BIOLOGICALLY ACTIVE COMPOUNDS FROM
PLANTS: 40 YEARS OF SEARCHING FOR A
SCIENTIFIC POT OF GOLD
Second Professor Frank Fish
Memorial Award Lecture
School of Pharmacy
University College London
October 9, 2013
Prof. A. Douglas Kinghorn
Professor and Jack L. Beal Chair
College of Pharmacy
The Ohio State University
Professor Frank Fish,
OBE
(1924-2011)
B. Pharm (London), 1946
Ph.D. (Glasgow), 1955
Established the M.Sc.
Course in Forensic
Science at the University
of Strathclyde in 1966
Dean, School of
Pharmaceutical
Sciences, University of
Strathclyde, 1977-1978
Dean, School of
Pharmacy, University of
London, 1978-1988
OUTLINE OF PRESENTATION
Continued Importance of Natural Product-Derived Drugs in the 21st Century.
The Crucial Role of Mentorship in Career Development – a Personal Perspective.
Examples of Promising Lead Compounds from Tropical Plants:
Hernandulcin, a Highly Sweet Sesquiterpenoid
Silvestrol, a Potential Agent to Combat B-Cell Malignancies
“Active Constituents” of Botanical Dietary Supplements, as Exemplified by 2-Methoxy-2,4,6-trihydroxyanthraquinone from Noni and -Mangostin from Mangosteen
Conclusions.
CONTINUED IMPORTANCE OF
NATURAL PRODUCT-DERIVED
DRUGS IN THE 21ST CENTURY
NUMBERS OF ORGANISMS FOR DRUG
DISCOVERY
Eubacteria (bacteria), cyanobacteria (blue-green algae) 4,000a
Archaea (halobacteria, cyanogens)
Protoctista (e.g., protozoa, diatoms, “algae”, including “red
algae” and “green algae”)
Unknown
80,000
Plantae (mosses and liverworts, ferns, seed plants)b 270,000
Fungi (e.g., molds, lichens, yeasts, mushrooms)c 72,000
Animalia (e.g., mesozoa, sponges, jellyfish, corals, flatworms,
roundworms, sea urchins, mollusks, segmented worms,
arthropods, insects, fish, amphibians, birds, mammals)d-f
1,320,000
a Figures are species described taxonomically to date in each group. b Plants are the second largest group of classified organisms, representing 15% of the known biodiversity. c Only a relatively small proportion (5%) of the estimated 1.5 m fungi have been classified taxonomically to date. d The largest numbers of organisms are the arthropods, inclusive of insects (ca. 950,000 species). e Of the 28 major animal phyla, 26 are found in a marine environment. f Over 200,000 species of invertebrate animals and algal species occur in the sea.
(Tan et al., Curr. Drug Targets 7, 265, 2006)
NUMBER OF DRUGS APPROVED IN
THE UNITED STATES (1981 TO 2007)
(Li and Vederas, Science 325, 161, 2009)
NATURAL PRODUCT-DERIVED DRUGS
INTRODUCED IN THE U.S. (2000-2008)
[Chin et al., AAPS J., 8 (2), E239-E253, (Article 28), 2006; http://www.aapsj.org; Butler, in Natural Product Chemistry for Drug Discovery, eds. A.D. Buss and M.S. Butler, RSC:
Cambridge, U.K., 2010; p. 321]
Source Organism Type Number Terrestrial Plants
(apomorphine HCl, arteether, dronabinol/cannabidiol (mixture), galanthamine
HBr, lisdexamfetamine, methylnatrexone Br, nitisinone, tiotropium Br)
8
Terrestrial Microorganisms
(amrubicin HCl, anidulafungin, biapenem, caspofungin acetate, cefditoren
pivoxil, ceftobiprole medocaril, daptomycin, doripenem, ertapenem, everolimus,
fumagillin, gentumazumab ozogamicin, ixabepilone, micafungin Na, miglustat,
mycophenolate Na, pimecrolimus, pitavastatin, retapamulin, rosuvastatin Ca,
telithromycin, temsirolimus, tigecycline, zotarolimus)
24
Marine Organisms
(trabectidin, ziconotide) 2
Terrestrial Animals
(bivalirudin; exenatide; synthetic versions of natural forms) 2
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IXABEPILONE (IXEMPRATM)
Lead compound was
epothilone B isolated
from Sorangium
cellulosum (a
myxobacterium).
Anticancer agent
(refractory breast
cancer) (B-MS, 2007).
