Allium Cepa Root Tip Assay Research Articles

Total aerobic plate count and onion (Allium cepa) root tip assay using banana (Musa acuminata x balbisiana) Pseudostem accumulated water with thin-layer chromatography as confirmatory test

Cancer is a group of diseases characterized by the uncontrolled growth of abnormal cells. It can originate from any of the trillions of cells in the human body. Normally, cells grow and divide as needed, but cancer disrupts this process, causing abnormal cells to multiply uncontrollably. According to Monda et al. (2021), the pseudostem of the banana tree possess anticancer activities due to the phytochemicals present, which is why the researchers want to determine whether the accumulated water inside the banana pseudostem also holds the potential to become an alternative anti-cancer treatment. The researchers utilized total aerobic plate counting and Allium cepa root tip assay for the researchers to evaluate the potability of the banana pseudostem accumulated water and assess its inhibitory properties for cell growth, respectively. Based on the findings of the study, the total number of aerobic plates is too numerous to be counted (TNTC) and from the ANOVA analysis conducted, there was no significant difference among the cell growth inhibition. To verify this result, thin-layer chromatography was used to determine if there are any phytochemicals present within the sample possessing anticancer properties. No phytochemicals with such characteristics were identified. In conclusion, the banana pseudostem accumulated water is not a suitable alternative for anticancer medications. The researchers recommended considering other factors that might affect the quality of the sample. They also suggested subjecting the data to a more in-depth analysis, such as examining the Mitotic Index and chromosomal aberrations, to obtain more specific information.

Tissue-specific variations of piperine in ten populations of Piper longum L.: bioactivities and toxicological profile

P. longum L., one of the most significant species of the genus Piperaceae, is most frequently employed in Indian-Ayurvedic and other traditional medicinal-systems for treating a variety of illnesses. The alkaloid piperine, is the key phytoconstituent of the plant, primarily responsible for its’ pharmacological-impacts. The aim of the study is to analyse the intra-specific variation in piperine content among different chemotypes (PL1 to PL 30) and identify high piperine yielding chemotype (elite-chemotype) collected from 10 different geographical regions of West Bengal by validated HPTLC chromatography method. The study also focused on the pharmacological-screening to better understand the antioxidant activity of the methanol extracts of P. longum by DPPH and ABTS radical-scavenging activity and genotoxic activity by Allium cepa root tip assay. It was found that the P. longum fruit chemotypes contain high amount piperine (highest 16.362 mg/g in chemotype PL9) than the stem and leaf chemotypes. Both DPPH and ABTS antioxidant assays revealed that P. longum showed moderate radical-scavenging activity and the highest activity was found in PL9 (fruit) chemotype with IC50 values of 124.2 ±0.97\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pm 0.97$$\\end{document} and 104 ±0.78\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pm 0.78$$\\end{document} µg/ml respectively. The A. cepa root tip assay showed no such significant genotoxic-effect and change in mitotic-index. The quick, reproducible, and validated HPTLC approach offers a useful tool for determining quantitative variations of piperine among P. longum chemotypes from different geographical-regions and also according to the different tissues and choose elite genotypes with high piperine production for continued propagation and commercialization for the pharmaceutical sector. Additionally, the plant's in-vitro antioxidant property and lack of genotoxicity directly supports its’ widespread and long history of use as a medicinal and culinary plant.

Antimitotic and Antiproliferative Action of <i>Ficus septica</i> Burm. F. Stem Bark Ethanolic Extract

