Gerald Blunden's research while affiliated with University of Portsmouth and other places

Publications (217)

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As the world desperately searches for ways to treat the coronavirus disease 2019 (COVID-19) pandemic, a growing number of people are turning to herbal remedies. The Artemisia species, such as A. annua and A. afra, in particular, exhibit positive effects against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and COVID-19 rela...
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Naringenin, widely distributed in fruits and vegetables, is endowed with antiviral and other health beneficial activities, such as immune-stimulating and anti-inflammatory actions that could play a role in contributing, to some extent, to either preventing or alleviating coronavirus infection. Several computational studies have identified naringeni...
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Hesperidin and hesperetin are flavonoids that are abundantly present as constituents of citrus fruits. These compounds have attracted attention as several computational methods, mostly docking studies, have shown that hesperidin may bind to multiple regions of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (spike protein, angiotensin-...
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Alzheimer’s disease (AD) is a progressive age-related neurodegenerative disease recognized as the most common form of dementia among elderly people. Due to the fact that the exact pathogenesis of AD still remains to be fully elucidated, the treatment is only symptomatic and available drugs are not able to modify AD progression. Considering the incr...
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Various computational studies, including in silico ones, have identified several existing compounds that could serve as effective inhibitors of the SARS-CoV-2 main protease (M pro ), and thus preventing replication of the virus. Among these, rutin has been identified as a potential hit, having prominent binding affinity to the virus. Moreover, its...
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Plants of the Amaryllidaceae family, have a wide distribution through both tropical and sub-tropical regions of the world. They have also a long and notable place in the history of traditional and Western medicine. Amaryllidaceae alkaloids are a structurally diverse group of plant metabolites with a wide range of biological properties including ant...
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Quercetin, a naturally occurring dietary flavonoid, is well known to ameliorate chronic diseases and aging processes in humans, and its antiviral properties have been investigated in numerous studies. In silico and in vitro studies demonstrated that quercetin can interfere with various stages of the coronavirus entry and replication cycle such as P...
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Plants of the Amaryllidaceae family are promising therapeutic tools for human diseases and have been used as alternative medicines. The specific secondary metabolites of this plant family, called Amaryllidaceae alkaloids (AA), have attracted considerable attention due to their interesting pharmacological activities. One of them, galantamine, is alr...
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The genus Melampyrum, belonging to the Scrophulariaceae family, represents about 25 species of herbaceous annual plants found in the Northern hemisphere. In traditional medicine, aerial parts of Melampyrum species have been used to alleviate rheumatic complaints, symptoms of gout and to treat different skin infections in decoction form [1 – 2]. The...
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Extracts of the calyces of Hibiscus sabdariffa are widely used in folk medicine to combat many illnesses. The active constituents of the extracts have been shown on several occasions to be anthocyanins. In our current studies the biological activities of an extract of H. sabdariffa calyces purchased in Oman, but grown in Sudan, are being compared w...
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Terrestrial plants have proven to be a prolific producer of clinically effective antimalarial drugs, but the antimalarial potential of seaweeds has been little explored. The main aim of this study was to assess the in vitro chemotherapeutical and prophylactic potential of the extracts of twenty-three seaweeds collected from the south coast of Engla...
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A thin-layer chromatographic (TLC)-densitometric method was used for the parallel quantification of rosmarinic acid (RA) and caffeic acid (CA) in crude extracts of Salvia species (Family Lamiaceae), obtained by ultrasonic extraction with 60% methanol. The densitometric measurement was performed in fluorescent mode as it has been published earlier....
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The volatile and semi-volatile terpenoids in the latex of Euphorbia amygdaloides, E. exigua, E. helioscopia, and E. peplus were analyzed by headspace, solid-phase micro-extraction (HS-SPME), coupled with gas chromatography-mass spectrometry. The volatiles were extracted using a 100 microm polydimethylsiloxane SPME fiber under optimized extraction c...
