Frontiers
in Natural Product Chemistry
ISSN: 1574-0897
Frontiers in Natural Product Chemistry
Volume 1, 2005
Contents
Editorial
Atta-ur-Rahman, M.Iqbal Choudhary and Khalid M.Khan
[Abstract]
Rhodium-Catalyzed Asymmetric 1,4-Addition of Organometallic
Reagents Pp. 3-17
Tamio Hayashi
[Abstract]
Tandem Stereospecific Radical Cation-Mediated Syntheses of
Oligostilbenoid Dimers Pp.19-30
Noel F. Thomas, Kiew C. Lee, Jean-Frederic F. Weber, Ibtisam
Abdul Wahab, Khalijah Awang, A. Hamid A. Hadi and Pascal Richomme
[Abstract]
Structure and Biological Activity – Diversity Orientated
Synthesis Pp. 31-36
E. Winterfeldt
[Abstract]
The Nitroaldol (Henry) Reaction as the Key Step for the Synthesis
of Some Natural Products Pp. 37-41
Roberto Ballini, Giovanna Bosica, Dennis Fiorini and Alessandro
Palmieri
[Abstract]
Synthesis of Vinblastine Derivatives Pp. 43-48
Hedvig Bölcskei, Lajos Szabo and Csaba Szantay
[Abstract]
Nature as Source and Inspiration for the Synthesis of New
Anticancer Drugs Pp. 51-54
Daniele Passarella, Alessandra Giardini, Giordano
Lesma, Alessandra Silvani and Bruno Danieli
[Abstract]
Stereocontrol in Organic Synthesis Using Silicon Compounds
Pp. 55-64
Ian Fleming
[Abstract] [Download
Full Text]
Natural Photoreceptors: Structure, Function and Applications
Pp. 65-71
Uma S. Palkar
[Abstract]
Molecular Cloning of Cellulase Genes from Trichoderma harzianum
Pp. 73-75
Sibtain Ahmed, Nighat Aslam, Farooq Latif, M.I. Rajoka
and Amer Jamil
[Abstract]
Binding of Betamethasone, Prednisolone and Theophylline to
Bovine Serum Albumin: Plausible Explanations for Mode of Binding
and Drug-drug Interactions Pp. 77-88
Nurun N. Rahman, S. Huda, Khondaker M. Rahman and Mohammad
H. Rahman
[Abstract]
Iron Acquisition and Iron Transport by Bacteria Pp.
89-98
Herbert Budzikiewicz
[Abstract]
Determination of Absolute Configuration of Natural Products
by X-ray Diffraction: A Novel Approach of Incorporating Heavy-Atom-Containing
Solvent Molecules into the Single Crystals and Refinement
of Flack Parameter Pp. 99-106
Suchada Chantrapromma, Hoong-Kun Fun, Surat Laphookhieo,
Saroj Cheenpracha and Chatchanok Karalai
[Abstract]
Researches on the Technology and Bioactive Properties of Phenolic
Lipids Pp. 107-120
J.H.P. Tyman
[Abstract]
Development of Pharmaceuticals from Indonesian Natural Resources,
Genetically Engineered Microbes and Diversification of Palm
Oil Products Pp. 121-132
Ignatius Suharto, and Leonardus B.S. Kardono
[Abstract]
Microbial Transformation of Natural Products- A Tool for the
Synthesis of Novel Analogues of Bioactive Substances Pp.
133-147
Atta-ur-Rahman, M. Iqbal Choudhary and S. Ghulam Musharraf
[Abstract]
Mistletoe Lectins, Structure and Function Pp. 149-162
Wolfgang Voelter, Roland Wacker, Stanka Stoeva, Rania
Tsitsilonis and Christian Betzel
[Abstract]
Polyacetylenes and Sterols from the Aerial Parts of Chrysanthemum
coronarium L. (Garland) Pp. 163-168
M.-Ch. Song, D.-H. Kim, Y.-H. Hong, H.-J. Yang, I.-S.
