Steroid sapogenins from Tristagma uniflorum

From bulbs of Tristagma uniflorum the known sapogenins tigogenin, neotigogenin and (20S,22R,25S)-5α-spirostan-3β,25-diol, as well as the new (20S,22R,25R)-5α-spirostan-3β,25-diol, (20S,22S,25S)-5α-furostan-22,25-epoxy-3β,26-diol and (20S,22S,25R) -5α-furostan-22,25-epoxy-3β,26-diol, were isolated and characterized by spectroscopic (IR, ¹H NMR, ¹³C NMR, MS) methods.     

Neo-clerodane diterpenoids from Teucrium salviastrum

From the aerial parts of Teucrium salviastrum six new neo-clerodane diterpenoids, teusalvins A–F, have been isolated, together with the previously known diterpenes teucvidin teucroxide. The structures of teusalvins A [15,16-epoxy-2,6-diketo-neo- cleroda-13(16),14-dien-20,12S-olide-18R19-hemiacetal], B [15,16-epoxy-2β-hydroxy-6-keto-neo-cleroda-13(16),14-dien-20,12S-olide-18R,19-hemiacetal], C [15,16-epoxy-6β,18,19-trihydroxy-neo-cleroda- 3,13(16),14-trien-20,12R-olide], D [15,16-epoxy-2β,6β,18,19-tetrahydroxy-neo-cleroda-3,13(16),14-trien-20,12S-olide], E [15,16-epoxy-2β,6β,12S,18-tetrahydroxy-neo-cleroda-3,13(16),14-trien-20,19-olide] and F [15,16; 19,2α-diepoxy-6β,8-dihydroxy-neo-cleroda-3,13(16),14-trien-20,12S-olide] were established mainly by spectroscopic means and, in the case of teusalvin F, by X-ray diffraction.     

(22<Emphasis Type="Italic">R</Emphasis>,23<Emphasis Type="Italic">R</Emphasis>)-3β-hydroxy-22,23-epoxy-5α-ergost-8(14)-en-15-one: Improved synthesis and toxicity to MCF-7 cells

The chemical synthesis of (22R,23R)-3β-hydroxy-22,23-epoxy-5α-ergost-8(14)-en-15-one from (22A)-3β-acetoxy-5α-ergosta-7,14,22-triene was improved. The stages of obtaining and isomerization of (22A)-3β-acetoxy-14α15α-epoxy-5α-ergosta-7,22-diene were optimized. The introduction of (22R,23R)-epoxide cycle was carried out by alkaline treatment of intermediate (22S,23R)-3β,23-diacetoxy-22-iodo-5α-ergost-8(14)-en-15-one. In cells of human breast carcinoma MCF-7, (22R,23R)-3β-hydroxy-22,23-epoxy-5α-ergost-8(14)-en-15-one showed a high toxicity (TC₅₀ = 0.4±0.1 μM at 48-h incubation in serum-free medium).     

New withanolides from a cross of a South African chemotype by chemotype II (Israel) in Withania somnifera

Three new withanolides have been isolated from hybrids obtained by crossing a chemotype of Withania somnifera received from South Africa and chemotype II originating in Israel. The compounds have been characterized as 4β,20α-dihydroxy-1-oxo-5β,6β-epoxy-20R,22R-witha-24-enolide, 20α-hydroxy-1,4-dioxo-5β,6β-epoxy-20R,22R-witha-2,24-dienolide, and 20α-hydroxy-1,4-dioxo-5β,6β-epoxy-20R,22R-witha-2-enolide. The major steroid of the plant is withanolide D, while the other known withanolides present are 4β,20α-dihydroxy-1-oxo-5β,6β-epoxy-20R,22R,24S,25R-witha-2-enolide and withaferin A. The structures assigned to the new compounds are based on spectral evidence, analysis of their fragmentation under electron impact, and on chemical correlation with known compounds. The formation of these withanolides in this new hybrid is discussed briefly.     

Dammarane triterpenes from Cabralea canjerana (Vell.) Mart. (Meliaceae): Their chemosystematic significance

The stem of Cabralea canjerana (Vell.) Mart. yielded three new dammarane triterpenes 20S,24S-epoxy-7β,25-dihydroxy-3,4-secodammar-4(28)-en-3-oic acid, 20S,24S-epoxy-7β,15α,25-trihydroxy-3,4-secodammar-4(28)-en-3-oic acid and 20S,24R-epoxy-7β,22ξ,25-trihydroxy-3,4-secodammar-4(28)-en-3-oic acid, which were identified on the basis of spectroscopic methods. The known dammarane triterpenes ocotillone, eichlerianic acid, shoreic acid and the sterols sitosterol, campesterol, stigmasterol, sitostenone and stigmast-5-en-3-one were also isolated and identified. The branches yielded the above three known dammaranes and eichlerialactone. The dammaranes in C. canjerana display strong similarities with Trichilieae tribe, which contains several dammaranes. The data reported herein thus provide firm support for placing Cabralea within the subfamily Melioideae, Trichilieae tribe.     

