Antioxidant and Protective Effect of Rubus Coreanus Miquel Stems and Leaves Ethanol Extract on HEK-293 Kidney Cell Damaged by Arsenic

Abstract

As the life span of human increases and the income level improves according to the economic development, people’s consumption condition has been changing greatly. The consumption of agricultural products has distinctly altered from the quantity-oriented to the quality-oriented. In particular, the cultivation areas and yield of Rubus coreanus Miquel (Rubus coreanus Miq.), the value of which for practical use is predominant as a material of high functional food and beverage products, have been highly increased in Gochang, Jeollabuk-do. The efficacy of Rubus coreanus Miq. was recorded in various oriental medical books, which could lighten the body, protect the feebleness of body, and heal the weak and cold lungs (including other respiratory organs) by increasing the amount of urine. In addition, it was reported that Rubus coreanus Miq. extract abstracted by using methanol or ethanol has the antibiotic effects on bacteria related to the food poisoning, cause bacteria of acne, etc.. Also, the various effects, such as improvement of skin wrinkles, whitening effect, antimutagenic activity, cancer cells growth suppression effect, and so forth, are studied. On this wise, the efficacy on Rubus coreanus Miq. fruits is being materialized through diverse researches. Because the excellence as a material of functional foods as well as a traditional medicinal herb has been recognized through several studies, the development feasibility of Rubus coreanus Miq. as an economic crop popular has been identified. However, currently, the studies are inadequate on the stems and leaves of Rubus coreanus Miq., besides its fruits which we are generally eating, and many stems and leaves are considered as byproducts of the fruits, and being thrown out each year. Recently, the researches on anitioxidant, such as antioxidant activity of each part of ginseng, functional characteristics of hydrothermal extract liquid of acanthopanax’s each part, antibiosis and antioxidant activity of solvent extract of each part of loquat, photoprotective effects and antioxidant activity of each part of a wild mulberry tree, and so on, are actively progressing. These researches are in order to taking advantage of other parts, not limited only to the fruits, as the materials utilized to develop natural preservatives and produce new functional foods. Therefore, this study tried to observe the antioxidant effects of stems and leaves considered as the byproducts and thrown away in the process of harvesting Rubus coreanus Miq. fruits, and investigate the protection effects on As, utilizing HEK-293 clls stimulated by arsenic(As). By depressurizing and concentrating the stems and leaves of Rubus coreanus Miq. harvested in Gochang in 2014, with ethanol of 25, 50, 75, 100%, the extract, Rubus coreanus Miq. Stems and Leaves Extract in Ethanol(RSLE), is gained. Each extract with the concentration of 100, 50, 10 μg/ml was used in the experiment. As a result of analyzing the proximate composition of the dried powder of stems and leaves of Rubus coreanus Miq., it showed moisture 5.75%, crude ash 5.17%, crude protein 10.07%, crude fat 2.20%, and dietary fiber 66.42%. The main free-sugar was investigated as glucose, and fructose, whose content was glucose of 9.83 mg/g, and fructose of 8.74 mg/g. In the case of minerals, a total of 10 mineral types were detected, and particularly, potassium and calcium was much content, 1463.96 mg/100g, and 810.92 mg/100g by each. Regarding to the total polyphenol of RSLE, the extract of ethanol 50% showed the highest, 226.6 ± 10.77 mg GAE/g, and in the research result on the activity of DPPH, FRAP, and SOD, excluding flavonoid, ethanol 100%, and RSLE 100 μg/ml showed the highest activity. As a result of cytotoxicity test where HEK-293 cells were put though RSLE and As, zero toxicity was confirmed at 100 μg/ml. Also, the revelation degree of HO-1 was investigated after HEK-293 kidney cells were put though RSLE and As by Western blot experiment. Therethrough, the fact could be confirmed that the lower the concentration of ethanol extract becomes, the more the revelation degree of HO-1 increases meaningfully. Thus, it was suggested that RSLE has the possibility as HO-1 inhibitor. From the biological activity foregoing, the capability on the antioxidant of RSLE and protection ability from As was identified, and it could be employed to produce functional foods through more researches in the future.