Chung, S. H. Kim, B.-M. Kwon, D.-K. Kim, M.-H. Park and N.-I.
Baek
[Abstract]
Cyclitols: Conduritols Aminoconduritols and Quercitols Pp.
169-175
Metin Balci, Murat Çelik, Emine Demir, Murat Ertas,
Serdar M. Gultekin, Nihal Ozturk, Yunus Kara and Nurhan Horasan-Kishali
[Abstract]
Efficient HPLC Procedures for Natural Product Isolation: Application
to Phenolics from Timber Pp. 177-184
Ibtisam Abdul Wahab, Noel F. Thomas, Jean-Frederic
F. Weber, Khalijah Awang, A. Hamid A. Hadi and Pascal Richomme
[Abstract]
Chemical Investigation on Zingiber zerumbet Sm Pp.
185-187
Mir Ezharul Hossain, Sreebash Chandra Bhattacharjee and
M.D. Enayetul Islam
[Abstract]
Bioflavonoids as Bioactive Natural Products from Plants Pp.
189-192
Evangeline C. Amor
[Abstract]
Search for Biologically Active Compounds from Sri Lankan Plants
Pp. 193-200
U.L.B. Jayasinghe, and Y. Fujimoto
[Abstract]
Chemical and Bioactive Constituents from Formosan Zanthoxylum
Species Pp. 201-208
Ih-Sheng Chen, and Che-Ming Teng
[Abstract]
Effect of Murraya paniculata (L.) Jack Extract on the Adult
Mortality of Callosobruchus maculatus F. (Coleoptera: Bruchidae)
Pp. 209-214
J.U. Mollah and W. Islam
[Abstract]
Abstracts
[Back to top]
Editorial
Atta ur Rahman, M.Iqbal Choudhary and Khalid
M.Khan
This Proceedings volume entitled “Frontiers in
Natural Product Chemistry” contains a feast of original
articles contributed by experts in the interdisciplinary field
of natural product science. They include articles on the synthesis
of several classes of natural products, isolation and structure
elucidation of natural compounds, pharmacology and bioassay
screening of natural substances and other related topics.
These papers were presented as Plenary and Invited Lectures
during the 9th International Symposium on Natural Product
Chemistry (9th ISNPC) held in Karachi during January 10-13,
2004. This series of symposia is well reputed for its excellence
and focused theme.
The Proceedings volume also contains several good articles
on the stereoselective synthesis of bioactive natural products,
which have been contributed by leading synthetic chemists
based on the recent research work. Besides these, several
contributions on the isolation, structural elucidation and
pharmacology of plant-based natural products including proteins
have been included. The volume also contains articles on a
variety of topics including biotechnology and value-addition
to natural products. We hope that this compilation of original
research articles will add to the useful literature of the
natural product chemistry.
We would like to express our thanks to Ms. Afshan Siddiq,
Ms. Madiha Rauf, Mr. Liaqat Raza and Mr. Muhammad Tariq for
their assistance in the preparation of the index. We are also
grateful to Mr. Wasim Ahmad for typing and to Mr. Mahmood
Alam for secretarial assistance.
[Back to top]
Rhodium-Catalyzed Asymmetric 1,4-Addition of Organometallic
Reagents
Tamio Hayashi
Asymmetric 1,4-arylation and -alkenylation was achieved
by use of organoboronic acids or their derivatives in the
presence of a rhodium catalyst coordinated with binap or its
related ligands. The scope of this asymmetric addition is
very broad, a,b-unsaturated ketones, esters, amides, 1-alkenylphosphonates,
and 1-nitroalkenes being efficiently converted into the corresponding
1,4-addition products with over 95% enantioselectivity. The
catalytic cycle of the reaction in water is proposed to involve
three intermediates (aryl- or alkenyl-rhodium, (oxa-p-allyl)rhodium,
and hydroxo-rhodium) by NMR studies on the rhodium intermediates.