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A collection of Laminariales species was made with examples in each of the presently recognized families of the order. Extracts of each species were examined for betaines, using primarily 'H NMR spectroscopy for their identification. Glycinebetaine was detected in all species tested and would appear to be a consistent feature of the Laminariales. G...
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The effects of Hibiscus sabdariffa (HS) in lowering blood pressure in human and animal hypertension have been documented. This study investigated the effect of the water extract of the dried calyx of HS and Hibiscus anthocyanins (HAs) on left ventricular myocardial capillary length and surface area in spontaneously hypertensive rats (SHRs). Twelve-...
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An aqueous extract of Hibiscus sabdariffa L. is a common beverage in many parts of the world. Reports on its effect on reproduction are conflicting, with anecdotal evidence that the plant is an aphrodisiac, while others report that it is estrogenic, and adversely affects spermatogenesis in rats. We have studied the effect of different concentration...
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The aminoglycoside antibiotic gentamicin (GM) is still widely used against infections by Gram-positive and Gram-negative aerobic bacteria. Its therapeutic efficacy, however, is limited by renal impairment that occurs in up to 30% of treated patients. The drug may accumulate in epithelial tubular cells causing a range of effects starting with loss o...
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Cyanobacteria (= blue-green algae) are prolific producers of structurally distinct and biologically active metabolites. In the continuation of our search for new sources of anti-infective natural products, we have assessed the in vitro antiprotozoal (Plasmodium falciparum, Trypanosoma brucei rhodesiense, T. cruzi, Leishmania donovani) and antituber...
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The cytotoxic activities of the n-hexane, chloroform and aqueous methanolic fractions prepared from the methanolic extract of the leaves of 23 Salvia taxa were studied for their cell growth-inhibitory activity against human cervix adenocarcinoma (HeLa), skin carcinoma (A431) and breast adenocarcinoma (MCF7) cells using the MTT assay. The n-hexane f...
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A steroid-yielding wild yam from British Honduras is shown to be Dioscorea belizensis Lundell. The macroscopical characters of the entire plant and the microscopical characters of the underground organs are described.
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The roots of six species of Salvia (S. argentea, S. aerea, S. cavaleriei, S. constanea, S. trijuga and S. yunnanensis) have been examined for the presence of diterpenoids.Diterpenoids were found in all except S. cavaleriei. Those extracted from S. aerea, S. constanea, S. trijuga and S. yunnanenis were very similar; tanshinone 1 and tanshinone 2A we...
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Aqueous extracts of Euphorbia myrsinites L. (Euphorbiaceae) were tested for molluscicidal activity against Biomphalaria glabrata; LC(50) values of 15.1 and 8.9 ppm were obtained for the stem and leaf extracts, respectively, which are within the WHO limit for an effective molluscicide. However, the extracts were found to be unstable at room temperat...
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In the continuation of our research on seaweeds, crude extracts of 21 brown algae collected from the south coast of England and the west coast of Ireland were screened for in vitro trypanocidal, leishmanicidal and antimycobacterial activities. Mammalian stages of a small set of parasitic protozoa; i.e. Trypanosoma brucei rhodesiense, T. cruzi and L...
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As part of our continuing research on seaweeds, we have screened the crude extracts of 23 red marine algae collected from England and Ireland. The clinically important blood-stage life forms of Trypanosoma brucei rhodesiense, T. cruzi, Leishmania donovani and Mycobacterium tuberculosis were used as test organisms in the in vitro assays. The selecti...
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Ascophyllum nodosum, and to a lesser extent, Laminaria digitata, L. hyperborea and Fucus serratus, are marine algal species utilized in the commercial production of seaweed extracts used in agriculture. Betaines have been shown to be important constituents of these extracts, but there appears to have been no study made on whether there are variatio...
