL;DR: Nine new minor dehydrogenated and cleavaged dammarane-type triterpenoid saponins were isolated from the steamed roots of Panax notoginseng, together with 14 known ones, which displayed the enhancing potential of neurite outgrowth of NGF-mediated PC12 cells at a concentration of 10 μM.
16 citations
TL;DR: In this paper, changes of water storage in northwestern China were determined by GRACE monthly gravity field data obtained from 2003 to 2010, which revealed similar patterns of change and a correlation coefficient of 0.71.
Abstract: The Gravity Recovery and Climate Experiment (GRACE) satellite mission provides measurements of Earth’s static and time-variable gravity fields with monthly resolution. In this study, changes of water storage in northwestern China were determined by GRACE monthly gravity field data obtained from 2003 to 2010. Comparisons of water storage change (WSC) simulated by a four-dimensional assimilation model (Noah) and observed by GRACE revealed similar patterns of change and a correlation coefficient of 0.71 . Trend analysis indicated significant changes in the spatiotemporal variation of WSC in northwestern China during the 8-year study period, which were stronger in the east than in the west and more pronounced in the south than in the north. The most pronounced increase in water storage occurred in Gansu and Qinghai provinces, but, overall, water storage increased by 0.61 mm/a over northwestern China during the study period. Clear seasonal variations of WSC and precipitation were found, because glacial meltwater and precipitation are the main sources of water in the hydrosphere; meanwhile, the distributions of glaciers and permafrost also affect the spatial distribution of WSC.
10 citations
TL;DR: A reliable, reproducible and accurate method for simultaneous and quantitative determination of 1–3 is developed by RP-HPLC analysis and this method should be appropriate for the quality assurance of unprocessed and processed materials of V. dunalianum.
10 citations
TL;DR: In this paper, Mosher's method was applied to establish the absolute configurations of six new highly oxygenated cleistanthane diterpenoid glucosides, phyllanembloids A-F (1,6), isolated from the roots of Phyllanthus emblica.
Abstract: Time-dependent density functional theory (TDDFT) calculated electronic circular dichroism (ECD) and Mosher’s method were applied to establish the absolute configurations of six new highly oxygenated cleistanthane diterpenoid glucosides, phyllanembloids A–F (1–6), isolated from the roots of Phyllanthus emblica. Compounds 1–5 featured a carboxyl group at C-13 adjacent to the hydroxyl group at C-12, and are the first examples of cleistanthane diterpenoids with a salicylic acid fragment. The carboxyl group at C-13 can significantly affect the CD spectrum of cleistanthane diterpenoids, and make the excitations of phenylethylene dominate the Cotton effects (240 and 280 nm), rather than the benzene ring excitations dominating the Cotton effects at 220 and 240 nm as in the 13-methyl analogues. The characteristic Cotton effects of cleistanthane diterpenoids were summarized according to the experimental and calculated ECD curves, which can be applied as a common method to determine the absolute configurations of this type of diterpenoid.
7 citations
TL;DR: In this paper, two phloroglucinol-coupled sesquiterpenoids, eucalmaidials A and B (1 and 2), were isolated from the juvenile leaves of Eucalyptus maideni, along with eight known macrocarpals (3, 5, 7, 8, and 10, 14).
Abstract: Two new phloroglucinol-coupled sesquiterpenoids, eucalmaidials A and B (1 and 2), were isolated from the juvenile leaves of Eucalyptus maideni, along with eight known macrocarpals (3–10), eucalyptone (11), and three known triterpenoids (12–14). Eucalmaidials A and B represent a new skeleton of phloroglucinol-coupled iphionane. Their structures were elucidated by extensive NMR spectroscopic analysis and theoretical calculation of the 13C NMR chemical shifts. The biosynthetic pathway of 1 and 2 was also postulated. Compounds 1, 3, 5, 7, 8, and 10–14 were evaluated for their antifungal and antibacterial activities. Compound 1 exhibited antifungal activity against Candida glabrata with an IC50 value of 0.75 μg mL−1.
1 citations