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  • Author: A. MADHAVAN x
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Abstract

Para rubber (Hevea brasiliensis), a native of the Amazon forests of South America, is the chief source of natural rubber in the world. With the objective of broadening the original gene pool collected by Sir Henry Wickham in 1876, the International Rubber Research and Development Board (IRRDB) made a large collection of wild germplasm from Acre, Rondonia and Mato Grosso states of Brazil in 1981, which was distributed to various member countries including India for conservation and evaluation. In the present study, variability was assessed in a set of 195 Hevea accessions belonging to the wild gene pool in India, using 22 characterization descriptors and eight quantitative growth characters in the juvenile stage. The Shannon-Weaver diversity indices worked out for each of the 22 qualitative traits indicated a high level of diversity in the collection. The range of variation for quantitative traits viz., plant height (0.43 to 3.16 m), basal diameter (0.81 to 2.52 cm), number of whorls (1.23 to 5.48), inter-node length (4.11 to 45.26 cm), number of leaves (11.44 to 91.26), single leaf area (80.22 to 223.57 cm2), total leaf area (2356.00 to 14660.50 cm2) and leaf area index (0.24 to 1.47), also represented wide variability in the collection. The accessions were ranked for overall performance and top 10% were selected for early growth vigour. The high level of variability observed in this germplasm indicates its potential use in crop improvement programmes and for broadening the genetic base of Hevea.

Abstract

Background: Many plant-derived products exhibit potent chemopreventive activity against animal tumor models as well as rodent and human cancer cell lines. They have low side effects and toxicity and presumably modulate the factors that are critical for cell proliferation, differentiation, senescence and apoptosis. The present study investigates the effects of some medicinal plant extracts from generally recognized as safe plants that may be useful in the prevention and treatment of cancer.

Methods: Clonogenic assays using logarithmically-growing cells were performed to test the effect. The cytotoxic effects of Curcuma longa and Zingiber officinale were studied using sulforhodamine B assay, tetrazolium dye assay, colony morphology and microscopic analysis.

Results: Out of the 13 lyophilized plant-derived extracts evaluated for growth-inhibitory effects on the PC-3M prostate cancer cell line, two extracts derived from C. longa and Z. officinale showed significant inhibitory effects on colony-forming ability. The individual and augmentative effects of these two extracts were tested for their narrow range effective lower concentration on PC-3M in clonogenic assays. At relatively lower concentrations, C. longa showed significant inhibition of colony formation in clonogenic assays; whereas at same concentrations Z. officinale showed only moderate inhibitory effects. However, when both the agents were tested together at the same concentrations, the combined effects were much more significant than their individual ones. On normal prostate epithelial cells both C. longa and Z. officinale had similar effects but at a lower magnitude. These observations were confirmed by several cytotoxicity assays involving the morphological appearance of the colonies, microscopic observations, per cent inhibition in comparison to control by sulforhodamine B and tetrazolium dye assay.

Conclusions: From these observations, it was concluded that the combined effects of C. longa and Z. officinale are much greater than their individual effects, suggesting the role of multiple components and their synergistic mode of actions to elicit stronger beneficial effects.