Cashmins A and B, Potent Antioxidant Coumarins from Sorbus cashmiriana

Abstract

Cashmins A (1) and B (2), two new coumarins, have been isolated from the chloroform-soluble subfraction of the methanolic extract of Sorbus cashmiriana Hedl. Both compounds showed potent antioxidant activity in different antioxidant assays.The genus Sorbus (Rosaceae) comprises of 200 species which are commonly grown in Asia, Africa, and South America. Out of these, seven species have so far been identified in Pakistan. One of these is Sorbus cashmiriana Hedl., which is a tree found in Kashmir and the western Himalayas. A tea made from its bark is used to treat nausea. The bark preparation is also used to treat heart diseases. Berries are used to cure scurvy [1][2][3][4][5]. Previously six new triterpenes have been reported by us from this plant [6][7][8]. Its methanolic extract showed significant antioxidant activity. On further fractionation, the major activity was detected in the chloroform-soluble subfraction. This prompted us to carry out bioassay-directed isolation studies on this fraction, resulting in the isolation of two new coumarins named cashmins A (1) and B (2). Both compounds showed potent antioxidant activity in different antioxidant assays.Cashmin A (1) was obtained as a white amorphous solid and gave a violet coloration with FeCl 3 for a phenol. The molecular formula was established as C 22 H 16 O 7 through HR-EI-MS, showing an [M] + peak at m/z 392.0896 (calcd 392.0899). The IR spectrum showed the presence of a hydroxyl group (3360 cm -1 ), an D,E-unsaturated lactone (1700 cm -1 ), and an olefinic bond (1630 cm -1 ). The UV spectrum was characteristic of a coumarin showing absorption maxima at 230, 262, and 322 nm [9]. The 13 C NMR (Table 1) and DEPT spectra of 1 showed 22 carbon signals, including one methyl, ten methines, and eleven quaternary carbons. The most downfield signal at G 162.2 was assigned to the carbonyl carbon of D,E-unsaturated lactone moiety.

Ethnopharmacologically important but underestimated genus Sorbus: a comprehensive review

“…Cashmin A and cashmin B showed significant antioxidant activity in DPPH and ABTS assays. Their Fe ?3 reducing and hydrogen peroxide scavenging activities were confirmed as well (Khan et al 2015).…”

“…Asia S. cashmiriana is a tree found in Kashmir and the western Himalayas, where its bark is used in folk medicine to treat nausea and heart diseases. The berries of this plant are a remedy for scurvy (Khan et al 2015). Another Asian species-S. commixtamainly distributed in Korea, Japan and China has also a long-standing folk use.…”

The Sorbus spp.—Underutilised Plants for Foods and Nutraceuticals: Review on Polyphenolic Phytochemicals and Antioxidant Potential

“…The bark preparation of S . cashmiriana has been used to treat nausea and heart diseases, while its berries have been used to cure scurvy [ 15 ]. The fruits, stems and bark S .…”

“…Both compounds demonstrated outstanding antioxidant activity in H 2 O 2 (IC 50 15.4 and 18.6 μmol/mL), as well as in ABTS •+ scavenging assays (IC 50 24.4 and 18.3 μmo/mL). For comparison, IC 50 of ascorbic acid were 11.4 μmol/mL in H 2 O 2 and 6.5 μmol/mL in ABTS •+ assays [ 15 ].…”

Cashmirins A and B, new antifungal and urease inhibitory prenylated coumarins from Sorbus cashmiriana

“…Berries are used to cure scurvy (Bhattacharjee, 2003;Perry, Metzger, 1980;Krishna, 1972;Jayaweera, 1982;Krachmal, 1980). Previously, six triterpenes (Kazmi et al, 2007;Kazmi et al, 2009;Kazmi et al, 2011) and two coumarins (Khan et al, 2015) have been reported by us from this species. The ethnopharmacologic and chemotaxonomic importance of the genus Sorbus prompted us to carry out further phytochemical studies on S. cashmiriana.…”