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PubMed2003

The pollination ecology of an assemblage of grassland asclepiads in South Africa.

The KwaZulu-Natal region of South Africa hosts a large diversity of asclepiads (Apocynaceae: Asclepiadoideae), many of which are endemic to the area. The asclepiads are of particular interest because of their characteristically highly evolved floral morphology. During 3 months of fieldwork (November 2000 to January 2001) the flower visitors and pollinators to an assemblage of nine asclepiads at an upland grassland site were studied. These observations were augmented by laboratory studies of flower morphology (including scanning electron microscopy) and flower colour (using a spectrometer). Two of the specialized pollination systems that were documented are new to the asclepiads: fruit chafer pollination and pompilid wasp pollination. The latter is almost unique in the angiosperms. Taxa possessing these specific pollination systems cluster together in multidimensional phenotype space, suggesting that there has been convergent evolution in response to similar selection to attract identical pollinators. Pollination niche breadth varied from the very specialized species, with only one pollinator, to the more generalized, with up to ten pollinators. Pollinator sharing by the specialized taxa does not appear to have resulted in niche differentiation in terms of the temporal or spatial dimensions, or with regards to placement of pollinaria. Nestedness analysis of the data set showed that there was predictability and structure to the pattern of plant-pollinator interactions, with generalist insects visiting specialized plants and vice versa. The research has shown that there is still much to be learned about plant-pollinator interactions in areas of high plant diversity such as South Africa.

Animals↗

PubMed2003

Internal oxygen transport in cuttings from flood-adapted várzea tree species.

Tree species from the Central Amazon inundation areas are subjected to extreme flooding, with trees being partially submerged for up to 10 months. The rapidly advancing floodwater table at the onset of the aquatic phase interrupts the inward diffusion of oxygen from the atmosphere to submerged plant parts. Salix martiana (Leyb.) (Salicaceae) and Tabernaemontana juruana ((Markgr.) Schumann ex J. F. Macbride) (Apocynaceae), tree species typical of Amazon floodplains, respond to low oxygen concentrations by forming adventitious roots capable of longitudinal oxygen transport. Cuttings of these tree species were subjected to simulated flooding and the oxygen concentration of the root cortex was temporally monitored by oxygen microelectrodes that penetrated the roots. Changes in the floodwater table made it possible to localize precisely the entry points of atmospheric oxygen. Under experimental conditions, mathematical description of the transport kinetics revealed that longitudinal transport of O2 in both species was mainly attributable to diffusion. Based on the finding that diffusion was inhibited by a small increase in the floodwater table, we conclude that internal oxygen transport during a rising water table is only attainable when adventitious roots are continuously and rapidly developed, as is the case in S. martiana. In T. juruana, slow growth of adventitious roots and low root porosity suggest that other adaptations are required to overcome long flooding periods.

Adaptation, Physiological↗

PubMed2000

Anvirzel, an extract of Nerium oleander, induces cell death in human but not murine cancer cells.

The purpose of this study was to examine the mechanism(s) and differential cell-killing effects of Anvirzel, an extract of oleander (Nerium oleander; family-Apocynaceae), and its derivative compound Oleandrin on human, canine and murine tumor cells. Cells received different concentrations of Anvirzel (1.0 ng/ml to 500 microg/ml) or Oleandrin (0.01 ng/ml to 50 microg/ml) in both continuously treated and pulse-treated/recovery cultures. The cytotoxicity of these compounds was then determined. Both Anvirzel and Oleandrin were able to induce cell killing in human cancer cells, but not in murine cancer cells; the cell-killing potency of Oleandrin was greater than that of Anvirzel. Canine oral cancer cells treated with Anvirzel showed intermediate levels of response, with some abnormal metaphases and cell death resulting from the treatment. From these results we conclude that Anvirzel and Oleandrin act in a species-specific manner, and while testing the effectiveness of a new compound for cancer treatment, one must use not only murine but a variety of cancer cells, including those of human origin.

Animals↗

PubMed2006

An insect countermeasure impacts plant physiology: midrib vein cutting, defoliation and leaf photosynthesis.