Interacts with tubulin.
http
s://ww
w.g
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.uni-b
ielefeld.d
e/Gen
oM
ik/clu
ster6.h
tml
Ixabepilone R = NH
Epothilone B R = O
ECTEINASCIDIN 743: AN ANTICANCER
AGENT FROM A MARINE TUNICATE
Ecteinascidia turbinata
Ecteinascidin 743; ET-743;
trabectedin, Yondelis® [Soft
tissue sarcoma (Europe)]
www.pharmamar.com
htt
p:/
/ww
w.t
erid
anie
lsb
ook
s.co
m/S
tate
s/re
pti
le_
liza
rd_gil
a_m
on
ster
.jp
g
GILA MONSTER (HELODERMA SUSPECTUM)
SOURCE OF EXENATIDE – ANTIDIABETIC AGENT
PLANT NATURAL PRODUCTS AND DERIVATIVES APPROVED BY THE
U.S. FDA FROM JANUARY 2001-FEBRUARY 2013a
Year
Approved
Generic Name Natural Lead Compound Trade
Name
Indication
2001 Galantamineb Galanthamine Razadyne Dementia associated with Alzheimer's disease
2002 Nitisinoneb Leptospermone Orfadin Hereditary tyrosinemia type 1
2003 Miglustatb 1-Deoxynojirimycin Zavesca Type 1 Gaucher disease
2004 Tiotropiumb bromide Atropine Spiriva COPD and exacerbation of COPD
2004 Trospiumb chloride Atropine Sanctura Overactive bladder
2004 Solifenacinb Quinine VESIcare Overactive bladder
2005 Paclitaxel (protein-bound) Paclitaxel (taxol) Abraxane Breast cancer (also approved for lung cancer in
2012 )
2006 Sinecatechinsb,c Green tea phenols Veregen Genital and perianal warts
2006d Nabiloneb Δ9-Tetrahydrocannabinol Cesamet Chemotherapy-induced nausea
2008 Methylnaltrexoneb bromide Morphine Relistor Opioid-induced constipation
2008 Tetrabenazineb Emetine Xenazine Huntington's-associated chorea
2009 Artemetherb and lumefantrine Artemesinin Coartem Malaria
2009 Colchicined Colchicine Colcrys Gout
2009 Capsaicin Capsaicin Qutenza Postherpetic neuralgia
2010 Cabazitaxelb Paclitaxel (taxol) Jevtana Hormone-refractory metastatic prostate cancer
2010 Dextromethorphan and
quinidine
Morphine and quinidine Nuedexta Pseudobulbar Affect
2011 Ioflupane I-123b Cocaine Datscan Brain imaging with suspected Parkinsonian
syndromes
2011 Gabapentin enacarbilb -Aminobutyric acid (GABA) Horizant Restless leg syndrome
2012 Ingenol mebutateb Ingenol-3-angelate Picato Actinic keratosis
2012 Lorcaserinb hydrochloride Ephedrine Belviq Obesity
2012 Icosapent ethyl Eicosapentaenoic acid (EPA) Vascepa Hypertriglyceridemia
2012 Omacetaxine mepesuccinateb Homoharringtonine Synribo Chronic myeloid leukemia
2012 Crofelemerb,c Croton lechleri oligomeric
proanthocyanidin
Fulyzaq HIV/AIDS anti-retroviral-associated diarrhea
2013 Trastuzumab emtansine
(antibody-conjugate)
Maytansine Kadcyla Breast cancer
2013 Ospemifeneb Phytoestrogens Osphena Menopause-associated dyspareunia
a Information taken from Drugs@FDA (http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm) and Kinghorn, et al. J.
Nat. Prod. 74, 1539, 2011 b New molecular entity. c Approved as a mixture of compounds as a “botanical drug”. d Originally
approved in combination therapy in 1985; newly approved as a monotherapy.
INGENOL MEBUTATE FOR THE TREATMENT
OF ACTINIC KERATOSIS
Approved by U.S. FDA in 2012 for the treatment of actinic keratosis, a precursor
to sun-related squamous cell carcinoma (used as a topical gel) (Lebwohl et al., N.
Engl. J. Med. 366, 1010, 2012; Mason, Pharm. J. 290, 141, 2013). This compound was isolated from Euphorbia peplus (Hohmann et al., Planta Med. 66, 291, 2000). New 14-step synthesis: Jorgensen et al., Science 341, 878, 2013.
Ingenol mebutate (Ingenol-3-angelate)
( Picato )
http://www.discoverlife.org/mp/20q?search=Euphorbia+peplus&mobile=iPhone
Euphorbia peplus (Euphorbiaceae)
http://luirig.altervista.org/flora/taxa/index1.php?scientific-name=euphorbia+peplus
DEFINITION OF A “BOTANICAL
DRUG PRODUCT”
In June 2004, the U.S. FDA issued the publication
“Guidance for Industry. Botanical Drug Products”
(http://www.fda.gov/cder/guidance/index.htm).
