연잎 추출물의 항산화, 항염증 및 피부상재균에 대한 항균활성 연구

Abstract

This study was conducted with the purpose of proposing a utilization possibility of lotus leaf extracts as cosmetics ingredients that are safe, with no side effects, for the acne-prone skins. Lotus flower, lotus leaf, lotus seed and lotus bulb, the four parts of the lotus, were extracted by using a 70% ethanol, and antimicrobial activation for the 3 species of resident skin flora Propionibacterium acnes, Staphylococcus aureus, Staphylococcus epidermidis was measured using paper discs and MIC and, while taking into consideration the heat and pH stability, lotus leaf extracts with the most outstanding antimicrobial activity and stability were selected as samples. We also evaluated antioxidant and anti-inflammatory activity and the results are as follows.

1. In all of the 4 types of samples that used lotus extracts from different parts of lotus and with which antimicrobial property was measured, all 3 species of resident skin flora displayed excellent antimicrobial property. And the order of excellence was lotus flower, followed by lotus leaf, lotus seed and lotus bulb.

2. By setting the concentration levels of the extracts from different parts of lotus plant to 1 mg/disc, the heat stability of strains was measured after heat treating them at 40℃, 80℃, 100℃ and 120℃ for 1 hour. The result showed that lotus flower, lotus leaf, lotus seed and lotus bulb all displayed antimicrobial activity that was stable under heat. By setting the concentration levels of each of the sample types to 1 mg/disc, pH levels were adjusted to 2, 5, 7, 9 and 11 and each sample type was allowed to stand for 1 hour at 37 ℃, and afterwards they were neutralized to pH 7 and their stability was measured: the result showed that only the lotus leaf extract sample displayed stable antimicrobial property at all pH levels. Based on these results, among the four samples lotus leaf extract with the most outstanding antimicrobial property and stability was selected as a sample for a next experiment.

3. By extracting from lotus leaf using 50%, 70% and 95% ethanol, the antimicrobial property of the extracts was measured and the result showed that antimicrobial activity was the highest in 50% ethanol extracts. In addition, MIC results showed antimicrobial activity of S. aureus was the highest, 250㎍/mL in the 50% ethanol extract. So the 50% ethanol extract was used as a sample in the following experiments.

4. It was observed that the total content of phenolic compounds increased as the concentration level of lotus leaf extract increased. 1 ㎍/ml of extract includes 0.3 ㎍/ml of phenol.

5. The DPPH radical scavenging activity of the lotus leaf extract increased proportionally with the concentration level of the sample, and it was the highest at a concentration level of 250 ㎍/ml with 79.76%. The ferric reducing antioxidant power of the lotus leaf extract -- in accordance with the concentration level of the extract in a manner dependent on the concentration level -- was 0.05 ~ 0.59mM/mL, whereby showing increases in antioxidant capacity. ABTS scavenging activity showed increases in its activity in proportion with the concentration levels of the samples, and it showed 46.31% at 250㎍/ml concentration. The β-carotene bleaching assay did not show any antioxidant capacity when the lotus leaf extract concentration levels were 10 ㎍/mL, 50 ㎍/mL and 100 ㎍/mL, however, in 250 ㎍/mL it showed some activity; therefore, it was possible to confirm the inhibitory capability of lipid peroxyl radical in the antioxidant mechanism. Above results proved that the lotus leaf has excellent anti-oxidation effect which is expected to inhibit lipid peroxyl radical.

6. As a result of the evaluation, by using MTT assay, of the effects exerted on the survival rate of RAW 264.7 cell in the lotus extract for the assessment of anti-inflammatory activity of lotus leaf, cytotoxicity did not appear.

7. By using RAW 264.7 cell, we measured the generation inhibitory effect of nitric oxide (NO) of the lotus leaf extract, and the result showed that, when the samples were treated with lipopolysaccharide(LPS), the creation of NO increased by about 6.5 times. In concentration levels of 10 ㎍/mL, 25 ㎍/mL and 50 ㎍/mL, the inhibitory effects were 51.6%, 64% and 65%, respectively, which is very sound. The dependence on concentration levels, however, was not observed. In a result of evaluating the inhibitory effect of cyclooxygenase (COX)-2 which concerns the inhibition of prostagrandin E2(PGE2) causing inflammation, the lotus leaf extract showed a PGE2 generation inhibitory effect of approximately 67.3% and 71.2% at 25 μg/mL and 50μg/mL concentration level, respectively. Therefore the lotus extracts proved to be excellent in anti-inflammatory effect.

8. In RT-PCR for the evaluation of IL-1β and TNF-α gene expressions, the lotus leaf extract was evaluated to be not exerting any effect on the IL-1β and TNF-α gene expressions.

As per the foregoing results, lotus leaf extracts were observed to have antimicrobial activity for resident skin flora and antioxidation and anti-inflammation activity. In addition, with no toxicity, they are safe to the human body and are deemed to be utilizable as the basic materials for the development of new functional ingredients for the management of skins that are susceptible to acne, with minimum side effects.