Pharmacological investigation of Choisya Aztec Pearl

Introduction: Choisya 'Aztec Pearl' is known as Mexican orange, a hybrid of C. ternata and C. dumosa var. Arizonica, is used in traditional medicine in Mexico, with infusions from the leaves claimed to have some effects such as antispasmodic and stimulant properties [1]. The aim of this study is to verify the antinoceptive properties of C. 'Aztec Pearl' using the hot plate model [2].

Methods: Leaves and branches of C. 'Aztec Pearl' were collected in Dublin (IE); a voucher specimen (ref. TCD Hodkinson & Ropero 01) was deposited at Trinity College Dublin Herbarium. An ethanol extract of the leaves (E) was prepared and submitted to liquid-liquid fractionation to obtain fractions in hexane (H), dichloromethane (D), ethyl acetate (EA), and n-butanol (B). The same was done to the branches (fractions called Eb, Hb, etc.). The phytochemical analysis of H led to the isolation and identification of the following alkaloids: anhydroevoxine (1) and choisyaternatine (2), besides 6-methoxy-7,8-methylenodioxycoumarin (3). Analysis of D afforded the same coumarin (3) besides the alkaloids anhydroevoxine (1) and choisyine (4) and an unknown compound (5). The chemical composition of EA, B and branches fractions are still under investigation. Mice (22 – 25 g, n = 4 – 6) were orally treated with different doses of fractions and pure compounds and antinoceptive activity was further evaluated using the hot plate assay. Protocol for animal use number was #ICBDFBC-015(COBEA/UFRJ/Brazil). Results are presented in the table expressed as AUC.

Results:

Dose (mg/kg) – LEAVES	Column 1	100	30	1	BRANCHES	1002	303
Vehicle	780
Morphine	5153
E		9086*	3165		Eb	3018	3225
H		2184	5579		Hb	10356*	2787
D		7938*	2280		Db	4377	5576
EA		4938	2661		EAb	7028*	7604*
B		5982	1541		Bb	7386*	1826
R		4217	2042		Rb	4905	5640
1				14547*
2				18714*
3				12131*
4				3819
5				7985*

Conclusions: E and D extracts from the leaves and Hb, EAb and Bb from the branches presented antinoceptive effects. The following compounds isolated from H and D, 1, 2, 3 and 5, showed significant antinoceptive activity.

References:

[1] Bayer RJ, Marbberley DJ, Morton C, Miller CH, Sharma IK, Pfeil BE, Rich S, Hitchcock R, Sykes S. Amer. J Bot. 2009; 96: 668 – 685.

[2] Sahley TL, Berntson GG. Psych. 1979; 65: 279 – 283.