One type of specialised herbivory receiving little study even though its importance has frequently been mentioned is vein cutting. We examined how injury to a leaf's midrib vein impairs gas exchange, whether impairment occurs downstream or upstream from injury, duration of impairment, compared the severity of midrib injury with non-midrib defoliation, and modelled how these two leaf injuries affect whole-leaf photosynthesis. Leaf gas exchange response to midrib injury was measured in five Asclepiadaceae (milkweed), one Apocynaceae (dogbane), one Polygonaceae and one Fabaceae species, which have been observed or reported to have midrib vein cutting injury in their habitats. Midrib vein injury impaired several leaf gas exchange parameters, but only downstream (distal) from the injury location. The degree of gas exchange impairment from midrib injury was usually more severe than from manually imposed and actual insect defoliation (non-midrib), where partial recovery occurred after 28 d in one milkweed species. Non-midrib tissue defoliation reduced whole-leaf photosynthetic activity mostly by removing photosynthetically active tissue, while midrib injury was most severe as the injury location came closer to the petiole. Midrib vein cutting has been suggested to have evolved as a countermeasure to deactivate induced leaf latex or cardenolide defences of milkweeds and dogbanes, yet vein cutting effects on leaf physiology seem more severe than the non-midrib defoliation the defences evolved to deter.

Analysis of Variance↗

PubMed1979

Purification and properties of strictosidine synthase, the key enzyme in indole alkaloid formation.

A new enzyme, strictosidine synthase, which catalyzes the synthesis of 3-alpha(S)-strictosidine from tryptamine and secologanin was isolated from the soluble protein extract of Catharanthus roseus cell suspension cultures and was purified approximately 50-fold by ammonium sulfate fractionation, column chromatography on DEAE-cellulose. Ultrogel AcA34 and isoelectric focusing. The apparent molecular weight of the enzyme was 34000. The pH optimum was 6.8, apparent Km values for tryptamine and secologanin were 2.3 mM and 3.4 mM respectively for the enzyme to synthesize strictosidine. Strictosidine synthase shows high substrate specificity. No apparent cofactor requirement could be demonstrated. Of several enzyme inhibitors tested, only p-chloromercuribenzoate inhibited the enzyme. The enzyme was relatively stable and could be stored at -20 degrees C for periods of up to 1 year without appreciable loss of catalytic activity. The enzyme was demonstrated to occur in suspension cultures of 15 different species belonging to 9 different genera of the indole-alkaloid-producing subfamily Plumerioideae of the Apocynaceae family. This enzyme is responsible for the synthesis of strictosidine the key intermediate in the formation of the majority of monoterpenoid indole alkaloids occurring in the plant kingdom.

Cells, Cultured↗

PubMed1985

The selective antagonism of bradykinin action on rat isolated uterus by crude Mandevilla velutina extract.

A crude aqueous alcoholic extract of Mandevilla velutina (Apocynaceae) rhizomes produced a concentration-dependent displacement to the right of the concentration-response curve to bradykinin (Bk) in the isolated uterus of the rat. Schild analysis of the data revealed a linear relationship (r = 0.99) and yielded a pA2 value of 3.3 + 0.08 (- log g ml-1) but the slope differed significantly from unity. The anti-Bk action was of rapid onset and was reversible upon washout. Contractions induced by acetylcholine, oxytocin, angiotensin II and BaCl2 were unaffected by the extract. This represents the first report of a selective Bk antagonist of plant origin. The isolation of the active principle(s) may result in a useful pharmacological tool for elucidating the physiological and physiopathological roles of endogenous Bk.

Animals↗

PubMed1988

The competitive antagonistic effect of compounds from Mandevilla velutina on kinin-induced contractions of rat uterus and guinea-pig ileum in vitro.

