Isolation, structural elucidation and cytotoxicity evaluation of a new pentahydroxy-pimarane diterpenoid along with other chemical constituents from Aerva lanata.

Aervalanata possesses various useful medicinal and pharmaceutical activities. Phytochemical investigation of the plant has now led to the isolation of a new 2α,3α,15,16,19-pentahydroxy pimar-8(14)-ene diterpenoid (1) together with 12 other known compounds identified as ß-sitosterol (2), ß-sitosterol-3-O-ß-D-glucoside (3), canthin-6-one (4), 10-hydroxycanthin-6-one (aervine, 5), 10-methoxycanthin-6-one (methylaervine, 6), ß-carboline-1-propionic acid (7), 1-O-ß-D-glucopyranosyl-(2S,3R,8E)-2-[(2'R)-2-hydroxylpalmitoylamino]-8-octadecene-1,3-diol (8), 1-O-(ß-D-glucopyranosyl)-(2S,3S,4R,8Z)-2-[(2'R)-2'-hydroxytetracosanoylamino]-8(Z)-octadene-1,3,4-triol (9), (2S,3S,4R,10E)-2-[(2'R)-2'-hydroxytetracosanoylamino]-10-octadecene-1,3,4-triol (10), 6'-O-(4″-hydroxy-trans-cinnamoyl)-kaempferol-3-O-ß-D-glucopyranoside (tribuloside, 11), 3-cinnamoyltribuloside (12) and sulfonoquinovosyldiacylglyceride (13). Among these, six compounds (8-13) are reported for the first time from this plant. Cytotoxicity evaluation of the compounds against five cancer cell lines (CHO, HepG2, HeLa, A-431 and MCF-7) shows promising IC50 values for compounds 4, 6 and 12.

Synthesis and biological evaluation of andrographolide analogues as anti-cancer agents.

A new family of andrographolide analogues were synthesized and screened in vitro against kidney (HEK-293) and breast (MCF-7) cancer cells. The anti-cancer effects of the active analogues (2b, 2c and 4c) were determined by multiple cell based assays such as MTT, immunostaining, FACS, western blotting and transcriptional inhibition of NF-κB activity. Importantly, these compounds were found to possess higher anti-cancer potency than andrographolide and low toxicity to normal (VERO and MCF-10A) cells. Increased level of Bax/Bcl-xL ratio, caspase 3, and sub G1 population, higher expression level of tumor suppressor protein p53 and lower expression level of NF-κB suggested potent apoptotic property of the active analogues. Data revealed that the andrographolide derivative-mediated cell death in cancer cells was p53 dependent.

Cytotoxic cycloartane triterpene and rare isomeric bisclerodane diterpenes from the leaves of Polyalthia longifolia var. pendula.

A 24-methylenecycloartane-3 ß, 16 ß, 23 ß-triol, Longitriol (1), rare bisclerodane imides, Longimide A (2) and previously known Longimide B (3) were isolated from ethanolic extract of the leaves of Polyalthia longifolia var. pendula. This is the first example of isolation of any cycloartane triterpene from this plant source. Structures were determined by extensive (1D and 2D NMR) spectroscopic data analysis combined with ESI MS/MS fragmentation and X-ray analysis. Furthermore, Compounds 1 and 2 were evaluated for their cytotoxic effects against four human cancer cell lines and found to be most active against cervical carcinoma cell lines with IC(50) value of 10.03 and 4.12 µg/mL, respectively.

Molecular characterization and localization of Plasmodium falciparum choline kinase.

