Exploration of acute genotoxic effects and antigenotoxic potential of gambogic acid using Allium cepa assay

Glutathione is required for nitric oxide-induced chilling tolerance by synergistically regulating antioxidant system, polyamine synthesis, and mitochondrial function in cucumber (Cucumis sativus L.)

In this paper, we discussed the physiological mechanism of enhanced chilling tolerance with combined treatment of nitric oxide (NO) and reduced glutathione (GSH) in cucumber seedlings. With prolonged low temperature (10 °C/6 °C), oxidative stress improved, which was manifested as an increase the hydrogen peroxide (H2O2) and malondialdehyde (MDA), causing cell membrane damage, particularly after 48 h of chilling stress. Exogenous sodium nitroprusside (SNP, NO donor) enhanced the activity of nitric oxide synthase NOS-like, the contents of GSH and polyamines (PAs), and the cellular redox state, thus regulating the activities of mitochondrial oxidative phosphorylation components (CI, CII, CIV, CV). However, buthionine sulfoximine (BSO, a GSH synthase inhibitor) treatment drastically reversed or attenuated the effects of NO. Importantly, the combination of SNP and GSH treatment had the best effect in alleviating chilling-induced oxidative stress by upregulating the activities of antioxidant enzyme, including superoxidase dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) and improved the PAs content, thereby increased activities of CI, CII, CIII, CIV, and CV. This potentially contributes to the maintenance of oxidative phosphorylation originating from mitochondria. In addition, the high activity of S-nitrosoglutathione reductase (GSNOR) in the combined treatment of SNP and GSH possibly mediates the conversion of NO and GSH to S-nitrosoglutathione. Our study revealed that the combined treatment with NO and GSH to synergistically improve the cold tolerance of cucumber seedlings under prolonged low-temperature stress.

Protective effect of kavain in meristematic cells of Allium cepa L

Kavain is one of the main kavalactones of Piper methysticum (Piperaceae) with anxiolytic, analgesic, and antioxidant activities. Therefore, the aim of the study was to evaluate the cytotoxic, mutagenic, and antimutagenic potential of kavain in Allium cepa cells. Roots of A. cepa were transferred to the negative (2% acetone) and positive (10 µg/mL of Methylmethanesulfonate, MMS) controls and to the concentrations of kavain (32, 64 and 128 µg/mL) for 48 h. A total of 5,000 meristematic cells were analyzed under an optical microscope to determine the mitotic index, mean number of chromosomal alterations and percentage of damage reduction. Data were analyzed by Kruskal-Wallis test (p <0.05). All concentrations of kavain were not cytotoxic and did not show significant chromosomal changes when compared to 2% acetone. Kavain showed a cytoprotective effect in the pre (128 μg/mL) and in the post-treatment (32 and 64 μg/mL) and reduced damage against the mutagenic action of MMS in all concentrations of the pre and simultaneous and at the highest of post (128 μg/mL). Kavain promoted a significant reduction in micronuclei, nuclear buds and chromosomal losses in relation to MMS. The observed data indicate the importance of kavain for the inhibition of damage and chemoprevention.

Assessment of allelopathic, cytotoxic, genotoxic and antigenotoxic potential of Smilax brasiliensis Sprengel leaves

Smilax brasiliensis (Smilacaceae) is a native Brazilian plant found in the Cerrado biome and commonly used in folk medicine. The aim of this study was to evaluate the allelopathic, cytotoxic, genotoxic, and antigenotoxic potential of extract and fractions of Smilax brasiliensis leaves. Quercetin and rutin isomers were observed in the subfractions. The dichloromethane fraction (1000 μg/mL) decreased lettuce (Lactuca sativa) seed vigor, while and ethyl acetate and hydromethanol fractions (1000 μg/mL) affected the germination, and quercetin and rutin affected the vigor and germination of onion seeds. The extract, fractions, quercetin, and rutin inhibited or promoted lettuce hypocotyl and radicle growth. The extract and fractions inhibited onion hypocotyl growth at all concentrations. With regards to radicle growth, the results were diversified: growth was either inhibited or promoted. Rutin and quercetin inhibited onion hypocotyl and radicle growth at all concentrations. The extract and fractions of Smilax brasiliensis, rutin, and quercetin did not cause cytotoxic effect evaluated by mitotic index. The extract and fractions showed genotoxic effects. Quercetin and rutin did not cause genotoxic effects. On the other hand, the extract and fractions showed antigenotoxic effects at all tested concentrations, where they were able to revert chromosomal abnormalities caused by glyphosate. However, additional studies are required to evaluate the possible use of the S. brasiliensis leaf methanol extract and fractions as natural sources of bioherbicides.

Antigenotoxic potential of plant leaf extracts of Parkinsonia aculeata L. using Allium cepa assay

The aim of the present study was to evaluate the antigenotoxic potential of P. aculeata L. leaf extract/fractions against maleic hydrazide (MH) using Allium cepa root chromosomal aberration assay. The excessive reduction in root growth and mitotic index value was observed after 3 h treatment of MH as compared to negative control (water). In case of MH treatment, frequency of aberrated cells significantly (p ≤ 0.05) raised from 129 to 337 at 0.1 ppm and 2.0 ppm concentrations respectively. From root growth inhibition test with MH treatment, EC₅₀ value i.e. 0.5 ppm was selected to study the antigenotoxic effect of different extract/fractions of P. aculeata L. leaves. All the extract/fractions showed increase in mitotic index and great reduction in chromosomal aberrations with rise in concentration against the genotoxicity of MH. Among all the extract/fractions, butanol and ethyl acetate fractions showed significant reduction in chromosomal aberrations in A. cepa cells and indicates the chemo preventive activity. Antigenotoxic property of this plant is due to the presence of various phytochemicals in leaf such as epi-orientin, Parkinsonin-A, Parkinsonin-B, orientin, iso-orientin, vitexin, iso-vitexin, C-glycosylflavone, parkintin, rotenoids, terpenoids, flavonoids, saponins, alkaloids, glycosides and anthraquinone etc. Our result showed that among all the treatments, simultaneous treatment showed best result followed by pre and post treatment. Further studies in animal model are suggested for further evaluation of the use of P. aculeata leaf extract in human welfare.