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Different parts of three Ballota species (B. nigra, B. hirsuta, and B. rupestris) have been analyzed for phenylpropanoid content by means of a simple extraction technique and a newly established TLC-densitometric method. The compounds studied were verbascoside (VE), forsythoside B (FB), and caffeoyl-malic acid (CM). The largest amounts were detecte...
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The increased use of natural product in the pharmaceutical industry has led to an increase in demand for screening for bioactive compounds in marine algae. An important economic algae, through chemical composition analysis and their antioxidant activities were investigated in this study. Chemical composition analysis of three algal samples from the...
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Fourteen fern, two horsetail (Pteridophyta), three clubmoss (Lycopodiophyta), nine moss and two liverwort (Bryophyta, Marchantiophyta) species were examined for the presence of betaines. Glycinebetaine was detected in some of the fern, clubmoss, moss and liverwort species, but not in either of the two horsetail species examined. However, trigonelli...
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In the continuation of our search for natural sources for antiprotozoal and antitubercular molecules, we have screened the crude extracts of four green marine algae (Cladophora rupestris, Codium fragile ssp. tomentosoides, Ulva intestinalis and Ulva lactuca) collected from the Dorset area of England. Trypanosoma brucei rhodesiense, Trypanosoma cruz...
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From the ethanol extract of the cauloms of Schisandra chinensis, a novel T-cadinol nerolidol ether has been isolated. Its structure was determined from mass spectrometric and NMR spectroscopic data.
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Gum arabic (GA) is a branched-chain, complex polysaccharide, either neutral or slightly acidic, found as a mixed calcium, magnesium and potassium salt of a polysaccharidic acid. The backbone is composed of 1,3-linked beta-D-galactopyranosyl units. The side chains are composed of two to five 1,3-linked beta-D-galactopyranosyl units, joined to the ma...
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Epidermal features, mesophyll differentiation and calcium oxalate characteristics of 19 species and 12 hybrids of Salix are described. The species and hybrids can be distinguished by the presence or absence of the following epidermal features: striated cuticle; stomata; covering trichomes; beaded anticlinal walls, and diosmin-like njstals. In or ne...
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The leaf anatomy is compared of 35 ppecies and one variety of Agave, three species of Furcraea, one species of Beschorneria and one species of Doryanrhes, four genera assigned to the tribe Agaveae by Hutchinson in his classification of the family Agavaceae. The genera can be readily differentiated by leaf anatomy. There are close similarities betwe...
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The morphology of Dioscorea sylvatica from Natal and the hills in the Lydenburg district of the Transvaal is described, as well as the anatomy of the leaf and stem. Differences were noticed between the Natal and Lydenberg types which are inconsistent with Burkill's classification of the species. From the differences it is suggested that the Lydenbe...
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The detailed anatomy of Yucca glauca leaf, a potential source of medicinally useful steroid precursors, is described. The most useful diagnostic features are papillose epidermal cells, large acicular crystals of calcium oxalate, partially lignified fibres and cells from the modified leaf margins. The characteristic cells of the margins are the epid...
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Ginger (Zingiber officinale Roscoe, Zingiberacae) is a medicinal plant that has been widely used in Chinese, Ayurvedic and Tibb-Unani herbal medicines all over the world, since antiquity, for a wide array of unrelated ailments that include arthritis, rheumatism, sprains, muscular aches, pains, sore throats, cramps, constipation, indigestion, vomiti...
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The aqueous fractions of the dry methanol extracts (500 ppm) of sixty marine algal species were screened for molluscicidal activity against Biomphalaria glabrata, which is an important host of the bilharzia-causing Schistosoma species. The majority of the extracts tested were inactive at the concentration used, but those of Fucus serratus, F. vesic...
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A methanolic extract of Rubus idaeus leaves, when fractionated by column chromatography, yielded two distinct bands containing compounds that demonstrated in vitro, dose dependent, smooth muscle relaxant activity using transmurally-stimulated Guinea pig ileum preparations. From band two, following extensive chromatographic separation, several compo...