A “botanical drug product” is defined as containing as
ingredients vegetable materials, which may include plant
materials, algae, macroscopic fungi, or combinations
thereof, for use as a drug. It may be prepared, for example,
as a solution (e.g., tea), powder, tablet, capsule, elixir,
topical agent, or injectable.
Excluded are: fermentation products, highly purified or
chemically modified botanical substances, genetically
modified plants, allergenic extracts, and vaccines that
contain botanical ingredients.
(J. Dou, U.S. FDA, CDER)
OVERVIEW OF NDA PROCESS OF
FDA FOR “BOTANICAL DRUGS”
Purification to single active molecules is not required, although strict documentation of “chemistry, manufacturing, and controls” (CMC) must be carried out.
Identification of “active principles” is not essential.
The same requirements for safety assurance and clinical efficacy as for synthetic drugs are needed for NDA approval.
Purification to single active molecules is not required.
The same levels of safety requirements and clinical efficacy as non-botanical drugs are needed for NDA approval.
Nearly 500 IND/pre-IND applications for botanical drugs have been submitted to CDER, FDA between 1999-2012.
Most of these are in Phase 2, with a few in Phase 3.
(J. Dou, U.S. FDA, CDER)
SINECATECHINS FROM GREEN TEA (CAMELLIA
SINENSIS) AS THE FIRST “BOTANICAL DRUG”
Green tea contains mixtures of a sub-type of flavonoids (flavans)
known as “catechins”, which are esterified with a small phenolic
acid, gallic acid.
Epigallocatechin gallate (EGCG), the major flavonoid ester in
green tea, is one of the most highly studied natural product
molecules in the biomedical literature.
A mixture of green tea catechins (“sinecatechins”; Veregen)
was the first “botanical drug” approved by the U.S. FDA in 2006
(used topically to treat venereal and perianal warts) (Chen et al.,
Nature Biotechnol. 26, 1077, 2008).
CROFELEMER, THE FIRST FDA-APPROVED
“BOTANICAL DRUG” TO BE TAKEN ORALLY J. D
ou
, CD
ER
, FD
A
Crofelemer is a complex
mixture of proanthocyanidins
(literally thousands of
compounds co-occur).
The plant of origin is called
“Dragon’s Blood”.
Crofelemer (Fulyzaq) was
approved as a “botanical drug”
by the USA FDA in 2012 as an
oral antidiarrheal agent.
THE CRUCIAL ROLE OF MENTORSHIP
IN CAREER DEVELOPMENT – A
PERSONAL PERSPECTIVE
B.PHARM. (SPECIAL IN
PHARMACOGNOSY) AT BRADFORD
(1966-1969)
Dr. Peter
A. Linley
Dr. Keith J.
Harkiss
served as
tutor and
supervised
a thee-part
under-
graduate
thesis
MASTER’S IN FORENSIC SCIENCE AT
STRATHCLYDE (1969-1970)
Prof. Frank Fish, Coordinator of the M.Sc. Course in Forensic
Science
(Thesis performed under the supervision of Mr. Peter F.
Nelson)
TEACHING FELLOWSHIP AND PH.D.
STUDENTSHIP AT THE SQUARE (1971-1975)
Late Prof. Fred
Evans, Ph.D.
Supervisor (Dissertation carried
out on the skin-irritant
diterpene esters of
Euphorbia species)
SENIOR PHARMACOGNOSY ACADEMIC STAFF
AT “BRUNSWICK SQUARE” (1970s-1990s)
LATE PROF. JAMES W. FAIRBAIRN
(ANTHRAQUINONES; OPIUM POPPY;
CANNABIS SATIVA)
EMER. PROF. J. DAVID
PHILLIPSON (ALKALOIDS; ANTIPROTO-
ZOALS; TISSUE CULTURE)
LATE PROF. FRED J. EVANS
(PHORBOL ESTERS; CANNABIS SATIVA;
PH.D. SUPERVISOR)
DR. MARGARET F. ROBERTS
(ALKALOID BIOSYNTHESIS;
PAPAVER ALKALOIDS)
U.K. PHARMACOGNOSISTS AT A CELEBRATION IN THE LATE 1970S
Photograph Provided by Prof. J. David Phillipson
PRESENT PHARMACOGNOSY LEADERS AT
“BRUNSWICK SQUARE”
PROF. SIMON GIBBONS (ANTI-
INFECTIVE AGENTS FROM PLANTS;
DRUGS OF ABUSE)
PROF. MICHAEL HEINRICH
(ETHNOBOTANY, PHYTOTHERAPY;
PHARMACEUTICAL BIOLOGY)
M.SC. DEGREE IN PHARMACOGNOSY
AT UCL SCHOOL OF PHARMACY
Dr. Jose Prieto-Garcia
Programme Director
Prof. Simon Gibbons
Deputy Programme Director
Invited Guest Lecturers from outside UCL include Dr. Colin Wright (University
of Bradford), Prof. Peter Houghton (King’s College London), Prof. Monique
Simmonds (RBC, Kew), and Prof. Elizabeth Williamson (University of Reading)
SABBATICAL OF PROFESSOR DAVE PHILLIPSON AT
THE OHIO STATE UNIVERSITY IN THE LATE 1960s
Late Professor Jack L.