Ficus septica is a widely documented ethnomedicinal plant that locals have used in varied applications due to its antibacterial, antioxidant, antimutagenic, renoprotective, and other biological activities. The present study investigates the antimitotic and antiproliferative actions of F. septica stem bark crude ethanolic extract using onion (Allium cepa) root tip assay and yeast (Saccharomyces cerevisiae) proliferation assay. A. cepa assay showed that the F. septica stem bark crude ethanolic extract can block mitosis in onion root cells by causing spindle and chromosome damage. The extract is genotoxic based on the increasing frequency of chromosomal aberrations at higher concentrations. Mitotic anomalies observed are sticky chromosomes, vagrant chromosomes, laggard, pole deviation, and polyploidy. It also showed that the extract decreased the cell viability of the yeast cells in a concentration-dependent manner. This study revealed that F. septica stem bark crude ethanolic extract has antimitotic and antiproliferative properties in A. cepa root tips and yeasts. Further study could be performed focusing on identifying and isolating antimitotic, and antiproliferative components of F. septica stem bark and conducting biological screening using other models.

In vitro Antimitotic Activity and Molecular Docking Studies of Isolated Compounds from Rhynchosia beddomei

The goal of this work was to use an exquisite combination of phytopharmacological and modern computational tools to examine the anticancer potential of Rhynchosia beddomei. The methanolic extract of Rhynchosia beddomei was screened for in vitro antimitotic activity like Allium cepa root tip assay. Molecular docking was carried out between the Bcl-2 Receptor, VEGFR-2 and bioactive compounds like apigenein, vitexin, isovitexin, quercetin, vicenin, orientin, rutin etc. Extract of Rhynchosia beddomei showed significant antimitotic activity, by decreasing rate of mitosis in comparison to water. Methotrexate (0.1 mg/mL) was used as a standard and shows highest antimitotic activity. Thus, the selected plant displayed significant antimitotic activity by showing good inhibition. Vitexin, rutin and lucenin have demonstrated remarkable binding affinity towards Bcl-2 and biochanin, isovitexin, orientin and apigenin have demonstrated remarkable binding affinity towards VEGFR-2 respectively. Molecular dynamic simulation studies have further confirmed the finding of docking analysis, suggesting that Bcl-2 and VEGFR-2 can act as an attractive molecular target for vitexin, rutin, biochanin, isovitexin, orientin and apigenin respectively.

Chromosomal instability and abnormal mitochondrial activity induced by two synthetic food colorants

The artificial colorants act as a potent cytotoxic agent at the consumer level, whose analysis is inevitable. The investigation is mainly focused to analyze the toxicity of two commonly used synthetic food colorants (Brilliant blue and Fast green) with the help of Allium cepa root tip assay. The frequency of aberrations and the concentrations of both the colorants were found to be positively correlated in the chromosome studies. The integrity of the cell membranes, which is a potent parameter to detect cellular damage was detected using Evan’s blue staining. 2,3,5-triphenyl tetrazolium chloride (TTC) method was also adopted to determine the damaging effects of the synthetic molecules on the mitochondrial oxidative properties in the root tip cells. Both food colorants showed prominent membrane damage and mitochondrial activity reduction in the test material.

Environmental Risk Characterization of an Antiretroviral (ARV) Lamivudine in Ecosystems.

Antiretroviral drugs for the treatment of human immunodeficiency virus (HIV) and other viral infections are among the emerging contaminants considered for ecological risk assessment. These compounds have been reported to be widely distributed in water bodies and other aquatic environments, while data concerning the risk they may pose to unintended non-target species in a different ecosystem (environment) is scanty. In South Africa and other developing countries, lamivudine is one of the common antiretrovirals applied. Despite this, little is known about its environmental impacts as an emerging contaminant. The present study employed a battery of ecotoxicity bioassays to assess the environmental threat lamivudine poses to aquatic fauna and flora. Daphnia magna (filter feeders), the Ames bacterial mutagenicity test, Lactuca sativa (lettuce) germination test, and the Allium cepa root tip assay were conducted, testing lamivudine at two concentrations (10 and 100 µg/L), with environmental relevance. The Daphnia magna toxicity test revealed a statistically significant response (p << 0.05) with a mortality rate of 85% on exposure to 100 µg/L lamivudine in freshwater, which increased to 100% at 48-h exposure. At lower concentrations of 10 µg/L lamivudine, 90% and 55% survival rates were observed at 24 h and 48 h, respectively. No potential mutagenic effects were observed from the Ames test at both concentrations of lamivudine. Allium cepa bioassays revealed a noticeable adverse impact on the root lengths on exposure to 100 µg/L lamivudine. This impact was further investigated through microscopic examination, revealing some chromosomal aberration in the exposed Allium cepa root tips. The Lactuca sativa bioassay showed a slight adverse impact on both the germination rate of the seeds and their respective hypocotyl lengths compared to the control. Overall, this indicates that lamivudine poses an ecological health risk at different trophic levels, to both flora and fauna, at concentrations previously found in the environment.