The asymmetric addition of B-aryl-9BBN and ArTi(OPr-i)3 in
aprotic solvents proceeded with high enantioselectivity under
mild conditions to give the corresponding metal enolates as
the 1,4-addition products.
[Back to top]
Tandem Stereospecific Radical Cation-Mediated Syntheses
of Oligostilbenoid Dimers
Noel F. Thomas, Kiew C. Lee, Jean-Frederic F.
Weber, Ibtisam Abdul Wahab, Khalijah Awang, A. Hamid A. Hadi
and Pascal Richomme
Protected trihydroxystilbenes have been synthesized by
Heck coupling methodology in three steps. Treatment of 3,4-dimethoxy-12-benzyloxymethyl
stilbene with ferric chloride in dichloromethane (room temperature),
gave catechol analogues of ampelopsin F and of restrytisol
C, while 3,4-dimethoxy-12-acetoxymethyl stilbene treated in
the same conditions yielded two other analogues of restrytisol
C (but no trace of ampelopsin F analogues). All the structures
were unambiguously confirmed by 1D- and 2D- homo- and heteronuclear
nmr experiments. All transformations were stereospecific.
The ampelopsin F-type compounds are the result of radical
cation pathways. By contrast, the restrytisol C-type compounds
are the products of pericyclic pathways.
[Back to top]
Structure and Biological Activity – Diversity
Orientated Synthesis
E. Winterfeldt
The cephalostatins ( Cephalodicus gilchristi ) and the agelorins
(Agelas oroides ) represent two groups of marine natural products
showing high biological activity. The total synthesis of enantiopure
analogues reveals for the cephalostatins and the decisive
role of molecular dissymmetry and of a chiral curvature, while
the agelorins were shown to be prodrugs, which under stress
conditions are undergoing an enzymatically induced fragmentation,
generating the highly active cyclohexadiene aeroplysinin.
Finally a simple diversity oriented enantioselective synthesis
of wistarin precursor is reported.
[Back to top]
The Nitroaldol (Henry) Reaction as the Key Step for
the Synthesis of Some Natural Products
Roberto Ballini, Giovanna Bosica, Dennis Fiorini
and Alessandro Palmieri
The nitroaldol (Henry) reaction although has been discovered
more than one century ago is still largely employed as the
key step for the synthesis of many targets. The reaction is
performed under basic condition by mixing primary or secondary
nitroalkanes (and nitromethane) with a carbonyl, allowing
the formation of a b-nitroalkanol. The latter shows an high
versatility since it can be converted into a lot of different
functionalities and many natural products have been prepared
using the Henry reaction as the key step. Some of these synthesis
will be reported.
[Back to top]
Synthesis of Vinblastine Derivatives
Hedvig Bölcskei, Lajos Szabo and Csaba Szantay
The bisindole alkaloids of the Madagascan periwinkle
Catharanthus Roseus vincristine 1 and vinblastine 2 are widely
used clinically in the chemotherapy of cancer. Many efforts
were made to synthesize more efficient new derivatives having
less side effects than vinblastine 2. New anhydrovinblastine
derivatives were obtained by the ferric chloride mediated
coupling reaction of catharanthine and vindoline and their
derivatives. The nitro- dinitro-, amino- and hydroxymethyl
analogues of the alkaloids 1, 2 and 3 showed promising antitumor
activity.
[Back to top]
Nature as Source and Inspiration for the Synthesis
of New Anticancer Drugs
Daniele Passarella, Alessandra Giardini, Giordano
Lesma, Alessandra Silvani and Bruno Danieli
The bifunctional taxoid-colchicinoid hybrids were synthesised
and evaluated in assays of cytotoxicity and tubulin assembly/disassembly.
All compounds showed a high degree of cytotoxicity.