Beal
The Ohio State
University
Emeritus Professor
Raymond W. Doskotch
The Ohio State
University
A NIGHT ON THE TOWN WITH PROFESSOR
NORMAN R. FARNSWORTH AT “TRADER VICS”
Photograph Provided by Prof. Norman R. Farnsworth
DEPARTMENT OF PHARMAGNOSY, UNIVERSITY OF
MISSISSIPPI, 1975 (HEAD: NORMAN J. DOORENBOS)
THE ARROWS SHOW PROF. DOORENBOS AND
THE FUTURE MRS. KINGHORN
Late Dr. Norman R. Farnsworth University of Illinois at Chicago
1930-2011
Slide Provided by Professor J. David Phillipson
(Photograph by Jimmy W. Crawford, RTI)
DRS. MONROE WALL AND MANSUKH WANI – DISCOVERERS OF TAXOL AND CAMPOTHECIN
EXAMPLES OF PROMISING
LEAD COMPOUNDS FROM
TROPICAL PLANTS
EXAMPLES OF LEAD COMPOUNDS OF
INTEREST FROM TROPICAL PLANTS
Pervilleine A (Cancer Res., 2001)
α-Mangostin
(Nutr. Res., 2012)
Abrusoside A (Chem. Commun., 1989)
trans-Resveratrol (Science, 1997)
2-Methoxy-1,3,6- anthraquinone
(J. Nat. Prod., 2005)
Betulinic acid (Nature Med., 1995)
Silvestrol
(J. Org. Chem., 2004)
Pentalinonsterol (Phytochemistry, 2012)
Hernandulcin (Science, 1985)
TASTE AND THE TONGUE Humans have ca. 10,000 taste buds with each taste bud
containing 50-100 taste receptor cells.
The popular taste map of the tongue taste is based on faulty
interpretation of a 1901 paper, in fact taste buds on many
areas of the tongue can detect different tastes.
Bitterness has a much lower taste threshold than sweetness
due to the biological imperative to select for nutritious foods
while avoiding toxins.
Lindeman, B. Nature Med., 1999, 5, 381-382. Scott, K. Neuron, 2005, 48, 455-464
Image from www.rickbakas.com Image from Lindeman
“Low-Caloric” (“High Potency Sweeteners”) “Reduced-Calorie” (“Bulk Sweeteners”)
Compound Sweetness Intensity1 Compound Sweetness Intensity1
Glycyrrhizin 50-100 Lactitol 0.4
Stevioside 150-250 Isomalt 0.45-0.65
Perillartine2 370 Sorbitol 0.6
Phyllodulcin 400 Mannitol 0.7
Rebaudioside A 200-300 Maltitol 0.9
Mogroside V 250-450 Xylitol 1.0
MGGR2 941 High-Fructose
Corn Syrup
(90%)
1.0
Hernandulcin 1500
Monellin 1500-2000
Neohesperidin
dihydrochalcone2
1800
Thaumatin 2000-3000
COMPARISON OF THE SWEETNESS INTENSITIES OF “LOW-
CALORIC” AND “REDUCED-CALORIE” NATURAL PRODUCT
SWEETENERS (ALL OF HIGHER PLANT ORIGIN)
1 Relative to sucrose (=1). Sweetness intensity varies with concentration being tasted.
2Semi-synthetic compound.
HERNANDULCIN, A HIGHLY SWEET COMPOUND
FROM LIPPIA DULCIS (VERBENACEAE) In Mexico, L. dulcis is used as an
emmenagogue, to induce menses, as an abortifacient, and to treat coughs and stomachache.
The plant was purchased in bulk at a marketplace in Mexico City, and collected in the field at Tlayacapan, Morelos, Mexico in May-June, 1982 by then graduate student Cesar M. Compadre.