Configurational studies on red algae carotenoids

The configurations of (6′R)-β,ε-carotene, (3′R,6′R)-β,ε-caroten-3′-ol (α-cryptoxanthin), (3R,3′R,6′R)-β,ε-carotene-3,3′-diol (lutein), (3R)-β,β-caroten-3-ol (β-cryptoxanthin), (3R,3′R)-β,β-carotene-3,3′-diol (zeaxanthin) and all-trans (3S,5R,6S,3′R)-5,6-epoxy-5,6-dihydro-β,β-carotene-3,3′-diol (antheraxanthin) were established by CD and ¹H NMR studies. The red algal carotenoids consequently possessed chiralities at each chiral center (C-3, C-5, C-6, C-3′, C-6′), corresponding to the chiralities established for the same carotenoids in higher plants. Two post mortem artifacts from Erythrotrichia carnea were assigned the chiral structures (3S,5R,8R,3′R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol [(8R)-mutatoxanthin] and (3S,5R,8S,3′R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol [(8S)-mutatoxanthin]. This is the first well documented report of a naturally occurring β,ε-caroten-3′-ol (¹H NMR, CD, chemical derivatization).     

A neo-clerodane glucoside and neo-clerodane diterpenoids from Teucrium flavum subsp. Glaucum

From the aerial part of Teucrium flavum subsp. glaucum a new neo-clerodane diterpenoid, teuflavin, and a new 19-nor-neo-clerodane glucoside, teuflavoside, have been isolated, besides the previously known diterpene teuflin. The structures of teuflavin (19-acetoxy-4α,18:15,16-diepoxy-6β-hydroxy-3-keto-neo-cleroda-13(16),14-diene-20,ξ,12S-hemiacetal) and teuflavoside (18-acetoxy-15,16-epoxy-19-nor-neo-cleroda-4,13(16),14-trien-20,12S-olid-6β-yl-2′-O-acetyl-β-d-glucopyranoside) were established by chemical and spectroscopic means and by correlation with known compounds. In addition, the previously known flavone salvigenin has also been obtained from the same source.     

22,23-Epoxides of Sitosterol and Related 7-Oxygenated Δ5-Sterols

(22S,23S)-22,23-Epoxysitosterol, (22R,23R)-22,23-epoxysitosterol, (22S, 23S)-22,23-epoxy-7-ketositosterol, (22R,23R)-22,23-epoxy-7-ketositosterol, (22S, 23S)-22,23-epoxy-7α-hydroxysitosterol, (22S,23S)-22,23-epoxy-7β-hydroxysitosterol, and (22R, 23R)-22,23-epoxy-7β-hydroxysitosterol were synthesized. Their ¹H and ¹³C NMR and the mass spectra of their trimethylsilyl derivatives were studied.     

The withanolides of Withania somnifera chemotypes I and II

Seven steroidal lactones of the withanolide series have been isolated as minor constituents of the leaves of Withania somnifera Dun. (Solanaceae) chemotype I, along with the major component withaferin A. Structures have been assigned to the new compounds: withanolide N (17α,27-dihydroxy-1-oxo-20R,22R-witha-2,5,14,24-tetraenolide) (6a) and withanolide O (4β,17α-dihydroxy-1-oxo-20R,22R-witha-2,5,8(14),24-tetraenolide) (7a). Similarly the leaves of W. somnifera chemotype II afforded three new withanolides along with the major component withanolide D (9a) and trace amounts of withanolide G (10). The new compounds are: 27-hydroxywithanolide D(4β,20α,27-trihydroxy-1-oxo-5β,6β-epoxy-20R,22R-witha-2,24-dienolide) (11a), 14α-hydroxywithanolide D (4β,14α,20α-trihydroxy-1-oxo-5β,6β-epoxy-20R,22R-witha-2,24-dienolide) (12a) and 17α-hydroxywithanolide D (4β,17β,20α-trihydroxy-1-oxo-5β,6β-epoxy-20S,22R-witha-2,24-dienolide) (13a). Whereas all the withanolides of chemotype I are unsubstituted at C-20 (20α-H), those of chemotype II possess an OH at this position (20α-OH).     

