Seasonal Variation of Phyto-Constituents of Tea Leaves Affects Antiproliferative Potential.

Objective: Tea (Camellia sinensis Linn.; family: Theaceae) is popular as a stimulant beverage across the globe and is also utilized as a functional antioxidant in alternative medicine. This study has evaluated the impact of seasonal variation on phyto-constituents of tea. Method: The antiproliferative potential of methanolic extracts of tea leaves collected in the rainy season (MECR) was compared with the extract of tea leaves collected in the autumn season (MECA) of the same mother plant. Evaluation of in vivo antitumor activity was carried out in adult female Swiss albino mice groups inoculated with Ehrlich ascites carcinoma (EAC) cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to compare efficacy of MECR with that of MECA in the EAC cell line. Both qualitative and quantitative tests for phytochemical constituents present in MECA and MECR were performed. Antitumor efficacy of both the extracts was determined by evaluating different tumor markers showing dose-dependent cytotoxicity. Results: Statistically significant reduction in EAC-induced tumor was observed in MECR treated mice compared to MECA treated ones. Cell decimation was significantly higher with MECR treatment, where restoration of different parameters including tissue structures returned to normal. Moreover, gas chromatography-mass spectrometry (GC-MS) study revealed the presence of cyclobarbital and benzazulene derivative in MECR, which is thought to be a novel source of these chemicals. Conclusions: To our knowledge, there is no report that has attempted to reveal nutritional changes in terms of efficacy and variation in anticancer constituents in tea leaves, plucked in two seasons. This study revealed a novel source of barbital and benzazulene derivative. The unique presence of cyclobarbital and benzazulene, as revealed from GC-MS data, in methanolic extract of tea leaves collected during the rainy season (MECR) may have contributed to its enhanced in vitro (adopting MTT assay) and in vivo (on EAC-infected Swiss albino mice) cytotoxicity vis-à-vis antiproliferative properties compared to methanolic extract of tea leaves collected during the autumn season (MECA). The nature of plucking leaves in the two selected seasons is different.

Antitumor activity and antioxidant property of Curcuma caesia against Ehrlich's ascites carcinoma bearing mice.

CONTEXT: Curcuma caesia Roxb. (Zingiberaceae), commonly known as "Kala Haldi" in Bengali, has been traditionally used for the treatment of cancer, bruises, inflammation and as an aphrodisiac. OBJECTIVE: To evaluate the antitumor activity and antioxidant status of the methanol extract of Curcuma caesia (MECC) rhizomes on Ehrlich's ascites carcinoma (EAC)-treated mice. MATERIALS AND METHODS: In vitro cytotoxicity assay of MECC was evaluated by using Trypan blue method. Determination of in vivo antitumor activity was performed after 24 h of EAC cells (2 × 10(6) cells/mouse) inoculation; MECC (50 and 100 mg/kg i.p.) was administered daily for nine consecutive days. On day 10, half of the mice were sacrificed and the rest were kept alive for assessment of increase in lifespan. Antitumor effect of MECC was assessed by the study of tumor volume, tumor weight, viable and non-viable cell count, hematological parameters and biochemical estimations. Furthermore, antioxidant parameters were assayed by estimating liver and kidney tissue enzymes. RESULTS: MECC showed direct cytotoxicity (IC50 90.70 ± 8.37 µg/mL) on EAC cell line. MECC exhibited significant (p < 0.01) decrease in tumor volume, tumor weight, viable cell count and percentage increased the lifespan (57.14 and 88.09%) of EAC-treated mice. Hematological profile, biochemical estimation, tissue antioxidant assay significantly (p < 0.01) reverted to normal level in MECC-treated mice. CONCLUSION: MECC possesses potent antitumor activity that may be due to its direct cytotoxic effect or antioxidant properties. Further research is in progress to find out the active principle(s) of MECC for its antitumor activity.

Modeling the closed and open state conformations of the GABA(A) ion channel--plausible structural insights for channel gating.

Recent disclosure of high resolution crystal structures of Gloeobacter violaceus (GLIC) in open state and Erwinia chrysanthemii (ELIC) in closed state provides newer avenues to advance our knowledge and understanding of the physiologically and pharmacologically important ionotropic GABA(A) ion channel. The present modeling study envisions understanding the complex molecular transitions involved in ionic conductance, which were not evident in earlier disclosed homology models. In particular, emphasis was put on understanding the structural basis of gating, gating transition from the closed to the open state on an atomic scale. Homology modeling of two different physiological states of GABA(A) was carried out using their respective templates. The ability of induced fit docking in breaking the critical inter residue salt bridge (Glu155ß(2) and Arg207ß(2)) upon endogenous GABA docking reflects the perceived side chain rearrangements that occur at the orthosteric site and consolidate the quality of the model. Biophysical calculations like electrostatic mapping, pore radius calculation, ion solvation profile, and normal-mode analysis (NMA) were undertaken to address pertinent questions like the following: How the change in state of the ion channel alters the electrostatic environment across the lumen; How accessible is the Cl(-) ion in the open state and closed state; What structural changes regulate channel gating. A "Twist to Turn" global motion evinced at the quaternary level accompanied by tilting and rotation of the M2 helices along the membrane normal rationalizes the structural transition involved in gating. This perceived global motion hints toward a conserved gating mechanism among pLGIC. To paraphrase, this modeling study proves to be a reliable framework for understanding the structure function relationship of the hitherto unresolved GABA(A) ion channel. The modeled structures presented herein not only reveal the structurally distinct conformational states of the GABA(A) ion channel but also explain the biophysical difference between the respective states.