Hydrogen sulphide alleviates cadmium stress in Trigonella foenum-graecum by modulating antioxidant enzymes and polyamine content

Cadmium (Cd) toxicity reduces growth and yield of crops grown in metal-polluted sites. Research was conducted to estimate the potential of hydrogen sulphide (H₂ S) to mitigate toxicity caused by Cd in fenugreek seedlings (Trigonella foenum-graecum L.). Different concentrations of CdCl₂ (Cd1-1 mM, Cd2-1.5 mM, Cd3-2mM) and H₂ S (HS1-100 µM, HS2-150 µM, HS3-200 µM) were assessed. Seeds of fenugreek were primed with sodium hydrosulphide (NaHS), as H₂ S donor. Seedlings growing in Cd-spiked media treated with H₂ S were harvested after 2 weeks. Cd stress affected growth of fenugreek seedlings. Cd toxicity decreased leaf relative water content (LRWC), intercellular CO₂ concentration, net photosynthesis, stomatal conductance and transpiration. However, application of H₂ S significantly improved seedling morphological attributes by increasing the activity of antioxidant enzymes, i.e. APX, CAT and SOD, in Cd-contaminated soil. H₂ S treatment also regulated phenolic and flavonoid content. H₂ S-induced biosynthesis of spermidine (Spd) and putrescine (Put) could account for the enhancement of growth and physiological performance of fenugreek seedlings under Cd stress. H₂ S treatment also reduced H₂ O₂ production (38%) and electrolyte leakage (EL, 51%) in seedlings grown in different concentrations of Cd. It is recommended to evaluate the efficacy of H₂ S in alleviating Cd toxicity in other crop plants.

Cytotoxic constituents of Baccharis gaudichaudiana

Three new labdane diterpenes, gaudichaudols A-C [1-3], a new clerodane diterpenoid, gaudichaudone [4], and the known clerodane, articulin acetate [5] have been isolated from the aerial parts of Baccharis gaudichaudiana, together with the known compounds, apigenin, hispidulin, spathulenol, and ursolic acid. Through the application of 1D- and 2D nmr spectroscopy, the structures of the new diterpenoids [1-4] were, in turn; elucidated as 15,16,18,19-tetrahydroxylabd-5-ene, 15-O-acetyl-16,18,19-trihydroxylabd-5-ene, 16-O-p-trans-coumaroyl-15,18,19-trihydroxylabd-5-ene, and 2 beta-hydroxy-15,16-epoxycleroda-1(10),15,16-trien-18,19-olide++ +. The isolated compounds were evaluated in P-388 lymphocytic leukemia cells as well as a battery of human cancer cell lines. Among the diterpenoids, gaudichaudol C [3], gaudichaudone [4], and articulin acetate [5] exhibited significant cytotoxic activity against certain cancer cells.

Estrous cycle modulation of O6-alkylguanine-DNA alkyltransferase expression in rat mammary epithelial cells

N-methyl-N-nitrosourea (MNU)-induced rat mammary tumor incidence and tumor number per rat, is directly correlated with an increase in the circulating level of estrogen(s) at the time of carcinogen administration and subsequent mammary epithelial O6-methylguanine content. We report that, expression of O6-alkyltransferase (AGT) is also regulated by reproductive hormones in a tissue specific manner. The level of mammary epithelial cell AGT activity on estrus (0.47 pmol/mg protein) and proestrus (0.32) was significantly higher than on metestrus (0.14) (P < 0.05, estrus vs. metestrus). However, no change was observed in liver AGT activity (0.52 pmol/mg protein). In contrast, the mean level of AGT protein was not significantly different between tumors from rats injected with MNU on different days of the estrous cycle. In conclusion, the different tumor biologies resulting from carcinogen injection on different days of the estrous cycle may be partially explained by variation in levels of DNA repair activity. However, the cells in the resulting tumors did not continue an obligatory differential expression of the AGT activity consistent with their stage of initiation.

