New cytotoxic clerodane diterpenes from the leaves of Premna tomentosa.

Bio-activity directed investigation of hexane extract from the leaves of Premna tomentosa led to the isolation of three new clerodane diterpenes (1-3) along with four known compounds (4-7). The structures of new compounds were established using IR, MS, 1D, and 2D NMR techniques. The in vitro cytotoxicity of the crude hexane extract and the isolated compounds were evaluated against seven human cancer cell lines and results indicated that compounds 2 and 4 depicted significant cytotoxicity against hepatocellular carcinoma cell line.

Synthesis, cytotoxic activity and structure-activity relationships of hedychenone analogues.

Hedychenone, a plant-derived labdane diterpenoid, showed potent in vitro cytotoxic activity against cancerous cells. In the present study, a series of analogues have been synthesized by modification of the furanoid ring, double bond and the vinylic methyl functionality of this natural product lead and evaluated for their cytotoxic activities against human cancer cell lines. The structures of the target compounds were established by IR, (1)H NMR and mass spectral analysis. Majority of the analogues displayed potent activity than the parent compound, hedychenone. Preliminary structure-activity relationship studies indicated that furanoid ring has a greater impact on cytotoxicity than that of the decalone nucleus. However, dimerization through C-8 significantly enhanced the cytotoxic activity of the hedychenone.

Gastroprotective flavonoid constituents from Oroxylum indicum Vent.

Chemical investigation of the stem bark of Oroxylum indicum resulted in the isolation and characterization of two new flavonoid glycosides (1, 2), along with seven known compounds (3-9). Their structures were established on the basis of extensive spectroscopic (IR, MS, 2D NMR) data analysis and by the comparison with spectroscopic data reported in the literature. In addition, all the compounds were tested for their ulcer protective effects against various gastric ulceritis inducing models in rats.

A new benzil derivative from Derris scandens: Structure-insecticidal activity study.

Bioactivity-directed investigation of root extract of Derris scandens has led to the isolation and characterization of a new benzil derivative (11), along with ten known compounds (1-10). Their structures were determined on the basis of extensive spectroscopic (IR, MS, 1D and 2D NMR) data analysis and by comparison with the literature data. The insect antifeedant activity and growth inhibitory studies of these compounds were investigated against castor semilooper pest, Achaea janata using a no-choice laboratory bioassay. Several of the isolates displayed potent feeding deterrence and were also toxic or caused developmental abnormalities following topical administration. The new compound, derrisdione A was moderately active with an antifeedant index of 58.6+/-1.7% at 10microg/cm(3) against A. janata.

Bioactivity-guided isolation of cytotoxic constituents from stem-bark of Premna tomentosa.

A bioassay-guided fractionation and chemical investigation of the stem bark of Premna tomentosa resulted in the isolation and characterization of four new icetexane diterpenes (1-4), along with the known compounds coniferaldehyde (5), syringaldehyde (6), lupeol (7), betulin (8), and 2-(4-methoxyphenyl)-2-butanone (9). Their structures were established on the basis of extensive spectroscopic (IR, MS, 2D NMR) data analysis and by comparison with the spectroscopic data reported in the literature. The new compounds exhibited diverse functionalities on a common icetexane diterpene skeleton. In addition, cytotoxic activities of the icetexanes (1-3) were evaluated by determining their inhibitory effects on the human cancer cell lines (MCF-7, HT-29, Hep-G2, A-431, and A-549). Compounds 1 and 3 showed selective inhibitory activity against MCF-7 (15.96microg/mL and 15.84microg/mL) and HT-29 cell lines (16.21microg/mL and 14.57microg/mL), respectively.

New furanoflavanoids, intestinal alpha-glucosidase inhibitory and free-radical (DPPH) scavenging, activity from antihyperglycemic root extract of Derris indica (Lam.).