1. Pure non-peptide compounds obtained in crystal form from the crude extract of the plant Mandevilla velutina (Apocynaceae) were analysed for their antagonistic effects on rat uterine and guinea-pig smooth muscle contractions induced by bradykinin (Bk), lisyl-bradykinin (L-Bk), acetylcholine (ACh), oxytocin and histamine, in vitro. 2. Pre-incubation of rat uterine muscle with compounds MV 8608, MV 8609, MV 8610, MV 8611 and MV 8612 (5 to 40 micrograms ml-1) caused parallel and concentration-dependent rightward displacements of the Bk concentration-response curves (1 to 1000 nM). Schild plots of these data were linear (correlation close to 1) and yielded nominal pA2 values (g ml-1) of 5.7, 5.6, 5.4, 5.7 and 5.3, respectively. Compounds MV 8608, MV 8611 and MV 8612 (5 to 20 micrograms ml-1) also caused concentration-dependent and parallel displacements to the right of the concentration-response curve to L-Bk (1 to 10,000 nM). The Schild plots were linear and furnished nominal pA2 values (g ml-1) of 5.4, 5.8 and 5.1, respectively. With the exception of the antagonist effect of compound MV 8606 against Bk-induced contraction, all compounds behaved as simple competitive kinin antagonists since the calculated slopes were not different from unity. 3. In the guinea-pig ileum, both MV 8608 and MV 8612 (5 to 20 micrograms ml-1), produced concentration-dependent rightward displacements of the concentration-response curve to Bk (0.1 to 1000 nM) when the experiments were performed in the presence but not in the absence of atropine (2.5 microM). However, in contrast to the result obtained in the rat uterus, compound MV 8608 also caused a significant reduction of the maximal response to Bk. The Schild plot for compound MV 8612 was linear (correlation close to unity) and furnished a nominal pA2 value (g ml-1) of 5.3 and a slope not different from unity. 4. In rat uterine muscle, compounds MV 8608 and MV 8612 at concentrations producing marked rightward displacements of the kinin concentration-response curves (10 and 20 micrograms ml-1), did not influence the uterine contractile response to oxytocin or ACh, indicating some selectivity towards kinin receptors. Similarly, compound MV 8612 (10 and 20 ygml 1) did not interfere with the sensitivities or the maximal responses to ACh and histamine in the guinea-pig ileum, whereas compound MV 8608 (10 and 20ug ml-1) caused a slight reduction of ACh- and histamine-induced maximal contractions, allied to decrease of the sensitivity to histamine at concentrations of 20pgml-1 or more. 5. These results extend our previous data, indicating the existence of several non-peptide compounds in the crude extract of Mandevilla velutina that act as simple, competitive, selective and reversible kinin receptor antagonists in the rat isolated uterus and guinea-pig ileum smooth muscle.

Acetylcholine↗

PubMed2000

Ibogaine: complex pharmacokinetics, concerns for safety, and preliminary efficacy measures.

Ibogaine is an indole alkaloid found in the roots of Tabernanthe Iboga (Apocynaceae family), a rain forest shrub that is native to western Africa. Ibogaine is used by indigenous peoples in low doses to combat fatigue, hunger and thirst, and in higher doses as a sacrament in religious rituals. Members of American and European addict self-help groups have claimed that ibogaine promotes long-term drug abstinence from addictive substances, including psychostimulants and opiates. Anecdotal reports attest that a single dose of ibogaine eliminates opiate withdrawal symptoms and reduces drug craving for extended periods of time. The purported efficacy of ibogaine for the treatment of drug dependence may be due in part to an active metabolite. The majority of ibogaine biotransformation proceeds via CYP2D6, including the O-demethylation of ibogaine to 12-hydroxyibogamine (noribogaine). Blood concentration-time effect profiles of ibogaine and noribogaine obtained for individual subjects after single oral dose administrations demonstrate complex pharmacokinetic profiles. Ibogaine has shown preliminary efficacy for opiate detoxification and for short-term stabilization of drug-dependent persons as they prepare to enter substance abuse treatment. We report here that ibogaine significantly decreased craving for cocaine and heroin during inpatient detoxification. Self-reports of depressive symptoms were also significantly lower after ibogaine treatment and at 30 days after program discharge. Because ibogaine is cleared rapidly from the blood, the beneficial aftereffects of the drug on craving and depressed mood may be related to the effects of noribogaine on the central nervous system.

Adult↗

PubMed1999

Isolation of opioid-active compounds from Tabernaemontana pachysiphon leaves.

A procedure for prefractionation of crude plant extracts by centrifugal partition chromatography (CPC) has been developed to enable rapid identification of known-positive compounds or false-positive compounds and to increase the chance of identifying minor unknown-active compounds. The study explored the use of CPC as a tool in the prefractionation step before investigation of bioactivity. Fractions obtained by CPC from an ethanolic extract of Tabernaemontana pachysiphon Stapf (Apocynaceae) were screened by means of an opiate-receptor-binding assay and an adenosine A1-receptor-binding assay. Fractions containing fatty acids, which had false-positive effects on the assay, were identified, as were unknown-positive fractions from which two opioid-active compounds, tubotaiwine and apparicine, were subsequently isolated. The affinities (Ki) of tubotaiwine and apparicine at the opiate receptor were 1.65 +/- 0.81 and 2.65 +/- 1.56 micromol, respectively. Both alkaloids had analgesic activity in the abdominal constriction test in mice. CPC prefractionation led to the rapid isolation of two opioid-active compounds, tubotaiwine and apparicine, from the unknown-positive fraction; false-positive fractions were rapidly identified. Both tubotaiwine and apparicine had affinity for adenosine receptors in the micromolar range and also had in-vivo analgesic activity in mice.

