Seema Zareen

α-Glucosidase Inhibitory Activity of Triterpenoids from Cichorium intybus

Two new triterpenoids, 18alpha,19beta-20(30)-taraxasten-3beta,21alpha-diol (cichoridiol) (1) and 17-epi-methyl-6-hydroxyangolensate (intybusoloid) (2), were obtained from the methanolic extract of seeds of Cichorium intybus along with 11 known compounds, lupeol (3), friedelin (4), beta-sitosterol (5), stigmasterol (6), betulinic acid (7), betulin (8), betulinaldehyde (9), syringic acid (10), vanillic acid (11) 6,7-dihydroxycoumarin (12), and methyl-alpha-D-galactopyranoside (13). Compounds 1, 1a, and 11 showed a good alpha-glucosidase inhibitory activity.

Terminalin A, a novel triterpenoid from Terminalia glaucescens

Terminalin A 1, a new A-seco-triterpene, was isolated from the stem bark of Terminalia glaucescens Planchon. This compound has an unprecedented rearranged seco-glutinane structure with a pyran ring-A and an isopropanol moiety, as determined by spectroscopic and single-crystal X-ray diffraction analysis. Other known triterpenes, friedelin, β-sitosterol, stigmasterol, lupeol, betulinic acid, β-amyrin and long chain fatty acids were also isolated.

Two saponins from Pteleopsis hylodendron

Abstract Two new saponins, 2α,3α,19α,23-tetrahydroxyolean-12-en-28-O-β- d -galactoside, and sitosterol α(1→3) diglucoside, were isolated from the stem barks of Pteleopsis hylodendron along with a known triterpenoid, 2α,3β,21β,23-tetrahydroxyolean-12-en-28-oic acid, which was isolated for the first time from this plant. The structures of these compounds were elucidated with the help of spectroscopic studies.

Total synthesis, cytotoxic effects of damnacanthal, nordamnacanthal and related anthraquinone analogues.

Naturally occurring anthraquinones, damnacanthal (1) and nordamnacanthal (2) were synthesized with modified reaction steps and investigated for their cytotoxicity against the MCF-7 and K-562 cancer cell lines, respectively. Intermediate analogues 2-bromomethyl-1,3-dimethoxyanthraquinone (5, IC50 = 5.70 ± 0.21 and 8.50 ± 1.18 μg/mL), 2-hydroxymethyl-1,3-dimethoxyanthraquinone (6, IC50 = 12.10 ± 0.14 and 14.00 ± 2.13), 2-formyl-1,3-dimethoxyantharquinone (7, IC50 = 13.10 ± 1.02 and 14.80 ± 0.74), 1,3-dimethoxy-2-methylanthraquinone (4, IC50 = 9.40 ± 3.51 and 28.40 ± 2.33), and 1,3-dihydroxy-2-methylanthraquinone (3, IC50 = 25.60 ± 0.42 and 28.40 ± 0.79) also exhibited moderate cytotoxicity against MCF-7 and K-562 cancer cell lines, respectively. Other structurally related compounds like 1,3-dihydroxyanthraquinone (13a, IC50 = 19.70 ± 0.35 and 14.50 ± 1.28), 1,3-dimethoxyanthraquinone (13b, IC50 = 6.50 ± 0.66 and 5.90 ± 0.95) were also showed good cytotoxicity. The target compound damnacanthal (1) was found to be the most cytotoxic against the MCF-7 and K-562 cancer cell lines, with IC50 values of 3.80 ± 0.57 and 5.50 ± 1.26, respectively. The structures of all compounds were elucidated with the help of detailed spectroscopic techniques.

A triterpenoidal saponin and sphingolipids from Pteleopsis hylodendron.

From the stem bark of Pteleopsis hylodendron, a triterpenoidal saponin bellericagenin [B 3-O-[beta-D-glucopyranosyl-(1-->2)-alpha-D-glucopyranoside] (1) (Pteleopsoside)] and two sphingolipids, hylodendroside-I (2), and hylodendroside-II (3) were isolated, along with a synthetically known compound, [2alpha, 3beta, 23-triacetoxy-19alpha-hydroxyolean-12-en-28-oic acid (4)]. Other known compounds, friedelin (5), beta-carotene (6), lupeol (7), sitosterol (8), and stigmasterol (9), were also obtained. Their structures were deduced with the help of detailed spectroscopic studies.

Prolyl endopeptidase and thrombin inhibitory diterpenoids from the bark of Xylopia aethiopica.

The inhibitory effects of seven diterpenes, belonging to three different structural classes and isolated from the bark of Xylopia aethiopica, were investigated against the enzymes prolyl endopeptidase (PEP) and α-thrombin. Five compounds exhibited inhibitory activity against them.

