Alkylphloroglucinol derivatives and triterpenoids with soluble epoxide hydrolase inhibitory activity from Callistemon citrinus.

Pham Ngoc Khanh, Ho Viet Duc, Tran Thu Huong, Ninh The Son, Vu Thi Ha, Doan Thi Van, Bui Huu Tai, Ji Eun Kim, Ah Reum Jo, Young Ho Kim, Nguyen Manh Cuong

Index: Fitoterapia 109 , 39-44, (2016)

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Abstract

Phytochemical analysis of the leaves and stems of Callistemon citrinus (Curtis) Skeels led to the isolation of two new alkylphloroglucinols, gallomyrtucommulone E and F (1 and 2), along with four other known alkylphloroglucinol derivatives, gallomyrtucommulone A (3), endoperoxide G3 (4), myrtucommulone B (5), callistenone B (6) and five known triterpenoids, including betulinic acid (7), 3β-acetylmorolic acid (8), 3β-hydroxy-urs-11-en-13(28)-olide (9), diospyrolide (10) and ursolic acid (11). The structures of the natural compounds were determined from the spectroscopic evidences including 1D-/2D-NMR and HR-MS spectrometry. All the isolated compounds were assessed for the effects on the sEH inhibitory activity. The acylphloroglucinols myrtucommulone B (5)/callistenone B (6) (in mixture), and two triterpenoids, ursolic acid (11) and 3β-hydroxy-urs-11-en-13(28)-olide (9) displayed strong inhibition of sEH activity, with IC50 values of 0.7, 11.2 and 24.8 μM, respectively.Copyright © 2015 Elsevier B.V. All rights reserved.