Monoterpene indole alkaloids from Gelsemium elegans.

Two new monoterpene indole alkaloids, Eleganine A (1) and Eleganine B (2), along with 11 known compounds (3-13) were isolated from the stems and leaves of Gelsemium elegans. Compound 1 is a gelsenicine-related monoterpenoid indole alkaloid possessing an iridoid unit. Their structures and absolute configurations of 1-2 were established by UV, IR, HR-ESI-MS, NMR spectroscopy, and electronic circular dichroism data analyses. All isolated compounds were evaluated for their anti-inflammatory and inhibiting glucose-induced mesanginal cell proliferation activities. None of them showed activity with IC50 far beyond 50 µM.

Monoterpene indole alkaloids from the roots of Alstonia rupestris and their anti-inflammatory activity.

Four new monoterpene indole alkaloids (1-4) together with twelve known alkaloids (5-16) were isolated from the roots of Alstonia rupestris. Compound 1 was the first example of C2-symmetric heteroyohimbine-type indole alkaloid homodimer obtained from natural plant resource. Their structures were elucidated on the basis of spectroscopic data. The absolute configuration of 1 was determined by comparison of its calculated and experimental electronic circular dichroism (ECD) spectra. All compounds were evaluated for their anti-inflammatory activities by measuring their NO inhibitory effects in LPS-stimulated RAW 264.7 cells. Compound 2 showed strong NO inhibition with IC50 value of 4.2 ± 1.3 µM. Moreover, compound 2 could decrease the expressions of cyclooxygenase-2 (COX-2) and transforming growth factor beta-1 (TGF-ß1).

New cyclic C-geranylflavanones isolated from Paulownia fortunei fruits with their anti-proliferative effects on three cancer cell lines.

Seven new C-geranylated flavanones, fortunones F - L (1-7), were isolated from the fresh mature fruits of Paulownia fortunei (Seem.) Hemsl. Their structures were determined by extensive spectroscopic data interpretation (UV, IR, HRMS, NMR, and CD). These new isolated compounds were all with a cyclic side chain modified from the geranyl group. Among them, compounds 1-3 all possessed a dicyclic geranyl modification, which was described firstly for Paulownia C-geranylated flavonoids. All the isolated compounds were subjected to the cytotoxic assay on human lung cancer cell A549, mouse prostate cancer cell RM1 and human bladder cancer cell T24, respectively. Results indicated A549 cell line was more sensitive to C-geranylated flavanones than the other two cancer cell lines and compounds 1, 7 and 8 exhibited potential anti-tumor effects (IC50 ˂ 10 µM). Further research revealed the effective C-geranylated flavanones could exert their anti-proliferative activity on A549 cells by inducing apoptosis and blocking cells in G1 phase.

Possible pharmaceutical applications can be developed from naturally occurring phenanthroindolizidine and phenanthroquinolizidine alkaloids.

Naturally occurring phenanthroindolizidine and phenanthroquinolizidine alkaloids (PIAs and PQAs) are two small groups of herbal metabolites sharing a similar pentacyclic structure with a highly oxygenated phenanthrene moiety fused with a saturated or an unsaturated N-heterocycle (indolizidine/quinolizidine moieties). Natural PIAs and PQAs only could be obtained from finite plant families (such as Asclepiadaceae, Lauraceae and Urticaceae families, etc.). Up to date, more than one hundred natural PIAs, while only nine natural PQAs had been described. PIA and PQA analogues have been applied to the development of potent anticancer agents all along because of their excellent cytotoxic activity. However, in the last two decades, other great biological properties, such as anti-inflammatory and antiviral activities were revealed successively by different pharmacological assays. Especially because of their potent antiviral activity against coronavirus (TGEV, SARS CoV and MHV) and tobacco mosaic virus, PIA and PQA analogues have attracted much pharmaceutical attention again, some of them have been used to present interesting targets for total or semi synthesis, and structure-activity relationship (SAR) study for the development of antiviral agents. In this review, natural PIA and PQA analogues obtained in the last two decades with their herbal origins, key spectroscopic characteristics for structural identification, biological activity with possible SARs and application prospects were systematically summarized. We hope this paper can stimulate further investigations on PIA and PQA analogues as an important source for potential drug discovery.