Synthesis of an anthraquinone derivative (DHAQC) and its effect on induction of G2/M arrest and apoptosis in breast cancer MCF-7 cell line

Anthraquinones are an important class of naturally occurring biologically active compounds. In this study, anthraquinone derivative 1,3-dihydroxy-9,10-anthraquinone-2- carboxylic acid (DHAQC) (2) was synthesized with 32% yield through the Friedel–Crafts condensation reaction. The mechanisms of cytotoxicity of DHAQC (2) in human breast cancer MCF-7 cells were further investigated. Results from the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that DHAQC (2) exhibited potential cytotoxicity and selectivity in the MCF-7 cell line, comparable with the naturally occurring anthraquinone damnacanthal. DHAQC (2) showed a slightly higher IC50 (inhibitory concentration with 50% cell viability) value in the MCF-7 cell line compared to damnacanthal, but it is more selective in terms of the ratio of IC50 on MCF-7 cells and normal MCF-10A cells. (selective index for DHAQC (2) was 2.3 and 1.7 for damnacanthal). The flow cytometry cell cycle analysis on the MCF-7 cell line treated with the IC50 dose of DHAQC (2) for 48 hours showed that DHAQC (2) arrested MCF-7 cell line at the G2/M phase in association with an inhibited expression of PLK1 genes. Western blot analysis also indicated that the DHAQC (2) increased BAX, p53, and cytochrome c levels in MCF-7 cells, which subsequently activated apoptosis as observed in annexin V/propidium iodide and cell cycle analyses. These results indicate that DHAQC (2) is a synthetic, cytotoxic, and selective anthraquinone, which is less toxic than the natural product damnacanthal, and which demonstrates potential in the induction of apoptosis in the breast cancer MCF-7 cell line.

Some Chemical Constituents of Terminalia glaucescens and their Enzymes Inhibition Activity

A new triterpenoid, glaucinoic acid (2α, 3β, 19α, 24-tetrahydroxyolean-12-en-30-oic acid) (1) along with several known compounds, arjunic acid (2), arjungenin (3), sericoside (4), and friedelin (5) were isolated from the stem barks of Terminalia glaucescens. These compounds showed β - glucuronidase inhibitory activity. The structures were identified on the basis of spectroscopic techniques

Neuroprotective effect from stem bark extracts of Knema laurina against H2O2- and Aβ1–42-induced cell death in human SH-SY5Y cells

The stem bark extracts of Knema laurina inhibited the hydrogen peroxide (H2O2)- and aggregated amyloid β-peptide 1–42 length (Aβ1–42)-induced cell death in differentiated SH-SY5Y cells. Exposure of 250 μM H2O2 or 20 μM Aβ1–42 to the cells for 24 h reduced 50% of cell viability. Pretreatment of cells with ethyl acetate extract (EAE) or n-butanol extract (BE) at 300 μg/mL and then exposure to H2O2 protected the cells against the neurotoxic effects of H2O2. Besides, methanolic extract (ME) at 1 and 10 μg/mL exerted neuroprotective effect on Aβ1–42-induced toxicity to the cells. These results showed that EAE, BE and ME exhibited neuroprotective activities against H2O2- and Aβ1–42-induced cell death. Flavonoids (3–6) and β-sitosterol glucoside (8) were isolated from the EAE. Compound 1 was isolated from hexane extract, and compounds 2 and 7 were isolated from dichloromethane extract. All these observations provide the possible evidence for contribution in the neuroprotective effects.

The in vivo anti-tumor effect of curcumin derivative (2E,6E)-2,6-bis(4-hydroxy-3-methoxybenzylidene)cyclohexanone (BHMC) on 4T1 breast cancer cells

Curcumin is one of the promising natural products extracted from the rhizomes of curcuma longa and has been extensively investigated by researchers to explore its potential as a chemopreventive and therapeutic agent against several chronic diseases. To further enhance the cytotoxic potential of curcumin, its derivative (2E,6E)-2,6-bis(4-hydroxy-3-methoxybenzylidene)cyclohexanone (BHMC) has been synthesized and investigated, and its antitumor effect on tested on 4T1 challenged mice. BHMC was recorded with in vitro cytotoxicity on murine 4T1 breast cancer cells with IC50 value 13.66 μM, which was 2 times lower than curcumin after 72 hours of treatment. An in vivo study indicated that BHMC possessed antitumor effect on the 4T1 cells of the challenged mice by induction of apoptosis, antiproliferation, anti-inflammation and antimetastasis. This effect is better compared to curcumin treatment at the same evaluated concentration. Thus, BHMC is a potential antitumor agent against breast cancer.