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Featured researches published by C.G.A. McNab.


Phytochemistry | 1972

Analysis of six Acacia gum exudates of the series phyllodineae

D.M.W. Anderson; P.C. Bell; C.G.A. McNab

Abstract Gum specimens from Acacia calamifolia, A. difformis, A. falcata, A. mabellae, A. retinodes, and A. rubida have been analysed; the first named belongs to Benthams Series 1, subseries 4C (Calamiformes Uninerves) and the others are in Benthams Series 1, subseries 6F (Uninerves Racemosae). This group of gum exudates, of which A. rubida is the most divergent, is characterized by a low rhamnose content (>2%), low acidity, low intrinsic viscosity, and a high galactose/arabinose ratio, which, for A. calamifolia and A. falcata, is higher than for any other species studied so far. Although these gum species have good solubility, their solutions are of low viscosity and are dark in colour; they are unlikely to be of commercial importance. In the light of the chemical data now available for Acacia gum exudates, A. cyanophylla appears to be a highly anomalous species within the Phyllodineae.


Phytochemistry | 1983

Some highly proteinaceous Acacia gum exudates of the subseries Juliflorae

D.M.W. Anderson; J.G.K. Farquhar; C.G.A. McNab

Abstract Analytical data for the gum exudates from Acacia difficilis , A. dimidiata , A. eriopoda , A. maidenii , A. stipuligera , A. torulosa and A. tumida are presented. Of these, five are highly proteinaceous; they also have high methoxyl contents and very low rhamnose contents. In contrast, A. dimidiata shows no unusual analytical parameters, and A. maidenii gum has alowarabinose content and a high rhamnose content, thus having a sugar composition of the type first observed in the gum from A. saligna . The gum from A. maidenii is also of interest as its analytical data are closely similar to those for A. longifolia , the only other tetramerous member of the subseries Juliflorae to have been studied. The data reported extend even further the unusual ranges of analytical parameters found within the Juliflorae , and confirm its great heterogeneity and chemotaxonomic interest.


Carbohydrate Research | 1971

An analytical study of some Acacia gum exudates of the series Botryocephalae

D.M.W. Anderson; P.C. Bell; C.G.A. McNab

An analytical study has been made of gum specimens from Acacia deanei, A. filicifolia (three specimens), A. leucoclada, A. parramattensis (two specimens), A. parvipinnula, A. silvestris, A. terminalis, and A. trachyphloia, which are species belonging to Series II ({Botryocephalae}) in Benthams classification of the genus. The three specimens from A. filicifolia are all closely similar, but the specimens from A. parramattensis differ appreciably in parameters other than their sugar ratios. Several of the analytical values reported increase considerably the range of values established so far for Acacia gum exudates. The Botryocephalae species give gum exudates of at least 2 chemically distinct types. Group A species (A. deanei, A. parramattensis, A. parvipinnula, and {A. trachyphloia}) have low galactose-arabinose ratios ( 41) but low negative or positive rotations, low intrinsic viscosities and molecular weights, and relatively low nitrogen, methoxyl, uronic anhydride, and rhamnose contents.


Phytochemistry | 1985

The gum exudates from Chloroxylon swietenia, Sclerocarya caffra, Azadirachta indica and Moringa oleifera☆

D.M.W. Anderson; P.C. Bell; M.C.L. Gill; F.J. McDougall; C.G.A. McNab

Abstract Analytical data are presented for the polysaccharide and proteinaceous components of the gum exudates from Chloroxylon swietenia and Sclerocarya caffra, and for the amino acid compositions of the exudates from Azadirachta indica (two specimens) and Moringa oleifera. The gums from C. swietenia and S. caffra contain 4-O-methylglucuronic acid, glucuronic acid, galactose and arabinose; rhamnose is absent. Amino acid analysis shows that proteinaceous material is present in the gums from C. swietenia, S. caffra and M. oleifera despite their low nitrogen content. Hydroxyproline accounts for 28 % of the amino acid content of S. caffra gum. In contrast, A. indica gum has a high nitrogen content but contains very little hydroxyproline.


Phytochemistry | 1986

The hydroxyproline content of gum exudates from several plant genera

D.M.W. Anderson; J. F. Howlett; C.G.A. McNab

Abstract Amino acid compositions are presented for the proteinaceous components of the gum exudates from Albizia glaberrima, A. sericocephala and A. anthelmintica; Aralia elata; Azadirachta indica; Entada africana; Grevillea robusta; Lannea humilis and L. schimperi ; and Moringa oleifera . The gums from four of these genera ( Albizia, Azadirachta, Grevillea and Moringa ) contain low proportions, and the others contain high proportions, of hydroxyproline. High proportions of hydroxyproline were found previously in gum exudates from genera within the Leguminosae ( Acacia, Astragalus and Prosopis ), to which must now be added Entada and Leucaena . In contrast, however, Albizia spp. (Leguminosae) have low proportions of hydroxyproline, whereas the non-leguminous genera Aralia and Lannea have high proportions of hydroxyproline.