Alkaloids↗

PubMed2001

Antidepressant effects of apocynum venetum leaves in a forced swimming test.

An extract of the leaves of Apocynum venetum L. (Apocynaceae) markedly shortened the immobility time of male rats in a forced swimming test (FST) in a dose range of 30-125 mg/kg, indicating a possible antidepressant activity. This effect was comparable to that of the tricyclic antidepressant imipramine (20 mg/kg). Neither imipramine (20 mg/kg) nor the Apocynum extract in various doses (30, 60, 125 mg/kg) produced any overt behavioural change or motor dysfunction in the open field test. This result confirms the assumption that the antidepressant effect of an Apocynum extract in the FST is specific. Further, it can be speculated that this effect might be related to hyperoside and isoquercitrin which are major flavonoids in the extract.

Animals↗

PubMed1990

Cardiac glycosides and pregnanes from Adenium obesum (studies on the constituents of Adenium. I).

Cardiac glycosides and pregnanes from the roots and the stems of Adenium obesum Roem. et Schult. were investigated. Among 30 cardiac glycosides including 15 known glycosides and 15 new combinations of the known aglycones and sugars, the structures of 11 glycosides were elucidated. Oleandrigenin beta-gentiobiosyl-beta-D-thevetoside was the main glycoside. Neridienone A and 16,17-dihydroneridienone A, common pregnanes in Apocynaceae, were also isolated.

Cardiac Glycosides↗

PubMed2001

Studies on the constituents of bark of Parameria laevigata Moldenke.

One new trimeric proanthocyanidin, epicatechin-(2beta-->O-->7, 4beta-->6)-epicatechin-(2beta-->O--->7, 4beta-->8)-epicatechin (5) and two new tetrameric proanthocyanidins, epicatechin-(2beta-->O-->7, 4beta-->8)-[epicatechin-(4beta-->6)]-epicatechin-(4beta-->8)-epicatechin, named as parameritannin A-1 (6), and epicatechin-(2beta-->O-->5, 4beta-->6)-[epicatechin-(2beta-->O-->7, 4beta-->8)]-epicatechin-(4beta-->8)-epicatechin, named as parameritannin A-2 (7), have been isolated from the bark of Parameria laevigata Moldenke (Apocynaceae) along with the two known dimers, proanthocyanidin A-2 (1) and proanthocyanidin A-6 (2), and two trimers, cinnamtannin B-1 (3) and aesculitannin B (4). These structures were elucidated by spectral and chemical evidence.

Anthocyanins↗

PubMed2002

[The plant origins of herbal medicines and their quality evaluation].

The caulis (stem and leaf) of Trachelospermum jasminoides (Lindl.) Lem. (Apocynaceae) is listed as the plant origin of Luoshiteng in the Chinese Pharmacopeia. However, preparations from the caulis of Ficus pumila L. (Moraceae) or Psychotria serpens L. (Rubiaceae) are distributed on the Chinese market. The fruit of Forsythia suspensa Vahl (Oleaceae) is listed as the plant origin of Forsythia Fruit in the Chinese Pharmacopeia, although the fruits of two Forsythia species, F. suspensa and F. viridissima Lindley, are listed as the plant origins in the Japanese Pharmacopeia, and fruits of three Forsythia species, F. viridissima, F. koreana Nakai, and F. suspensa, are listed in the Korean Pharmacopeia. The whole plant of Plantago asiatica L. (Plantaginaceae) is listed as the plant origin of Plantago Herb in the Japanese Phamacopeia, but the whole plants of two Plantago species, P. asiatica and P. depressa Wild, are listed as the plant origins in the Chinese Pharmacopeia. The leaves of two Plantago species, P. lanceolata L. and P. major L., are distributed as Plantain on the European market. Each of these herbal medicines is reviewed based on the differences in plant origins and their quality evaluation from the viewpoints of the morphological properties, chemical components, and biological activities, respectively.

Animals↗

PubMed2004

[Studies on antihypertensive effect of Luobuma (Apocynum venetum L.) leaf extract (3)].