Isolation and structural elucidation of cucurbitaxanthin a and b from pumpkin cucurbita maxima

Two new carotenoids, cucurbitaxanthin A [(3S,5R,6,R3′R)-3,6-epoxy-5,6-dihydro-β,β-carotene-5,3′-diol] and cucurbitaxanthin B [(3S,5R,6R,3′S,5′R,6′S)-3,6,5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β-β-carotene-5,3′-diol] have been isolated from the pumpkin Cucurbita maxima.     

Cucurbitane-type triterpenoids from the aerial parts of Momordica charantia L.

Six new cucurbitane-type triterpenoids (1–6), together with two known analogues (7 and 8) were isolated from the aerial parts of Momordica charantia L. The structures of new compounds were identified as cucurbita-6,24-dien-3β,23-diol-19,5β-olide (1), (19R)-5β,19-epoxy-19-methoxycucurbita-6,24-dien-3β,23-diol (2), (19S)-5β,19-epoxy-19-methoxycucurbita-6,24-dien-3β,23-diol (3), (19R)-5β,19-epoxy-19-isopropoxycucurbita-6,24-dien-3β,23-diol (4), 3β,23-dihydroxy-5-methoxycucurbita-6,24-dien-19-al (5) and (19R)-7β,19-epoxy-19-methoxycucurbita-5,24-dien-3β,23-diol (6), by extensive MS, 1D and 2D NMR spectroscopic technologies. This is the first report of the isolation of tetracyclic triterpenoids possessing a 7β,19-epoxy system, viz., 6, from M. charantia L.     

Passiflorine,a new glycoside from Passiflora edulis

Passiflorine, a new glycoside isolated from P. edulis, was shown by chemical and spectroscopic considerations to be (22R), (24S)-22,31-epoxy-24-methyl-1α,3β,24,31-tetrahydroxy-9,19-cyclo-9β-lanostan-28-oic acid β-d-glucosyl ester (1).     

Absolute configuration of heteroxanthin and diadinoxanthin

The absolute configurations of heteroxanthin ((3S,5S,6S,3′R)- 7′,8′-didehydro-5,6-dihydro-β,β-carotene-3,5,3′,6′-tetrol) ex Euglena gracilis and of diadinoxanthin ((3S,5R,6S,3′R)-5,6-epoxy-7′,8′-didehydro-5,6-dihydro-β,β-carotene-3,3′-diol) from the same source have been established by chemical reactions, hydrogen bonding studies, ¹H NMR and CD. Two previously unknown carotenoids (artefacts?) from Trollius europaeus, assigned the structures (3S,5S,6S,3′S,5′R,6′R)-6,7-didehydro-5,6,5′,6′-tetrahydro-β,β -carotene-3,5,6,3′,5′-pentol and its 5R epimer, served as useful models.     

Characterization of chlorinated valepotriates from Valeriana jatamansi

HPLC–PDA–MS and TLC analysis were used to look for minor cytotoxic chlorinated valepotriates from whole plants of Valeriana jatamansi (syn. Valeriana wallichii DC.). This resulted in isolation of 15 chlorinated valepotriates, designated as chlorovaltrates A-O, together with six known analogues, (1S,3R,5R,7S,8S,9S)-3,8-epoxy-1,5-dihydroxyvalechlorine, volvaltrate B, chlorovaltrate, rupesin B, (1S,3R,5R,7S,8S,9S)-3,8-epoxy-1-O-ethyl-5-hydroxyvalechlorine, and (1R,3R,5R,7S,8S,9S)-3,8-epoxy-1-O-ethyl-5-hydroxyvalechlorine. Their structures were elucidated by spectroscopic methods including homo- and heteronuclear two-dimensional NMR experiments. Chlorovaltrates K-N, chlorovaltrate and rupesin B showed moderate cytotoxicity against lung adenocarcinoma (A 549), metastatic prostate cancer (PC-3M), colon cancer (HCT-8) and hepatoma (Bel 7402) cell lines with IC₅₀ values of 0.89–9.76 μM.     

Occurrence of some mono-cis-isomers of asymmetric C40-carotenoids

The 9-cis-isomers of antheraxanthin [(3S,5R,6S)-5,6-epoxy-5,6- dihydro-β, β-carotene-3,3′-diol] and lutein epoxide [(3S,5R,6S, 3′R,6′R)-5,6-epoxy-5,6-dihydro-β, ε-carotene-3,3′-diol] were found to occur without their 9′-cis counterparts in the non-photosynthetic tissues of several higher plants. 9-cis-lutein [(3R,3′R,6′R)- β,ε-carotene-3,3′-diol], on the other hand, was observed together with its 9′-cis counterpart in the samples investigated. The qualitative distribution of carotenoids is also reported.     

