New phenylpropanoid-conjugated pentacyclic triterpenoids from the whole plants of Leptopus lolonum with their antiproliferative activities on cancer cells

Discovery of new triterpenoids from Leptopus clarkei and their antiproliferative activity on cancer cells

Two new triterpenoids (1-2), along with six known analogues (3-8) were obtained from the dried whole plant of Leptopus clarkei. Compound 1 is a 3,4-seco-lupane-type triterpenoid, and compound 2 is a phenylpropanoid-conjugated pentacyclic triterpenoid possessing trans-p-coumaroyl unit attached to oleanane-type skeleton. This is the first report on chemical investigation of the L. clarkei, and the triterpenoid derivatives were found in this plant for the first time. The structures of the new compounds were unequivocally elucidated by HRESIMS and 1D/2D NMR data. Additionally, the isolated compounds were evaluated for theircytotoxicities against four cancer cell lines including HepG2, MCF-7, A549 and HeLa. Notably, compound 2 exhibited the most significant antiproliferative activity with IC50 less than 20 μM for four cancer lines.

Phytochemical investigation of the fruits of Xanthium strumarium and their cytotoxic activity

Eight pentacyclic triterpenoids including two new ones (1, 2) were isolated from the fruits of Xanthium strumarium. Their structures were elucidated by extensive spectroscopic analysis. All isolates were evaluated for in vitro cytotoxic activity on HepG2, A549, HCT116 and SW480 cancer cells. Among them, the new compound 2 was found to exhibit significant cytotoxic activity on A549, HCT116 and SW480 cancer cells with IC₅₀ values of 9.68, 4.27 and 7.58 μM, respectively. Further, 2 was selected for cell cycle analysis and results revealed that 2 could cause HCT116 cell cycle arrest in G1 phase. In addition, Annexin V-FITC/PI staining assay showed that 2 could induce the death of HCT116 cells.

Molecular and morphological evidence for a new species of Leptopus (Phyllanthaceae) from Southeast Yunnan, China

Leptopus malipoensis, a new species of Phyllanthaceae from Southeast Yunnan Province, China, is described. The phylogenetic position of the new species within the genus Leptopus was analyzed based on nuclear ribosomal Internal Transcribed Spacer (nrITS) and plastid matK sequence data. The results show that L. malipoensis is highly supported to be the sister of L. fangdingianus (P. T. Li) Voronts. & Petra Hoff., a species endemic to western Guangxi Province, China. Morphologically, the new species can be distinguished from all known congeneric taxa by its long and slim branches usually pendulous or procumbent, some of its leaf laminas up to 15 cm long and 7 cm wide. It further differs from its sister species by its hirsute stems, leaves and pedicel of female flowers, longer pedicel of male flowers, 3-locular ovary and three styles. A key to all 10 accepted Leptopus species is provided.

Pentacyclic Triterpenoid Saponins, Poterinasides A-J, from Silverweed Cinquefoil Roots Promising Hepatoprotective and Anti-inflammatory Agents

Silverweed cinquefoil roots, as dietary supplements, foods, and medicines, are widely used in western areas of China, specifically in Tibet Autonomous Region and Gansu and Qinghai Provinces. In this paper, 10 new natural pentacyclic triterpenoid saponins (1-10), named poterinasides A-J, along with 14 known compounds (11-24) were isolated and purified from silverweed cinquefoil roots. The chemical structures of 1-10 were established by extensive analysis of 1D and 2D NMR data and mass spectrometric data. Poterinasides A (1), B (2), and G (7) with the unique position of substituents on the E ring had never been discovered in natural products before. Saponins 1-8, 14, and 22 displayed potent hepatoprotective activities, and 1-8, 10, 11, 14, 16, 19, and 22-24 showed outstanding anti-inflammatory effects. On the basis of the present results, some structure-activity relationships were summarized, in which 3α-OH, 19β-CH₃, 20α-CH₃, 20β-CH₃, 21α-OH, and 30-OH groups in isolated pentacyclic triterpenoid saponins were found to strengthen the hepatoprotective and anti-inflammatory activities, respectively. Further, the following pharmacophore-based virtual screening and docking studies on special targets proteins, SIRT1 and COX-2, revealed roughly similar results with the structure-activity relationships, and this combination method was used for the first time for active natural compound screening.

Phenylpropanoid-conjugated pentacyclic triterpenoids from the whole plants of Leptopus lolonum induced cell apoptosis via MAPK and Akt pathways in human hepatocellular carcinoma cells

Our present and previous phytochemical investigations on Leptopus lolonum have resulted in the isolation of almost 30 phenylpropanoid-conjugated pentacyclic triterpenoids (PCPTs). During the continuous study on PCPTs, this kind of triterpenoid ester is considered as a natural product with low toxicity because of it's widely distribution in natural plants and edible fruits including kiwi fruit, durian, jujube, pawpaw, apple and pear. In the present work, we report the isolation, structural elucidation and cytotoxic evaluation of four new PCPTs (1-4) which obtained from L. lolonum. In addition, the possible biosynthesis pathway for 28-norlupane triterpenoid and potent effect of phenylpropanoid moiety for increasing the cytotxic effect of triterpenoids were also discussed. Among these compounds, compound 1 exhibited the highest cytotoxic effect on HepG2 cells with IC₅₀ value of 11.87 μM. Further flow cytometry and western blot analysis demonstrated that 1 caused G1 cell cycle arrest by up-regulated the expression of phosphorylated p53 protein in HepG2 cells and induced cell apoptosis via MAPK and Akt pathways. These results emphasized the potential of PCPTs as lead compounds for developing anti-cancer drugs.