Phytochemical and chemotaxonomic study on the leaves of Rhododendron amesiae

The phytochemical study of the leaves of Rhododendron amesiae (Ericaceae) led to the isolation and identification of 19 compounds, including six diterpenoids (1–6), six triterpenoids (7–12) and seven flavonoids (13–19). The chemical structures of these compounds were identified by spectroscopic data, as well as by comparison with previously reported data in literature. This is the first systematic study on the chemical constituents of Rhododendron amesiae. All the compounds were isolated from this plant for the first time. Compounds 12, 14 and 15 were first isolated and reported from the genus Rhododendron and the family Ericaceae. Furthermore, the chemotaxonomic significance of these compounds was discussed.     

Synthesis of the novel elemonic acid derivatives as Pin1 inhibitors

A novel series of elemonic acid derivatives were synthesized and evaluated for their inhibitory activity on Pin1. Five compounds displayed significantly improved ability to inhibit Pin1 activity at micromolar levels. Compound 10 with 2-carboxylmethylene was the most active one with an IC₅₀ value of 0.57 μM. The docking models of Pin1 support that introduction of an acidic group to elemonic acid enhance the Pin1 inhibitory activity.     

New Cytotoxic Triterpenoid Saponins from the Roots of Albizia gummifera (J.F.Gmel.) C.A.Sm.

As part of our search for new bioactive saponins from Cameroonian medicinal plants, two new oleanane‐type saponins, named gummiferaosides D and E ( 1 and 2 ), along with one known saponin, julibroside J₈ ( 3 ), were isolated from the roots of Albizia gummifera. Their structures were established on the basis of extensive 1D‐ and 2D‐NMR (¹H‐ and ¹³C‐NMR, DEPT, COSY, TOCSY, NOESY, HSQC, HSQC‐TOCSY, and HMBC) and HR‐ESI‐MS studies, and by chemical evidence. The apoptotic effect of saponins 1  –  3 was evaluated on the A431 human epidermoid cancer cell. Flow cytometric analyses showed that saponins 1  –  3 induced apoptosis of human epidermoid cancer cell (A431) in a dose‐dependent manner.     

Three new compounds from the roots of Juglans mandshurica Maxim.

A new biflavone glycoside juglbiflavone A (1) along with two new lupane-type triterpenes (2-3) were identified from the roots of Juglans mandshurica Maxim. Their structures and absolute configurations were elucidated by extensive spectroscopic methods including 1D/2D NMR, HRESIMS and CD. Compound 1 is the first example of biflavone glycoside consisted of a flavanol unit and a flavone unit from this genus, which also exhibited moderate cytotoxic activity against SGC-7901 and A549 cell lines in vitro with IC₅₀ values of 10.08 ± 0.52 μM and 12.44 ± 1.21 μM, respectively.     

Structure-activity relationships of ganoderma acids from Ganoderma lucidum as aldose reductase inhibitors

A series of lanostane-type triterpenoids, known as ganoderma acids were isolated from the fruiting body of Ganoderma lucidum. Some of these compounds were identified as active inhibitors of the in vitro human recombinant aldose reductase. To clarify the structural requirement for inhibition, some structure–activity relationships were determined. Our structure–activity studies of ganoderma acids revealed that the OH substituent at C-11 is an important feature and the carboxylic group in the side chain is essential for the recognition of aldose reductase inhibitory activity. Moreover, double bond moiety at C-20 and C-22 in the side chain contributes to improving aldose reductase inhibitory activity. In the case of ganoderic acid C2, all of OH substituent at C-3, C-7 and C-15 is important for potent aldose reductase inhibition. These results provide an approach to understanding the structural requirements of ganoderma acids from G. lucidum for aldose reductase inhibitor. This understanding is necessary to design a new-type of aldose reductase inhibitor.     