Δ5-7-Ketosterols with modified side chain: The synthesis and the effects on viability and cholesterol biosynthesis in Hep G2 cells

(22E)-3β-Hydroxysitosta-5,22-dien-7-one, (22R,23R)-3β,22,23-trihydroxysitost-5-en-7-one, and (22R,23R)-3β-hydroxy-22,23-isopropylidenedioxysitost-5-en-7-one were synthesized. The cytotoxicity and effects on cholesterol biosynthesis of the resulting 7-ketosterols, 7-ketocholesterol, and (22S,23S)-3β-hydroxy-22,23-oxidositost-5-en-7-one were studied in hepatoblastoma Hep G2 cells.     

New steroid glycosides from the starfish Fromia milleporella

Two new steroid glycosides from the starfish Fromia milleporella collected in the Seychelles were isolated and characterized: milleporoside A, (20R, 24R)-29-O-[3-O-methyl-β-D-xylopyranosyl-(1→4)-3-O-methyl-β-D-xylopyranosyl]-24-ethyl-5α-cholestane-3β,4β,6α,8,15β,16β,29-heptaol, and milleporoside B, (20R, 24R)-(22E)-28-O-[3-O-methyl-β-D-xylopyranosyl-(1→4)-3-O-methyl-β-D-xylopyranosyl]-24-methyl-5α-cholest-22-ene-3β,4β,6α,8,15β,16β,28-heptaol. The structures of the glycosides were determined from their spectra and a comparison with spectral characteristics of known compounds. These compounds exhibit a moderate cytostatic activity toward the embryos of the sea urchin Strongylocentrotus intermedius.     

A unique immuno-stimulant steroidal sapogenin acid from the roots of Asparagus racemosus

A new steroidal sapogenin molecule 1 having unique characteristics, 21-nor and unusual C19 carboxylic acid has been isolated from the roots of Asparagus racemosus. On the basis of chemical evidence, extensive spectroscopic analysis including two dimensional (2D) NMR and X-ray studies of single crystal, the structure of 1 was determined as (1S,2R,3S,8S,9S,10S,13S,14S,16S,17R,22R,25R)-21-nor-18β,27α-dimethyl-1β,2β,3β-trihydroxy-25-spirost-4-en-19β-oic acid. 1 crystallizes in monoclinic space group P2₁ with a = 9.295(2), b = 11.238(2), c = 11.376(2) Å; β = 91.993(4)°, Z = 2, D_cal = 1.344 Mg/m³. The structure was solved by direct methods and refined by full-matrix least-squares procedure to a final R-value of 0.0561 for 4064 observed reflections. 1 was tested against the type of immune responses generated during treatment in normal and immune-suppressed animals and detailed biological activity evaluation suggests it to be a potent immunostimulator.     

Cycloartane-type glycosides from Astragalus schottianus

Three new cycloartane-type triterpene glycosides were isolated from the roots of Astragalus schottianus Boiss. Their structures were established as 20(R),25-epoxy-3-O-β-d-xylopyranosyl-24-O-β-d-glucopyranosyl-3β,6α,16β,24α-tetrahydroxycycloartane (1), 20(R),25-epoxy-3-O-[β-d-glucopyranosyl(1 → 2)]-β-d-xylopyranosyl-24-O-β-d-glucopyranosyl-3β,6α,16β,24α-tetrahydroxycycloartane (2), 3-O-β-d-xylopyranosyl-3β,6α,16β,20(S),24(S),25-hexahydroxycycloartane (3) by the extensive use of 1D and 2D-NMR techniques and mass spectrometry.     

Revised structures of daturalactone and 12-oxowithanolide

Recently Dhar et al. reported the isolation of two new steroidal lactones from the leaves of Datura quercifolia HBK and formulated them as 5α,12α,17α-trihydroxy-1-oxo-6α, 7α-epoxy-22 S-witha-2,24-dienolide and 5α,17α-dihydroxy-1, 12-dioxo-6α,7α-epoxy-22 S-witha-2,24-dienolide on the basis of UV, IR, NMR and MS studies. Further detailed chemical and spectral studies have led to revised structures, namely 5α, 12α-dihydroxy-1-oxo-6α,7α: 24α, 25α-diepoxy-20 S, 22 R-with-2-enolide and 5α-hydroxy-1, 12-dioxo-6α, 7α: 24α, 25α-diepoxy-20 S, 22 R-with-2-enolide, respectively, for the above two compounds.