Steroidal sapogenins from leaves of some species of Agave and Furcraea

The steroidal sapogenins yielded by the leaves of Agave aurea, A. avellanidens, A. cerulata, A. cerulata ssp. subcerulata, A. cocui, A. goldmaniana, A. shawii and Furcraeamacrophylla are recorded. In all these species, hecogenin and tigogenin were the major sapogenins isolated. Gitogenin was found in the extracts of all the leaf samples, except that of A. shawii, and manogenin and 9-dehydromanogenin in all but that of A. cocui. Chlorogenin was isolated from A. cocui, but was not detected in any of the other species examined. Qualitative and quantitative variations were found in the sapogenin contents of extracts of different regions of the same leaves of A. cocui and F. macrophylla. In particular, hecogenin predominated in the basal regions and tigogenin in the apical.     

Steroidal saponins from the whole plants of Agave utahensis and their cytotoxic activity

Phytochemical investigation of the whole plants of Agave utahensis Engelm. (Agavaceae) has resulted in the isolation of 15 steroidal saponins (1-15), including five spirostanol saponins (1-5) and three furostanol saponins (11-13). Structures of compounds 1-5 and 11-13 were determined by spectroscopic analysis and the results of hydrolytic cleavage. The isolated compounds were evaluated for their cytotoxic activity against HL-60 human promyelocytic leukemia cells.     

Steroidal sapogenins from leaves of Agaveae species

The steroidal sapogenins yielded by the leaves of 34 species and 1 cultivar of Agave, 1 species of Beschorneria, 1 species of Doryanthes and 3 species of Furcraea have been studied. Steroidal sapogenins were found in extracts of most of the species examined. Smilagenin, sarsasapogenin, diosgenin, yamogenin, tigogenin, neotigogenin, gloriogenin, gentrogenin, hecogenin, sisalagenin, 9-dehydrohecogenin and gitogenin were detected. Gloriogenin was found only in A. ghiesbrechtii, yamogenin in A. horrida and A. rigidissima, neo-tigogenin in A. horrida and A. toneliana and gitogenin in A. filifera, F. cabua, F. gigantea and F. selloa cv marginata. The highest yield of smilagenin was obtained from both A. haynaldii and A. rigidissima, of sarsasapogenin from A. attenuata, of diosgenin from A. ellemeetiana, of tigogenin from A. haynaldii and of hecogenin from F. cabua.     

Sapogenins of Yucca glauca seeds

From the seeds of Yucca glauca Nutt., sarsasapogenin. markogenin. tigogenin. neo-tigogenin. neo-gitogenin, hecogenin and gloriogenin have been isolated and identified. Sarsasapogenin was the predominant sapogenin. Markogenin and gloriogenin have not been reported in leaves, roots or rhizomes of this species before. Small amounts of a sapogenin believed to be either diosgenin or yamogenin were also detected.     

Steroidal saponins from the leaves of Beaucarnea recurvata

Thirteen steroidal saponins were isolated from the leaves of Beaucarnea recurvata Lem. Their structures were established using one- and two-dimensional NMR spectroscopy and mass spectrometry. Six of them were identified as: 26-O-β-d-glucopyranosyl (25S)-furosta-5,20(22)-diene 1β,3β,26-triol 1-O-α-l-rhamnopyranosyl-(1 → 2) β-d-fucopyranoside, 26-O-β-d-glucopyranosyl (25S)-furosta-5,20(22)-diene 1β,3β,26-triol 1-O-α-l-rhamnopyranosyl-(1 → 2)-4-O-acetyl-β-d-fucopyranoside, 26-O-β-d-glucopyranosyl (25R)-furosta-5,20(22)-diene-23-one-1β,3β,26-triol 1-O-α-l-rhamnopyranosyl-(1 → 2) β-d-fucopyranoside, 26-O-β-d-glucopyranosyl (25S)-furosta-5-ene-1β,3β,22α,26-tetrol 1-O-α-l-rhamnopyranosyl-(1 → 4)-6-O-acetyl-β-d-glucopyranoside, 26-O-β-d-glucopyranosyl (25S)-furosta-5-ene-1β,3β,22α,26-tetrol 1-O-α-l-rhamnopyranosyl-(1 → 2) β-d-fucopyranoside, and 24-O-β-d-glucopyranosyl (25R)-spirost-5-ene-1β,3β,24-triol 1-O-α-l-rhamnopyranosyl-(1 → 2)-4-O-acetyl-β-d-fucopyranoside. The chemotaxonomic classification of B. recurvata in the family Ruscaceae was discussed.     

An aminopeptidase from Agave americana thermodynamic studies

Purified Agave aminopeptidase was characterized with respect to the thermodynamic properties of the reaction catalysed by the enzyme. Kinetic studies were conducted at different temperatures ranging from 7.8 to 45°. The energy of activation, E_a, as well as the constants ΔH, ΔF and ΔS were calculated for both the formation of the enzyme-substrate complex, and the dissociation of the enzyme-product complex. Kinetic studies in buffers with varying dielectric constants enabled the determination of the electrostatic as well as the non-electrostatic components of ΔS. These results fit well into the overall kinetic picture of this enzyme-catalysed reaction as reported previously.     

