Medicinal foodstuffs. XXIV. Chemical constituents of the processed leaves of Apocynum venetum L.: absolute stereostructures of apocynosides I and II.
Two new ionone glucosides, named apocynosides I and II, were isolated from the roasted leaves of Apocynum venetum L. together with nine known compounds. The absolute stereostructures of apocynosides I and II were determined by chemical and physicochemical evidence, which included the application of a modified Mosher's method and the circular dichroism helicity rule. (+info)
A bioactive spirolactone iridoid and triterpenoids from Himatanthus sucuuba.
Himatanthus sucuuba is an Amazonian tree with abundant, yet conflicting ethnobotanical information. Investigation of the polar and non-polar constituents led to the isolation of plumericin, a bioactive spirolactone iridoid, and four known pentacylic triterpenes: lupeol acetate, lupeol cinnamate, lupeol beta-phenyl propionate, and alpha-amyrin cinnamate. (+info)
Morphological and ultrastructural diversity of orbicules in relation to evolutionary tendencies in apocynaceae s.L.
Minute granules of sporopollenin, called orbicules, can be observed on the innermost tangential and/or radial walls of secretory tapetum cells. Orbicules were investigated in 62 species (50 genera) of Apocynaceae s.l. using light microscopy, scanning electron microscopy and transmission electron microscopy. Orbicules were found in 43 species (34 genera) distributed amongst the subfamilies Rauvolfioideae, Apocynoideae, Periplocoideae, and in the genus Riocreuxia (Asclepiadoideae). Absence of orbicules is apparent in Secamonoideae and Asclepiadoideae (except Riocreuxia). The orbicule types described are based on observed morphological and ultrastructural variation. Of the six orbicule types previously described, Type I and Type II orbicules are lacking. In the majority of species, Type III orbicules were recorded in addition to Types IV, V and VI. In this study we suggest that embedded Type VI orbicules are more derived. A correlation between orbicule typology and evolutionary tendencies in Apocynaceae s.l. palynology was found. A trend was observed from the presence of Type III orbicules in the majority of species belonging to the basal group of genera characterized by colporate to porate single pollen grains, or 3-6-porate tetrads, towards the more derived embedded Type VI orbicules in the more advanced Periplocoideae genera with multiporate tetrads or pollinia. Orbicule data have proven not to be useful for evaluating tribal delimitation within the Apocynaceae s.l. contrary to the Rubiaceae and Loganiaceae s.l. (+info)
Wrightiamines A and B, two new cytotoxic pregnane alkaloids from Wrightia javanica.
Two new pregnane alkaloids, wrightiamines A (1) and B (2), were isolated from the extract of the tropical Apocynaceous plant Wrightia javanica collected in Thailand, and their structures were elucidated by spectral data. Wrightiamine B (2) was preparaed from 3beta-hydroxy-5alpha-pregnan-20-one to establish the configuration of the C-20 position as S. Wrightiamine A (1) exhibited cytotoxic activity against vincristine-resistant murine leukemia P388 cells. (+info)
Generic delimitations in tuberous Periplocoideae (Apocynaceae) from Africa and Madagascar.
BACKGROUND AND AIMS: The number of genera included in Apocynaceae subfamily Periplocoideae is a matter of debate. DNA sequences are used here as an independent dataset to clarify generic relationships and classification of the tuberous periplocoid genera and to address the question of the phylogenetic interpretation of pollinia formation in Schlechterella. METHODS: Representatives of nearly all African and Malagasy genera of Periplocoideae possessing root tubers were analysed using ITS and plastid DNA sequence characters. RESULTS: Sequence data from non-coding molecular markers (ITS of nrDNA and the trnT-L and trnL-F spacers as well as the trnL intron of plastid DNA) give support for a broad taxonomic concept of Raphionacme including Pentagonanthus. Together with Schlechterella, which is sister to Raphionacme, all Raphionacme-like taxa form a derived monophyletic group of somewhat diverse species. Sister to the Schlechterella/Raphionacme clade is a clade comprising Stomatostemma and the not truly tuberous vine Mondia. In the combined analysis, sister to these two clades combined is a clade formed by Petopentia natalensis and Periploca. CONCLUSIONS: The recent inclusion of the monotypic South African Petopentia in the monotypic Malagasy endemic Ischnolepis is to be rejected. The Malagasy Camptocarpus is sister to the remainder of Periplocoideae in the ITS and combined analyses, and a Malagasy origin for the subfamily is discussed. (+info)
New cytotoxic cardenolide glycoside from the seeds of Cerbera manghas.