Phytochemistry | 1985

The amino acid composition of gum exudates from Prosopis species

D.M.W. Anderson; J.F. Howlett; C.G.A. McNab

Abstract The amino acid compositions of the proteinaceous components of the gum exudates from Prosopis alba, P. chilensis, P. glandulosa, P. laevigata, P. torreyana and P. velutina, and for a sample of commercial gum mesquite, are presented. In agreement with data published previously for the polysaccharide components of their gums, only minor differences in composition are shown by these species. The amino acid compositions are characterized by very high proportions of hydroxyproline and by high proportions of proline and serine; these three amino acids account for 62.5% of those present in the gum from Prosopis velutina. The amino acid compositions of these Prosopis gums are remarkably similar to that established recently for the gum from Acacia senegal (gum arabic).


Carbohydrate Research | 1973

The gum exudates from acacia dealbata and acacia sieberana: corrections to previous analytical data

D.M.W. Anderson; P.C. Bell; G.H. Conant; C.G.A. McNab

Abstract In the light of the analytical data acquired for the gum exudates from a greatly increased number of Acacia species in recent years, the data published for A . sieberana gum in 1939, and for A . dealbata gum in 1966, differ considerably, in several respects, from the range of values established for some closely related species. Seven specimens of gum from A. dealbata and four specimens from A. sieberana have therefore been studied; from the analytical results, it must be concluded that much of the data published earlier for A. dealbata and A. sieberana cannot be regarded as typical of these species.


Phytochemistry | 1984

Some Acacia gum exudates of the section Phyllodineae

D.M.W. Anderson; M.C.L. Gill; C.G.A. McNab; G.L. De Pinto

Abstract Australian gum specimens from Acacia saliciformis, A. xanthina, A. rostellifera, A. murrayana (two specimens differing in the mode of initiation of gum exudation), A. georginae, A. cyclops, A. implexa , and an un-named species (Maslin ‘P31’) have been analysed. The first four of these are placed within Benthams Series 1, subseries 6F, A. georginae within subseries 7E, and the remainder within subseries 7F. These data extend considerably the ranges of the analytical parameters reported previously for phyllodine species. The molecular weights of the gums from A. cyclops and A. implexa are much higher than those reported earlier for South African specimens; this may affect some taxonomic deductions based on their examination. The gum composition of A. saligna can no longer be regarded as atypical of a phyllodinous species; a suggestion that A. saligna should be transferred to the section Juliflorae may require reconsideration. The major difference between the specimens of gum from A. murrayana lies in their nitrogenous content. Data are reported for the amino acid compositions of the gums from A. saliciformis and A. xanthina .


Phytochemistry | 1984

The gum exudates from some Acacia subspecies of the series botryocephalae

D.M.W. Anderson; J.G.K. Farquhar; C.G.A. McNab

Abstract Gum specimens from A. deanei subsp. paucijuga (two samples), A. irrorata subsp. irrorata, and A. dealbata subsp. subalpina have been analysed. There are minor differences between the two specimens from A. deanei subsp. paucijuga, but they, and the gum from A. irrorata subsp. irrorata, have analytical parameters that correspond well with those for species in the proposed Group A within the Botryocephalae. In contrast, the gum from A. dealbata subsp. subalpina conforms well with the analytical parameters established for A. dealbata gum, and the slight analytical differences lead to it being assigned with greater confidence to the proposed Group B. Now that the gum exudates from approximately 40% of the species within the Botryocephalae have been studied and shown to fall into two different types, it is hoped that the chemical data may be meaningful taxonomically.


Food Hydrocolloids | 1986

The amino acid composition of the proteinaceous components of konjac mannan, seed endosperm galactomannans and xanthan gum

D.M.W. Anderson; J. F. Howlett; C.G.A. McNab

Abstract Analytical data are presented for the amino acid compositions of commercial samples of konjac mannan, locust bean (carob) gum, tara gum, Sesbania (Dhaincha) gum and xanthan gum. Konjac mannan contains high proportions of aspartic acid, glutamic acid and glycine. Major amino acids in xanthan gum are alanine, glutamic acid, aspartic acid and glycine. There are similarities in the amino acid compositions of the seed endosperm galactomannans studied; all contain major amounts of glutamic acid, aspartic acid and glycine and similar proportions of all the other amino acids, with the exception of tara gum and Sesbania gum, which contain high proportions of alanine and histidine respectively. All the gums studied have very low hydroxyproline contents, in marked contrast to the values reported previously for the tree exudates from the leguminous genera Acacia (gum arabic), Astragalus (gum tragacanth) and Prosopis (gum mesquite).

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P.C. Bell

University of Edinburgh

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J.F. Howlett

University of Edinburgh

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M.C.L. Gill

University of Edinburgh

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G.H. Conant

University of Edinburgh

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