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A new oligostilbene trimer, malaysianol F (1), together with ten known stilbenes (2–11), were successfully separated and purified from the acetone extract of the lianas of Gnetum microcarpum. Malaysianol D (2) was isolated for the first time in Gnetum plants. The tanninless crude extract (52.5 g) was fractionated using a vacuum liquid chromatography (VLC) technique to give five major fractions. Fraction 2 (4.68 g), 3 (4.79 g) and 4 (9.29 g) were all subjected to further isolation and purification using VLC, column chromatography (CC) and repetitive radial chromatography (RC) techniques with the best solvent system to yield malaysianol F (1) (6.2 mg), malaysianol D (2) (62.5 mg), malaysianol E (3) (2.4 mg), ε-viniferin (4) (10 mg), resveratrol (5) (6.5 mg), gnetol (6) (3.5 mg), gnetucleistol C (7) (12.2 mg), isorhapontigenin (8) (8 mg), cuspidan B (9) (3.2 mg), parvifolol D (10) (4.8 mg) and gnetifolin M (11) (2.5 mg). Their structures were determined on the basis of the analysis of spectral evidence by extensive NMR data analyses and comparison with the related published data. Several compounds were tested for anti-inflammatory activity. Their inhibitory effect on Prostaglandin E2 (PGE2) was tested using radioimmunoassay techniques. Compound 6 exhibited significant concentration-dependent inhibitory effects on PGE2 production with IC50 values of 1.84 µM comparable with the positive control, indomethacin (IC50 1.29 µM). [ABSTRACT FROM AUTHOR]

A new oligostilbene trimer, malaysianol F (1), together with ten known stilbenes (2–11), were successfully separated and purified from the acetone extract of the lianas of Gnetum microcarpum. Malaysianol D (2) was isolated for the first time in Gnetum plants. The tanninless crude extract (52.5 g) was fractionated using a vacuum liquid chromatography (VLC) technique to give five major fractions. Fraction 2 (4.68 g), 3 (4.79 g) and 4 (9.29 g) were all subjected to further isolation and purification using VLC, column chromatography (CC) and repetitive radial chromatography (RC) techniques with the best solvent system to yield malaysianol F (1) (6.2 mg), malaysianol D (2) (62.5 mg), malaysianol E (3) (2.4 mg), ε-viniferin (4) (10 mg), resveratrol (5) (6.5 mg), gnetol (6) (3.5 mg), gnetucleistol C (7) (12.2 mg), isorhapontigenin (8) (8 mg), cuspidan B (9) (3.2 mg), parvifolol D (10) (4.8 mg) and gnetifolin M (11) (2.5 mg). Their structures were determined on the basis of the analysis of spectral evidence by extensive NMR data analyses and comparison with the related published data. Several compounds were tested for anti-inflammatory activity. Their inhibitory effect on Prostaglandin E2 (PGE2) was tested using radioimmunoassay techniques. Compound 6 exhibited significant concentration-dependent inhibitory effects on PGE2 production with IC50 values of 1.84 µM comparable with the positive control, indomethacin (IC50 1.29 µM).

Phytochemical study on the EtOAC-soluble extract of the leaves of Gnetum gnemon furnished the isolation of a new phenylheptanoid, gnetumal (1), along with five known compounds (2–6). Their isolation was carried out by using the column chromatography and their structures were elucidated based on the basis of the spectral interpretation. Bioactivity assay of these compounds indicated that gnetumal (1) and p-coumaric acid (5) possessed more potent tyrosinase inhibitory activity, with IC50 values of 31.6 and 2.3 µM, respectively, than that of a positive control kojic acid (IC50; 44.6 µM). [ABSTRACT FROM AUTHOR]