三叶木通转录组分析及三萜皂苷生物合成途径关键酶基因的发掘

为了解三叶木通(Akebia trifoliata(Thunb.)Koidz.)的三萜皂苷合成途径及其关键酶,本研究对其花、叶、根、茎进行转录组测序,组装获得了57.25 Gb数据,含140 859个unigenes,序列平均长度为1350 bp。KEGG代谢通路富集结果显示,517个unigenes参与三萜皂苷合成相关的3条代谢途径,其中415个unigenes编码三萜皂苷生物合成途径的19个关键酶。对三萜皂苷生物合成过程中的关键酶角鲨烯环氧酶(SE)进行序列分析和同源建模,发现其具有保守的底物结合结构域。将三叶木通茎与花、叶、根的基因表达水平进行比较,发现茎与根相比较其上调基因数目最多,其中295个差异表达基因(DEGs)与三萜皂苷生物合成途径相关。     

Bioactive oleanane-type saponins from the rhizomes of Anemone taipaiensis

Investigation of the n-BuOH extract of the rhizomes of Anemone taipaiensis led to the isolation of five new oleanane-type triterpenoid saponins (1–5), together with seven known saponins (6–12). Their structures were determined by the extensive use of ¹D and ²D NMR experiments along with ESIMS analyses and acid hydrolysis. The aglycone of 1, 2 and 4 was determined as siaresinolic acid, which was reported in this genus for the first time. The cytotoxicities of the saponins 1–12, prosapogenins 4a, 5a, 10a–12a and sapogenins siaresinolic acid (SA), oleanolic acid (OA), hederagenin (HE) were evaluated against five human cancer cell lines, including HepG2, HL-60, A549, HeLa and U87MG. The monodesmosidic saponins 6–8, 5a, 10a–12a and sapogenins SA, OA, HE exhibited cytotoxic activity toward all cancer cell lines, with IC₅₀ values ranging from 2.25 to 57.28 μM. Remarkably, the bisdesmosidic saponins 1–4 and 9 showed selective cytotoxicity against the U87MG cells.     

Triterpene saponins of Genista ulicina Spach

From the n-BuOH extract of the aerial parts of Genista ulicina, six triterpene saponins, 3-O-β-d-glucopyranosyl-olean-12-ene-3β,27,28,30-tetraol, 3-O-β-d-glucopyranosyl-olean-12-ene-3β,27,28,29-tetraol, 3,29-di-O-β-d-glucopyranosyl-olean-12-ene-3β,27,28,29-tetraol, 3-O-β-d-glucopyranosyl-olean-12-ene-3β,28,29-triol-27-oic acid, 3-O-β-d-glucopyranosyl-olean-12-ene-3β,27,28-triol-29-oic acid, and 3-O-β-d-glucopyranosyl-14-H-27-nor-olean-12-ene-3β,28,29-triol, were isolated together with eight known triterpene saponins and six flavonoids. Their structures were established mainly by means of spectroscopic methods (1D and 2D-NMR as well as HR-ESI-MS). The n-BuOH extract, investigated for its antitumor growth inhibition of human colon cancer HT-29 cells, presented no significant activity (IC₅₀ > 100 μg).     

Isolation of triterpenoid saponins from Medicago sativa L. with neuroprotective activities

Three new pentacyclic triterpenoid saponins (1–3), together with medicagenic acid (4) were isolated and purified from 70% EtOH extract of Medicago sativa L. by different column chromatographic and semi-preparative HPLC. Their structures were established by direct interpretation of their spectral data, mainly HR-ESI-MS, 1D-NMR, 2D-NMR, and chemical methods, as well as comparison with literature data. Additionally, all isolates were evaluated for their neuroprotective activities against H₂O₂-induced damage in human neuroblastoma SHSY5Y cells. As a results, compounds 1 and 2 (67.14% and 73.05%) exhibited potent neuroprotective activities. These findings provide new insights into developing better treatment of neurodegenerative diseases for M. sativa in the future.     

Biomarkers for Ilex pubescens under anti-platelet activity-oriented isolation

In the present study, eleven ursane triterpenoids (1—11), seven oleanane triterpenoids (12—18), one lupine sapogenin (19) as well as two sterols (20 and 21) were obtained from Ilex pubescens under the anti-platelet activity-oriented isolation. Among them, compounds 2 and 4 were isolated from I. pubescens for the first time, while the isolation of the compounds 12, 15, 16 and 17 was a new finding in the Aquifoliaceae family. Our present study exhibited the taxonomic relationships (similarities and differences) between I. pubescens and some other species of genus Ilex. The result also suggested that triterpenoids are the anti-platelet components which may be fingerprints and serve as biomarkers for seeking alternative sources for I. pubescens.