[Back to top]
Stereocontrol in Organic Synthesis Using Silicon
Compounds
Ian Fleming
[Full text
article]
Electronic control of diastereoselectivity is discussed; only
electrophilic attack adjacent to a stereogenic centre carrying
an electropositive element 3 makes a coherent story.
[Back to top]
Natural Photoreceptors: Structure, Function and Applications
Uma S. Palkar
Natural photoreceptors evoke a biological response on
absorption of light signal. A reversible change in the structure
of photoreceptors occurs by energy or sensory transduction.
Chemically they are conjugated trans-membrane proteins with
retinal or tetrapyrrole based chromophores in most of them.
Photosynthesis, photomorphogenesis, photoperiodism, vision
and phototaxis are various functions of photoreceptors.
Bacteriorhodopsin (bR), from H. salinarium acts as a light
driven proton pump for the synthesis of ATP. bR undergoes
an interesting reversible photocycle. During the photocycle,
retinylidene chromophore undergoes a reversible all-trans-to
13-cis- isomerisation, and proton translocation takes place.Chemical
modifications of bR and 3D – structure of bR at 1.5-Angstrom
resolution help to know the binding site of chromophore and
proton translocation at molecular level. Many colour control
mechanisms have been suggested for bR. A large number of bR
analogues can be made as follows:
bR + NH2OH.HCl -® Bacterial opsin (bOP) + Retinal, and
bOP + retinal analogue ® bR analogue, which can be used
to study structure, function and likely applications. bR can
act as a bistable photobiological switch with potential applications
in optical memory, optical data processing.
Photoactive Yellow Protein (PYP), a cytosolic photoreceptor
from E. halophila also undergoes a photocycle and can be put
to similar uses. PYP uses p-hydroxy cinnamoyl thioester, a
novel chromophore that isomerises with change in conformation
of protein during the photocycle, resulting in a signalling
state in yet unknown sensory path.
Natural photoreceptors constitute a novel and unique field
of natural product chemistry.
[Back to top]
Molecular Cloning of Cellulase Genes from Trichoderma
harzianum
Sibtain Ahmed, Nighat Aslam, Farooq Latif, M.I.
Rajoka and Amer Jamil
Cellulases are attractive source for utilization of the
agro-industrial waste materials. Exoglucanase (EC; 3.2.1.91),
Endoglucanase (EC. 3.2.1.4) and b-glucosidase (EC. 3.2.1.21)
were isolated from Trichoderma harzianum (E-58 strain). The
fungus was grown on Vogel's medium with different carbon sources.
Maximal production of the enzymes was achieved at 28 0C, pH
5.5 under continuous shaking at 120 rpm for 5 days. Glucose
repressed the synthesis of the enzymes whereas carboxymethylcellulose
(CMC) produced the enzymes in substantial amounts. Maximum
activity of cellulases (exoglucanase, endoglucanase and b-glucosidase)
were found to be 2.764, 14.4 and 0.629IU mL-1, respectively.
Corresponding genes for cellulases were isolated with the
help of RT-PCR. RNA was isolated from mycelia of T. harzianum
grown on CMC and xylan. First strand of cDNA was synthesized
using oligo dT (18) primer and subjected to PCR with specific
primers. The amplified products were purified through agarose
gel electrophoresis and ligated into SmaI site of pUC18. The
plasmids containing exg, egl and bgl genes were transformed
into E. coli for further characterization.
[Back to top]
Binding of Betamethasone, Prednisolone and Theophylline
to Bovine Serum Albumin: Plausible Explanations for Mode of
Binding and Drug-drug Interactions
Nurun N. Rahman, S. Huda, Khondaker M. Rahman
and Mohammad H. Rahman
The binding of betamethasone sodium phosphate and prednisolone,
two steroidal antiinflammatory drugs and theophylline sodium
glycinate, a bronchodilator, to bovine serum albumin (BSA),
has been studied by equilibrium dialysis (ED) method at different
temperature and pH values for characterizing the binding of
these drugs to BSA. Binding was exothermic, entropically driven
and spontaneous, as indicated by the thermodynamic analysis.