• The stilbenoids were isolated from the rhizome of Gnetum africanum. • Separation was performed by centrifugal partition chromatography and Prep. HPLC. • Structure was investigated by NMR, vibrational- and electronic- circular dichroism. • Isolated stilbenoids have been tested for their iron chelating activity. • Two novel diastereomeric stilbenoid glucosides were discovered. In a continuing search for neuroprotective stilbenoids, two uncommon diastereomeric stilbenoid glucosides, africanoside A (1) and B (2) as well as fifteen known stilbenes, E -resveratrol, E -gnetifolin E, E -piceid, E -resveratroloside, E -gnetifolin K, E -gnetol, E -isorhapontigenin, E -isorhapontin, E -isorhapontigenin-4′- O -glucopyranoside, E -gnetin C, E -bisisorhapontigenin B, E -gnemonoside A, E -gnemonoside C, E -gnemonoside D, and E -gnetin E, were isolated from rhizomes of Gnetum africanum , using a combination of centrifugal partition chromatography and preparative HPLC. The structure of these two stilbenoids was investigated by NMR, vibrational circular dichroism (VCD), and electronic circular dichroism (ECD) experiments. The absolute configurations of 1 , and 2 were established by VCD as (7a S ,8a S) and (7a R ,8a R), respectively. Compound 1 significantly chelated Fe(II) at 100, 250 and 500 μM. The ability of stilbenoids to chelate ferrous ions which are implicated in physiopathological hallmark of Alzheimer's disease provides useful data for potential treatment. [ABSTRACT FROM AUTHOR]

India is the home of numerous medicinally significant plants. These plants are used by people from over centuries. Among these plants, we have Gnetum ula (G. ula) which is found in India (Western Ghats). It belongs to the Gnetaceae family with one genus (Gnetum) and approximately 40 species. It is valued for its taxonomic distinctiveness and outstanding biological interest. Conventionally, it is extensively used to treat several ailments such as arthritis, jaundice, rheumatism, inflammation, etc. Initial phytochemicals analysis of Gnetum ula (G. ula) displayed the existence of saponins, tannins, resin and alkaloids, etc. Although, the plant has less economic significance. It has no official monograph and less scientific reports. These backdrops lead to lacking the attention for the plant during policy framing for conservation. Hence, the present article is an effort to compile and review the morphology, uses and importance in Gnetum ula and also explores the phytochemicals present in various species of Gnetum. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fifteen new and eight known stilbenes were isolated from Gnetum parvifolium. • Compound 12 is the first stilbene dimer connected through a benzyl group. • Twelve compounds showed significant anti-neuroinflammatory activities. • Compound 10 with the most potent activity was selected for further research. Phytochemical investigation on the aerial parts of Gnetum parvifolium led to the isolation of 15 new and eight known structurally diverse stilbenes. The isolated compounds comprised (E)- or (Z)-stilbene (1 – 6 , 15 – 20), dihydrostilbene (21), phenylbenzofuran (7 , 8 , 22), benzylated stilbene (9 – 11), benzylated stilbene dimer (12), and nitrogen-containing stilbene (13a , 13b , 14) types. The structures of the new compounds (1 – 12 , 13a , 13b , 14) were established through spectroscopic analyses and experimental and calculated ECD data. Compound 12 is the first stilbene dimer connected through a benzyl group. In the anti-neuroinflammatory activity assay, compounds 4 , 5 , 9 – 11 , 13b , and 16 – 21 displayed significant inhibitory effects against LPS-induced NO release in BV-2 microglial cells, with IC 50 values of 0.35–16.1 μM. Compound 10 had the most potent activity (IC 50 = 0.35 μM), and the further research indicated that it could decrease the mRNA levels of iNOS, IL-1 β , IL-6, and TNF- α in a dose-dependent manner. [ABSTRACT FROM AUTHOR]

This article describes the complete chloroplast genome of Gnetum luofuense. The G. luofense plastome was 114,795 bp in length, containing a large single copy region (66,103 bp) and a small single copy region (9438 bp), separated by two inverted repeat regions (19,627 bp). The genome lost all ndh genes and contained 116 genes, including 68 protein-coding genes, 40 tRNA genes, and eight rRNA genes. The GC content was 33.3%, 12 genes all contained an intron, ycf3 gene contained two introns while rps12 was a transpliced gene. Phylogenetic analysis using 61 concatenated protein-coding genes suggests that G. luofuense with the rest of other gnetophytes were sister to or nested within all conifers.

