6-Benzylaminopurine: Synthesis and Uses

6-Benzylaminopurine is a type of cytokinin, a broad-spectrum plant growth regulator. It stimulates plant cell growth, inhibits plant chlorophyll degradation, increases the content of amino acids, and delays leaf senescence.6-Benzylaminopurine is a safe and efficient synthetic cytokinin mainly used for increasing productivity to promote undifferentiated tissue differentiation and lateral bud outgrowth (Sprent et al. 1967). 

Synthesis of 6-Benzylaminopurine

In a three-neck reaction vessel, 0.1 mol (13.6 g) of hypoxanthine, 0.15 mol (16 g) of benzylamine, 4 g (I2-P2O5-ZnCl2) catalyst and 100 mL of DMF solvent were added.The mass ratio of P2O5:ZnCl2:I2 is 1:0.2:0.02. Then, the temperature is raised to about 75 DEG C., and the temperature is controlled at 75 DEG C for 4 hours. After the reaction,Slowly add 1mol (18g) of process water and control the temperature at 75°C to adjust the pH to neutral. After adjustment, a large amount of solids are precipitated and directly heated.After suction filtration, the crude product of 6-benzylaminopurine was obtained. After drying, the yield was 21.7 g. The equivalent yield was 96.2% and the content was 98.1%.The obtained crude product was tested for chloride ion content and the chloride ion content was ≤ 0.1 ppm. In order to better improve the purity of the product, you can further refine it, specifically:Into another three-necked flask was added 20 g of the crude 6-benzylaminopurine obtained above and 250 g of ethanol, and the mixture was heated to reflux, dissolved, and 1.6 g of activated charcoal was added while hot.Decoloring treatment by stirring for 30 minutes, while hot suction filtration, the filtrate was stirred and slowly cooled to 5 °C -10 °C for analysis, filtration, drying, to obtain refined product 6-benzylaminopurine 18.2g, the content is 99.6 %.The quality product will be tested for chloride ion content, chloride ion content ≤ 0.05ppm. The mother liquor can be applied to the next batch.[1]

Research related to 6-Benzylaminopurine

The influence of 6-Benzylaminopurine on yield responses of soybean

Cytokinins play a role in the regulation of soybean flowering and pod formation. The use of cytokinins is popular for controlling ontogenesis and promoting plant immunity under the influence of severe environmental factors and crop yields (Fagherazzi et al., 2016). Nagel et al.(2001) and reported that an exogenous application of cytokinin to raceme soybean tissues promotes flower development and prevents flower abortion.  [2]The use of plant hormones can artificially modify morphogenesis (Sugiura et al., 2015) such as growth operations (Rogach et al., 2018), increase the plants' resistance to adverse environmental conditions (Zhao et al., 2017), photosynthetic processes (Yan et al., 2015), promote flowering (Lima et al., 2016) and control plant loading with fruits and seeds. These changes influence the development of an efficient assimilative system capable of supplying active synthesis of plastic compounds that are directed in greater abundance towards generative bodies and reserve bodies (Rogach et al., 2018). The primitive effects of 6-Benzylaminopurine added on pod-forming racemes were studied in several experiments, indicating that cytokinin contributes to enhancing soybean pod numbers. Its primitive effect was evident in pot-grown plants but not studied in field conditions. Thus, keeping in mind, the present study planned to explore the impact of different concentrations of 6-Benzylaminopurine on photosynthetic physiological indexes and yield, as well as genes expression of chlorophyll synthesis at transcript levels in soybean plants.

Soybean plants produce a large number of flower buds. However, the majority of them do not become pods and die during development. The bulk of total reproductive abscission is caused by flower and pod drop, or abortion, which impacts prospective soybean yield. Plant growth regulators serve critical functions in plant development, but only recently have their tasks been recognized in the manifestation of yield components, product, and seed qualities in soybean. The objectives of this study were to see how different concentrations of 6-Benzylaminopurine  affected photosynthetic physiological indexes, as well as gene expression of chlorophyll synthesis at the transcript level in soybean plants. In the current investigation, spraying different concentrations of 6-Benzylaminopurine had no significant effect on the soybean yield. However, the 6-Benzylaminopurine generated significant alterations in chlorophyll content as compared to the control. Consequently, the use of 6-Benzylaminopurine significantly boosted the net photosynthetic rate. Furthermore, the current study found that 6-Benzylaminopurine significantly influenced stomatal conductance and net transpiration compared to the control plant. The application of 6-Benzylaminopurine significantly improves the expression of all genes that encode for chlorophyll biosynthesis. The expression of genes in leaves exhibited more up-regulation as compared to the stem. In general, this work offers a new and better understanding of how 6-Benzylaminopurine might be employed to boost yield and chlorophyll biosynthesis.