The major part of the binding energy at site II results from
electrostatic and hydrophobic interactions. The free fraction
of either betamethasone or prednisolone in the presence of
theophylline sodium glycinate and vice versa was monitored
in the presence and absence of site specific probes. The free
fraction of betamethasone sodium phosphate by theophylline
sodium glycinate and vice versa was increased during concurrent
administration causing reduced binding of these drugs to BSA.
This increment of free fraction was more prominent in the
presence of site I specific probe, which suggested that in
the absence of site I specific probe, betamethasone after
being displaced by theophylline from its high affinity site
rebound to its low affinity site. Similar type of result was
observed in case of prednisolone- theophylline interaction.
[Back to top]
Iron Acquisition and Iron Transport by Bacteria
Herbert Budzikiewicz
Most bacteria have developed specific systems to procure
sufficient amounts of iron which is not generally available
in water soluble form. One possibility is the production of
Fe3+ chelating substances, so-called siderophores. Structural
varieties, the transport mechanism through the cell wall,
and the importance of siderophores in health, agriculture
and environment will be discussed.
[Back to top]
Determination of Absolute Configuration of Natural
Products by X-ray Diffraction: A Novel Approach of Incorporating
Heavy-Atom-Containing Solvent Molecules into the Single Crystals
and Refinement of Flack Parameter
Suchada Chantrapromma, Hoong-Kun Fun, Surat Laphookhieo,
Saroj Cheenpracha and Chatchanok Karalai
In this study, the method of determining the absolute
configurations of 14b-hydroxy-3b-O-(L-thevetosyl)-5b-card-20(22)-enolide
(I) which was isolated from the air-dried fruits of Cerbera
odollam and 3a-feruloyl-taraxerol (II) which was isolated
from the air-dried fruits of Bruguiera cylindrica will be
presented. The novel method [1] of incorporating heavy-atom-containing
solvent molecules into the single crystal structure of the
compounds and refinement of the Flack parameter [2] was used
to find the absolute configurations of these natural products.
Compounds (I) has a cardenolide skeleton whereas compound
(II) has a taraxerol skeleton. The present X-ray study shows
the absolute L-form of (I) and the absolute a-form of (II).
We have clearly demonstrated for the first time a novel approach
which is an extremely useful and easy method to determine
the absolute stereochemistry of natural products by X-ray
diffraction. The importance of determining the absolute stereochemistry
of natural products is emphasised in this work.
[Back to top]
Researches on the Technology and Bioactive Properties of Phenolic
Lipids
J.H.P. Tyman
Anacardium occidentale (cashew) containing the principal component
phenols, anacardic acid, cardol, 2-methylcardol and cardanol
is a unique source of materials useful both for industrial
technology, in semi-synthesis and for biological/pharmaceutical
applications. Thus, by industrial decarboxylation, anacardic
acid in the natural cashew gives predominantly cardanol in
the product; technical cashew nutshell liquid (CNSL) together
with cardol/2-methylcardol and the cashew kernel is the valuable
desired main edible commercial product. Anacardic acid itself
together with cardol is best recovered by cold cutting of
raw cashew shells followed by solvent extraction to afford
natural CNSL. Either from technical or natural CNSL, the individual
component phenols, cardanol, anacardic acid, cardol, 2-methylcardol,
respectively can be separated by several different techniques
notably by phase separation. Each separated component phenol
contains saturated, 8(Z)-monoene, 8(Z),11(Z)-diene and 8(Z).11(Z),14-triene
constituents. Subsidiary chromatographic separation can give
the individual constituents. Technical CNSL without separation
is widely used in the production of friction dusts for the
automobile industry and in certain polymeric/surface coating
applications. Cardanol separated from technical CNSL has uses
in semi-synthesis, e.g. in the formation of polyethoxylate
surfactants, chelatants for metals and for boron. Natural
CNSL and anacardic acid separated from it, has potential industrial
applications in semi-synthesis and in biological studies.