A bioassay-guided fractionation and chemical examination of antihyperglycemic root extract of Derris indica resulted in isolation and characterization of two new furanoflavanoids (1, 2) along with thirteen known compounds (3-15). Their structures were determined on the basis of extensive spectroscopic (IR, MS, 1D and 2D NMR) data analysis and by comparison with the literature data. All the compounds were tested in vitro for intestinal alpha-glucosidase inhibitory and DPPH radical activity. New compounds (1, 2) displayed moderate intestinal alpha-glucosidase inhibitory as well as free radical scavenging activity. Other compounds also displayed varying degrees of moderate intestinal alpha-glucosidase inhibitory activity. Pongamol (6) displayed potent intestinal alpha-glucosidase inhibition.

Diferuloylmethane augments the cytotoxic effects of piplartine isolated from Piper chaba.

Natural compound based anticancer drug discovery is gaining interest against a wide variety of tumors. E-piplartine (trans-piplartine), a natural compound isolated from Piper chaba roots is examined against rat histiocytoma (BC-8), mouse embryonal carcinoma (PCC4), mouse macrophages (P388D1 and J774), and human neuroblastoma (IMR32) tumor cells. While Z-piplartine (cis-piplartine) failed to induce cytotoxicity (even at higher concentrations, 50 microM), E-piplartine induced a dose-dependent cytotoxicity (2-24 microM) in different tumor cells. The combinatorial treatment of piplartine with diferuloylmethane (curcumin), an anti-inflammatory and anticancer agent, significantly enhanced the piplartine induced cytotoxicity in tumor cells. Diferuloylmethane itself is not cytotoxic at 15 microM concentration; however, potentiated the piplartine induced cytotoxicity. The tumor cell killing with piplartine is preceded by G1 cell cycle arrest, and surpassed diferuloylmethane induced G2/M arrest when used in combination. In PCC4 cells, piplartine inhibited the cell cycle progression by inactivating cdk2 and destabilizing cyclin D1, whereas diferuloylmethane combination inhibited the ERK1/2 and Raf-1 signaling in addition to the inhibition of cell cycle progression. The over expression of heat shock protein 70, Hsp70 in rat histiocytic tumor cells interfered with piplartine induced cytotoxicity, hence, a cross talk between stress response and anticancer agents is presented. Our data demonstrates the biological and medicinal importance of piplartine isolated from the roots of P. chaba, and indicates that E-piplartine may be a promising candidate to use in combinatorial treatments to combat cancer.

New Labdane diterpenes as intestinal alpha-glucosidase inhibitor from antihyperglycemic extract of Hedychium spicatum (Ham. Ex Smith) rhizomes.

Phytochemical investigation of antihyperglycemic extract of rhizomes of Hedychium spicatum led to the isolation of two new labdane type diterpenes 2, 3 along with seven known compounds (1, 4-9). Their structures were established on the basis of NMR (1D and 2D) and mass spectroscopic analysis. The new compound 2 displayed strong intestinal alpha-glucosidase inhibitory activity. Other compounds also displayed varying degree of intestinal alpha-glucosidase inhibitory potential.

Synthesis and biological evaluation of novel 8-aminomethylated oroxylin A analogues as alpha-glucosidase inhibitors.

A series of 8-aminomethylated derivatives (1a-1j) were prepared by Mannich reaction of oroxylin A (1) with appropriate primary or secondary amines and para-formaldehyde. All the compounds were tested for their alpha-glucosidase inhibition activity against both yeast and rat intestinal alpha-glucosidase. Some of the compounds demonstrated significantly better alpha-glucosidase inhibitory activity than the parent compound (oroxylin A).

Synthesis and biological activity of amide derivatives of nimbolide.

Nimbolide (1), a limonoid isolated from Azadirachta indica, is the chief cytotoxic principle in Neem leaves extract. Using nimbolide as a lead compound for anti-cancer analogue design, a series of nimbolide derivatives have been synthesized and evaluated for in vitro cytotoxic activity against a panel of human cancer cell lines. Out of 10 compounds screened 2g, 2h and 2i showed potent activity.

A novel lignan composition from Cedrus deodara induces apoptosis and early nitric oxide generation in human leukemia Molt-4 and HL-60 cells.