The compound was determined as a novel bisabolane sesquiterpene by spectroscopic methods.
The structure was checked by synthesis in the (±)-form by directed-aldol condensation of the ketones 3-methyl-2-cyclohexen-1-one (I) and 6-methyl-5-hepten-2-one (II).
(Compadre et al., Science 227, 417, 1985)
Prof. Cesar M. Compadre
IDEAL PROPERTIES OF A NONCALORIC AND NONCARIOGENIC SWEETENER FOR POTENTIAL
USE AS A SUCROSE SUBSTITUTE
Highly sweet, odorless, colorless, with taste
characteristics similar to sucrose.
Water soluble, stable.
No toxicity nor cariogenicity, from either the
parent substance or its metabolites.
Easy to synthesize or to obtain by cultivation.
Should fit existing techniques for the application
of sweeteners.
Economically competitive with currently
approved sweeteners.
(Hough et al., Eds. In Developments in Sweeteners – 1; Applied Science Publishers, London, 1979; p. v)
STRUCTURAL CHARACTERIZATION OF
SILVESTROL FROM AGLAIA FOVEOLATA
Drs. Bang Yeon Hwang and Baoning Su
Silvestrol
X-ray Structure by Drs. Bernard Santarsiero and Andrew Mesecar (UIC)
(Hwang et al., J. Org. Chem. 69, 3350, 2004;
ibid., 69, 6156)
Collaboration between:
The Ohio State University, Columbus, OH;
University of Illinois at Chicago, Chicago, IL;
University of North Carolina at Greensboro, NC;
Mycosynthetix Inc., NC;
Bristol-Myers Squibb, Princeton, NJ.
Funded by the United States National Cancer Institute, NIH (1990-2006; 2007-2013)
COLLABORATIVE PROJECTS ON NATURAL
PRODUCT ANTICANCER DRUG DISCOVERY
National Cooperative Drug Discovery Group (NCDDG) Grant
(U19 CA52956)
Program Project Grant
(P01 CA125066)
[Most recent review: Kinghorn et al., Pure Appl. Chem. 81, 1051, 2009]
NCDDG GROUP AT THE MEDICINAL PLANT GARDEN,
UNIVERSITY OF ILLINOIS AT CHICAGO IN 2003
SHOWS LEFT TO RIGHT (UIC UNLESS STATED) MARCY BALUNAS, GEOFF
CORDELL, STEVE SWANSON, DOEL SOEJARTO, YALI FU (NCI), NORM
FARNSWORTH, GORDON CRAGG (NCI), MANSUKH WANI (RTI), DOUG
KINGHORN, WILL JONES, NICK OBERLIES (RTI), TATIANA LOBO, AIKO ITO,
YINGMEI TAN. GHEE TAN, BANG YEON HWANG, AND FAUSTO RIVERO-CRUZ
IN VITRO CYTOTOXICITY OF SILVESTROL
Compound Cell linea
Lu1 LNCaP MCF-7 HUVEC
Silvestrol 1.2 1.5 1.5 4.6
Methyl rocaglateb
163 325 Not determined
203
Paclitaxelc 2.3 4.7 0.7 105.5
Camptothecinc 28.7 28.7 28.7 258.6
a ED50 values (nM) - Lu1 = human lung cancer; LNCaP
= hormone-dependent human prostate cancer; MCF-7
= human breast cancer; HUVEC = human umbilical
vein endothelial cells. b Isolated in our previous work (Rivero-Cruz et al., J.
Nat. Prod., 67, 343, 2004). c Used as positive control.
(Hwang et al., J. Org. Chem. 69, 3350, 2004)
EFFECT OF SILVESTROL IN THE IN VIVO HOLLOW FIBER TEST AND IN THE MURINE P-388 LEUKEMIA
MODEL
Active at maximum tolerated dose of
2.5 mg/kg/inj, given by intraperitoneal
injection daily for five consecutive
days (qd5) in ip P388 model.
Achieved maximum lifespan increase
corresponding to T/C of 150%.
Hollow fiber: Murine P-388 leukemia:
Inactive (T/C = 100%) in iv P388 leukemia model when administered by either the iv or ip route using a daily times five schedule (qd5).
Active (T/C = 129%) in same tumor model when injected iv on a twice-daily schedule (2qd5) using the same cumulative dose (2 mg/kg/day).