Evaluation of antimitotic activity of herbal extracts using plant-based model systems and their cytotoxic potential against human colon carcinoma cells.

The aim of this study was to screen plant extracts for antimitotic activity using Vigna radiata germination inhibition assay, followed by Allium cepa root tip assay and evaluation of their cytotoxic potential on colon carcinoma (HCT-116) cell lines. Aqueous extracts of Aconitum heterophyllum, Terminalia bellirica, Bauhinia variegata, Vanda roxburghii, and Cassia angustifolia were prepared by maceration method, and preliminary screening studies to check their antimitotic activity were done by V. radiata germination inhibition assay, followed by A. cepa root tip assay. Furthermore, cytotoxic actions were evaluated by cell proliferation assay. Effect of T. bellirica aqueous extract was analyzed to induce morphological changes, cell death, lactate dehydrogenase release, and cell survival of HCT-116 cells. The data represented were analyzed by Student's t-test using SigmaStat 2.0 statistical analysis software. The normality of data was tested by the Shapiro-Wilk test before the Student's t-test. P values *P ≤ 0.05, **P ≤ 0.01, and ***P ≤ 0.001 were considered as statistically significant. All the plant extracts showed promising antimitotic activity. Out of all, T. bellirica was highly effective on HCT-116 cells and promising effect on cell proliferation assay and Annexin-propidium iodide staining revealed that T. bellirica efficiently induces apoptosis. T. bellirica inhibits cancer cell growth and induces apoptotic cell death. Collectively, it may hold potential for cancer therapeutics.

GENOTOXIC AND ANTIGENOTOXIC POTENTIAL OF THE LAGENANDRA TOXICARIA DALZ. RHIZOME METHANOL EXTRACT USING ALLIUM CEPA ASSAY

Objective: The study is to evaluate the possible genotoxic and antigenotoxic potential of Lagenandra toxicaria rhizome methanol extract using Allium cepa root tip assay.&#x0D; Methods: The rhizome methanol extract was prepared using Soxhlet apparatus. The A. cepa roots were treated with various concentrations of the extract at different time points and stained with aceto-orcein. The mitotic index (MI) was calculated.&#x0D; Results: A significant decrease in MI and increase in the percentage of clastogenicity was observed in a time- and dose-dependent manner in the roots treated with the extract at 0.2 mg/ml, 0.5 mg/ml, 1 mg/ml, 5 mg/ml, and 10 mg/ml concentration for 1, 2, and 4 h. The field emission scanning electron microscopy and Fourier-transform infrared spectroscopy revealed evident morphological and biochemical changes at 10 mg/ml treatment when compared to control for 4 h. The agarose gel electrophoresis showed loss of DNA integrity at 10 mg/ml extract for 4 h. In situ histochemical staining by Schiff’s reagent and nitroblue tetrazolium confirmed the increased lipid peroxidation and free radical generation at 4 h treatment. Subsequently, the possible antigenotoxic potential of the plant extract was explored using H2O2 standard assays. The increased percentage of H2O2 induced nuclear lesions was reduced significantly after the modulatory treatment with extract.&#x0D; Conclusion: The L. toxicaria rhizome methanol extract acts as an antigenotoxic agent at lower doses and at higher doses the extract induces clastogenic effects. Further studies are needed to unravel the active component in the extract that mediates the observed phenomenon in the current study.