Paulownia C-geranylated flavonoids: their structural variety, biological activity and application prospects.

Paulownia species, especially their flowers and fruits, are traditionally used in Chinese herbal medicines for the treatment of infectious diseases. C-geranylated flavonoids were found to be the major special metabolites in Paulownia flowers and fruits, and 76 C-geranylated flavonoids had been isolated and characterized thus far. Structural variations in Paulownia C-geranylated flavonoids are mainly due to the complicated structural modifications in their geranyl substituents. These natural compounds have attracted much attention because of their various biological activities, including antioxidation, anti-inflammation, cytotoxic activity and various enzymatic inhibitions, etc. Among them, diplacone, a major Paulownia component, was considered to have promise for applications in medicine. This paper summarizes the information from current publications on Paulownia C-geranylated flavonoids, with a focus on their structural variety, key spectroscopic characteristics, biological activity with structure-activity relationships and application prospects. We hope that this paper will stimulate further investigations of Paulownia species and this kind of natural product.

Undescribed C-geranylflavonoids isolated from the fruit peel of Paulownia catalpifolia T. Gong ex D.Y. Hong with their protection on human umbilical vein endothelial cells injury induced by hydrogen peroxide.

Six undescribed C-geranylated flavonoids, including five C-geranylflavanones named as paucatalinones F - J, one C-geranylflavonol named as paucatalinone K, along with seven known geranylated flavanones, were isolated from the fruit peel of Paulownia catalpifolia T. Gong ex D.Y. Hong. Their structures were elucidated distinctly according to their UV, IR, MS, NMR, and CD data. Among them, two compounds were substituted with unusual modified geranyl groups, namely paucatalinone F with an oxygenated cyclogeranyl substituent and paucatalinone H with a terminal pyranoid geranyl substituent. Furthermore, the protective effects on human umbilical vein endothelial cells (HUVECs) injury induced by H2O2 were evaluated, and paucatalinone F showed the most potential activity. The bioactive results suggested that the geranyl substituent may be an important factor for restraining oxidative HUVECs damage and Paulownia C-geranylated flavonoids might have the potential for preventing cardiovascular complications.

[Studies on the chemical constituents of Salsola collina].

OBJECTIVE: To study the chemical constituents of Salsola collina. METHODS: The compounds were isolated by column chromatography, and their structures were identified by physical and chemical properties and spectral data. RESULTS: Seven compounds were isolated and identified as n-lignoceric acid (1), n-dotriacontanic acid (2), beta-sitosterol (3), 5, 2'-dihydroxy-6, 7-methylenedioxy-isoflavone (4), vanillic acid (5), (-)syringaresinol 4,4'-bis-O-beta-D-glucopyranoside (6), salicylic acid (7). CONCLUSION: The compounds of 1, 2, 4, 5 and 6 are isolated from the plant for the first time.

[Primary studies on chemical constituents from butanol extraction of the thorny elaeagnus leaf and their cytotoxicity].

OBJECTIVE: To study the chemical constituents and test the cytotoxicity of the purified compounds from the Thorny Elaeagnus Leaf. METHODS: The constituents were isolated by column chromatography and their structures were elucidated by chemical properties and spectroscopic analysis. The cytotoxicity of the chemical components for SGC-7901 and Hela cells was measured by MuT method. RESULTS: Four components were isolated and identified as 3'-O-methylquercetin( 1),kaempferol-3-O-beta-D-6-O-(p-hydroxycinnamoyl) -glucopyranoside(2), kakkalide(3),3'-O-methyl-ellagic acid-4-O-alpha-L-rhamnicoside(4). These components had cytotoxicity for SGC-7901 and Hela cells. CONCLUSION: Compounds 1,3 and 4 are isolated from Thorny Elaeagnus Leaf for the first time. The results of pharmacological experiments indicate that compounds 1 and 2 show strong cytotoxicity to Hela cells.