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A collection of tropical Angiosperms, mainly collected in Amazonas and Apure States in Venezuela, has been examined for the presence of betaines and N-methylprolines, which were found in 58 out of the 65 species investigated. Betaine yields were generally low, but in the species that contained N-methylprolines, the yields of these compounds were ge...
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A methanol extract of Rubus idaeus leaves had a relaxant activity on transmurally stimulated Guinea pig ileum preparations in vitro. The extract, when fractionated by column chromatography, yielded two distinct bands with pharmacological activity. After extensive column and preparative TLC separation, several compounds with smooth muscle relaxant p...
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A methanol extract of Rubus idaeus leaves was fractionated by column chromatography and the eluted samples were tested for their ability to relax transmurally stimulated Guinea pig ileum preparations in vitro. Two distinct bands of activity were detected. From band one sitosterol and eight triterpenoids were characterized, but only olean-18-ene-1β,...
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N-Methylprolines were detected in all fourteen species of Rhamnaceae tested, representing eleven genera and it is probable that these compounds are a chemotaxonomic feature of the family. Various species in different genera of other families previously reported to contain N-methylprolines were examined for their presence, but these were found as co...
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The bromophenol content of Polysiphonia lanosa, determined by GLC-MS, was shown to vary considerably between late spring and early autumn. The lowest content was found in material collected in early May and then the levels rose until a peak was reached in July. When the extracts were tested for cytotoxicity against DLD-1 cells, a direct correlation...
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Essential oils of Haplophyllum tuberculatum (Forssk.) A. Juss., produced from plants collected in the United Arab Emirates, were analyzed by GC and GC/MS. The composition of the oils varied considerably. Those obtained from plants collected in May (1997 and 2001) were similar, with α-phellandrene (10.7–32.9%) being the major component and with sign...
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Over 140 Angiosperm species, included in 45 of the 62 orders listed by Engler, have been investigated for the presence of betaines, which were detected in 86% of the species examined and in 43 of the orders. Moreover, betaines were reported earlier in a further seven of the orders. Thus, it can be concluded that betaines are very widely distributed...
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This article reviews the reported phytochemical, pharmacological and toxicological properties of Hibiscus sabdariffa L. (English: roselle, red sorrel; Arabic: karkade), the calyces of which are used in many parts of the world to make cold and hot drinks. Nutritionally, these contain ascorbic acid (vitamin C). In folk medicine, the calyx extracts ar...
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Trans-4-hydroxy-N-methylproline and N-methylproline have been isolated from several Angiosperm species, but the striking feature is the high content of these two proline derivatives, being in excess of 1% of the dry weight of Berchemia zeyheri, Critoniella vargasiana, Hovenia dulcis and Serjania communis and in excess of 0.8% of Berberis aggregata...
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Bioassay-guided fractionation was applied to the cytotoxic chloroform fraction of the red alga Polysiphonia lanosa. The major compounds of the most active fraction were identified using GLC-MS analysis as lanosol (1), methyl, ethyl, and n-propyl ethers of lanosol (1a, 1b, and 1c, respectively), and aldehyde of lanosol (2), although 1b appears to be...
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The steroidal sapogenins obtained by hydrolysis of the saponins found in the leaves of eight species of Cordyline have been studied. With the exception of C. terminalis var. petiolaris, the extracts of all species yielded 1,3-dihydroxy sapogenins, which were usually the predominant compounds. C. terminalis var. petiolaris differed from all the othe...
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From the monohydroxy steroidal sapogenin fraction of Cordyline cannifolia R. Br. leaves, 3-epi-neotigogenin (1a) and 3-epi-tigogenin (1b) were isolated and characterized from tlc, ir, nmr and mass spectral data and by conversion into known spirostanes. Neither compound has been isolated previously from a plant source. In addition, yamogenin and dio...
