Cell and Tissue Journal

Abstract Aim: The stinging nettle (Urtica dioica L.) is a very important medicinal plant that is used in the treatment of many diseases. Considering the important medicinal properties (flavonoid compounds and antioxidant enzymes) of nettle and the numerous advantages of using elicitors in plant tissue culture to enhance the production of medicinal compounds, this study investigated the effect of different concentrations of the chitosan elicitor on the production of some secondary metabolites and antioxidant enzyme activities in callus suspension culture of nettle.
Material and methods: Nettle seeds were cultured in 1/2MS medium after surface sterilization (with 1% sodium hypochlorite and 70% ethanol). leaf explants were isolated from sterile seedling (at the four-leaf stage). The explants were cultured in MS hormone-containing medium (NAA and BA 2.5 and 1 mg L^-1, respectively) and maintained under light conditions of 16 : 8 (light : darkness) hours  at 25 °C. After several stages of subculturing, uniform callus was produced. Eight days after transfer of calli to MS liquid culture medium, calli were treated with chitosan elicitor at concentrations of 0, 50, and 100 mg L^-1. Calli were sampled at 24, 48, and 120 hours after treatment. Finally, the production of secondary metabolites (quercetin, kaempferol, and rutin) was determined using HPLC and the standard line equation. Also, the activities of antioxidant enzymes (phenylalanine ammonia-lyase, polyphenol oxidase, and peroxidase) and the total content of phenol, flavonoid and protein were measured and analyzed by spectrophotometry method. The experiment was conducted in completely randomized design with three replications and was analyzed as a split-time statistical design.
Results: According to the results of the analysis of variance, the effect of chitosan elicitor concentration, sampling time after elicitor application and the interaction effect of elicitor concentration and sampling time on all measured parameters except for the total flavonoid content (the effect of elicitor concentration was not significant) were significant. The highest phenylalanine ammonia-lyase and polyphenol oxidase enzyme activities were at sampling times of 120 and 24 hours after elicitor application at 100 mg L^-1 chitosan concentration, respectively. The peroxidase enzyme activity at the sampling time of 120 hours and a concentration of 50 mg L^-1 of chitosan was 2.57 times that of the control sample. The total protein content decreased at concentrations of 50 and 100 mg L^-1 chitosan compared with the control. The highest amount of quercetin production was in the treatment of 100 mg L^-1 chitosan and sampling time of 48 hours after elicitor application, which increased 25 times compared with the control. Kaempferol and rutin had the highest production at sampling times of 48 and 24 hours and a concentration of 50 mg L^-1, respectively, which increased by 72.6 and 51.2 percent compared with the control.
Conclusion: Chitosan elicitor is known as a biotic elicitor with a positive effect on medicinal and antioxidant properties in various plants. In this study, chitosan elicitor increased the production of quercetin, kaempferol, and rutin metabolites as well as the activity of antioxidant enzymes in nettle callus culture. So, chitosan elicitor can be introduced as an enhancer of medicinal properties of nettle plant under in vitro culture conditions. Obviously, for the commercial production of medicinal compounds, the conditions for large-scale callus production in bioreactors must be optimized.

Abstract Aim: Cancer is one of the leading causes of death worldwide, and its treatment is always associated with side effects such as drug resistance. So, there is a strong tendency for the identification of new herbal anti-cancer compounds.
Material and Methods: In this study, a range of 0.5-12 µg/mL of hydroalcoholic extract of Tamarindus indica kernel and 5-Fluorouracil was applied to prostate cancer (LNCaP), colon cancer (HT-29) and normal fibroblast (HSkMC) cells for 24 hours. The cytotoxic effect of the extracts was measured by the MTT method. The rate of DNA synthesis and incidence of apoptosis was measured by BrdU and TUNEL assays, respectively.
Results: Following treatment with the highest amount of the extract, the viability of prostate, colon, and fibroblast cells was reduced to 4.8, 65.1, and 60.5%, respectively. The IC₅₀ for the three cell lines was 4.60, 17.0 and 13.79 μg/mL respectively. The rate of DNA synthesis also reduced by 32, 37 and 15% for prostate, colon and fibroblast cancer cells, respectively. The rate of apoptosis in LNCaP and HT-29 cells was 31 and 4%, respectively.
Conclusion: Collectively, the toxicity of the extract was higher for LNCaP cells than for the other two cells (p-value ˂0.01). Further studies in vivo and analysis of compounds in tamarind can lead to the identification of anti-cancer compounds from this plant.