An evidence based efficacy and safety assessment of the ethnobiologicals against poisonous and non-poisonous bites used by the tribals of three westernmost districts of West Bengal, India: Anti-phospholipase A2 and genotoxic effects.

To explore the ethnobiological wisdom of the tribals of three western districts of West Bengal, India against poisonous and non-poisonous bites and stings, a quantitative approach was adopted. These age-old yet unexplored knowledge can be utilized in finding lead-molecules against poisonous and non-poisonous animal-bites. Further, an evidence-based approach is needed to assess the venom-neutralization ability of plants by experimental studies. During 2008-2009 and 2012-2017, 11 ethnomedicinal surveys were carried out to explore the use of medicinal flora and fauna via conducting open semi-structured interviews with 47 traditional healers (THs) or informants. The retrieved dataset was statistically evaluated using seven quantitative-indexes: use-value (UV), informants'-consensus-factor (ICF), fidelity-level (FL), relative-importance (RI), cultural importance-index (CI), index of agreement on remedies (IAR) and cultural agreement-index (CAI). Anti-phospholipaseA2 (PLA2) properties of selected plant extracts were also examined. In addition, the cytotoxicity and genotoxicity of the water extract of the plants showing high FL as well as significant PLA2 inhibitory potential were investigated using Allium cepa root tip assay. A total of 41 traditional-formulations (TFs) containing 40 plant species (of 39 genera from 28 families) and 3 animal species were prescribed by the THs. Fabaceae exhibited most number of medicinal plants. Piper nigrum (1.78) and Apis cerana indica and Crossopriza lyoni (both 0.21) exhibited the highest UV among the plants and the animals respectively. Stinging of centipede and dog/cat/hyena bite displayed highest ICF (1.00 each). Among the plants, the maximum RI (0.91) and CI (4.98) values were observed for Aristolochia indica. IAR (1.00) was recorded maximum for Achyranthes aspera, Gloriosa superba, Lycopodium cernuum, Smilax zeylanica and Streblus asper. Maximum CAI value was noted for Piper nigrum (5.5096). Among the animals, Apis cerana indica (0.31) and Crossopriza lyoni (1.52) displayed the highest RI and CI values respectively. Crossopriza lyoni (0.99) and Apis cerana indica (1.3871) exhibited maximum IAR and CAI values respectively. Plants showing higher FL exhibited higher anti-PLA2 activity via selective inhibition of human-group PLA2. In addition, Allium cepa root tip assay has indicated the safety and/or toxicity of the plant parts prescribed by the THs. Root water extracts of Aristolochia indica and Gloriosa superba exhibited significant genotoxicity and cytotoxicity. Three western districts of West Bengal is the natural abode for many tribal and non-tribal communities. A noteworthy correlation was established between the plants used against poisonous-bites and their anti-PLA2 activity. A few plant parts used by the THs also exhibited high toxicity. Such alternative medical practices serve as the only option in these underprivileged and backward areas during medical-exigencies.

ASSESSMENT OF ANTIOXIDANT POTENTIAL AND ANTIGENOTOXICITY ANALYSIS THROUGH HYDROGEN PEROXIDE-INDUCED OXIDATIVE STRESS IN TERMINALIA PANICULATA ROTH

Objective: The present study is mainly focused on the antigenotoxicity and antioxidant potential of the fruit extract of an important dye yielding plant Terminalia paniculata Roth.&#x0D; Methods: Genoprotective activity of the fruit extract was studied by Allium cepa root tip assay. Three modes of treatment were used to perform the antigenotoxicity, that is, pre-treatment, post-treatment, and simultaneous treatment. For the study of antioxidant potential, four different assays were performed.&#x0D; Results: Antigenotoxicity studies revealed the protective role of the extract in chromosomal aberrations induced by 2% hydrogen peroxide (H2O2) on A. cepa root tip meristem. The fruit extract showed a significant modulatory effect by means of an inhibition percentage and also it showed a characteristic reversing of chromosomal aberrations induced by H2O2. While in the case of antioxidant activity, the plant extract showed an appreciable antioxidant potential. Four different assays were used to determine the antioxidant potential of T. paniculata. Of these 2,2-diphenyl-1-picryl-hydrazyl-hydrate radical scavenging activity revealed almost equal effect to that of the standard.&#x0D; Conclusions: In the present investigation, it has been found that the important dye yielding plant T. paniculata has a significant role in various commercial industries such as food, cosmetics, clothes, and pharmaceutics due to its efficient protective role.