Phytochemical investigation of the trunks from Gnetum latifolium led to the isolation of a novel phenolic glucoside, 2 E -2,4-di-(3,4-dihydroxyphenyl)but-2-en-1-yl- O - β -D-glucopyranoside ( 1 ), along with five known stilbene derivatives ( 2-6 ). Their structures were determined mainly using high-resolution electrospray ionisation mass spectrometry and nuclear magnetic resonance spectroscopic analyses, followed by comparisons of observed spectral data with reported values. The novel compound 1 in G. latifolium was found to be useful as a chemotaxonomic marker. Biological evaluation revealed that compound 6 had remarkable inhibitory effects on nitric oxide production, with a half-maximal inhibitory concentration (IC 50 ) value of 4.85 ± 0.20 µM, which was much higher than that of the positive control dexamethasone (IC 50 = 14.20 ± 0.54  µ M).

The morphological plasticity that can occur in pollen of Gnetum due to harmomegathy demands a comparative overview of pollen characters in Gnetum when studying systematics, particularly when fossil pollen grains are taken into account. Using LM and SEM, we studied acetolyzed and dry and rehydrated non-acetolyzed pollen grains of eight Gnetum spp. in Thailand. They are subspheroidal, inaperturate, microechinate monads with blunt-ended microechini. In acetolyzed and non-acetolyzed pollen grains, the raised exine regions and the ridge–like folds appear to be characteristic of the dehydrated state, whereas a psilate surface between microechini is representative of the hydrated state. Although we were able to measure and record some variation in average values of certain features of all the pollen studied and in some characters of the dehydrated specimens, the general morphological similarity of all the examined Gnetum pollen makes it difficult to establish any systematic significance. Nonetheless, their continuous tectum supports the molecular phylogenetic information that suggests Asian Gnetum spp. are monophyletic. This study presents the first report of the pollen morphology of Gnetum microcarpum Blume and G. tenuifolium Ridl. © 2018 The Linnean Society of London, Biological Journal of the Linnean Society , 2018, XX , 000–000. [ABSTRACT FROM AUTHOR]

A new genus and two new species of the subfamily Diptilomiopinae (Acari: Diptilomiopidae) from China's Hainan Island are described and illustrated. They are Dividilobus parvifolius gen. nov. and sp. nov. on Gnetum parvifolium (Warb.) C. Y. Cheng (Gnetaceae) and Vimola samarangensis sp. nov. on Syzygium samarangense(Blume.) Merr. et Perry (Myrtaceae). Both of the two new species are vagrant on leaf lower surface. No damage to the host was observed. A key to species of Vimola is provided. [ABSTRACT FROM AUTHOR]

Four new stilbeno-phenylpropanoids, gnetumonins A−C ( 1 − 3 ) and (−)-gnetucleistol F ( 4 ), together with two known compounds, gnetupendin A and (+)-gnetofuran A, were isolated from the caulis of Gnetum montanum Markgr. (Gnetaceae). The structures of those new compounds were established by extensive analysis of MS, 1D and 2D NMR spectroscopic data. The relative configurations of 1 − 3 were elucidated by means of the analysis of shielded effect correlating their key 1 H NMR shift changes. [ABSTRACT FROM AUTHOR]

The development of drug-resistant strains is rising and the search for new and novel ways of fighting new or reemerging microbes goes on. A hope of treating such multidrug-resistant infections came from plants mediated nanoparticles since nature is a generous source which provides a variety of chemical compounds that can be used for new drug discovery. Silver nanoparticles are reported to possess antiviral, antibacterial, antifungal, antiparasitic, larvicidal activity and anticancer properties. We reported green synthesis of silver nanoparticles mediated food plants Megaphrynium macrostachyum, Corchorus olitorus, Ricinodendron heudelotii, Gnetum bucholzianum, and Ipomoea batatas and their antibacterial efficacy against the Enterobacteriaceae Escherichia coli. The nature and size of the obtained nanoparticles are discussed as well as their Minimum Inhibitory Concentration (MIC) and the Minimum Bactericide Concentration (MBC) values considering their application in medical industry. [ABSTRACT FROM AUTHOR]