Generation of phosphocholine by choline kinase is important for phosphatidylcholine biosynthesis via Kennedy pathway and phosphatidylcholine biosynthesis is essential for intraerythrocytic growth of malaria parasite. A putative gene (Gene ID PF14_0020) in chromosome 14, having highest sequence homology with choline kinase, has been identified by BLAST searches from P. falciparum genome sequence database. This gene has been PCR amplified, cloned, over-expressed and characterized. Choline kinase activity of the recombinant protein (PfCK) was validated as it catalyzed the formation of phosphocholine from choline in presence of ATP. The K(m) values for choline and ATP are found to be 145+/-20 microM and 2.5+/-0.3 mM, respectively. PfCK can phosphorylate choline efficiently but not ethanolamine. Southern blotting indicates that PfCK is a single copy gene and it is a cytosolic protein as evidenced by Western immunoblotting and confocal microscopy. A model structure of PfCK was constructed based on the crystal structure of choline kinase of C. elegans to search the structural homology. Consistent with the homology modeling predictions, CD analysis indicates that the alpha and beta content of PfCK are 33% and 14%, respectively. Since choline kinase plays a vital role for growth and multiplication of P. falciparum during intraerythrocytic stages, we can suggest that this well characterized PfCK may be exploited in the screening of new choline kinase inhibitors to evaluate their antimalarial activity.

Taxoid from the needles of the Himalayan yew Taxus wallichiana with cytotoxic and immunomodulatory activities.

The needles of Taxus wallichiana gave a taxoid 1-hydroxy- 2-deacetoxy-5-decinnamoyl-taxinine j, whose structure has been established by spectroscopic data and confirmed by X-ray crystallography. The taxoid possesses significant cytotoxic and immunomodulatory activity.

Clotrimazole inhibits hemoperoxidase of Plasmodium falciparum and induces oxidative stress. Proposed antimalarial mechanism of clotrimazole.

The mechanism of antimalarial activity of clotrimazole was studied placing emphasis on its role in inhibiting hemoperoxidase for inducing oxidative stress in Plasmodium falciparum. Clotrimazole, in the presence of H2O2, causes irreversible inactivation of the enzyme, and the inactivation follows pseudo-first order kinetics, consistent with a mechanism-based (suicide) mode. The pseudo-first order kinetic constants are ki = 2.85 microM, k(inact) = 0.9 min(-1), and t(1/2) = 0.77 min. The one-electron oxidation product of clotrimazole has been identified by EPR spectroscopy as the 5,5'-dimethyl-1-pyrroline N-oxide (DMPO) adduct of the nitrogen-centered radical (aN = 15 G), and as DMPO protects against inactivation, this radical is involved in the inactivation process. Binding studies indicate that the clotrimazole oxidation product interacts at the heme moiety, and the heme-clotrimazole adduct has been dissociated from the inactivated enzyme and identified (m/z 1363) by mass analysis. We found that the inhibition of hemoperoxidase increases the accumulation of H2O2 in P. falciparum and causes oxidative stress. Furthermore, the inhibition of hemoperoxidase correlates well with the inhibition of parasite growth. The results described herein indicate that the antimalarial activity of clotrimazole might be due to the inhibition of hemoperoxidase and subsequent development of oxidative stress in P. falciparum.

Absolute configuration and anticancer activity of taxiresinol and related lignans of Taxus wallichiana.

Absolute configuration of taxiresinol 1, a lignan from the heartwood of Taxus wallichiana has been determined as 8R, 8'R, and 7'R with the help of chemical correlation method and X-ray crystallography. The anticancer activity of taxiresinol 1 and other two lignans 2, 3 were also studied. Taxiresinol 1 showed notable anticancer activity in the in vitro bioassays against colon, liver, ovarian and breast cancer cell lines.

Structure-based drug design: synthesis, crystal structure, biological evaluation and docking studies of mono- and bis-benzo[b]oxepines as non-steroidal estrogens.

Mono- and bis-benzo[b]oxepine derivatives have been rationally synthesized to meet the molecular requirement for interaction with estrogen receptor. Bis-benzo[b]oxepines (7 and 9) and mono-benzo[b]oxepine (10) acquire geometry with phenolic groups disposed in a fashion to stimulate estrogen receptor. Structure-based investigation, in vivo activity and docking studies have been described and correlated to demonstrate a practical approach for suitable ligand design.