Moringa oleifera : Its Phytochemicals and Their Usage
Dewan Md. Badruddoza
Crop Protection and
Toxicology Laboratory, Dept. of Zoology, University of Rajshahi, Bangladesh.
e-mail: dewan_zoo@ymail.com.
Systematic
position
Kingdom: Plantae
Divition: Magnoliophyta
Class: Magnoliopsida
Family: Moringaceae
Genus: Moringa
Species: Moringa oleifera
Scientific name : Moringa
oleifera
Common names :
Sajina, the horseradish tree,
drumstick tree, benzolive tree, kelor, marango, mlonge, moonga, mulangay,
nébéday, saijhan, sajna or Ben oil tree.
Introduction and
geographical distribution
Moringa oleifera is the most widely
cultivated species in the sub-Himalayan tracts of India, Pakistan, Bangladesh
and Afghanistan. This rapidly-growing tree was utilized by the ancient Romans,
Greeks and Egyptians; it is now widely cultivated and has become naturalized in
many locations in the tropics. It is a perennial softwood tree with timber of
low quality, but which for centuries has been advocated for traditional
medicinal and industrial uses. It is already an important crop in India,
Ethiopia, the Philippines and the Sudan, and is being grown in West, East and
South Africa, tropical Asia, Latin America, the Caribbean, Florida and the
Pacific Islands. All parts of the Moringa
tree are edible and have long been consumed by humans. (Jed W. Fahey, 2005)
Fig-1:
Leaves of Moringa oleifera.
According to Fuglie (1999), the many uses for Moringa include: alley cropping (biomass production), animal forage
(leaves and treated seed-cake), biogas (from leaves), domestic cleaning agent
(crushed leaves), blue dye (wood), fencing (living trees), fertilizer
(seed-cake), foliar nutrient (juice expressed from the leaves), green manure
(from leaves), gum (from tree trunks), honey- and sugar cane juice-clarifier
(powdered seeds), honey (flower nectar), medicine (all plant parts), ornamental
plantings, biopesticide (soil incorporation of leaves to prevent seedling
damping off), pulp (wood), rope (bark), tannin for tanning hides (bark and
gum), water purification (powdered seeds). Moringa
seed oil (yield 30-40% by weight), also known as Ben oil, is a sweet
non-sticking, non-drying oil that resists rancidity. It has been used in
salads, for fine machine lubrication, and in the manufacture of perfume and
hair care products (Tsaknis, 1999). In the West, one of the best known uses for
Moringa is the use of powdered seeds
to flocculate contaminants and purify drinking water (Berger, 1984), but the
seeds are also eaten green, roasted, powdered and steeped for tea or used in
curries (Gassenschmidt, 1995). This tree has in recent times been advocated as
an outstanding indigenous source of highly digestible protein, Ca, Fe, Vitamin
C, and carotenoids suitable for utilization in many of the so-called
“developing” regions of the world where undernourishment is a major concern.
(Jed W. Fahey, 2005)
Nutrition
Moringa trees have been used to
combat malnutrition, especially among infants and nursing mothers. Three non-governmental
organizations in particular—Trees for Life, Church World Service and
Educational Concerns for Hunger Organization—have advocated Moringa as “natural nutrition for the tropics.” Leaves can
be eaten fresh, cooked, or stored as dried powder for many months without
refrigeration, and reportedly without loss of nutritional value. Moringa is especially promising as a
food source in the tropics because the tree is in full leaf at the end of the
dry season when other foods are typically scarce. (Jed W. Fahey, 2005)
Fig-2:
Moringa oleifera plant.
A large number of
reports on the nutritional qualities of Moringa
now exist in both the scientific and the popular literature. Moringa leaves contain more Vitamin A
than carrots, more calcium than milk, more iron than spinach, more Vitamin C
than oranges, and more potassium than bananas,” and that the protein quality of
Moringa leaves rivals that of milk
and eggs. The oral histories recorded by Lowell Fuglie in Senegal and
throughout West Africa, who reports countless instances of lifesaving
nutritional rescue that are attributed to
Moringa (Fuglie, L.J., 1999, 2000). In fact, the nutritional properties of Moringa are now so well known that there
seems to be little doubt of the substantial health benefit to be realized by
consumption of Moringa leaf powder in
situations where starvation is imminent. Nonetheless, the outcomes of well
controlled and well documented clinical studies are still clearly of great
value. (Jed W. Fahey, 2005)
In many cultures throughout the tropics, differentiation between
food and medicinal uses of plants (e.g. bark, fruit, leaves, nuts, seeds,
tubers, roots, flowers), is very difficult since plant uses span both
categories and this is deeply ingrained in the traditions and the fabric of the
community (Lockett et al., 2000).