Cardol separated, either from technical or natural CNSL also
has potential interest in semi-synthesis, and its homologues,
more recently as a potential biological marker.
[Back to top]
Development of Pharmaceuticals from Indonesian Natural
Resources, Genetically Engineered Microbes and Diversification
of Palm Oil Products
Ignatius Suharto, and Leonardus B.S. Kardono
The objective of this paper is to give an overview on
natural resources in terms of renewable resources as well
as non-renewable resources for the development of new pharmaceuticals,
chemical and food products, the roles of microbial cells in
solid substrate fermentation and submerged fermentation. The
benefit of this paper is to present current information on
the role of traditional and modern biotechnology.
The methods used, namely traditional and modern biotechnology
and chemical synthesis are developed and implemented to produce
pharmaceutical and chemical products. Results can be shown
that microorganisms have been engineered to commercially produce
such substances as the hormone insulin, the virus fighting
compound interferon, and a new vaccine against foot-and-mouth
disease. Traditional fermentation technology has been done
to produce low cost protein food using natural product as
a substrate and the development of palm oil derived products
for food, oleo chemicals, bio-plastic, bio-diesel and lubricants,
respectively.
[Back to top]
Microbial Transformation of Natural Products- A Tool for the
Synthesis of Novel Analogues of Bioactive Substances
Atta-ur-Rahman, M. Iqbal Choudhary and S. Ghulam
Musharraf
Microbial transformation is an effective tool for the
structural modification of bioactive natural and synthetic
compounds. Its application in asymmetric synthesis is increasing
due to its versatility and ease. The present article reviews
our contributions in the field of microbial transformation
of different classes of bioactive natural products. The microbial
transformation of monoterpenoids [(1R, 2S, 5R)-(-)-menthol
and (-)-a-pinene], sesquiterpenoids [(+)-sclareolide, 7a-hydroxyfrullanolide,
nootkatone, a-santonin, (-)-ambrox and isolongifolen-4-one],
sapogenins (sarsasapogenin), alkaloids (vindoline) and steroids
(E-guggulsterone, withaferin-A, (+)-adrenosterone, androst-1,4-dien-3,17-dione,
dehydroepiandrosterone, norethisterone, 17a-ethynylestradiol,
prednisone, testosterone and danazol) are described here along
with biological activities of transformed products.
[Back to top]
Mistletoe Lectins, Structure and Function
Wolfgang Voelter, Roland Wacker, Stanka Stoeva,
Rania Tsitsilonis and Christian Betzel
Based on isolation, sequence determination and X-ray
studies, the primary and three-dimensional structure of the
glycoprotein mistletoe lectin I (ML-I) are determined. ML-I
is constituted of two chains (A chain: 254 amino acid residues;
B chain: 264 amino acid residues) linked by a disulfide bridge.
Three different structurally identified oligosaccharides (I,
II, III) are attached to four N-type glycosylation sites (NA112,
NB61, NB96 and NB136). According to these structural characterizations,
ML-I is a member of ribosome inactivating proteins (RIP) of
type II. The three-dimensional X-ray structure allows a clear-cut
picture of the highly toxic effects of ML-I caused by its
RNA-N-glycosidase activity, which is in contrast to its immunomodulating
activity, applied for the treatment of cancer patients.