The economically important gymnosperm Gnetum L. is distributed in humid tropical forests of Africa. Its leaves are used as commercialized vegetables and greatly alleviate poverty for local people. Previously, the number of species recognized in Africa was uncertain, and Gnetum africanum Welw. and G. buchholzianum Engl. had been variously, and erroneously, applied to specimens. Based on recent morphological studies, species limits were clarified and two new African species, Gnetum interruptum E.H.Biye and G. latispicum E.H.Biye, were described. The purpose of this study was to determine species limits, to investigate potential infraspecific variation in wild African Gnetum species and to determine which features distinguish them in order to assess the validity of four species recognized by Biye et al. (Pl Syst Evol 300(2):263-272, 2014). Sixty-seven morphological characters were scored for a total of 175 (56 male and 119 female) specimens and analysed using cluster, principal components and principal coordinates analyses. Four distinct clusters of Gnetum specimens were recognized that correspond to the species now described as G. africanum, G. buchholzianum, G. interuptum and G. latispicum. A lack of geographical correlation with subclusters as well as their structure suggests there is no justification for recognizing infraspecific taxa. Characters that describe features of the spikes should be used to differentiate between and identify the species in Africa. In view of the high levels of utilization of two species and rarity of a third, it is urgent to assess the threat status of Gnetum species in Africa and to design appropriate conservation strategies to conserve these economically valuable plants. [ABSTRACT FROM AUTHOR]

O Município de Presidente Figueiredo, no Estado do Amazonas, foi visitado durante três anos consecutivos, de 1996 a 1999, com o objetivo de se obter amostras botânicas da área, para estudos no Subprojeto "Elaboração de Revisões e Monografias Taxonômicas" com a finalidade de se elaborar uma Flórula para o Município. As coleções feitas neste período encontram-se depositadas no acervo do Herbário do INPA e as informações gerais sobre os taxa aqui estudados foram complementadas com as obtidas das coleções feitas anteriormente por outros pesquisadores. Para a família Annonaceae Juss. (Magnoliopsida) foram identificadas 39 espécies distribuídas em 15 gêneros. Destes, Duguetia A. St. Hill., Guatteria Ruiz & Pavon, Annona L., Unonopsis R.E.Fries e Xylopia L.destacaram-se pela diversidade em espécies, sendo os dois primeiros representados por oito e seis espécies, respectivamente, e os três últimos, com quatro espécies. A família Gnetaceae Lindl. (Gimnospermae) está representada no Município apenas pelo gênero Gnetum L., com a espécie G. leyboldii Tul.The Township of Presidente Figueiredo, in the State of Amazonas, was visited for three consecutive years, from 1996 to 1999, with the aim of acquiring botanical samples from the area, in order to carry out studies in the "Taxonomic Monographies and Revisions Preparation" SubProject, for the purpose of preparing a survey of the flora. Collections pertaining to the present work are deposited at INPA's herbarium and, general information on the taxa studied here were complemented with those obtained from earlier collections conducted by other researchers. Thirty nine (39) species distributed into 15 genera were identified for the family Annonaceae Juss. (Magnoliopsida). Of these, Duguetia A. St. Hill., Guatteria Ruiz & Pavon, Annona L., Unonopsis R.E.Fries and Xylopia L. stood out on account of their species diversity, the former two were represented by eight and six species respectively, and the latter three by four species each. Family Gnetaceae Lindl. (Gimnospermae) is only represented in the surveyed township by genus Gnetum L., with species G. leyboldii Tul.