Steroidal glycosides from the marine sponge Pandaros acanthifolium

The chemical composition of the Caribbean sponge Pandaros acanthifolium was investigated and led to the isolation of seven new steroidal glycosides namely pandarosides A-D (1, 3, 4 and 6) along with the three methyl esters of pandarosides A, C, and D (2, 5 and 7). Their structures were characterized as 3β-[β-glucopyranosyl-(1→2)-β-glucopyranosyloxyuronic acid]-16-hydroxy-5α,14β-poriferast-16-ene-15,23-dione (1) and its methyl ester (2), 3β-[β-glucopyranosyloxyuronic acid]-16-hydroxy-5α,14β-poriferast-16-ene-15,23-dione (3), 3β-[β-glucopyranosyl-(1→2)-β-glucopyranosyloxyuronic acid]-16-hydroxy-5α,14β-cholest-16-ene-15,23-dione (4) and its methyl ester (5), 3β-(β-glucopyranosyloxyuronic acid)-16-hydroxy-5α,14β-cholest-16-ene-15,23-dione (6) and its methyl ester (7) on the basis of detailed spectroscopic analyses, including 2D NMR and HRESIMS studies. Pandarosides A-D and their methyl esters (1-7) are all characterized by a rare 2-hydroxycyclopentenone D-ring with a 14β configuration. The absolute configuration of the aglycon part of pandaroside A (1) was assigned by comparison between experimental and TDDFT calculated circular dichroism spectra on the more stable conformer.     

New steroidal saponins of Agave americana

Two new saponins, agavasaponin E and agavasaponin H have been isolated from the methanolic extract of Agave americana leaves and their structures elucidated. Agavasaponin E is 3-O-[β-d-xylopyranosyl-(1→2glc1)-α-l-rhamnopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→3glc 1)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-α-d-galactopyranosyl]-(25R)-5α-spirostan-12-on-3β-ol, whereas agavasaponin H is 3-O-[β-d-xylopyranosyl-(1→2 glc 1)-α-l-rhamnopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→3 glc 1)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-β-d-galactopyranosyl]-26-O-[β-d-glucopyranosyl]-(25R)-5α-furostan-12-on-3β,22α,26-triol.     

Applications of the hexanic fraction of Agave sisalana Perrine ex Engelm (Asparagaceae): control of inflammation and pain screening

The present study evaluated the anti-inflammatory and analgesic properties of Agave sisalana Perrine in classic models of inflammation and pain. The hexanic fraction of A. sisalana (HFAS) was obtained by acid hydrolysis followed by hexanic reflux. Anti-inflammatory properties were examined in three acute mouse models (xylene ear oedema, hind paw oedema and pleurisy) and a chronic mouse model (granuloma cotton pellet). The antinociceptive potential was evaluated in chemical (acetic-acid) and thermal (tail-flick and hot-plate test) models of pain. When given orally, HFAS (5, 10, 25 and 50 mg/kg) reduced ear oedema (p < 0.0001; 52%, 71%, 62% and 42%, respectively). HFAS also reduced hind paw oedema at doses of 10 mg/kg and 25 mg/kg (p < 0.05; 42% and 58%, respectively) and pleurisy at doses of 10 mg/kg and 25 mg/kg (41% and 50%, respectively). In a chronic model, HFAS reduced inflammation by 46% and 58% at doses of 10 mg/kg and 25 mg/kg, respectively. Moreover, this fraction showed analgesic properties against the abdominal writhing in an acetic acid model (at doses of 5-25 mg/kg) with inhibitory rates of 24%, 54% and 48%. The HFAS also showed an increased latency time in the hot-plate (23% and 28%) and tail-flick tests (61% and 66%) for the 25 mg/kg and 50 mg/kg doses, respectively. These results suggest that HFAS has anti-inflammatory and analgesic properties.     

Novel dammarane-type sapogenins from Panax ginseng berry and their biological activities

Three new dammarane-type sapogenins (1, 3, and 5) together with two known ones (2 and 4) were isolated from the total hydrolyzed saponins extracted from Panax ginseng berry. Their structures were elucidated using a combination of 1D and 2D ¹H and ¹³C NMR spectra and mass spectroscopy as 20(R)-25-methoxyl-dammarane-3β,12β,20-triol (1), 20(R)-25-methoxyl-dammarane-3β,6α,12β,20-tetrol (2), 20(R)-20-methoxyl-dammarane-3β,12β,25-triol (3), 20(R)-20,25-dimethoxyl-dammarane-3β,12β-diol (4), and (12R,20S,24S)-20,24-; 12,24-diepoxy-dammarane-3β-ol (5). Their antitumor activities were evaluated in six human cancer cell lines. The novel compounds 1 and 3 showed significant cytotoxic activity against the six cell lines. The IC₅₀ values of 3 against HepG2, Colon205, and HL-60 were the lowest (8.78, 8.64, and 3.98 μM, respectively). Compounds 1 and 20(S)-25-OCH₃-PPD, which are a pair of configuration isomers, showed a 10- to 100-fold greater growth inhibition than ginsenoside-Rg₃ (an anti-cancer clinical agent in China). The data presented here may be useful for the development of novel anti-cancer agents.     