To clarify the mechanisms underlying the antihypertensive effect of Luobuma (Apocynum venetum L. (Apocynaceae)) leaf extract (LLE), we investigated the vasodilator effect of LLE in the rat mesenteric vascular bed, which plays an important role in changes in peripheral resistance and thus the regulation of blood pressure. In the perfused mesenteric vascular bed with active tone and intact endothelium, perfusion of LLE (0.1 ng to 100 mg/ml for 15 min) caused dose-dependent vasodilation, which was abolished by chemical removal of the endothelial layer with perfusion of sodium deoxycholate, but not by N(G)-nitro-L-arginine-methyl ester (L-NAME), a competitive inhibitor of nitric oxide (NO), which instead increased the effect. The LLE-induced vasodilation was partially inhibited by high K(+)-containing Krebs solution and tetraethylammonium (a K(+) channel blocker) and completely by the combination of L-NAME and high K(+)-Krebs solution. However, atropine (a muscarinic acetylcholine receptor antagonist) did not affect the vasodilation. These results suggest that the vasodilation induced by LLE is endothelium-dependent and mediated by endothelium-derived hyperpolarizing factor, which involves the activation of K(+)-channels. The higher concentrations of LLE may enhance NO production/release to cause vasodilation.

Animals↗

PubMed1995

[Chemical studies of indole alkaloids].

Up to now, more than two thousands indole alkaloids having structural variety have been found from the three families of Gentianales: Loganiaceae, Apocynaceae, and Rubiaceae plants. These compounds generally possess characteristic biological activities and many of them are utilized for the medicinal purpose and for the lead-compounds to develop new synthetic drugs. The author of this review has been investigated the alkaloidal constituents of the above mentioned plants native to Japan and overseas countries. Especially, a cooperative work with Thai researchers concerning the plants in Thailand was developed. On the basis of biogenetic consideration of the structures of monoterpenoid indole alkaloids, chemical bond cleavage between the C3-N4 linkage in the C/D ring of indole alkaloids was discovered. It was speculated that, either in biogenesis, the flexibility of the ring-opening compounds having ten membered ring enabled the construction of indole alkaloids having highly strained polycyclic structures. Along with this conception, the syntheses of structurally complex indole alkaloids utilizing a biomimetic procedure have been investigated. In this review, recent results on the chemical synthesis of many skeletally varied Gelsemium alkaloids (Loganiaceae plant) are mainly described.

Alkaloids↗

PubMed1996

[Chemical study of Indonesian medicinal plants].

A series of scientific expeditions in Indonesia for collecting informations and materials concerning locally used medicinal plants and Javanese traditional medicine "jamu" have been carried out by us since 1985. This article reviews pharmacochemical investigations of nine Indonesian medicinal plants: i.e. Pongamia pinnata (Papilionaceae), Fagara rhetza (Rutaceae), Calotropis gigantea (Asclepiadaceae), Beilschmiedia madang (Lauraceae), Caesalpinia major (Fabaceae), Peronema canescens (Verbenaceae), Taxus sumatrana (Taxaceae), Alyxia reinwardtii (Apocynaceae), and Merremia mammosa (Convolvulaceae), which were selected among plant materials collected in those surveys.

Animals↗

PubMedDate not supplied

Suggested pharmacophagy of the African bushhopper Phymateus leprosus (Fabricius) (Pyrgomorphidae, Orthoptera).

The bushhopper Phymateus leprosus (Fabricius) in the field shows a special appetite for the milkweed Asclepias fruticosa. Asclepiadaceae, like Apocynaceae and Scrophulariaceae, contain cardiac glycosides. Raw and purified extracts of these plants phagostimulate larval and adult P. leprosus. We also screened natural and half-synthetic compounds found in those plant extracts. While saponins and sapogenins did not stimulate the animals, many cardiac glycosides and aglycones, offered on filter paper, proved to be phagostimulants.

Animals↗

PubMed2004

Anti-leishmanial activity of alkaloidal extract from Aspidosperma ramiflorum.

Infections due to protozoa of the genus Leishmania are a major worldwide health problem, with high endemicity in developing countries. The drugs of choice for the treatment of leishmaniasis are the pentavalent antimonials (SbV), which present renal and cardiac toxicity. Besides, the precise chemical structure and mechanism of action of these drugs are unknown up to date. In order to find new drugs against leishmaniasis, we have been studying extracts of Brazilian trees. In the present study, we have evaluated the effectiveness of an alkaloid extract of Aspidosperma ramiflorum Muell. Arg. (Apocynaceae), against the extracellular forms promastigotes of L. (L.) amazonensis and L. (V.) braziliensis. The alkaloid extract of A. ramiflorum was much more effective against L. (L.) amazonensis (LD50 < 47 microg/ml) than L. (V.) braziliensis. Based on these in vitro results against L. (L.) amazonensis new studies should be made to find the compounds with anti-leishmanial activity.

Alkaloids↗