(Hwang et al., J. Org. Chem. 69,
3350, 2004)
Incubation Time (hours)
B Cells
0
20
40
60
80
100
120
0 24 48 72
Incubation Time (hours)
T Cells
0
20
40
60
80
100
120
0 24 48 72
EFFECTS OF SILVESTROL ON B AND T CELLS
IN WHOLE BLOOD FROM CHRONIC
LYMPHOCYTIC LEUKEMIA (CLL) PATIENTS
80 nM Silvestrol 1 µM 2-F-ara A
% L
ive C
ell
s R
ela
tive t
o U
ntr
eate
d
(Lucas et al., Blood 113, 4656, 2009)
The remaining three mice appeared normal 12+ weeks post-
engraftment, 6 weeks after the last treatment.
SILVESTROL SIGNIFICANTLY IMPROVED
SURVIVAL IN AN ACUTE LYMPHOBLASTIC
LEUKEMIA (ALL) XENOGRAFT MOUSE MODEL
0
20
40
60
80
100
0 5 10 15 20 25 30 35 40 45
Days Post Engraftment
% S
urv
ival
Control (N=13)
Silvestrol (N=14)
1.5 mg/kg i.p. M, W, F; started 1
wk post-engraftment
Treatment stopped
85
Median survival difference P = 0.002
(Lucas et al., Blood 113, 4656, 2009)
Silvestrol was totally synthesized by two groups in 2007, the
groups of Porco (Boston University) (Gerard et al., Angew.
Chem. Int. Ed., 46, 7831, 2007) and Rizzacasa (University of
Melbourne) (El Sous et al., ibid., 46, 7835, 2007).
Pelletier and co-workers have shown that silvestrol is a
translation inhibitor by targeting eukaryotic initiation factor
(eIF) 4A (Cencic et al., PLoS ONE 4(4), e5223, 2009).
SILVESTROL: WORK PERFORMED BY OTHER GROUPS
The figure shows the translation
initiation complex and known
inhibitors (Lucas et al., Curr. Drug
Targets 11, 811, 2010); based in part
on Cencic et al., 2009, as cited
above).
In very recent work, using
biotinylated 5-epi-silvestrol, a
specific interaction was shown with
eIF4AI and eIF4AII (Chambers et al.,
Org. Lett. 15, 1406, 2013).
SILVESTROL: A POTENTIAL NEW THERAPEUTIC
AGENT FOR B-CELL MALIGNANCIES
At The Ohio State University, silvestrol has shown promising in vivo
activity in models of acute lymphoblastic leukemia, acute myeloid
leukemia, EBV-driven lymphoma, and mantle cell lymphoma (Lucas et
al., Blood 113, 4656, 2009; Alinari et al., Clin. Cancer Res. 18, 4600, 2012;
Alahkar et al., J. Hematol. Oncol. 6, 21, 2013).
Silvestrol was selected for preclinical development by NCI through the
DDG IIA mechanism in 2007, and is now in the NCI NExT program having
been subjected to additional peer and program review in August 2013.
The mechanism of antileukemic action is being further investigated
through Project 5 of a NCI/NIH SPORE (P50) award (J. C. Byrd, PI) (M.R.
Grever, D.M. Lucas) (2009-2014).
EFFECTS OF SILVESTROL ANALOGUES ON GROWTH
INHIBITORY ACTIVITY OF HUMAN CANCER CELLS
Methyl ester group is
required for potency
Absence of OCH3 at C-4' diminishes
resultant cytotoxicity slightly
Esterification or change
in configuration of the
hydroxy group at C-1
diminishes cytotoxicity
(Hwang et al., J. Org. Chem. 69, 3350, 2004; Adams et al., J. Am. Chem. Soc. 131, 1607, 2009; Pan et
al., J. Nat. Prod. 73, 1873, 2010; Woodard IV et al., Unpublished results)
The presence of a 1,4-dioxanyloxy moiety at C-6
enhances activity dramatically
The cyclopenta[b]benzofuran moiety
and other aromatic units confer basic
cytotoxicity to this compound class
Inversion of configuration at C-2'''
reduces cytotoxicity much more
than when inverted at C-5'''
Esterification of the hydroxy
groups at C-5''' and C-6'''
decreases resultant cytotoxicity
The natural product silvestrol is the most potent of ca. 15 close analogues investigated
AGREEMENT FOR DEVELOPMENT OF SILVESTROL
FOR POTENTIAL TREATMENT OF B-CELL MALIGNANCIES
In June 2012, after protracted
negotiations, an agreement was
signed to jointly develop silvestrol
between The Ohio State University
and the Sarawak Biodiversity Center,
with the immediate goal of
conducting preclinical toxicology.
The U.S. NCI will be involved
through the NExT program.