Phytochemistry
Phytochemicals are, in
the strictest sense of the word, chemicals produced by plants. Commonly,
though, the word refers to only those chemicals which may have an impact on
health, or on flavor, texture, smell, or color of the plants, but are not
required by humans as essential nutrients. An examination of the phytochemicals
of Moringa species affords the
opportunity to examine a range of fairly unique compounds. In particular, this
plant family is rich in compounds containing the simple sugar, rhamnose, and it
is rich in a fairly unique group of compounds called glucosinolates and
isothiocyanates (Bennett et. al.,
2003; Fahey et. al., 2001). For
example, specific components of Moringa
preparations that have been reported to have hypotensive, anticancer, and
antibacterial activity include 4-(4'-O-acetyl-a-L-rhamnopyranosyloxy)
benzyl isothiocyanate (Abrams B, D
Duncan, & I Hertz-Piccioto, 1993), 4-(a-L-rhamnopyranosyloxy) benzyl
isothiocyanate (Abuye et. al., 1999), niazimicin (Akhtar AH, KU Ahmad, 1995),
pterygospermin (Anderson et. al.,1986), benzyl
isothiocyanate (Anwar F. and MI
Bhanger, 2003), and 4-(a-L-rhamnopyranosyloxy) benzyl glucosinolate (Asres K., 1995).
Figure
3. Structures of selected
phytochemicals from Moringa spp.: 4-(4'-O-acetyl-a-L-rhamnopyranosyloxy)benzyl
isothiocyanate [1], 4-(-L-rhamnopyranosyloxy)benzyl isothiocyanate [2],
niazimicin [3], pterygospermin [4], benzyl isothiocyanate [5],
and 4-(a-L-rhamnopyranosyloxy)benzyl glucosinolate [6].
While these compounds are relatively unique to the Moringa family, it is also rich in a
number of vitamins and minerals as well as other more commonly recognized
phytochemicals such as the carotenoids (including b-carotene or pro-vitamin A).
These attributes are all discussed extensively by Lowell Fuglie (1999) and
others, and will be the subject of a future review in this series. (Jed W.
Fahey, 2005)
Disease Treatment and
Prevention
The benefits for the
treatment or prevention of disease or infection that may accrue from either
dietary or topical administration of Moringa
preparations (e.g. extracts, decoctions, poultices, creams, oils, emollients,
salves, powders, porridges) are not quite so well known (Palada MC, 1996).
Although the oral history here is also voluminous, it has been subject to much
less intense scientific scrutiny, and it is useful to review the claims that
have been made and to assess the quality of evidence available for the more
well-documented claims. The readers of this review are encouraged to examine
two recent papers that do an excellent job of contrasting the dilemma of
balancing evidence from complementary and alternative medicine (e.g.
traditional medicine, tribal lore, oral histories and anecdotes) with the
burden of proof required in order to make sound scientific judgments on the
efficacy of these traditional cures (Sampson W, 2005 ; Talalay P, and P
Talalay, 2001). Clearly much more research is justified, but just as clearly
this will be a very fruitful field of endeavor for both basic and applied
researchers over the next decade. (Jed W. Fahey, 2005)
Widespread claims of the
medicinal effectiveness of various Moringa
tree preparations have encouraged the author and his colleagues at The Johns
Hopkins University to further investigate some of these possibilities. A
plethora of traditional medicine references attest to its curative power, and
scientific validation of these popular uses is developing to support at least
some of the claims. Moringa preparations
have been cited in the scientific literature as having antibiotic,
antitrypanosomal, hypotensive, antispasmodic, antiulcer, anti-inflammatory,
hypocholesterolemic, and hypoglycemic activities, as well as having
considerable efficacy in water purification by flocculation, sedimentation,
antibiosis and even reduction of Schistosome cercariae titer. (Jed W. Fahey,
2005)
Unfortunately, many of
these reports of efficacy in human beings are not supported by placebo
controlled, randomized clinical trials, nor have they been published in high
visibility journals. For example, on the surface a report published almost 27
years ago (Shaw BP, and P Jana, 1982) appears to establish Moringa as a powerful cure for urinary tract infection, but it
provides the reader with no source of comparison (no control subjects). Thus,
to the extent to which this is antithetical to Western medicine, Moringa has not yet been and will not be
embraced by Western-trained medical practitioners for either its medicinal or
nutritional properties. (Jed W. Fahey, 2005)
In many cases, published
in-vitro (cultured cells) and in-vivo (animal) trials do provide
a degree of mechanistic support for some of the claims that have sprung from
the traditional medicine lore. For example, numerous studies now point to the
elevation of a variety of detoxication and antioxidant enzymes and biomarkers
as a result of treatment with Moringa
or with phytochemicals isolated from
Moringa (Fahey JW, AT Dinkova-Kostova, and P Talalay, 2004; Faizi et. al., 1994; Kumar NA, and L Pari,
2003, Rao KNV., V
Gopalakrishnan, V Loganathan, and S Shanmuganathan, 1999).