O Município de Presidente Figueiredo, no Estado do Amazonas, foi visitado durante três anos consecutivos, de 1996 a 1999, com o objetivo de se obter amostras botânicas da área, para estudos no Subprojeto "Elaboração de Revisões e Monografias Taxonômicas" com a finalidade de se elaborar uma Flórula para o Município. As coleções feitas neste período encontram-se depositadas no acervo do Herbário do INPA e as informações gerais sobre os taxa aqui estudados foram complementadas com as obtidas das coleções feitas anteriormente por outros pesquisadores. Para a família Annonaceae Juss. (Magnoliopsida) foram identificadas 39 espécies distribuídas em 15 gêneros. Destes, Duguetia A. St. Hill., Guatteria Ruiz & Pavon, Annona L., Unonopsis R.E.Fries e Xylopia L.destacaram-se pela diversidade em espécies, sendo os dois primeiros representados por oito e seis espécies, respectivamente, e os três últimos, com quatro espécies. A família Gnetaceae Lindl. (Gimnospermae) está representada no Município apenas pelo gênero Gnetum L., com a espécie G. leyboldii Tul.

Gnetum L. is a genus of economic importance distributed in the humid rainforests of Central Africa. The African species of Gnetum are dioecious climbers and only two species ( Gnetum africanum Welw. and G. buchholzianum Engl.) have been described previously. The names G. africanum and G. buchholzianum have been applied interchangeably to similar morphological forms of Gnetum specimens in Africa or on duplicates of specimens causing taxonomic confusion. The nomenclature of Gnetum species in Africa is thus in need of reappraisal. Morphological descriptions are based on examination of over 300 specimens from various herbaria, mainly B, BR, FHI, J, K, LISC, P, PRE, WAG and YA. The original applications of the names Gnetum africanum and Gnetum buchholzianum are clarified and two new African species ( Gnetum interruptum E.H. Biye sp. nov. and Gnetum latispicum E.H. Biye sp. nov.) are described on the basis of morphological features. A key to the African species is provided and the main characters, such as the shape and size of spike that are essential in the recognition of species in the genus Gnetum in Africa as well as the importance of conservation are discussed. These species are assessed as threatened and at a high risk of global extinction according to the IUCN Red List categories and criteria, and are in need of conservation measures for their protection. [ABSTRACT FROM AUTHOR]

The neotropical liana Gnetum leyboldii (Gnetaceae) is a gymnosperm that resembles angiosperms in wood anatomy, overall morphology, and seed dispersal mechanism. Like other woody lianas, seedlings germinate in the shaded forest understory and start climbing towards the canopy, being exposed to sites with extreme differences in light conditions. However, the extent of physiological and structural adjustment to contrasting light conditions in the early regeneration stages of Gnetum is unknown. To answer this question, we analyzed seedling growth and photosynthetic responses using a common garden experiment with two light regimes: full sun and low light (20% of full sun) at La Selva Biological Station, Costa Rica. We also characterized the germination pattern of this species. We monitored one and half-month old seedlings for four months. Leaf structure finely adapted to light treatments, but gas exchange properties were buffered by large seed reserves, which dominated biomass distribution (about 50% of the total biomass), followed by stem (27%), leaf (16%) and root biomass (6%) across light conditions. The presence of large seeds and the low photosynthetic rates of seedlings in both environments show that G. leyboldii is specialized to exploit deep shade. More research is needed to determine if the patterns found in G. leyboldii are typical of similar lianas that initially exploit deep-shaded understories in their ascension to the canopy. [ABSTRACT FROM AUTHOR]

This article describes the complete chloroplast genome of Gnetum luofuense. The G. luofense plastome was 114,795 bp in length, containing a large single copy region (66,103 bp) and a small single copy region (9438 bp), separated by two inverted repeat regions (19,627 bp). The genome lost all ndh genes and contained 116 genes, including 68 protein-coding genes, 40 tRNA genes, and eight rRNA genes. The GC content was 33.3%, 12 genes all contained an intron, ycf3 gene contained two introns while rps12 was a transpliced gene. Phylogenetic analysis using 61 concatenated protein-coding genes suggests that G. luofuense with the rest of other gnetophytes were sister to or nested within all conifers. [ABSTRACT FROM AUTHOR]

