The effects of streptonigrin on cultured human leukocytes

Antigenotoxic and cosmetic potential of elderberry (Sambucus nigra) extract: protection against oxidative DNA damage

The integrity of the genome is under constant threat from both endogenous and exogenous factors that induce oxidative stress and accelerate ageing. The demand for natural and organic cosmetics is rising due to the harmful effects of synthetic genotoxic agents on human health and the environment. Elderberry (Sambucus nigra L.), a fruit rich in bioactive compounds such as polyphenols, has demonstrated significant antioxidant properties. This study aimed to evaluate elderberry extract's chemical characterization and biological activities in peripheral blood mononuclear cells exposed to streptonigrin and H2O2, both known for causing DNA damage. The antigenotoxic evaluation and antioxidant assays (ABTS and DPPH) were conducted to assess its biological properties. Using the Comet assay enhanced with formamidopyrimidine-DNA glycosylase (Fpg) to detect oxidized purines, we found that elderberry extract significantly reduced DNA damage. These findings suggest that elderberry has potential as a natural alternative to synthetic ingredients in cosmetics, offering protective benefits against DNA damage and contributing to anti-ageing and skin health.

Fifty years of cytogenetics: a parallel view of the evolution of cytogenetics and genotoxicology

A parallelism exists between human cytogenetics and cytogenetic toxicology. The breakthroughs, mostly coming from and used in clinical genetics, are widely used in genetic toxicology. The birth of human cytogenetics occurred in 1956 when it was published that the diploid number of chromosomes in humans is 46. The first stage in chromosome-induced mutagenesis began in 1938 when Sax published the effects of X-rays on the chromosomes of Drosophila. In 1959, the cytogenetic anomalies for Down, Klinefelter, and Turner syndromes were described, and parallelly in 1960, the first publication on chromosomal aberrations in man caused by ionizing radiation appeared. The cytogenetic analysis of chromosomal aberrations in cell cultures is considered one of the primary methods to evaluate induced mutagenesis. At the end of the 1960s, banding techniques allowed chromosomes to be individually identified, in parallel, the sister chromatid exchange analysis technology was described. Another milestone in the history of induced mutagenesis was the discovery that mutagenic agents were able to alter chromosomal division and segregation in gonads inducing meiotic nondisjunction. Here we review new approaches and applications such as biological dosimetry, translocation scoring using FISH, and micronucleus test. Chromosomal aberrations and micronucleus test are now effective cytogenetic biomarkers of early effect used as cancer predictors. Human cytogenetics has proven to be effective over its 50-year lifespan and, although each new technique that has appeared seemed to announce its end, the fact is that the current state of cytogenetics is in reality a collection of techniques that, while common, are cheap, fast, and wide-ranging. Therefore, in genotoxicology, they continue to be useful to identify mutagenic agents as well as to evaluate and analyze exposed populations.

Genotoxicity of streptonigrin: a review

Streptonigrin (SN, CAS no. 3930-19-6) is an aminoquinone antitumor antibiotic isolated from cultures of Streptomyces flocculus. This compound is a member of a group of antitumor agents which possess the aminoquinone moiety and that includes also mitomycin C, porfiromycin, actinomycin, rifamycin and geldanamycin. Because of the potential use of SN in clinical chemotherapy, the study of its genotoxicity has considerable practical significance.SN inhibits the synthesis of DNA and RNA, causes DNA strand breaks after reduction with NADH, induces unscheduled DNA synthesis and DNA adducts and inhibits topoisomerase II. At the chromosome level, this antibiotic causes chromosome damage and increases the frequency of sister-chromatid exchanges.SN cleaves DNA in cell-free systems by a mechanism that involves complexing with metal ions and autoxidation of the quinone moiety to semiquinone in the presence of NADH with production of oxygen-derived reactive species. Recent evidence strongly suggests that the clastogenic action of this compound is partially mediated by free radicals. The present review aims at summarizing past and current knowledge concerning the genotoxic effects of SN.

Analysis of ku80-mutant mice and cells with deficient levels of p53

Absence of Ku80 results in increased sensitivity to ionizing radiation, defective lymphocyte development, early onset of an age-related phenotype, and premature replicative senescence. Here we investigate the role of p53 on the phenotype of ku80-mutant mice and cells. Reducing levels of p53 increased the cancer incidence for ku80(-/-) mice. About 20% of ku80(-/-) p53(+/-) mice developed a broad spectrum of cancer by 40 weeks and all ku80(-/-) p53(-/-) mice developed pro-B-cell lymphoma by 16 weeks. Reducing levels of p53 rescued populations of ku80(-/-) cells from replicative senescence by enabling spontaneous immortalization. The double-mutant cells are impaired for the G(1)/S checkpoint due to the p53 mutation and are hypersensitive to gamma-radiation and reactive oxygen species due to the Ku80 mutation. These data show that replicative senescence is caused by a p53-dependent cell cycle response to damaged DNA in ku80(-/-) cells and that p53 is essential for preventing very early onset of pro-B-cell lymphoma in ku80(-/-) mice.

