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Clinical Application
Herbal Medicines for Diabetes and
Cancer—A Global Perspective
by
Peter Natesan Pushparaj
D
Introduction
Averrhoa bilimbi plant
Herbal Remedies
for Diabetes
Mellitus
iabetes mellitus is a principal cause of morbidity and mortality in
human populations. It is a syndrome characterized by hyperglycemia,
polydipsia and polyuria and causes complications to the eyes, kidneys
and nerves. It is also associated with an increased incidence of cardiovascular
disease.1 The clinical manifestations and development of diabetes often differ
significantly between countries and also between racial groups within a country.
For example, diabetes currently affects an estimated 15.1 million people in
North America, 18.5 million in Europe, 51.4 million in Asia, and just under
one million in Oceania.2 It is estimated that globally, the number
of people will rise from 151 million in the year 2000 to 221 million
by the year 2010,3 and to 300 million by 2025.4 However, diabetes
mellitus is becoming increasingly common in the Singapore
population. The prevalence of type 2 diabetes doubled between
1984 and 1992 in Singaporean Chinese.5 This increase can be
attributed to many factors, including a stressful lifestyle as well as
improper dietary habits. This is of economic concern as the disease
requires life-long treatment and associated with high morbidity from
the resulting complications.
Herbal remedies typically are part of traditional and folk healing
methods with long histories of use. Some forms of the herbal
medicines are found in most areas of the world and across all
cultures historically. Before the advent of insulin, diabetes was
treated with plant medicines. In 1980, the World Health
Organization (WHO) urged researchers to examine whether
traditional medicines produced any beneficial clinical results. The
plant kingdom represents a largely unexplored reservoir of
biologically active compounds not only as drugs, but also as unique templates
that could serve as a starting point for synthetic analogs and an interesting tool
that can be applied for a better understanding of biological processes. Folkloric
uses are supported by a long history of human experience. Numerous
biologically active plants are discovered by evaluation of ethnopharmacological
data, and these plants may offer the local population immediately accessible
therapeutic products.6
The earliest known documentation of plant-derived treatments for diabetes
is found in the Ebers Papyrus of about 1550 BC. Since then, multitudes of
herbs, spices and other plant materials have been described for the treatment
of diabetes throughout the world.7 Traditional anti-diabetic plants might provide
a useful source of new oral hypoglycemic compounds for development as
pharmaceutical entities, or as simple dietary adjuncts to existing therapies.
However, since the availability of insulin, folklore medicines for diabetes have
almost disappeared from occidental societies, although they continue to be
the cornerstone of therapy in underdeveloped regions. Renewed attention to
alternative medicines and natural therapies has stimulated a new wave of
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Clinical Application
research interest in traditional practices. In the last 20 years,
scientific investigation has confirmed the efficacy of many of these
preparations, some of which are remarkably effective. Mentioned
hereafter are those plants that appear most effective, are least toxic
and have substantial documentation of efficacy.
Fruits of Averrhoa bilimbi
Averrhoa bilimbi
(Family: Oxalidaceae, Common Name: Bilimbi)
A common plant in Asia, which has been
widely used in traditional medicine as a cure
for cough, cold, itches, boils, rheumatism,
syphilis, diabetes, Whooping cough, and
hypertension. In addition, A. bilimbi has been
widely reported for its anti-inflammatory, antiscorbutic, astringent, anti-bacterial, and postpartum protective properties. In Indonesia, it
has a considerable medicinal reputation as a
potent folk remedy for the treatment of
diabetes mellitus.
Herbal Remedies
for Cancer
1308
More than 400 different plants and plant extracts have been
described for the diabetic patient. From these, various molecular
species with hypoglycemic activity have been identified, including
alkaloids, flavonoids, glycosides, and polysaccharides. For example,
castanospermine, an alkaloid isolated from seeds of
Castanospermum australe; epicatechin, a flavonoid isolated from
the heartwood of Pterocarpus marsupium; and neomyrtillin, a
glycoside isolated from Vaccinium myrtillus, were claimed to exert
hypoglycaemic effect.8 Like the sulfonylureas, some plants act by
increasing the release of insulin and require a minimum of β-cells
to exert their action. These plants include Momordica foetida,
Euphorbia prostrata and Fumaria parviflora, Taraxacum officinale
and Eribotry japonica. These plants include Momordica foetida,9
Euphorbia prostrata and Fumaria parviflora,10 Taraxacum officinale
11
and Eribotry japonica.12 Some are shown to correct complications
of diabetes, for example, masoprocol, a pure compound isolated
from Larrea tridentata, which decreases the elevated levels of serum
cholesterol, free fatty acids and triglycerides in fat-fed/diabetic rats.13
Even with the use of these herbs, which possess blood glucose
lowering effects, proper and effective natural treatment of diabetics
require careful integration of diet, nutritional supplements, lifestyle
and botanical medicine.