Properties and partial purification of mevalonate kinase from Agave americana

Mevalonate kinase activity was demonstrated in acetone powder extracts from Agave americana leaves, flowers and scape. ATP was the most effective phosphate donor. The enzyme had an optimum pH of 7.9 in Tris-HCl buffer. Dialysis decreased the ability to phosphorylate mevalonic acid (MVA). Partially purified mevalonate kinase reached maximum activity in the presence of 2 mM Mn²⁺ or 6–8 mM Mg²⁺. Higher concentrations of Mn²⁺ were inhibitory, whereas higher concentrations of Mg²⁺ produced only a small decrease in the activity. The amount of mevalonate-5-phosphate (MVAP) formed depended on protein concentration and incubation time. During short incubations, the MVAP formed increased as protein concentration rose, whereas during prolonged incubations (1–6 hr), there was a decrease in the MVAP formed when a certain amount of protein was exceeded. It is suggested that MVAP formed was hydrolysed by a phosphatase present in the extracts. This interfering activity was eliminated when mevalonate kinase is partially purified. The apparent K_m values of the enzyme from leaves were 0.05 mM for MVA and 0. 14 mM for ATP. Similar K_m values are obtained with partially purified mevalonate kinase. The enzyme was purified by ammonium sulphate precipitation, Sephadex G-100 filtration and DEAE-Sephadex A-50 fractionation.     

Steroidal alkaloids of Marsdenia rostrata

Some of the main constituents of Marsdenia rostrata, originating from two localities, were isolated and identified. The sample from the Toonumbar State Forest in northern New South Wales contains the known alkaloid anabasine and two new steroidal ester alkaloids, rostratine and dihydrorostratine. They were identified as O-acetyl-O-nicotinoylsarcostin and O-acetyl-O-nicotinoyldihydrosarcostin. The sample from the South Coast of N.S.W. yielded the two new ester alkaloids and a number of neutral polyhydroxy pregnane aglycones, one of which has been identified as metaplexigenin, but there was no anabasine.     

Steroidal saponins and ecdysterone from Asparagus filicinus and their cytotoxic activities

Two new spirostanoides, filiasparosides E (1) and F (2), one new furostanoside, filiasparoside G (3), and one new ecdysterone, stachysterone A-20, 22-acetonide (4), together with six known steroidal saponins, asparagusin A (5), filiasparoside A (6), filiasparoside B (7), aspafilioside A (8), aspafilioside B (9), and filiasparoside C (10) were isolated from the roots of Asparagus filicinus Buch.-Ham. Their structures were elucidated on the basis of spectroscopic and chemical evidence. Compounds 1-10 were investigated for their cytotoxicities against human breast adenocarcinoma MDA-MB-231 cell line and compounds 8-10 exhibited cytotoxic activities with IC₅₀ values ranging from 3.4 to 6.6 μM.     

Floral and macroecological evolution within Cyrtanthus (Amaryllidaceae): Inferences from combined analyses of plastid ndhF and nrDNA ITS sequences

One of the most diverse members of Amaryllidaceae is Cyrtanthus Aiton, a large, sub-Saharan Africa genus of approximately 55 species found mostly in South Africa. To investigate phylogenetic and biogeographic relationships within Cyrtanthus, sequence data from the plastid ndhF gene and the ITS nrDNA region for 41 species were analyzed with parsimony, maximum likelihood, and Bayesian-inference approaches. Various recombination detection algorithms were used to test for interspecific hybridization in the ITS alignment. The genus resolved as monophyletic, comprising three poorly to well-supported major lineages: a predominantly Afrotemperate lineage, largely restricted to seasonally moist sites in summer rainfall southern Africa, a subtropical lineage found mostly in nonseasonal rainfall regions, often in dry habitats, and a Cape Floristic Region-centered lineage in which most species are concentrated in the summer-dry to nonseasonal rainfall southwest. The ITS sequence alignment shows no evidence for reticulation between any of the species. Relationships inferred by the molecular data disagree with those derived from morphological data, but agree with previously published groupings based on karyotype morphology. Fitch optimization of selected floral characters on the combined gene tree reveals recurrent patterns of convergence. Ornithophilous floral forms occur in parallel among the three primary clades, putatively sphingophilous species are concentrated in the Afrotemperate lineage in seasonally moist upland grasslands; the brush-type Aeropetes tulbaghia butterfly and inferred long-proboscid fly pollination syndromes are unique in the Cape lineage. Macroecological factors inferred to have influenced the evolution of Cyrtanthus are changes in rainfall seasonality, the advent of fire, and the availability of new habitats at high and low altitudes and in rock-free soils or rock crevices. This study gives greater clarity on relationships within the genus and enables its division into three informal infrageneric groups.     

Incorporation of 5α-furostan-3β,26-diol into tigogenin by digitalis lanata

2,2′,4,4′-³H₄-dihydrotigogenin was converted by Digitalis lanata plants into tigogenin.