Antibiotic Activity
This is clearly the area
in which the preponderance of evidence—both classical scientific and extensive
anecdotal evidence—is overwhelming. The scientific evidence has now been
available for over 50 years, although much of it is completely unknown to
western scientists. In the late 1940’s and early 1950’s a team from the
University of Bombay (BR Das), Travancore University (PA Kurup), and the
Department of Biochemistry at the Indian Institute of Science in Bangalore (PLN
Rao), identified a compound they called pterygospermin a compound which they
reported readily dissociated into two molecules of benzyl isothiocyanate (Anwar F, and MI Bhanger, 2003). Benzyl isothiocyanate
was already understood at that time to have antimicrobial properties. This
group not only identified pterygospermin, but performed extensive and elegant
characterization of its mode of antimicrobial action in the mid 1950’s. (Jed W.
Fahey, 2005)
Bennie Badgett (1964)
identified a number of glyosylated derivatives of benzyl isothiocyanate (e.g. compounds containing the
6-carbon simple sugar, rhamnose) (Badgett BL, 1964). The identity of these
compounds was not available in the refereed scientific literature until
“re-discovered” 15 years later by Kjaer and co-workers (1979). Seminal reports
on the antibiotic activity of the primary rhamnosylated compound then followed,
from U Eilert and colleagues in Braunschweig, Germany (Eilert U, 1978; Eilert U, B Wolters and
A Nahrstedt, 1981). They re-isolated and confirmed the identity of
4-(a-L-rhamnopyranosyloxy) benzyl glucosinolate (Asres K, 1995) and its cognate isothiocyanate and
verified the activity of the latter compound against a wide range of bacteria
and fungi. (Abuye
C, AM Omwega, JK Imungi, 1999)
Extensive field reports
and ecological studies forming part of a rich traditional medicine history,
claim efficacy of leaf, seed, root, bark, and flowers against a variety of
dermal and internal infections. Unfortunately, many of the reports of
antibiotic efficacy in humans are not supported by placebo controlled,
randomized clinical trials. Again, in keeping with Western medical prejudices,
practitioners may not be expected to embrace Moringa for its antibiotic
properties. In this case, however, the in-vitro (bacterial cultures) and
observational studies provide a very plausible mechanistic underpinning for the
plethora of efficacy claims that have accumulated over the years. (Jed W.
Fahey, 2005)
Aware of the reported
antibiotic activity of 4-(-L-rhamnopyranosyloxy)
benzyl isothiocyanate, benzyl
isothiocyanate, and other isothiocyanates and plants containing them, we
undertook to determine whether some of them were also active as antibiotics
against Helicobacter pylori. This bacterium was not discovered until the
mid-1980’s, a discovery for which the 2005 Nobel Prize in Medicine was just
awarded. H. pylori is an omnipresent pathogen of human beings in
medically underserved areas of the world, and amongst the poorest of poor
populations worldwide. It is a major cause of gastritis, and of gastric and
duodenal ulcers, and it is a major risk factor for gastric cancer (having been
classified as a carcinogen by the W.H.O. in 1993). Cultures of H. pylori,
it turned out, were extraordinarily susceptible to 4-(-L-rhamnopyranosyloxy) benzyl isothiocyanate, and to a number
of other isothiocyanates (Fahey et al.,
2002; Haristoy
et al., 2005). These compounds had
antibiotic activity against H. pylori at concentrations up to 1000-fold
lower than those which had been used in earlier studies against a wide range of
bacteria and fungi. The extension of this finding to human H. pylori
infection is now being pursued in the clinic, and the prototypical
isothiocyanate has already demonstrated some efficacy in pilot studies (Galan
MV, AA Kishan and AL Silverman, 2004; Yanaka et al., 2005).
Cancer
Prevention
Since Moringa species
have long been recognized by folk medicine practitioners as having value in
tumor therapy (Hartwell JL., 1967-1971), we examined compounds O-acetyl-a-L-rhamnopyranosyloxy)benzyl
isothiocyanate and
4-(-L-rhamnopyranosyloxy)benzyl isothiocyanate for their cancer preventive potential (Fahey JW, AT
Dinkova-Kostova, and P Talalay, 2004). Recently, 4-(4'-O-acetyl-a-L-rhamnopyranosyloxy)benzyl
isothiocyanate and the related
compound niazimicin were shown
to be potent inhibitors of phorbol ester (TPA)-induced Epstein-Barr virus early
antigen activation in lymphoblastoid (Burkitt’s lymphoma) cells (Murakami et al., 1998; Guevara et al., 1999). In one of these studies,
niazimicin also inhibited tumor promotion in a mouse two-stage DMBA-TPA tumor
model (Murakami et al., 1998). In an
even more recent study, Bharali and colleagues have examined skin tumor
prevention following ingestion of drumstick (Moringa seedpod) extracts (Bharali R, J Tabassum, MRH Azad, 2003).
In this mouse model, which included appropriate positive and negative controls,
a dramatic reduction in skin papillomas was demonstrated.
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