Although many herbal remedies are claimed to have anticancer
effects, only a few have gained substantial popularity as alternative
cancer therapies. For decades, Essiac has been one of the most
well-known herbal cancer alternatives in North America. It was
developed by a Native healer from Southwestern Canada, it was
popularized by a Canadian nurse, Rene Caisse (Essiac is Caisse
spelled backwards). Essiac comprises four herbs: burdock, Turkey
rhubarb, sorrel and slippery elm. Conversely, researchers at the
National Cancer Institute of USA (NCI) and other institutes found
that it has no anticancer property. Even though Essiac is illegal in
Canada, it is widely available in American pharmacies and health
food stores.14, 15
A derivative of mistletoe, called Iscador, is a popular cancer
remedy in Europe, where it is said to have been in continuous use
as folk treatment since the druids. Iscador is available in many
mainstream European cancer clinics. European governments have
funded studies of iscador’s effectiveness against cancer, but
definitive data have not emerged.14–17
Pau d’arco tea is said to be an old Inca Indian remedy for
many illnesses, including cancer. Made from the bark of an
indigenous South American evergreen tree, its active ingredient,
lapachol (2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphtho-quinone),
has been isolated. Although lapachol showed antitumor activity in
animal studies conducted in the 1970s, it does not appear to affect
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Clinical Application
human malignancies. The tea does induce nausea and vomiting.
Despite the absence of efficacy, pau d’arco tea is sold as a cancer
remedy in health food stores, by mail, and on the internet.14
Herbal remedies in Asia show greater promise. For example,
in Japan, several mushroom-derived compounds are approved for
use as cancer treatments. PC-SPES (PC for prostate cancer; SPES is
the Latin word for hope), a combination of eight herbs, all but two
from traditional Chinese medicine, was found to reduce prostatespecific antigen (PSA) levels in men with advanced prostate cancer.
The recipe came from a great-grandfather of one of the researchers,
that ancestor having been a physician to the Chinese emperor.
Estrogenic side effects occurred with PC-SPES, and its mechanism
of action, although uncertain, may relate to its phytoestrogen
effects.18–21
Vinca rosea
Vinca rosea
(Family: APOCYNACEAE, Common Name: Rosy
Periwinkle)
It is also known as Madagascar periwinkle.
Madagascar periwinkle’s traditional use as a
treatment for diabetes has led to extensive
investigation into its properties. Vincristine
and vinblastine are powerful anticancer
agents, and are two of the most important
medicinal compounds found in plants in the
last 40 years. Vincristine has proved most
effective in treating childhood leukemia;
vinblastine in treating testicular cancer and
Hodgkin’s disease (cancer of the lymphatic
system). Like many drugs used in
chemotherapy, both alkaloids produce such
side-effects as nausea and hair loss.
Long before modern researchers learned
of the plant’s valuable and varied properties,
folk healers in faraway places were using the
Madagascar periwinkle for a host of
medicinal purposes. In India, they treated
wasp stings with the juice from the leaves.
In Hawaii, they prescribed an extract of the
boiled plant to arrest bleeding. In Central
America and parts of South America, they
made a gargle to ease sore throats and chest
ailments. In Cuba, Puerto Rico, Jamaica, and
other islands, an extract of the flowers was
commonly administered as a soothing
eyewash. Periwinkle is used in folk medicine
Chinese medicinal herbs (CMH) can improve chemotherapy
treatment in lung cancer according to researchers at the Jiangxi
Cancer Hospital, Nanchang. The researchers observed the effect of
Chinese medicinal herbs (CMH) and chemotherapy on non-small
cell lung cancer. Comparing the therapeutic effects of three treatment
regimens on 110 patients diagnosed with advanced non-small cell
lung cancer patients — 58 patients were treated with CMH plus
chemotherapy, 28 cases treated with chemotherapy only and 24
cases treated with CMH alone. The results showed that the effective
rates (i.e. partial remission or complete remission) were 22.9% in
CMH and chemotherapy (CT) group, but just 13.6% both in
chemotherapy and in the CMH groups. The survival rate of both
the CMH and chemotherapy group and the CMH group were
significantly higher than that of the chemotherapy group but there
were no significant differences between CMH and CMH + CT group.
The researchers concluded that Chinese medicinal herbs were
helpful to improve average survival times and survival rates of
patients with advanced non-small cell lung cancer. The herbs could
be used in conjunction with chemotherapy and the evidence
suggests that they may be equally effective used alone which would
mean that patients may be able to avoid the side effects of
chemotherapy treatment.22
A study developed by researchers at the University of California
at San Francisco Breast Cancer Center involves patients from that
institution and from the Memorial Sloan-Kettering Cancer Center.
Women with advanced metastatic breast cancer, receiving a Tibetan
herbal formula, are being followed for clinical outcome, including
survival. These investigations suggest that historic herbal cancer
remedies, pre-tested to insure purity and consistency of product
and studied carefully, may produce potentially useful, non-toxic
cancer treatments. The difficulty with time-honored herbal remedies
is that they are rarely tested for purity, examined for consistency, or
studied carefully. They are, nonetheless, in common use. Herb sales
in drugstores and food stores increased 35% from 1993 to 1994,
totaling US$106.7 million for the year.23
in the Philippines as a remedy for diabetes.