Effects of iron loading on uptake, speciation, and chelation of iron in cultured myocardial cells

Accumulation of Fe in the myocardium in circumstances of transferrin saturation is associated with heart failure in Fe-loaded patients. To characterize the underlying causes of this phenomenon, we measured the flux as well as the speciation of Fe in normal and Fe-loaded cultures of rat myocardiocytes. Fe loading with low-molecular-weight Fe (ferric ammonium citrate) promoted a dose- and time-dependent increase in the rate of uptake of non-transferrin-bound Fe (NTBI) that was positively correlated (R = 0.9, p < 0.005) with cellular iron content. At concentrations sufficient to produce this up-regulation, membrane integrity was unaffected but the rate of spontaneous beating of the cells was decreased by 60%. The enhanced rate of NTBI uptake in Fe-loaded cells reverted to control rates after treatment with therapeutic concentrations of Fe chelators deferoxamine, 1,2-dimethyl-3-hydroxypyrid-4-one and 1,2-diethyl-3-hydroxypyrid-4-one under conditions where approximately 80% of the cellular Fe was removed by chelation. Fe loading of cultured myocytes also induced shifts in Fe speciation. Thus the ratio of Fe bound in hemosiderin-like precipitates to ferritin-bound Fe increased twofold, from a range of 0.84 to 1.44 in control cells to 1.96 to 3.3 in iron-loaded cells. This increased ratio was similar to that measured in the heart and liver of a thalassemic patient who underwent a double transplant for the failure of both organs, even though the Fe content of the heart (mean, 5.8 mg Fe/gm dry weight) was much less than that of the liver (28.1 mg/gm dry weight). These results suggest that increased rates of uptake of NTBI may exacerbate iron loading of the heart and contribute to iron-mediated cardiotoxicity, whereas the clinical benefits of chelation therapy may be enhanced by the down-regulation of NTBI uptake.

Estrous cycle dependence of nitrosomethylurea (NMU)-induced preneoplastic lesions in rat mammary gland

Virgin 50-55-day-old rats exhibiting regular estrous cycles were injected i.v. with the direct acting carcinogen 1-nitroso-1-methylurea (NMU) on the morning of proestrus, estrus, or diestrus. Rats were killed at weekly intervals following NMU administration to identify source and number of microscopically identifiable dysplasias. Terminal end bud (TEB) abnormalities appeared within 1 week following NMU administration, with a significantly greater number of abnormal TEBs in mammary glands of rats injected on proestrus (PE) and estrus (E) than on diestrus (DE). Ductal (DH) and ductal alveolar hyperplasias (DAH) and hyperplastic alveolar nodules (HAN) appeared during week 3, with significantly more of each type of lesion appearing by 6 weeks after NMU injection. HAN were most numerous in glands from rats injected on estrus. Adenocarcinomas arose from both the proximal and distal ductal network; at 10 and 12 weeks post NMU, significantly more tumors were found in rats injected on proestrus than diestrus and estrus. These results support the theory that the hormonal environment at the time of NMU administration significantly alters early development of mammary tumors in the rat.

Pattern of accumulation of elastin and the level of mRNA for elastin in aortic tissue of growing chickens

Synthesis and accumulation of elastin in many elastic tissues begins in the last third of fetal development, reaches a maximum shortly after birth, and then declines rapidly. For the aorta of the chick and the pig and the ligamentum nuchae and lung of the sheep, it has been shown that increased levels of elastin production with fetal development are correlated with increased levels of elastin mRNA in the tissue, measured both by cell-free translation and by hybridization to cDNA probes. In this study we examine the relationship between insoluble elastin accumulation and message levels for tropoelastin in aortic tissue of chickens during posthatching development and growth. Whether evaluated by cell-free translation or by dot blot hybridization, steady state levels of tropoelastin message increase to a maximum at 2 weeks after hatching, and then fall rapidly with further development and growth. This pattern correlates well with production of insoluble elastin by the aorta, determined either by direct measurements of synthesis or by rate of accumulation of insoluble elastin. The data indicate that the major site of regulation of elastin production is pretranslational throughout the entire period of development and growth of the chicken aorta.

An intensely sweet dihydroflavonol derivative based on a natural product lead compound

The dihydroflavonol dihydroquercetin 3-acetate (1) was isolated as a sweet constituent of the young shoots of Tessaria dodoneifolia (Hook. & Arn.) Cabrera (Compositae). Compound 1 and dihydroquercetin 3-acetate 4'-(methyl ether) (2), a novel synthetic analogue of this natural product lead compound, were rated by a taste panel as being 80 and 400 times sweeter than a 2% w/v sucrose solution, respectively. Synthetic dihydroquercetin 4'-(methyl ether) (3) showed a reduced sweetness intensity when compared to 2, while (+)-dihydroquercetin (4) was devoid of sweetness. Dihydroflavonol derivatives 1-3 represent a new class of potentially noncaloric and noncariogenic intense sweeteners.