This slide shows the two other
faculty participants in this work at
Ohio State, Drs. Michael Grever (top
left) and David Lucas (top right), and
Dr. Rita Manurung, Chief Operating
Officer, Sarawak Biodiversity Center,
Kuching, Sarawak, Malaysia
(bottom). Silvestrol will be sourced
from Aglaia stellatopilosa grown in
Sarawak.
DIETARY HEALTH SUPPLEMENT AND
EDUCATION ACT (DSHEA) (1994)
Defined terms “dietary supplement” (including
herbal remedies) and “dietary ingredient”.
These are taken orally and may be used as in forms
such as tablets, capsules, soft gels, gel liquids, and
powders.
Exempted dietary supplements marketed before
October 15, 1994 from new dietary ingredient (NDI)
review.
Established requirements for new dietary
ingredients.
A dietary supplement may be declared as a hazard
to public health or safety.
“Structure and function” claims may be made, but
most labels have a disclaimer about health benefits.
NONI AS A DIETARY SUPPLEMENT
Marketed in the U.S. by several companies. Noni juice is available in many retail outlets, including supermarkets, health-food stores, and pharmacies.
Tahitian and Hawaiian noni juice are both available.
Marketing toward layman primarily based on the likely fictitious alkaloid, “xeronine”.
(Heinecke, Pac. Trop. Bot. Gard.
Bull. 10, 15, 1985)
NONI (MORINDA CITRIFOLIA)
(RUBIACEAE) Occurs in tropical and subtropical regions.
All parts (fruit, leaf, bark, flower, and seed) have been utilized medicinally.
Roots and bark are used as a dye.
In initial isolation work performed at The Ohio State University, a lignan (americanin A) and a flavonoid glycoside (narcissoside) were isolated as antioxidant constituents of noni fruits.
No trace of xeronine was found!
(Su et al., J. Nat. Prod. 68, 592, 2005).
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(Review: Pawlus and Kinghorn, J. Pharm. Pharmacol. 59, 1587, 2007)
Dr. Alison Pawlus
QUINONE REDUCTASE-INDUCING ACTIVITY OF
ISOLATED CONSTITUENTS OF NONI FRUITS
1 (new, 2-methoxy-1,3,6,- trihydroxyanthraquinone)
aCD = Concentration required to double quinone reductase induction. bIC50 = Concentration
for 50% inhibition of cell viability. cCI = Chemopreventive Index. d Only 2 mg of 1,3,6-
trihydroxy-2-methoxyanthraquinone (1) isolated from ca. 9 kg dried noni fruits. * = Control.
(Pawlus et al., J. Nat. Prod. 68, 1720, 2005)
2
Compound CDa, M (g/mL) IC50b, M (g/mL) CIc
1d 0.009 (0.0027) >69.9 (>20) >7770
2 1.67 (0.52) >66.6 (>20) >39.9
L-sulforaphane* 0.34 (0.061) 9.77 (1.73) 28.7
INHIBITORY EFFECT OF NONI FRUITS
ON RAT ESOPHAGEAL TUMORIGENESIS
Male F344 rats were fed a diet of 5% w/w dried
powdered fruits of M. citrifolia (noni), and six other
dried fruits, including black raspberry (Rubus
occidentalis), in a comparison study.
The standard carcinogen, NMBA (N-
nitrosomethylbenzylamine was used to treat rats for
five weeks, and the experiment was terminated after
35 weeks.
All seven fruits had similar effects on reducing
esophageal tumor incidence, size, and multiplicity,
and also reduced the levels of two serum cytokines.
Noni fruits have lower levels of anthocyanins and
ellagitannins than black raspberries.
(Stoner et al., Pharm. Res. 27, 1138, 2010)
GARCINIA MANGOSTANA (MANGOSTEEN) (CLUSIACEAE)
The tropical fruit Garcinia
mangostana L. (Clusiaceae;
Mangosteen), has become a
major botanical dietary
supplement in the U.S.
Mangosteen extracts and/or their
purified xanthone constituents,
such as -mangostin, have
antioxidant and e.g., putative
anti-inflammatory and
antimicrobial activities.
In initial collaborative work with
Dr. Bill Keller, several
mangosteen xanthones were
found to be potent antioxidants
(Jung et al., J. Agric. Food
Chem., 54, 2077, 2006).
DR. WILLIAM J.
KELLER
NATURE’S SUNSHINE
PRODUCTS, INC.
XANTHONES ISOLATED FROM THE PERICARP OF MANGOSTEEN
PROFILE OF XANTHONE CONTENT IN THE MANGOSTEEN JUICE USED IN THE STUDY
(Chitchumroonchokchai et al., J. Nutr. 142, 675, 2012)
When analyzed by
HPLC, the 100%
mangosteen juice
used in the study
provided 5.3 + 0.1 mM
total xanthones, with
-mangostin being the
most abundant
(59.9%), as indicated
in the table opposite.