Genotoxicity study of nano Al2O3, TiO2 and ZnO along with UV-B exposure: An Allium cepa root tip assay

The present effort aims to investigate the cytotoxic and genotoxic impact of three widely used nanoparticles (ZnO, TiO2 and Al2O3) on root cells of Allium cepa as a test organism. The root tip of Allium cepa were treated with three different concentrations (0.1 10 and 100 mg/L) of the above-mentioned NPs and the observations were recorded after proper growth of root under both nanoparticle solutions and UV-B exposure in combined conditions and separately. The parameters such as mitotic index, various forms of chromosomal aberrations, various reactive oxygen species (ROS) generation such as superoxide radical (O−2·), hydrogen peroxide, hydroxyl radical (·OH), lipid peroxidation and bio-uptake of nanoparticles were assessed. The results revealed that for all the three nanoparticles, mitotic index (MI) was highly reduced in comparison to control. Among the three nanoparticles, the MI value of TiO2 was 59.5% at 0.1 mg/L. Chromosomal aberration data suggest that nano Al2O3 exhibited disturbed metaphase at 0.1 mg/L, and abnormal anaphase and sticky metaphase at 10 and 100 mg/L, respectively. Similarly, lagged metaphase and anaphase with multiple chromatin bridges were recorded for both nano ZnO and nano TiO2 at 0.1 mg/L. But, nonsignificant (p > 0.05) results were recorded between only nano metal oxide and UV-B along with nano metal oxide. ROS generation data revealed that ZnO is more active under UV-B than TiO2 and Al2O3. The cellular deformation and the existence of metal in A. cepa under nano ZnO, TiO2 and Al2O3 treatment were evaluated by Scanning Electron Micrograph (SEM) and X-ray fluorescence (XRF) study, respectively. It may safely be concluded that with respect to chromosomal aberration and mitotic index, out of the three nanoparticles, Al2O3 is the most severe at higher concentrations and nano ZnO shows lowest mitotic index under UV-B exposure.

Evaluation of Antimitotic Activity of Momordica Dioica Fruits on Allium Cepa Root Meristamatic Cells

Natural occurring phenolic compounds play an important role in cancer prevention and shows antimitotic activity. Number of active constituents like phenolic acid, curcuminoids, coumarine, ligans, quinones, etc. is showing antimitotic activity of Momordica dioica. The present work is on phytochemical investigation and examines antimitotic activity of aqueous extract of fruits Momordica dioica at concentration of 15 mg/ml on Allium cepa root meristamatic cells. The fruits are air dried and extracted with solvents like water by maceration method. The evaluation of antimitotic activity is done by using Allium cepa root meristamatic cells parameters where and methotrexate was used as a standard drugs. In Allium assay, aqueous extract of fruits of Momordica diocia(15 mg/ml) and methotrexate act against cells of allium roots and lesser the growth of root and mitotic index when compared with distilled water as control group. The result indicated that cytotoxic property is due to presence of phenolic, alkaloids and flavonoids compounds in 15 mg/ml concentration of aqueous extract of Momordica diocia fruits extract. On the basis of result, we concluded that, 15 mg/ml concentration of Momordica dioica fruits shows good antimitotic activity on the Allium cepa root tip assay.

Cytogenetic effects of silver and gold nanoparticles on Allium cepa roots.

