Mutagenic and cytotoxic properties of three herbal plants from Southeast Asia.

Three popular medicinal plants regarded as improving human sexual function in some parts of Southeast Asia were analysed for their mutagenic properties using modified Ames test (fluctuation test). Extract of one of the plants, Tacca integrifolia Ker-Gawl., was found to be mutagenic using Salmonella typhimurium strains TA98 and TA100. Extract of T. integrifolia, Eurycoma longifolia Jack and Helmintostachys zeylanica (L.) Hook were cytotoxic to human cell lines, Hep2 and HFL1, with IC50 ranging from 11 mug/ml to 55 mug/ml. Extract of E. longifolia was the most cytotoxic with IC50 of 11 mug/ml and 13 mug/ml on Hep2 and HFL1 cell lines respectively. Combined extract of T. integrifolia and H. zeylanica was more cytotoxic than single extract on both Hep2 and HFL1 cell lines while combined extract of E. longifolia and H. zeylanica was more cytotoxic than single extract on Hep2 cell lines. Under the conditions of this study it can be concluded that T. integrifolia is mutagenic and the combined extracts of the medicinal plants was highly cytotoxic.

Molecular weight manipulation of chitosan. I: Kinetics of depolymerization by nitrous acid.

The kinetics of the depolymerization of chitosan in dilute aqueous HCl solutions by nitrous acid were studied. The rate of depolymerization is independent of the molecular weight of chitosan, first order with respect to the concentrations of both nitrous acid and glucosamine moieties, not catalysed by either hydrogen or chloride ions, and Arrhenius temperature dependent. Chitosan exhibits significantly decreased reactivity as the degree of deacetylation of the polymer increases. These results are consistent with a depolymerization reaction mechanism in which the rate-limiting step is nitrosation of the unprotonated amine by nitrous acidium ion.

A new simple controlled release delivery system.

The chemical pulping of wood without subsequent drying affords low-cost hollow fibers with microporous multilamellar cell walls saturated with water. Simple impregnation of these never-dried pulp fibers with solutions of biologically active chemicals followed by drying yields collapsed cellulose ribbons containing entrapped impregnant. The release characteristics of exemplary composites containing an analgesic (acetylsalicylic acid), a growth stimulant (alpha-naphthylacetic acid), or a herbicide (2,4-dichlorophenoxyacetic acid) are reported both for in vitro and in vivo evaluations.

New bromoperoxidases of marine origin: partial purification and characterization.

Enzymes capable of catalyzing the bromination of p-hydroxybenzyl alcohol by Br- have been shown to be present in crude homogenates of the alga Rhodomela larix (Rhodophyta). There are also indications of such activity in the marine invertebrates Thelepus setosus and Ptychodera flava laysanica. Detailed analysis of R. larix samples indicated that the activity in this species is greatest in the late spring and summer. After partial purification the enzyme had a pH optimum of approx. 4.4, a temperature optimum around 32 degrees C and was inhibited by NaN3. This algal bromoperoxidase requires the presence of H2O2 and can brominate monochlorodimedon and oxidize iodide, but it cannot oxidize chloride. The enzyme appears to be particulate.