Majority of autotrophic plants and fungi associate with multiple mycorrhizal partners, with notable exceptions being Gnetum africanum, Pisonia grandis, and Alnus spp from the phytobiont perspective. We hypothesized that an understorey tree species Gnetum gnemon hosts a narrow range of mycobionts as shown in G. africanum and suggested for South American species. Sampling and molecular analysis of G. gnemon root tips revealed that besides Scleroderma spp. this gymnosperm tree associates with several fungal species from unrelated lineages. However, all Scleroderma isolates that associate with Gnetum spp. belong to a narrow clade close to Scleroderma sinnamariense. Our results demonstrate for the first time that specificity for mycobionts may substantially differ within an ectomycorrhizal plant genus. [ABSTRACT FROM AUTHOR]

Abstract: Four new oligostilbenes, macrostachyols A–D (1–4) along with six known stilbenoids (5–10), were isolated from the roots of Gnetum macrostachyum. These compounds were also evaluated for their cytotoxicity towards HeLa and KB cell lines. Only compound 4 showed the significant cytotoxicity to HeLa cells with IC50 value of 4.13μM. [Copyright &y& Elsevier]

The present study was undertaken to evaluate in vitro antioxidant activity of methanolic extract from leaves of four plants viz. Clerodendron colebrookianum Walp. (Verbinaceae), Gnetum gnemon L. (Gnetaceae), Sarcochlamys pulcherrima (Roxb.) Gaud. (Urticaceae), Garcinia lancifolia (Don) Roxb. (Cluciaceae), from Cachar district, Assam, India. DPPH (1,1-diphenyl 2-picrylhydrazyl) radical scavenging capacity, reducing power assay (RPA) and photochemiluminescence (PCL) assay were used for evaluating in vitro antioxidant activity. Total phenolic content (TPC) was estimated by Folin-Ciocalteu's method. Sarcochlamys pulcherrima showed highest antioxidant activity (DPPH EC50 9.70 ±1.51ppm), as compared to C. colebrookianum (121.05 ±1.09ppm), G. gnemon (255.99 ±0.82ppm), and G. lancifolia (344.96 ±0.76ppm). Highest activity of S. pulcherrima was also supported by RPA and PCL and highest TPC (0.33 mg gallic acid equivalent/mg of dry extract) amongst the plants, indicated that phenolic compound are mainly responsible for the activity. [ABSTRACT FROM AUTHOR]

A new flavonoid, named 5,7,2'-trihydroxy-5'-methoxyflavone (1), was isolated from the acetone extract of the lianas of Gnetum macrostachyum together with 5,7,4'-trihydroxy-3'-methoxyflavanone (2) and seven known stilbenoids (3-7). The structure of the new compound was determined by interpretation of its spectral data and chemical transformation. The isolated compounds showed radical scavenging activity against DPPH with IC50 values in the range of 0.21-19.90 mM. [ABSTRACT FROM AUTHOR]

Bennettitales is an extinct group of seed plants with reproductive structures that are similar in some respects to both Gnetales and angiosperms, but systematic relationships among the three clades remain controversial. This study summarizes characters of bennettitalean plants and presents new evidence for the structure of cones and seeds that help clarify relationships of Bennettitales to flowering plants, Gnetales, and other potential angiosperm sister groups. Bennettitales have simple mono- or bisporangiate cones. Seeds are borne terminally on sporophylls. They have a unique structure that includes a nucellus with a solid apex, no pollen chamber, and a single integument, and they are clearly not enclosed by a cupule or other specialized structures. Such features differ substantially from Gnetales, flowering plants, and the seed fern Caytonia, providing no compelling evidence for the origin of the angiospermous camel. Cladistic tests were performed to assess the strength of the "anthophyte hypothesis" and possible relation- ships of Bennettitales, Gnetales, and Caytonia to flowering plants. Our results do not support the anthophyte hypothesis for the origin of angiosperms by a transformation of fertile organs that were already aggregated into a cone or flower-like structure. However, the anthophyte topology of the seed plant tree continues to be supported by morphological analyses of living and extinct taxa. [ABSTRACT FROM AUTHOR]

