Lactobacillus rhamnosus BHN-LAB 76에 의한 Pueraria 발효 추출물의 항산화 활성 평가

Evaluation of the Anti-oxidant Activity of Pueraria Extract Fermented by Lactobacillus rhamnosus BHN-LAB 76

Abstract

칡의 화합물은 동양 전통 의학에서 매우 중요한 콩과 식물로서 다량의 이소플라본을 함유한다고 보고되었다. 그러나, 칡의 주요 함유 이소플라본은 생물학적으로 이용가능성이 낮기 때문에, 생물학적 이용가능성을 증대시키기 위해서는 가수분해나 ${\beta}$-glucosidase를 사용하여 생물전환을 통해 이용 효율성을 증대시킬 수 있다. 본 연구는 김치로 부터 분리된 Lactobacillus rhamnosus BHN-76를 이용해 발효한 칡 추출물의 항산화 효과를 조사하였다. L. rhamnosus BHN-76 발효는 $37^{\circ}C$에서 3일간 발효하였으며, 발효하지 않은 칡 추출물에 비해 L. rhamnosus BHN-76 발효 칡 추출물에서 총 폴리페놀 함량은 약 134%, 총 플라보노이드 함량은 약 110% 증가된 것을 확인하였다. 또한, SOD 유사활성능, DPPH radical 소거 활성능과 ABTS radical 소거활성능은 각각 약 213%, 190%와 107% 항산화능이 증가하는 것을 확인하였다. 이 결과를 통해 L. rhamnosus BHN-76을 이용한 칡의 발효가 가능하며, 유산균 발효가 칡의 항산화능 증대에 효과적인 것을 확인하였으며 본 연구를 기반으로 한 기능성 식품 또는 화장품 소재로의 개발 및 응용이 가능할 것으로 기대된다.

The phytochemical compounds of Pueraria, a medicinally important leguminous plant, include various isoflavones that have weak estrogenic activity and a potential role in preventing chronic disease, cancer, osteoporosis, and postmenopausal syndrome. However, the major isoflavones are derivatives of puerarin and occur mainly as unabsorbable and biologically inactive glycosides. The bioavailability of the glucosides can be increased by hydrolysis of the sugar moiety using ${\beta}$-glucosidase. In this study, we investigated the antioxidant effects of a Pueraria extract after fermentation by Lactobacillus rhamnosus BHN-LAB 76. The L. rhamnosus BHN-LAB 76 strain was inoculated into Pueraria powder and fermented at $37^{\circ}C$ for 72 hr. The total polyphenol content of the Pueraria extract increased by about 134% and the total flavonoid content increased around 110% after fermentation with L. rhamnosus BHN-LAB 76 when compared to a non-fermented Pueraria extract. Superoxide dismutase-like activities, DPPH radical scavenging, and ABTS radical scavenging increased by approximately 213%, 190%, and 107%, respectively, in the fermented Pueraria extract compared to the non-fermented Pueraria extract. Fermentation of Pueraria extracts with L. rhamnosus BHN-LAB 76 is therefore possible and can effectively increase the antioxidant effects. These results can be applied to the development of improved foods and cosmetic materials.

Fig. 1. Phylogenetic tree of the L. rhamnosus BHN-LAB 76 and related bacteria of the Lactobacillus group based on 16S rRNA gene sequence comparisons. The sequences of isolated strains were compared with available from the GenBank database.

Fig. 2. Quantitative analysis of L. rhamnosus BHN-LAB 76 in the P. thunbergiana fermentation process by the Realtime PCR.

Fig. 3. Superoxide dismutase like activity of extracts from the fermented P. thunbergiana extracts with L. rhamnosus BHN-LAB 76. SOD-like activity was measured at 420 nm. NF; Non-fermented P. thunbergiana extracts, F; fermented P. thunbergiana extracts by L. rhamnosus BHNLAB 76, C; vitamin C 500 ppm.

Fig. 4. DPPH radical scavenging activity of extracts from the fermented P. thunbergiana extracts with L. rhamnosus BHNLAB 76. DPPH radical scavenging activity was measured at 517 nm. Percent scavenging of the DPPH free radical was quantified compared to the control. NF; Non-fermented P. thunbergiana extracts, F; fermented P. thunbergiana extracts by L. rhamnosus BHN-LAB 76, C; vitamin C 500 ppm.

Fig. 5. ABTS radical activity of extracts from the fermented P. thunbergiana extracts with L. rhamnosus BHN-LAB 76. SOD-like activity was measured at 734 nm. NF; Non-fermented P. thunbergiana extracts, F; fermented P. thunbergiana extracts by L. rhamnosus BHN-LAB 76, C; vitamin C 500 ppm.

Fig. 6. Reducing power of extracts from the fermented P. thunbergiana extracts with L. rhamnosus BHN-LAB 76. Reducing power was measured at 700 nm. NF; Non-fermented P. thunbergiana extracts, F; fermented P. thunbergiana extracts by L. rhamnosus BHN-LAB 76, C; vitamin C 500 ppm.

Table 1. Quantification of L. rhamnosus BHN-LAB 76 in the P. thunbergiana fermentation process using the Lactobacillus sp. 16S rRNA gene by the Real-time PCR

Table 2. Total polyphenol and total flavonoid contents of extracts from the fermented P. thunbergiana extracts with L. rhamnosus BHN-LAB 76