6-Benzylaminopurine Promotes Growth and Flavonoid Accumulation in Mulberry 

6-Benzylaminopurine application directly promotes lateral bud growth. For example, Liu et al. (2009) reported that 6-Benzylaminopurine stimulates the outgrowth of wheat tiller buds. Similarly, foliar spray application of 6-Benzylaminopurine promotes the outgrowth of lateral buds in jatropha (Jatropha curcas) and nursery apple trees (Elfving et al. 2006; Ni et al. 2015).[3]

However, the effects of 6-Benzylaminopurine on the differential growth and contents of medicinal ingredients in mulberry seedlings are unknown. In our previous experiment, eight different concentrations of 6-Benzylaminopurine were evaluated using preliminary field trials, and optimal results were obtained when mulberry leaves were treated with 30 mg/L 6-Benzylaminopurine. The new shoots and buds of mulberry seedlings treated with 30 mg/L 6-Benzylaminopurine were higher than those of seedlings treated with other concentrations of 6-Benzylaminopurine, indicating that the optimal concentration of 6-Benzylaminopurine of 30 mg/L. In the present study, we used 30 mg/L 6-Benzylaminopurine solution to treat mulberry seedlings, and we determined the growth, chlorophyll contents, soluble sugar contents, malonaldehyde (MDA) contents, antioxidant (POD) levels, superoxide dismutase (SOD) activity levels, flavonoid accumulation and expression of enzyme-related genes involved in the flavonoid synthesis pathway. According to the maximum residue limit (MRL) of 6-Benzylaminopurine and the current European Union standard of acceptable daily intake (ADI) as well as the average body weight (bw) and daily intake of food in different age groups in China, the dietary risk of 6-Benzylaminopurine was assessed by calculating the estimated daily intake (EDI) and the risk quotient (RQ). Among them, the maximum residue limit (MRL) of 6-Benzylaminopurine was 0.2 mg/kg, and the acceptable daily intake (ADI) was 0.01 mg/ (kg bw·d) (European Food Safety Authority 2020). The results showed that application of 30 mg/L 6-Benzylaminopurine did not cause higher dietary risk.

Mulberry (Morus alba L.) leaf contains antioxidant ingredients such as flavonoids, alkaloids and polyphenols. The effects of 6-benzylaminopurine (6-Benzylaminopurine) treatment on plant growth and flavonoid contents in mulberry leaves were investigated in this study. The expression of rutin (Rut), chlorogenic acid (ChA), isoquercitrin (IQ) and astragaloside IV (Ast) related genes in the flavonoid synthesis pathways was investigated in mulberry leaves. The results showed that 6-Benzylaminopurine treatment significantly promoted mulberry differentiation and growth as well as, increased the numbers of new shoots and buds compared to the control. In addition, 30 mg/L 6-Benzylaminopurine significantly increased the contents of Rut, IQ and Ast, and it strongly induced the expression of flavonoid biosynthesis-related genes, including flavonoid 3-O-glucosyltransferase (F3GT), 4-xoumarate-CoA ligase (4CL), phenylalanine (PAL) and chalcone synthase (CHS). The dietary risk assessment of mulberry leaves was based on hormone residues 5 days after treatment with 30 mg /L 6-Benzylaminopurine, and the results showed that the dietary exposure risk of 6-Benzylaminopurine was extremely low without causing any health concern. Thus, treatment with 30 mg/L 6-Benzylaminopurine is a new method to improve the medicinal quality and development of high-value mulberry leaf foods without any potential risk.

References

[1] Current Patent Assignee: TAIZHOU DAPENG PHARMACEUTICAL - CN107488177, 2017, A

[2] He H, Qin J, Cheng X, Xu K, Teng L, Zhang D (2018) Effects of exogenous 6-BA and NAA on growth and contents of medicinal ingredient of Phellodendron chinense seedlings. Saudi J Bio Sci 25:1189–1195.

[3] Liu QZ, Xi B, Sun YL, Xu WR, Dai HJ (2019) Effects of exogenous 6-BA on anthocyanin content and expression of related genes in grape berry. Nat Sci Ed 47:112–125.

You may like