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From the fruits of Cordyline australis, the new steroidal sapogenin australigenin [5α-spirost-25(27)-ene-1β,3β-diol] has been isolated and characterized from ir, pmr, and mass spectral data. Thirteen other steroidal sapogenins have been identified, including polygenin, 1β-hydroxycrabbogenin, and sceptrumgenin.
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The quaternary ammonium compounds extracted from the British species of Laminariales have been studied. Both laminine and lysine betaine, as their dioxalates, have been isolated from Laminaria hyperborea and characterized by tic and by ir and nmr spectroscopy. Lysine betaine has not been isolated previously from a natural source. Tlc evidence suppo...
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From the aerial parts of Cissampelos pareira L. (Menispermaceae), a chalcone-flavone dimer has been isolated which, mainly from NMR spectroscopic and MS data, was proved to be 2-(4-hydroxy-3-methoxyphenyl)-7-(4-methoxyphenyl)-6-(2-hydroxy-4,6-dimethoxybenzoyl)-furano[3,2-g]benzopyran-4-one. This has been assigned the trivial name cissampeloflavone....
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The seeds of Nigella sativa Linn. (Ranunculaceae), commonly known as black seed or black cumin, are used in folk (herbal) medicine all over the world for the treatment and prevention of a number of diseases and conditions that include asthma, diarrhoea and dyslipidaemia. This article reviews the main reports of the pharmacological and toxicological...
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Aerial parts of 49 species, distributed in 39 genera, all previously included in Scrophulariaceae, but now distributed in several families, have been examined for the presence of betaines. Glycinebetaine was detected in all the plants, but the yield was always low, varying from 0.001% (based on dry weight) from Rhodochitonsanguineum to 0.2% from Rh...
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Sage (Salvia officinalis L., Lamiaceae) is a common medicinal and aromatic plant widely used in foods and in herbal medicinal products. Aerial parts of this plant were gathered in July 1999 in the Botanical Garden of the Institute of Ecology and Botany of the Hungarian Academy of Sciences, Vacratot, Hungary (VBI), where a voucher specimen (L 963/A)...
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The volatile oil compositions of five Stachys species (Stachys officinalis L., St. grandiflora Host., St. byzantina Koch., St. germanica L. and St. sylvatica L.) have been studied using a GC/MS technique. All species gave low yields of oil. From St. officinalis 38 compounds were separated and partly identified, from St. grandiflora 24, St. byzantin...
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Betaines have a widespread distribution in the plant and animal kingdoms. The most studied role of these compounds is that of compatible osmolytes, facilitating adaptation to saline and dry environments. Betaines can be accumulated to levels greater than 5 umol g-1 dry weight, at which concentration they are likely to function as compatible osmolyt...
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A three-year surveillance program assessed the extent of mycotoxin contamination of key foods and feeds grown in Bangladesh. The study also included groundnuts utilized as snack food. In the first two phases of the program the samples collected were analyzed only for aflatoxins, but in the third phase, as well as for aflatoxins, samples were tested...
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From the whole plant of Salvia aegyptiaca, 6-methylcryptoacetalide, 6-methyl-epicryptoacetalide and 6-methylcryptotanshinone have been isolated and characterized, mainly by spectroscopic means. In addition to these novel diterpenoids, the known compounds 3beta-hydroxy-olean-12-en-28-oic acid, 3beta-hydroxy-oleana-11,13(18)-dien-28-oic acid, sitoste...
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The analgesic activity of the methanol and acetone extracts of Leucas inflata L. (family Labiatae) was evaluated in mice using different experimental models. The effect of the two extracts on pentobarbitone-sleeping time, motor activity, sensorimotor coordination, carrageen induced inflammation, and brewer's yeast-induced pyrexia has also been inve...
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Salvia aegyptiaca L. is used for treating various unrelated conditions that include nervous disorders, dizziness, trembling, diarrhoea and piles. This work examines some effects of the crude acetone and methanol extracts of the plant given at single oral doses of 0.25, 0.5,