Chemical constituents from leaves of Uncaria rhynchophylla / 中草药

Objective: To study the chemical constituents from the leaves of Uncaria rhynchophylla and their antioxidant activities. Methods: The compounds were isolated by various column chromatography. Their structures were identified by spectroscopic methods including 1H-NMR, 13C-NMR, MS, HR-MS, etc. The antioxidant activities were evaluated by DPPH radical scavenging assay. Results: Seventeen compounds were isolated from the leaves of U. rhynchophylla, and identified as 18, 19-hydroxy- vincosamide (1), α-tocopherol (2), α-tocospiro A (3), dihydroactinidiolide (4), ursolic acid lactone (5), 3, 4-dehydrotheaspirone (6), chakyunglupulin A (7), ursolic acid (8), protocatechuic acid (9), quercetin (10), epicatechin (11), chlorogenic acid ethyl ester (12), quercetin-3-O-robinobioside (13), rutin (14), methyl caffeate (15), strictosamide (16), and vincosamide (17). The anti-oxidative IC50 values of compounds 10, 11, and 13-15 were 7.52, 8.21, 8.14, 2.13, and 5.35 μmol/L, respectively, which were better than the positive control Vit E (IC50 value was 9.53 μmol/L). Conclusion: Compound 1 is a new compound named as vincosamide A, and compounds 2-7, 9, 12, 13, and 15 are isolated from genus Uncaria Schreber nom. cons. for the first time. Moreover, compounds 10, 11, and 13-15 have the certain prospects in the development of natural anti-oxidative agents.

Chemical Constituents from Leaves of Pileostegia viburnoides Hook.f.et Thoms

Phytochemical investigation on the leaves of Pileostegia viburnoides Hook.f.et Thoms led to the isolation of twenty-five compounds, and their structures were identified as n-dotriacontane (1), taraxeryl acetate (2), friedelin (3), epifriedelinol (4), canophyllal (5), stigmast-4-en-3-one (6), stigmasterol (7), (24R)-5A-stigmastane-3,6-dione (8), ursolic acid (9), pomolic acid (10), umbelliferone (11), 4-epifriedelin (12), n-octatriacontanol (13), β-amyrin (14), α-amyrin (15), taraxerol (16), nonadecanol (17), friedelane (18), arachic acid (19), protocatechuic acid (20), n-pentatriacontanol (21), hexadecanoic acid (22), vincosamide (23), daucosterol (24), and skimming (25), respectively. To our best knowledge, compounds 1, 2, 12, 13, 17 - 19 and 21-23 were new within Saxifragaceae family. Compounds 15, 16, and 20 were produced from this genus for the first time. Compounds 4, 14 and 25 were first obtained from species P. viburnoides and compounds 3, 5 - 11, and 24 were achieved from the leaves of P. viburnoides for the first time. Furthermore, the anti-neuroinflammatory activity of these isolates was evaluated.

Alkaloids from stems of Nauclea officinalis / 中草药

Objective: To study the alkaloids from the stems of Nauclea officinalis. Methods: The chemical constituents were separated and purified by silica gel, ODS column chromatography, and preparative HPLC. Their structures were determined by UV, MS, and NMR spectroscopic analyses. Results: Thirteen compounds were isolated from the stems of N. officinalis, the structures were identified as 3-R-3,4-dihydroangustoline (1), blumenol A (2), naucleofficine D (3), 1,2,3,4-tetrahydro-β-carboline (4), 3-S-3,4-dihydroangustoline (5), latifoliamide D (6), latifoliamide B (7), angustoline (8), 3,14-dihydroangustine (9), 3,14,18,19- tetrahydroangustine (10), 6'-acetyl-strictosamide (11), vincosamide (12), and strictosamide (13). Conclusion: Compounds 2 and 4 are obtained from the plants of Nauclea L. for the first time. Compounds 2, 4, 6, 7, 9, and 10 are obtained from N. officinalis for the first time.