Analysis of structural features responsible for the sweetness of the sesquiterpene, hernandulcin

The relationship between sweetness and structure was studied for several analogues of the intensely sweet sesquiterpene, hernandulcin. These derivatives were prepared synthetically, and were spectroscopic and conformational analysis. With the exception of the parent substance, none of the derivatives tested proved to be sweet. Evidence gathered in this study suggests that hernandulcin binds to its putative receptor through a three-point interaction, involving the C-1 carbonyl and C-1' hydroxyl groups, and the double bond between C-4' and C-5'. In the course of a preliminary safety assessment, the 3-desmethyl derivative of hernandulcin was found to be mutagenic toward Salmonella typhimurium strain TM677.

Mass spectral analysis of some derivatives and in vitro metabolites of steviol, the aglycone of the natural sweeteners, stevioside, rebaudioside A, and rubusoside

Steviol (ent-13-hydroxykaur-16-en-19-oic acid), the aglycone of various plant-derived glycoside sweeteners consumed by human populations, is known to be mutagenic toward Salmonella tymphimurium strain TM677 when metabolically activated using a 9000 x g supernatant fraction derived from the liver of Aroclor 1254-pretreated rats. Mass spectral analysis of this diterpenoid and some analogs revealed characteristic patterns reflecting differential stereochemistry at the C/D rings and variations in the nature of the substituents present. Such information has been used to help identify several in vitro metabolites of steviol in conditions known to produce a mutagenic response, when analyzed by gas chromatography/mass spectrometry. The major pathways of such steviol mammalian metabolism proved to be allylic oxidation and epoxidation. 15-Oxosteviol, a product of oxidation of the major steviol metabolite, 15alpha-hydroxysteviol, was found to be a direct-acting mutagen [corrected].

Volatile Constituents of Montanoa tomentosa and Lippia graveolens

The constituents of the volatile oils of MONTANOA TOMENTOSA and LIPPIA GRAVEOLENS, were investigated using capillary GC/MS. Borneol acetate, beta-cubebene, and beta-caryophyllene were found to be the major constituents of the volatile oil of M. TOMENTOSA, while P-cymene, 1,8-cineol, thymol, and carvacrol were the major volatile components of L. GRAVEOLENS. The possible correlation between the high concentration of monoterpenes and the alleged antifertility effect of the title plants is discussed.

Modulation by phenobarbital of the differentiation of 3T3 preadipocytes

The effect of phenobarbital upon the differentiation of two preadipocyte cell lines, 3T3 F442A and 3T3 L-1, was examined by measuring the synthesis and secretion of lipoprotein lipase. Extracellular enzyme was measured by treating intact cells with heparin, and the intracellular enzyme was subsequently assayed in cell homogenates. When confluent cultures of 3T3 F442A cells were treated with insulin, the cells underwent differentiation as indicated by increased activity of lipoprotein lipase within 6 days, followed in turn by increased levels of protein and triglyceride. Addition of phenobarbital with insulin enhanced total lipoprotein lipase, protein, and triglyceride content. The activity of lipoprotein lipase accumulated in the heparin-releasable fraction during differentiation was increased 2- to 3-fold and the intracellular enzyme was enhanced 15- to 20-fold by the addition of phenobarbital. The ability of phenobarbital to modulate differentiation was dependent upon the time of addition. When added early in the postconfluent period, there was a greater increase in lipoprotein lipase activity than when the drug was added at later times. Phenobarbital also stimulated lipoprotein lipase in differentiating 3T3 L-1 cells in the presence of insulin, although lipoprotein lipase activity was moderately enhanced by phenobarbital alone in these cells. These results suggest that phenobarbital may affect the conversion of adipoblasts into preadipocytes and thereby increase the proportion of cells susceptible to the differentiating stimulus.

Isolation of a Highly Sweet Constituent from Cinnamomum osmophloeum Leaves1

The sweetness of the leaf sample of the Taiwanese species, CINNAMOMUM OSMOPHLOEUM, was traced by activity-guided fractionation to its major volatile oil constituent, TRANS-cinnamaldehyde. Cinnamaldehyde represents a further class of intensely sweet compounds of plant origin.