Withanolides with phytotoxic activity from two species of the genus Salpichroa: S. origanifolia and S. tristis var. lehmannii

Natural withanolides, an update

Covering: March 2010 to December 2020. Previous review: Nat. Prod. Rep., 2011, 28, 705This review summarizes the latest progress and perspectives on the structural classification, biological activities and mechanisms, metabolism and pharmacokinetic investigations, biosynthesis, chemical synthesis and structural modifications, as well as future research directions of the promising natural withanolides. The literature from March 2010 to December 2020 is reviewed, and 287 references are cited.

Phytochemical Study of the Genus Salpichroa (Solanaceae), Chemotaxonomic Considerations, and Biological Evaluation in Prostate and Breast Cancer Cells

Twelve Salpichroa taxa have been phytochemically analyzed. From the aerial parts of S. scandens, four known salpichrolides A, C, I, S, and an unreported withanolide named salpichrolide V (1), were isolated. In S. dependens, S. gayi, S. glandulosa subsp. glandulosa, S. glandulosa subps. weddellii, S. leucantha, S. micrantha, S. microloba, S. proboscidea, S. ramosissima, S. tristis var. tristis, and S. weberbauerii, no withanolides were found. The chemical content of ca. 85% of the Salpichroa taxa is in agreement with molecular studies, which suggest that Salpichroa and Jaborosa, a genus considered morphologically close to Salpichroa, are distant in the systematic of the Solanoideae subfamily. Moreover, the in vitro cytotoxic activity of a set of natural salpichrolides and derivatives was examined against two prostate carcinoma cell lines (PC3 and LNCaP) and two human breast cancer cell lines (MCF-7 and T47D). Several compounds showed moderate activity (IC₅₀  = 64.91 - 29.97 μm).

Biotransformation of Salpichrolides A, C, and G by Three Filamentous Fungi

Incubation of salpichrolide A (1) with Rhizomucor miehei produced hydroxylation in rings B and C (C-7 and C-12) and led to C-5-C-6 epoxide opening, while incubation of salpichrolides C (2) and G (3) with R. miehei led to epoxide opening at the C-24-C-25 and C-5-C-6 positions, respectively. Biotransformation of salpichrolide A (1) with Cunninghamella elegans produced stereoselective hydroxylated, oxidized, and reduced derivatives in different positions of the A, B, and C rings and C-5-C-6 epoxide opening. In addition, selective epoxide opening at the C-5-C-6 or C-24-C-25 positions was obtained from the incubation of salpichrolide A (1) with Curvularia lunata.

New withanolides with TRAIL-sensitizing effect from Physalis pubescens L

Physalis pubescens L. plant produces nutritious and healthy fruits, called husk tomato or hairy ground cherry. However, its bioactive components are largely unknown. Four new withanolide steroids (1-4) together with one known withanolide (5) were isolated from the extract of P. pubescens L. and their chemical structures were established by extensive spectroscopic analyses. Compounds 1, 3 and 5 showed potent growth inhibitory effects against four human renal cell carcinoma (RCC) cell lines (i.e. 786-O, A-498, Caki-2 and ACHN). Among them, compound 1 was the most potent one with IC50s ranged from 0.30 to 0.77 μM. Further experiment showed that 1 sensitized human RCC cells 786-O to the tumor necrosis factor related apoptosis ligand (TRAIL)-induced apoptosis and increased the expression of C/EBP-homologous protein (CHOP) and death receptor-5 (DR5), leading to activation of the DR5 and caspase-8/3 mediated apoptosis pathway. Molecular docking analysis revealed that compound 1 could bind stably to the TRAIL/DR5 complex through hydrogen bonds. These results suggest that the new withanolide (1) is a lead anti-cancer compound existing in P. pubescens L. and deserves further investigation for RCC prevention and treatment.

Withanolides from Physalis hispida

Nine new withanolides (1-9), withahisolides A-I, were isolated along with nine known compounds (10-18) from the aerial parts of Physalis hispida. The structures of 1-9 were elucidated through a variety of spectroscopic techniques, while the structures of 1 and 2 were confirmed by X-ray crystallographic analysis. Compounds 1-3 are the first withanolides with nonaromatic six-membered ring D moieties. In addition, withanolide 8 represents a novel withanolide skeleton due to the absence of a C-13-C-17 bond within the steroidal nucleus.