[Back to top]
Polyacetylenes and Sterols from the Aerial Parts of
Chrysanthemum coronarium L. (Garland)
M.-Ch. Song, D.-H. Kim, Y.-H. Hong, H.-J. Yang,
I.-S. Chung, S.-H. Kim, B.-M. Kwon, D.-K. Kim, M.-H. Park
and N.-I. Baek
The aerial parts of Chrysanthemum coronarium were extracted
in MeOH, and the extract was partitioned using EtOAc, n-BuOH
and H2O. The repeated column chromatography of EtOAc fraction
gave four sterols, whose chemical structures were identified
as stigmast-4-en-6b-o1-3-one (1), stigmast-4-en-6a-ol-3-one
(2), which have been so far reported only in the aquatic plants
and were isolated for the first time from the land plants,
b-sitosterol (3) and daucosterol (4) based on several spectral
data including gCOSY, gHSQC, gHMBC and comparison of the data
with those of literature. And the repeated column chromatography
of EtOAc and n-BuOH fractions gave nine polyacetylens, which
were identified as 2-[(lZ,4Z)-5-methylsulfinyl-2-pentyn-4-enyliden]-1,6-dioxaspiro[4,4]non-3-ene
(5), 2-[(IE,4Z)-5-methylsulfinyl-2-pentyn-4-enyliden]-1,6-dioxaspiro[4,4]non-3-ene
(6), 2-[lZ-2,4-dipentyn-6-methyliden]-1,6-dioxaspiro [4,4]non-3-ene
(7), 2-[lE-2,4-dipentyn-6-methyliden]-1,6-ioxaspiro[4,4]non-3-ene
(8), 2-[lE-2,4-dipentyn-6-methyliden]-1,6-dioxaspiro[4,5]non-3-ene(9),2-[lZ-2,4-dipentyn-6-methylidene]-1,6-dioxaspiro[4,4]non-3,7-dien-9a-ol
(10), 2-[lE-2, 4-dipentyn-6-methyliden]-1,6-dioxaspiro[4,4]non-3,7-dien-9b-ol
(11), 2-[lE-2,4-dipentyn-6-methyliden]-1,6-dioxaspiro[4,4]
non-3,7-dien-9a-ol (12) and 2-[1Z-2,4-dipentyn-6-methyliden
]-1,6-dioxaspiro[4,4]non-3,7-dien-9b-o1 (13). Some of them
showed the inhibitory effect on the activity of ACAT (Acyl-CoA:
cholesterol acyltransferase), the catalyzing enzymes of the
intracellular esterification of cholesterol, and FPTase (Farnesyl-protein
transferase), the farnesylation enzymes for Ras protein in
charge of cancer promotion, PLT aggregation, and the growth
of HUVEC (Human umbilical vascular endothelial cell) or A549
cells.
[Back to top]
Cyclitols: Conduritols Aminoconduritols and Quercitols
Metin Balci, Murat Çelik, Emine Demir,
Murat Ertas, Serdar M. Gultekin, Nihal Ozturk, Yunus Kara
and Nurhan Horasan-Kishali
All of the possible conduritol isomers have already been
synthesized starting from completely different materials and
their biological importance studied. Conduritols are useful
precursors in the preparation of cyclitols such as myo-inositols
phosphates, and pseudo-sugars, some of which are important
mediators in many cellular processes. The synthesis of conduritpls,
quercitols and the development of new synthetic methods are
discussed in this paper.
[Back to top]
Efficient HPLC Procedures for Natural Product Isolation:
Application to Phenolics from Timber
Ibtisam Abdul Wahab, Noel F. Thomas, Jean-Frederic
F. Weber, Khalijah Awang, A. Hamid A. Hadi and Pascal Richomme
We undertook the (re-)investigations of the chemical
composition of the phenolic contents of Malaysian timber species.
In order to efficiently isolate these constituents, we developed
semi-automated separation procedures. It includes the extensive
use of HPLC systems, operated at low or high pressure, in
conjunction with automatic injection and automatic fraction
collection. The efficiency of this procedure is demonstrated
by the isolation of an array of oligostilbenoids from the
heartwood of chengal (Neobalanocarpus heimii, Dipterocarpaceae),
when only a single compound was isolated by the previous investigators.
