Novel Withanolides from Jaborosa sativa

Abstract

Four new withanolides [1-4] have been isolated from the aerial parts of Jaborosa sativa. Jaborosalactones R [1], S [2], and T [3] contain a hemiketal (or ketal) ring formed between a 21-hydroxyl and a 12-ketone and the characteristic -lactone side-chain of the withanolides. Jaborosalactone U [4] possesses an epoxy-"y-lactone side-chain and was identified as the 24,25-epoxy analogue of trechonolide A [5]• Jaborosa Miers is a South American genus belonging to the Solanaceae that comprises about 23 different species which grow mainly in Argentina (1). To date, sixJaborosa spp.have been reported to contain withanolides, namely,J. integrifolia (2-4),J. leucotricha (5-7),J. bergii (8),J. odonelliana (9),J-laciniata (formerly in the genus Trechonaetes) (10), and J. magellanica (11)(12)(13)(14)). These C2S steroidal lactones have been isolated from several genera of the Solanaceae and many of these compounds exhibit interesting biological activities, such as cytotoxic, immunosuppressive, anti-inflammatory, insecticidal, and antifeedant properties (15).FromJaborosa sativa (Miers) A.T. Hunziker & G. Barbosa (Trechonaetes sativa Miers), we have isolated four new withanolides. Three of them, jaborosalactones R [1], S [2], and T [3] incorporate, in addition to the typical -lactone side-chain, a six-membered hemiketal (or ketal) ring involving what must have been originally a C-12 keto group and a C-21 hydroxyl functionality, a novel arrangement in the withanolide class of compounds. The fourth withanolide, jaborosalactone U [4} was characterized as the 24,25-epoxy analogue of trechonolide A [51 (10). The epoxy-'y-lactone side-chain found in 4 has no precedent among the withanolides, although epoxy-b-lactones (and epoxy--lactols) and unsaturated -lactones are commonly found among this group of compounds (8,13). Preliminary biological testing has shown that jaborosalactone S has strong antifeedant activity on larvae of Tenebrio molitor (R.

Withanolides and Related Steroids

“…Although epoxy-d-lactones and lactols are quite common among the withanolides, this did not appear to be the case for the g-lactone side chains. Jaborosalactone U (381) isolated from J. sativa (Argentina), is the only known example of a 24,25-epoxy-g-lactone (119). The (23R) configuration was originally proposed for this compound based on NOE data, however, more recently X-ray crystallography showed that the configuration is (23S) (Fig.…”

New Withanolides from Two Varieties of Jaborosa Caulescens

“…caulescens yielded the withanolides 1 and 2. These two compounds resemble the structures of Jaborosalactona R, S and T (isolated from J. sativa [3]), with respect to the presence of the hemiketal function between C-21 and C-12, but differ in the substitution pattern of ring A and B.…”

Chlorinated Plant Steroids and their Biological Activities

“…Nicotra and co-authors (2006) reported the isomeric clorohydrin, jaborosalactone 37 (20) from Jaborosa rotacea, and jaborosalactone T (21) was isolated from Jaborosa sativa (synonym Trechonaetes sativa) collected in Argentina (Bonetto et al, 1995).…”

“…1 and 2, and the biological activities of plant chlorinated steroids are presented in Table 1. Physalis peruviana Withania somnifera and Acnistus breviflorus (Nittala et al, 1981;Bessalle and Lavie, 1992) Not studied (Bonetto et al, 1995) Not studied Tubocapsicum anomalum (Shingu et al, 1990) Not studied (Makino et al, 1995;Kawai et al, 1996) Not studied (Ripperger and Kamperdick, 1998) (Kawai et al, 1996) Not studied …”