ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Antioxidant and binding properties of methanol extracts from indigo plant leaves

Yun-Jum Park, Chang-Sik Shin, Bo-Eun Kim, Gil-Yong Cheon, Jong-Hyang Bae, Yang-Gyu Ku, Su-Min Park, Buk-Gu Heo, Dae-Guk Kim, Ja-Yong Cho, and Shela Gorinstein

Department of Horticulture, Wonkwang University, Iksan, 570-749, Korea

E-mail: bukgu@naver.com

Abstract: This study was conducted to clarify the effect of ultra-pressure treatment on the extraction of bioactive compounds from indigo plant leaves (Polygonum tinctorium Lour.) and on their properties. Leaves were harvested the in mid-August, 2013, from Naju City (Korea), and treated using two methods: ultra-pressure (550 MPa, 3 min) and hot-air (70°C, 24 h). Then, the leaves were ultrasonically extracted with methanol. The content of indirubin in leaves treated with ultra pressure and hot air was (535.55 ± 26.14) mg kg⁻¹ and (52.63 ± 6.45) mg kg⁻¹, respectively, and that of tryptanthrin was (165.55 ± 8.74) mg kg⁻¹ and (153.00 ± 7.62) mg kg⁻¹, respectively. Polyphenolic content in the leaves extract was (127.24 ± 13.67) mg kg⁻¹ after the ultrapressure and (88.22 ± 5.33) mg kg⁻¹ after the hot-air treatment. The content of flavonoids was (2298.67 ± 83.27) mg kg⁻¹ after the ultra-pressure and (3224.00 ± 21.45) mg kg⁻¹ after the hotair treatment. Di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH) radical scavenging activities of the indigo extract obtained by ultra-pressure and hot-air treatment methods at the concentration of 1 mg mL⁻¹ were (80.25 ± 0.73) % and (66.54 ± 2.35) %, respectively, and 2,2′-azinobis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging activities were estimated as (90.14 ± 0.79) % and (64.45 ± 8.97) %, respectively. The methanol leaf extract after ultra-pressure treatment exhibited higher binding properties to human serum albumin in comparison with catechin and conventional treatments. Consequently, it was assumed that the ultra-pressure treatment is an effective method for the extraction of bioactive compounds from indigo leaves.

Keywords: indigo leaves – bioactive compounds – antioxidant activity – binding properties

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-014-0572-4

Chemical Papers 68 (10) 1421–1427 (2014)