[Back to top]
Chemical Investigation on Zingiber zerumbet Sm
Mir Ezharul Hossain, Sreebash Chandra Bhattacharjee
and M.D. Enayetul Islam
Essential oil (0.51%) has been isolated from the rhizomes
of Zingiber zerumbet from which a white crystalline fraction-A
(m.p.620C) has been separated and purified. Another fraction-B
(m.p. 660C) has been isolated from petroleum ether (40-600C)
extract. The fraction-A & B have been analyzed by, IR,
GC/MS. From the above observation it appears that the major
constituent of fraction-A & B is same and the structure
is possibly 2,6,10- cycloundecatriene-1-one 2,6,9,9-tetramethyl.
[Back to top]
Bioflavonoids as Bioactive Natural Products from
Plants
Evangeline C. Amor
Bioflavonoids were once known as vitamin P and are also
considered semi-essential nutrients that are responsible for
the color of fruits and flowers. They are used in the treatment
or prevention of various diseases. There are four categories
and these are the proanthocyanidins, quercetin, the citrus
flavonoids and green tea polyphenols. The major sources of
these bioflavonoids are from plants. The bioflavonoids are
known for their antioxidant activity but a great number of
other bioactivities are also attributed to them. Some of these
bioactivities will be presented as well as the bioactivities
of the rare flavonoids isolated from Syzygium samarangense
(Blume) Merr. & L.M. Perry. Plant natural products, arguably,
will still play a major role in providing the world with an
alternative and a more effective health care.
[Back to top]
Search for Biologically Active Compounds from
Sri Lankan Plants
U.L.B. Jayasinghe, and Y. Fujimoto
In a continuation of our studies towards the discovery
of biologically active compounds from Sri Lankan plants, recently
we have chemically investigated the various parts of Diploclisia
glaucescens (Menispermaceae), Filicium decipiens, Pometia
eximia (Sapindaceae), Artocarpus nobilis (Moraceae) and Bridelia
retusa (Euphorbiaceae). These work led to the isolation of
a number of ecdysones, triterpenes, saponins, chalcones, stilbenes,
flavonoids including over twenty-five new natural products.
Some of these compounds showed high molluscicidal, insecticidal,
antifungal activities and radical scavenging properties towards
DPPH.
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Chemical and Bioactive Constituents from Formosan
Zanthoxylum Species
Ih-Sheng Chen, and Che-Ming Teng
There are approximately 100 species of Zanthoxylum in
the tropical and subtropical regions, and 10 of them are indigenous
to Taiwan. For the last 10 years, our laboratory has examined
six species of Zanthoxylum in Taiwan (Z. ailanthoides, Z.
integrifoliolum, Z. nitidum, Z. pistaciiflorum, Z. schinifolium
and Z. simulans) for their chemical and bioactive compounds.
This research has led to the isolation of 59 new compounds
and around 200 known compounds. The structures of the new
compounds were established by spectroscopic data and chemical
evidence. These new compounds showed diversity of structures
including benzo[c]phenanthridine, 2-phenyl-1-N-methylphthaliamide,
pyrano-quinoline, 2-quinolone, isobutylamide, indolopyridoquinazoline,
aporphine, phenylacetonitrile, coumarin, phenylpropanoid,
lignan, and flavonoid. Several isolates showed antiplatelet
aggregation activity in vitro.
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Effect of Murraya paniculata (L.) Jack Extract on the Adult
Mortality of Callosobruchus maculatus F. (Coleoptera: Bruchidae)
J.U. Mollah and W. Islam
Leaf, stem and root of Murraya paniculata (L.) Jack was
extracted in four different organic solvents (petroleum ether,
ethyl acetate, acetone and methanol). The extracts were tested
on the mortality of adult male and female of Callosobruchus
maculatus F. All the evaluated extract was toxic to both the
sexes. Males generally showed higher susceptibility compared
to females. Petroleum ether extract was more toxic than others.
It was in the order: pet. ether>EtOAc>acetone>MeOH
extract. Leaf extract was most toxic in comparison to stem
and root extracts. It was in order: Leaf>root>stem.
Generally, 72 hours exposure exhibited lower LD50 values compared
to 24 and 48 hours.
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