Most of these practices are still followed.
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Clinical Application
Safety and Regulatory Issues on
Herbal Medicines
No legal standards exist for the processing or packaging
of herbs. Quality-control standards and reviews are needed.
Because they are not mandatory, however, few food
supplement companies voluntarily self-impose quality
evaluation and control. Consumer protection and
enforcement agencies cannot provide protection against
contaminated or falsely advertised products. Current federal
regulations do not permit such oversight, and regulatory
capability would prohibit full analysis and ongoing oversight
of the estimated 20,000 food supplement items now sold
over the counter. Cancer patients use over-the-counter herbal
products in addition to or instead of those promoted
specifically as cancer treatments. It is therefore important to
recognize herbal remedies that may help cancer patients and
those that are toxic or interact with other medications.
Because neither the US Food and Drug Administration (FDA)
nor any other agency examines herbal remedies for safety
and effectiveness, few products have been formally tested
for side effects or quality control, but information is beginning
to emerge on the basis of public experience with over-thecounter supplements.
Recent reports emphasize the fact that “natural”
products, contrary to apparent consumer belief, are not
necessarily safe or harmless. Most members of the public
apparently are not well aware that herbs are dilute natural
drugs that contain scores of different chemicals, most of
which have not been documented. Effects are not always
predictable. Moreover, the potential for herb-drug interaction
is sufficiently problematic that patients on chemotherapy
should be told to stop using herbal remedies during treatment.
Similar cautions are necessary for patients receiving radiation,
as some herbs photosensitize the skin and cause severe
reactions. Patients scheduled for surgery should be alerted
to the fact that some herbs produce dangerous blood pressure
swings and other unwanted interactions with anesthetics.
Herbs such as feverfew, garlic, ginger and ginkgo have anticoagulant effects and should be avoided by patients on
coumadin, heparin, aspirin, and related agents. The risk of
herb-drug interactions appears to be greatest for patients with
kidney or liver problems.
Moreover, botanical remedies are sold in many forms,
including capsules, liquids and tea leaves. They may contain
one or a collection of herbs and other ingredients, which
typically are not described and often are unknown. According
to research conducted by Consumer Reports, the content of
herbal remedies often differs widely from one bottle to the
next, even within the same brand, as well as from claims
made on the label. The California Department of Health
found unsafe levels of mercury and other toxic metals in
more than a third of Asian patent medicines studied. Several
instances of heart problems resulting from digitaliscontaminated supplements have been reported. Concerns
have been raised recently even about dietary antioxidants,
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which may interact with chemotherapeutic agents.
Hence, Canada is establishing a federal office to
evaluate and regulate herbal remedies, which they
will treat as a new category distinct from drugs and
foods. Organizations such as the American Medical
Association and the American Cancer Society have
produced position papers, and hearings have been
held on food supplement issues by the FDA.24
In conclusion, the enormity and seriousness
of the problem probably will lead to the
establishment of government programs, despite the
anticipated efforts on the part of the food
supplement industry to block efforts that could lead
to regulation of herbal products.
7.
Clinical Application
Bailey CJ, Day C, Traditional plant medicines as treatments
for diabetes, Diab Care 12:553–564, 1989.
8.
Day C, Hypoglycaemic compounds from plants, in Bailey
CJ, Flatt PR (eds.), New Antidiabetic Drugs, Smith-Gordon
and Nishimura Company Limited, London, Japan, Chap.
26, 1990.
9.
Marquis VO, Adanlawo TA, Olaniyi AA, The effect of
foetidin from Momordica foetida on blood glucose level
of albino rats, Planta Med 31:367-374, 1977.
10. Akhtar
MS,
Khan
QM,
Khaliq
T,
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Euphorbia prostrata and Fumaria parviflora in
normoglycaemic and alloxan-treated hyperglycaemic
rabbits, Planta Med 50(2):138–142, 1984.
11. Akhtar MS, Ali MR, Study of hypoglycaemic
activity of Cuminum nigrum seeds in normal and alloxan
diabetic rabbits, Planta Med 51(2):81–85, 1985.
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Clinical Application
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About the Author
Dr PETER Natesan Pushparaj is currently teaching at the Department of
Biochemistry, Faculty of Medicine, National University of Singapore,
Singapore. He has extensive experience in teaching Biochemistry. His research
has cast new light upon the anti-diabetic properties of Averrhoa bilimbi.
Dr Pushparaj has identified and characterized the active com-ponents,
nicotinic acid (NA) and magnesium (Mg) in A. bilimbi which is believed to
improve the blood glucose tolerance in diabetes. He has published scientific
articles in many international journals and a book chapter in Herbal Medicines:
Molecular Basis of Health and Disease (published by Marcel Dekker Inc.,
August 2004).
Contact Details:
Dr Peter Natesan Pushparaj
Address: Department of Physiology
Faculty of Medicine,
10 Kent Ridge Crescent,
National University of
Tel:
Email:
1312
Singapore, Singapore 119260
+65 6874 1668
[email protected]
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