Synthesis, Characterization, and Crystal Structure of Negundoside (2′-p-Hydroxybenzoyl Mussaenosidic Acid)

The structure of title compound Negundoside (2′-p-hydroxybenzoyl mussaenosidic acid) was established by spectral and X-ray diffraction studies. The compound crystallizes in the monoclinic crystal system with space group P21 having unit cell parameters: (5) ？, (4) ？, (5) ？, (4)°, and . The crystal structure was solved by direct method using single crystal X-ray diffraction data collected at room temperature and refined by full-matrix least-squares procedures to a final R value of 0.0520 for 3389 observed reflections. 1. Introduction Vitex negundo Linn (family: Verbenaceae) is widely used in the indigenous system of medicine in India. The roots and leaves of the plant are used as expectorant, febrifuge, vermifuge tonic, and aromatic [1]. The plant is reported to have anti-inflammatory and antiarthritic properties [2]. A variety of constituents have been reported from this plant. From the leaves Ghosh and Krishna isolated glucononitol, p-hydroxybenzoic acid, 5-hydroxyisophthalic acid, and 3,4-dihydroxy-benzoic acid along with two glucosides and an amorphous alkaloid [3]. In the essential oil of leaves -pinene, camphene, citral, and -caryophyllene have been reported [4]. A large number of flavonoids, namely, casticin, orientin, isoorientin, luteolin, luteolin-7-0-glucoside, corymbosin, gardenins A and B, 3-0-desmethyl-artemetin, 5-0-desmethylnobiletin, 3′,4′,5,5′,6,7,8-heptamethoxyflavone, 3′,5-dihydroxy-4′, 7,8-trimethoxy flavanone, and 3′,5-dihydroxy-4′,6,7-trimethoxy-flavanone, have also been reported from this plant [5–8]. However the major chemical constituents of the plant are the iridoid glycosides. Five iridoid glycosides have been reported from the leaves of V. negundo; these are aucubin, agnuside [9], negundoside, and nishindaside [10]. Negundoside have been found to have significant hepatoprotective activity [11]. A number of pharmacological properties have been attributed to V. negundo including snake venom neutralization [12], hepatoprotective [13], tyrosinase inhibition [14], antiandrogenic [15], antifeeding [16], antifungal [17], analgesic, anti-inflammatory [18], central nervous system activity [19], mosquito repellent [20], nitric oxide scavenging [21], antiradical, antilipoperoxidative [22], antibacterial [23], and larvicidal [24]. 2. Experimental 2.1. Synthesis 2.1.1. Extraction of Plant Material The shade dried and powdered leaves (1？kg) of V. negundo were soaked in ethanol (5？L) and kept overnight. The percolate was filtered and concentrated under reduced pressure at below 50°C. The extraction procedure was repeated three times more