Phytochemical investigation of the leaves and stems of Callistemon citrinus (Curtis) Skeels led to the isolation of 12 flavonoid and triterpenoid compounds, including one new flavonoid, callistine A (1) and six known flavonoids, 6,7- dimethyl-5,7-dihydroxy-4'-methoxy flavone (2), astragalin (3), quercetin (4), catechin (5), eucalyptin (6), and 8-demethyleucalyptin (7), along with 5 known triterpenoids, 3-β-acetylmorolic acid (8), 3β-hydroxy-urs-11-en-13(28)-olide (9), betulinic acid (10), diospyrolide (11) and ursolic acid (12). | Journal of Science and Technology 54 (2) (2016) 214-223 DOI: FLAVONOIDS AND TRITERPENOIDS FROM CALLISTEMON CITRINUS AND THEIR INHIBITORY EFFECT ON NO PRODUCTION IN LPS-STIMULATED MACROPHAGES Nguyen Manh Cuong1, Pham Ngoc Khanh1, Ho Viet Duc2, Tran Thu Huong1, Youn-Chul Kim3, Pham Quoc Long1, Young Ho Kim4 1 Institute of Natural Products Chemistry, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi 2 Faculty of Pharmacy, Hue University of Medicine and Pharmacy, Hue University, 06 Ngo Quyen, Hue, Vietnam 3 College of Pharmacy, Wonkwang University, Iksan 570-749, Korea 4 College of Pharmacy, Chungnam National University, Daejeon 305-764, Korea * Email: nmcuong_inpc@ Received: 11 August 2015; Accepted for publication: 2 January 2016 ABSTRACT Phytochemical investigation of the leaves and stems of Callistemon citrinus (Curtis) Skeels led to the isolation of 12 flavonoid and triterpenoid compounds, including one new flavonoid, callistine A (1) and six known flavonoids, 6,7- dimethyl-5,7-dihydroxy-4'-methoxy flavone (2), astragalin (3), quercetin (4), catechin (5), eucalyptin (6), and 8-demethyleucalyptin (7), along with 5 known triterpenoids, 3-β-acetylmorolic acid (8), 3β-hydroxy-urs-11-en-13(28)-olide (9), betulinic acid (10), diospyrolide (11) and ursolic acid (12). Their chemical structures were determined by analysis of their 1D- and 2D-NMR and HR-MS data. All isolated compounds were examined for their inhibitory activity against LPS-activated NO production in macrophage cells. Among them, quercetin (4) and 3β-hydroxy-urs-11-en-13(28)-olide (9) showed the most potent activities. Keywords: Callistemon macrophage. citrinus (Curtis) Skeels, flavonoid, triterpenoid, 1. INTRODUCTION Nitric oxide (NO) is an important molecule. It acts as a defense factor against invading bacterial pathogens and is an essential element in the regulation of immune reactions [1]. .