AP9-cd, a standardized lignan composition from Cedrus deodara consisting of (-)-wikstromal, (-)-matairesinol, and dibenzyl butyrolactol, showed cytotoxicity in several human cancer cell lines reported earlier. An attempt was made in this study to investigate the mechanism of cell death in human leukemia Molt-4 and HL-60 cells. It inhibited Molt-4 cell proliferation with 48-h IC(50) of approximately 15 microg/ml, increased sub-G0 cell fraction with no mitotic block, produced apoptotic bodies and induced DNA ladder formation. Flow cytometric analysis of annexinV-FITC/PI-stained cells showed time-related increase in apoptosis and post-apoptotic necrosis. All these biological end-points indicated cell death by apoptosis. Further, initial events involved massive nitric oxide (NO) formation within 4 h with subsequent late appearance of peroxides in cells; measured by flow cytometry using specific fluorescent probes. Persistently high levels of NO and peroxide appeared to decrease mitochondrial membrane potential (Psi(mt)) which was recovered by cyclosporin A in Molt-4 cells. AP9-cd caused 2-fold activation of caspase-3 in Molt-4 and 5-fold activation in HL-60 cells. Also caspases-8 and -9 were activated in HL-60 cells. Ascorbate suppressed the enhanced caspases activities indicating a pro-oxidant effect of AP9-cd. Further, caspase-3 activation correlated with NO generation that was partially impaired by nitric oxide synthase (NOS) inhibitors and ascorbate suggesting a role of pro-oxidant species in caspase-3 activation. AP9-cd produced no cytotoxicity in primary rat hepatocyte culture at the concentrations used. The studies indicated that AP9-cd mediated early NO formation leads to caspases activation, peroxide generation, and mitochondrial depolarization which may be responsible for mitochondrial-dependent and -independent apoptotic pathways involved in the killing of leukemia cells by AP9-cd.

Synthesis and in vitro study of novel 7-O-acyl derivatives of Oroxylin A as antibacterial agents.

A series of Oroxylin A derivatives, prepared by alkylation and condensation, were fully characterized by spectroscopic methods. All the derivatives were screened for antibacterial activity against a panel of susceptible and resistant Gram-positive and Gram-negative organisms. It was observed that acylation of 7-OH group in Oroxylin A significantly enhanced the activity as compared to their parent compound (Oroxylin A).

Diurnal changes in adenylates and nicotinamide nucleotides in sugar beet leaves.

Sugar beets (Beta vulgaris L. cv. F58-554H1) were cultured hydroponically in growth chambers at 25°C, with a photon flux density of 500 µmol m(-2)s(-1). Measurements were made of net CO2 exchange, leaf adenylates (ATP, ADP and AMP), and leaf nicotinamide nucleotides (NAD(+), NADP(+), NADH, NADPH), over the diurnal period (16h light/8 h dark) and during photosynthetic induction. All the measurements were carried out on recently expanded leaves from 5-week-old plants. When the lights were switched on in the growth chamber, the rate of photosynthetic CO2 uptake, and the levels of leaf ATP and NADPH increased to a maximum in 30 min and remained there throughout the light period. The increase in ATP over the first few minutes of illumination was associated with the phosphorylation of ADP to ATP and the increase in NADPH with the reduction of NADP(+); subsequently, the increase in ATP was associated with an increase in total adenylates while the increase in NADPH was associated with an accumulation of NADP(+) and NADPH due to the light-driven phosphorylation of NAD(+) to NADP(+). On return to darkness, ATP and NADPH values decreased much more slowly, requiring 2 to 4 hours to reach minimum values. From these results we suggest that (i) the total adenylate and NADPH and NADP(+) (but not NAD(+) and NADH) pools increase following exposure to light; (ii) the increase in pool size is not accompanied by any large change in the energy or redox states of the system; and (iii) the measured ratios of ATP/ADP and NADPH/NADP(+) for intact leaves are low and constant during steady-state illumination.