A new cytotoxic cardenolide glycoside, 3beta-O-(2'-O-acetyl-alpha-L-thevetosyl)-14beta-hydroxy-7-en-5beta-card-20(22)-en olide, (7,8-dehydrocerberin), together with five known cardenolides, 17beta-neriifolin, deacetyltanghinin, tanghinin, cerberin and 2'-O-acetyl-cerleaside A were isolated from the seeds of Cerbera manghas L. Their structures were elucidated by 1D- and 2D-NMR techniques as well as UV, IR and mass spectral data. 7,8-Dehydrocerberin, deacetyltanghinin and tanghinin exhibited cytotoxic activities against oral human epidermoid carcinoma (KB), human breast cancer cell (BC) and human small cells lung cancer (NCI-H187). (+info)
Characterization of graphislactone A as the antioxidant and free radical-scavenging substance from the culture of Cephalosporium sp. IFB-E001, an endophytic fungus in Trachelospermum jasminoides.
The extracts derived from cultures of 1626 endophytic strains harbored in Trachelospermum jasminoides were assayed for more potent antioxidant and/or free radical-scavenging agents. The free radical-scavenging assessment was carried out using l,l-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical assays, and the antioxidant actions on linoleic acid and human low-density lipoprotein (LDL) models. After extensive spectroscopic analyses, graphislactone A was characterized as the most bioactive secondary metabolite of endophytic Cephalosporium sp. IFB-E001 with its free radical-scavenging (in a dose-dependent manner) and antioxidant activities ascertained in vitro to be stronger than those of butylated hydroxytoluene (BHT) and ascorbic acid, the two positive references coassayed in the study. From the demonstrated efficacy of graphislactone A in preventing and protecting against oxidative injury, it can be predicted that this metabolite could be a potential agent in the management of oxidative damage-initiated diseases. (+info)
Morphological and secretory characterization of extrafloral nectaries in plants of coastal Veracruz, Mexico.
BACKGROUND AND AIMS: Morphological descriptions of the extrafloral nectaries (EFNs) of certain plant species are common in the literature, but they rarely relate morphology with histology, gland distribution and secretory attributes. In this study a morphological/secretory characterization of EFNs occurring on several plant species in a tropical coastal community is made and the implications of gland attributes discussed from a functional perspective. METHODS: The morphology and nectar secretion of the EFNs of 20 plant species are characterized through scanning electron microscopy, histochemical detection of reducing sugars (Fehling's reagent) and nectar volume/concentration estimates. KEY RESULTS: Sixty-five per cent of plant species in coastal communities had EFNs on vegetative structures and 35 % of species had glands on reproductive and vegetative organs. The Fabaceae is the plant family with the most species with EFNs and most diversity of gland morphologies. Four types of vascularized nectaries and four of glandular trichomes are described; sugar-secreting trichomes are characterized using Fehling's technique, and the first descriptions of unicellular and peltate trichomes functioning as EFNs are provided. Glands of ten plant species and six genera are described for the first time. Four plant species possess more than one morphological type of EFN. Eleven species have EFNs in more than one location or organ. More complex glands secrete more nectar, but are functionally homologous to the aggregations of numerous secretory trichomes on specific and valuable plant organs. CONCLUSION: Important diversity of EFN morphology was foundin the coastal plant community studied. Both vascularized and non-vascularized EFNs are observed in plants and, for the latter, previously non-existent morpho-secretory characterizations are provided with a methodological approach to study them. It is recommended that studies relating EFN attributes (i.e. morphology, distribution) with their differential visitation by insects (i.e. ants) and the cost of maintenance to the plants are carried out to understand the evolution of these glands. (+info)