The present study evaluates the cytogenetic effects of both silver and gold nanoparticles on the root cells of Allium cepa. In this study, the root cells of Allium cepa were treated with both gold and silver nanoparticles of different concentrations (1 mg/L, 5 mg/L and 10 mg/L) along with control for 72 h. Experimental results revealed that after 72 h of exposure, a significant decrease in mitotic index (MI) from 68% (control) to 52.4% (1 mg/L), 47.3% (5 mg/L) and 41.4% (10 mg/L) for gold nanoparticles and 57.1% (1 mg/L), 53% (5 mg/l), 55.8% (10 mg/L) for silver nanoparticles. Through minute observation of the photograph, it was recorded that some specific chromosomal abnormalities such as stickiness of chromosome, chromosome breaks, nuclear notch, and clumped chromosome at different exposure conditions. Therefore, present results clearly suggest that Allium cepa root tip assay could be a viable path through which negative impact of both gold and silver nanoparticles can be demonstrated over a wide range of concentrations.

In vitro antimitotic, antiproliferative and antioxidant activity of stem bark extracts of Ficus benghalensis L.

In vitro antimitotic, antiproliferative and antioxidant activities of stem bark extracts of Ficus benghalensis were evaluated as a preliminary study for anticancer activity using Allium cepa root tip assay and yeast cell model respectively. The crude methanol extract and subsequent solvent fractions were employed in the study. In antimitotic assay, the n-butanol fraction showed strongest antimitotic activity with mitotic index of 28±0.577% at 4mg/mL concentration. The extracts also caused chromosomal and mitotic aberrations including accumulation of prophases, sticky chromosomes at metaphase, spindle disturbance at prophase and anaphase bridges. In antiproliferative assay, strongest antiproliferative activity was determined for n-butanol fraction with only 8±0.577% viable cells at 4mg/mL. The antioxidant activity ranged between 21.42±0.457 to 82.6±2.395% DPPH inhibition at tested concentrations for different plant extracts with highest antioxidant activity observed for crude methanol extract and lowest for aqueous fraction. The study concluded that the stem bark of F. benghalensis can be used as a source of biologically active compounds with antimitotic, antiproliferative and antioxidant activities.

EVALUATION OF CYTOTOXICITY OF THE AQUEOUS LEAF EXTRACT OF Pogostemon heyneanus BENTH. (JAVA PATCHOULI)

Several plants have been recently reported to possess anticancer potential. Allium cepa root tip assay is a preliminary study to assess the cytotoxic effect of plant extracts. The cytotoxic activity of plants can be correlated to their anticancer potential. Cytotoxic potential of Pogostemon heyneanus (Lamiaceae) was evaluated using A. cepa root meristematic cells. This study was aimed at analyzing cytotoxic potential of P. heyneanus using Allium cepa root tip assay. Four different concentrations of the aqueous leaf extracts at three different durations were examined. Distilled water was used as control. The extract was found to be cytotoxic at all tested concentrations, when compared to control. Mitotic index was found to be decreasing with the increase in extract concentrations and treatment durations. The aqueous extract of P. heyneanus was found to be an effective cytotoxic agent, inducing various clastogenic and non-clastogenic aberrations such as chromosome gaps, bridges, multipolar anaphase, fragments, nuclear budding and lesions, hyperchromasia, laggards and mitotic pairing.