Xanthone
Content
in juice
(µM)
Percentage of
total xanthones
identified (%)
garcinone C 291 + 11.2 5.5
garcinone D 520 + 10.9 10.2
garcinone E 239 + 18.5 5.1
-mangostin 3190 + 123 59.9
β-mangostin 121 + 9.3 2.3
-mangostin 356 + 4.3 6.5
8-deoxygartanin 176 + 4.5 3.1
gartanin 157 + 6.9 2.8
tovophillin B 50 + 2.9 1.1
9-hydroxycalabaxanthone 193 + 7.4 3.6
Total 5290 + 166 100
Values are means + SD; n = 5 independent replicates
-Mangostin
DETERMINATION OF BIOAVAILABILITY IN HUMANS
OF XANTHONES FROM MANGOSTEEN JUICE
The bioavailability of mangosteen xanthones using
human subjects is of interest, since milligram amounts
are ingested on a daily basis.
In a preliminary study, Kondo et al. administered ca. 60
mL of a supplement (mangosteen; aloe vera; green tea;
multivitamins) to 20 fasted healthy human volunteers,
and it was concluded that -mangostin is bioavailable
(observed Cmax at tmax of ca. 1 hour) (Kondo et al. J. Agric.
Food Chem., 57, 8788, 2009).
In a study carried out at The Ohio State University, the
bioavailability of xanthones was investigated in ten
healthy adults (five females; five males), who consumed
a single dose of 100% mangosteen juice along with a
typical fast-food (high-fat) breakfast, which was
supplemented with canola oil and soybean oil
(Chitchumroonchokchai et al. J. Nutr., 142, 675, 2012).
EFFECT OF DIETARY α-MANGOSTIN IN A MURINE
HT-29 COLON CANCER CELL XENOGRAFT MODEL
(Chitchumroonchokchai et al., Mol. Nutr. Food Res. 57, 203, 2013)
Balb/c nu/nu mice were fed either the control diet AIN-93G or the control diet with
-mangostin (-MG; 900 mg/kg). After one week of acclimation to diet, mice were
injected sc with HT-29 cells, and then fed the same diets. After two weeks (panel A) or four weeks (panel B) from the initial injection of HT-
29 cells, the tumor masses were 27% and 41% less, respectively, in mice fed the
diet with -mangostin compared to those fed the control diet.
Xanthones and their metabolites were found in the serum, liver, and feces.
This work was carried out in collaboration with Professors Mark Failla and Steve
Clinton at The Ohio State University.
Values are
means + SD; n =
12 and 6 mice
for panels A and
B, respectively
0
200
400
600
800
1000
1200
Tum
or
mas
s (m
g)
AIN-93G AIN-93G+ α-MG
a
b
0
10
20
30
40
50
60
70
80
90
100
Tum
or
mas
s (m
g)
AIN-93G AIN-93G+ α-MG
a
b
A B
CONCLUSIONS: COLLABORATIVE APPROACH
TO THE DISCOVERY OF ANTICANCER AGENTS
FROM TROPICAL PLANTS
Tropical plants are more biodiverse than temperate plants, and thus hold the potential of offering greater chemical diversity for anticancer drug discovery.
Plant collections for drug discovery must cover the source country in terms of intellectual property agreements.
Efforts to harness plant compounds as potential cancer chemotherapeutic agents require a multidisciplinary approach with open and frequent communications.
Photograph by Jon Gladden (April 2013)
Shown (left to right) are Tony Gromovsky, Ben Naman, Lynette Bueno, Dr. Heebyung
Chai, Dr. Li Pan, Ms. Anecie Benatrahina, Dr. Patrick Still, and Dr. Yulin Ren
Support was obtained from NIH grants N01-DE-02425, R03-07560; R01-DE-
08937, U19 CA52956, and P01 CA125066 and faculty start-up funding from the
Molecular Carcinogenesis and Chemoprevention Program of the OSUCCC.
Many faculty, visiting scholars, postdoctorals, and graduate students at the
University of Illinois at Chicago and The Ohio State University are thanked for
very their kind collaboration.
This is a long-running
and well-respected
book series that was
established in 1938 by
Laszlo Zechmeister.
The series has
featured contributions
by nine Nobel
laureates. The
chapters refer to the
origin, distribution,
chemistry, synthesis,
biochemistry,
functions, and uses of
naturally occurring
substances, ranging
from small molecules
to biopolymers.
College of Pharmacy and OSU Comprehensive Cancer Center