ATM heterozygote cells exhibit intermediate levels of apoptosis in response to streptonigrin and etoposide

Ataxia-telangiectasia (A-T) is a rare recessive disease characterised by cerebellar ataxia, immunodeficiency, sensitivity to ionising radiation and increased cancer risk. Heterozygotes have an increased risk of cancer and may comprise 1% of the population. In vitro, A-T heterozygote cell lines show radiosensitivity intermediate between normal and A-T homozygotes. Furthermore, in A-T homozygotes, hypersensitivity to chemical agents which cause DNA damage, similar to that produced by ionising radiation, has been observed. To investigate the chemosensitivity of A-T heterozygote cell lines, we used TUNEL to analyse the level of apoptosis after drug treatment with etoposide and streptonigrin. Our samples included four normal, eight A-T heterozygote and 10 A-T homozygote lymphoblastoid cell lines. All cell lines were exposed to drugs for 24 h, then cultivated in fresh media for 0 and 72 h. The levels of apoptosis increased significantly in all cell lines, with the greatest increase in homozygote cells and an intermediate increase in heterozygote cells (P values of < 0.01 for etoposide treatment and < 0.02 for streptonigrin treatment were obtained using the Kruskal-Wallis H-test). Our results indicate that A-T heterozygotes express intermediate sensitivity to etoposide and streptonigrin similar to that observed in response to ionising radiation.

Sister chromatid exchange distributions in rabbit lymphocytes treated with streptonigrin

Streptonigrin (NSC-45383), a direct-acting clastogen which induces SCEs in vivo and chromosome aberrations both in vivo and in vitro, was evaluated for SCE induction in both G0 and stimulated rabbit lymphocytes. Determinations were made for 16 cultures from seven female rabbits. These included controls as well as cells exposed to 90 micrograms/kg in vivo, cells pulse-treated with 50 ng/ml in vitro, and a culture continuously exposed to 5 ng/ml in vitro. For all cultures the SCE/cell frequency was determined from 20 complete (44 chromosome) metaphases and, in selected cultures, SCEs on individual chromosomes (880 per culture from 20 cells) were enumerated to determine SCE/chromosome frequency and the chromosomal distribution of SCEs. Analysis of variance and least significant difference tests of the square root x transformed SCE/cell data show that cells exposed to streptonigrin while dividing have significantly higher (P less than 0.01) frequencies (over double the control 5.3 SCE/cell value) whereas treated G0 cells were not significantly different from the controls. Dispersion analysis of both SCE/cell and SCE/chromosome data confirms the adequacy of the Poisson distribution for spontaneous or baseline but not streptonigrin-induced SCEs.

The role of antitumor antibiotics in current oncologic practice

The antitumor antibiotics have thus made a major impact on oncologic practice. The continued search for productive strains of these organisms should be encouraged; in addition, the activity and toxicity spectrum suggests the need for vigorous analogue development. An active anthracycline devoid of cardiotoxicity, a bleomycin with no effect on pulmonary tissue, an analogue of streptozoticin devoid of nephrotoxicity -- these would be advances of inestimable benefit to the cancer patient of the future.

Role of antitumor antibiotics in current oncologic practice

The antitumor antibiotics have thus made a major impact on oncologic practice. The continued search for productive strains of these organisms should be encouraged. In addition, the activity and toxicity spectrum suggests the need for vigorous analog development. An active anthracycline devoid of cardiotoxicity; a bleomycin with no effect on pulmonary tissue; an analog of streptozotocin devoid of nephrotoxicity; these would be advances of inestimable benefit to the cancer patient of the future.

Chromosomal damage in human leukocytes induced by lysergic acid diethylamide

Addition of lysergic acid diethylamide to cultured human leukocytes resulted in a marked increase of chromosomal abnormalities. The distribution of chromosome breaks deviated significantly from random, with an accumulation of aberrations in chromosome No. 1. Cytogenetic investigation of a patient extensively treated with this drug over a 4-year period for paranoid schizophrenia showed a similar increase in chromosomal damage.

A FAMILIAL 4/5 RECIPROCAL TRANSLOCATION RESULTING IN PARTIAL TRISOMY B

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Phenethyl Alcohol Synergism with Mitomycin C, Porfiromycin, and Streptonigrin

Cyanide and phenethyl alcohol greatly enhance the lethal action of mitomycin C, porfiromycin, and streptonigrin on an exponentially growing culture of Escherichia coli. Dinitrophenol similarly enhances the lethal action of mitomycin C and porfiromycin, but only slightly that of streptonigrin. Phenethyl alcohol may be functioning in these experiments as an inhibitor of electron transport.