Antimitotic activity of Borassus flabellifer Seed Coat

The Antimitotic Activity of Methanolic extract of Borassus flabellifer L. ( Arecaceae ) seed coat (soft outer shell) was studied by using Seed Germination Assay and Allium cepa Root Tip Assay. The preliminary phytochemical screening of methanolic seed coat extract of Borassus flabellifer revealed that presence of carbohydrates, reducing sugars, coumarins, triterpenes, tannins and phenolic compounds. In Seed Germination Assay, the methanolic seed coat extract of Borassus flabellifer has significantly increased the percentage of inhibition after 24hrs, 48hrs and 72hrs treatment which was comparable with percentage of inhibition of methotrexate. At dose 50mg/ml (p<0.0001) extract has shown the inhibition of seed germination as significant as the standard drug methotrexate (0.1mg/ml)(p<0.0001). In Allium cepa root tip assay, the percentage of mitotic index was decreased significantly after 1, 3 and 6 hrs of drug treatment which was comparable with the percentage mitotic index of methotrexate. At dose 150mg/ml (p<0.0001) extract has shown antimitotic activity i.e., mitotic index as significant as of methotrexate of 0.1mg/ml (p<0.0001). Thus, the Methanolic seed coat extract of Borassus flabellifer is recommended for the treatment of cancer. Further in-vivo parameters need to be done for mechanistic evaluation of drug.

Correction: In Vivo Genotoxicity Assessment of Titanium Dioxide Nanoparticles by Allium cepa Root Tip Assay at High Exposure Concentrations

Correction: In Vivo Genotoxicity Assessment of Titanium Dioxide Nanoparticles by Allium cepa Root Tip Assay at High Exposure Concentrations

Exposure of Allium cepa Root Cells to Zidovudine or Nevirapine Induces Cytogenotoxic Changes

Antiretroviral drugs have proved useful in the clinical management of HIV-infected persons, though there are concerns about the effects of exposure to these DNA-reactive drugs. We investigated the potential of the plant model Allium cepa root tip assay to demonstrate the cytogenotoxicity of zidovudine and nevirapine and as a replace-reduce-refine programme amenable to resource–poor research settings. Cells mitotic index were determined in squashed root cells from Allium cepa bulbs exposed to zidovudine or nevirapine for 48 hr. The concentration of zidovudine and nevirapine inhibiting 50% root growth after 96 hr exposure was 65.0 µM and 92.5 µM respectively. Root length of all antiretroviral-exposed roots after 96 hr exposure was significantly shorter than the unexposed roots while additional root growth during a subsequent 48 hr recovery period in the absence of drug was not significantly different. By ANOVA, there was a significant association between percentage of cells in mitosis and zidovudine dose (p = 0.004), but not nevirapine dose (p = 0.68). Chromosomal aberrations such as sticky chromosomes, chromatin bridges, multipolar mitoses and binucleated cells were observed in root cells exposed to zidovudine and nevirapine for 48 hr. The most notable chromosomal aberration was drug-related increases in sticky chromosomes. Overall, the study showed inhibition in root length growth, changes in the mitotic index, and the induction of chromosomal aberrations in Allium bulbs treated for 96 hr or 48 hr with zidovudine and nevirapine. The study reveals generalized cytogenotoxic damage induced by exposure to zidovudine and nevirapine, and further show that the two compounds differ in their effects on mitosis and the types of chromosomal aberrations induced.

In Vivo Genotoxicity Assessment of Titanium Dioxide Nanoparticles by Allium cepa Root Tip Assay at High Exposure Concentrations

The industrial production and commercial applications of titanium dioxide nanoparticles have increased considerably in recent times, which has increased the probability of environmental contamination with these agents and their adverse effects on living systems. This study was designed to assess the genotoxicity potential of TiO2 NPs at high exposure concentrations, its bio-uptake, and the oxidative stress it generated, a recognised cause of genotoxicity. Allium cepa root tips were treated with TiO2 NP dispersions at four different concentrations (12.5, 25, 50, 100 µg/mL). A dose dependant decrease in the mitotic index (69 to 21) and an increase in the number of distinctive chromosomal aberrations were observed. Optical, fluorescence and confocal laser scanning microscopy revealed chromosomal aberrations, including chromosomal breaks and sticky, multipolar, and laggard chromosomes, and micronucleus formation. The chromosomal aberrations and DNA damage were also validated by the comet assay. The bio-uptake of TiO2 in particulate form was the key cause of reactive oxygen species generation, which in turn was probably the cause of the DNA aberrations and genotoxicity observed in this study.