Two new stilbene dimers, named bisisorhapontigenin A (1) and cis shegansu B (2), together with gnetuhainin P (3) and gnetulin (4), were isolated from the lianas of Gnetum cleistostachyum C. Y. Cheng. Their structures were elucidated by means of spectroscopic evidences, including UV, IR, MS, 1H NMR, 13C NMR, NOE and 2D NMR, respectively. The pharmacological activities of compounds 1, 2 and 3 also have been tested. [ABSTRACT FROM AUTHOR]

Three new stilbene derivatives, named gnetucleistol A ( 1 ), B ( 2 ) and C ( 3 ), together with four known compounds, gnetifolin A ( 4 ), p -hydroxycinnamic acid ( 5 ), piceatannol ( 6 ) and resveratrol ( 7 ), were isolated from Gnetum cleistostachyum C.Y. Cheng (Gnetaceae). Their structures were elucidated on the basis of spectroscopic evidence (EI-MS, UV, IR, NOE, 1 H, 13 C and 2D NMR). [ABSTRACT FROM AUTHOR]

Pollen grains of six species ofGnetum,G. parvifolium,G. hainanense,G. luofuense,G. pendulum,G. cleistostachyumandG. montanum, collected from China were examined using light, scanning and transmission electron microscopy. Pollen grains ofGnetumare subspheroidal or irregular-apolar, inaperturate, 11.21–22.44 µm in long axis and 9.34–20.47 µm in short axis. The exine surface is covered with spinules, 0.50(0.30–0.71) µm long spaced on average 1.12(0.81–1.46) µm apart. The exine is about 0.55 µm thick and comprises ectexine and endexine. The ectexine includes a thin tectum and an infratectal granular layer. The tectum protrudes outwards, forming the spinules. The endexine is composed of discontinuous lamellae, with lacunae between lamellae. The pollen grains ofGnetumare compared with those ofEphedraandWelwitschia, and also those of the ANITA Group of angiosperms, including Amborellaceae, Nymphaeales, Illiciales, Trimeniaceae and Austrobaileyaceae. The exine ultrastructures ofGnetum,EphedraandWelwitschiaare quite similar, consisting of tectum, granular layer and lamellated endexine. The exine ultrastructure ofGnetumis also similar to that ofNymphaea colorata(Nymphaeaceae) in the transitional region between the proximal and distal poles, but differs from that of Amborellaceae,Illicium religiosum(Illiciaceae),Schisandra(Schisandraceae), Trimeniaceae and Austrobaileyaceae. This comparison of exine ultrastructure provides new evidence for consideration of the relationship betweenGnetumand the ANITA Group. © 2004 The Linnean Society of London,Botanical Journal of the Linnean Society, 2004,146, 415–425. [ABSTRACT FROM AUTHOR]

The first new isorhapontigenin dimer glucoside gnetupendin D ( 1 ) and a stilbene dimer coupled by a resveratrol and an oxyresveratrol with a cis -dihydrobenzofuran were obtained from the lianas of Gnetum pendulum C. Y. Cheng (Gnetaceae), along with nine known compounds. Their structures and stereochemistry were elucidated by chemical and spectral evidence, especially 2D NMR spectroscopic techniques. Pharmacological activities on anti-inflammation have been tested. [ABSTRACT FROM AUTHOR]

Four stilbene derivatives, gnemonols K and L (resveratrol trimers), M (isorhapontigenin dimer), and gnemonoside K (glucoside of resveratrol trimer) together with eleven known stilbenoids and a lignan were isolated from the acetone, methanol and 70% methanol soluble parts of the root of Gnetum gnemon (Gnetaceae). The structures of the isolates were determined by spectral analysis. The antioxidant activity of the stilbenoids on lipid peroxide inhibition and super oxide scavenging activity were also investigated. [Copyright &y& Elsevier]