Biology concepts – sap, resin, latex, mucilage
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Frankincense
is a solid material than starts out
as a
liquid that oozes from a tree. In the presence
of air,
the resin turns hard. When burned,
many
fragrant and brain altering compounds
are released.
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A 2008 study may have defined just why frankincense is used in religious rituals.
Burning the resin releases incensole acetate (IA), one of the resin’s key
components, which activates transient receptor potential vanilloid (TRPV3) ion
channels in the skin and brain. This ion channel is responsible for mediating a warm feeling in the skin, but TRPV3 channels also mediate brain activity.
The researchers in Israel found that IA activates the cFos
transcription factor in the brain, leading to anxiolytic (anxio = anxiety,
and lytic = destroying) and anti-depressive feelings. Mice without TRPV3
channels did not show cFos activation or behavior changes when exposed to IA.
It appears that burning frankincense makes one feel happier and more in tune
with whatever activity is going on at the time, including religious rituals.
The fact that there is a psychoactive agent in frankincense is amazing enough, but there’s
more biology to this second gift. Recent evidence indicates that the oils and other
compounds in frankincense may save lives– if the trees that produce
frankincense don’t disappear in the next 50 years. Unfortunately, their
extinction is a distinct possibility – we must save this precious sap, or
resin, or whatever it is.
Trees can produce various oozings and liquids. Pancake syrup
most often comes from the sap of a
maple tree, while your stick of Wrigley’s spearmint uses the latex that exude from many different
kinds of plants. Gum drippings may
also be used in chewing gum (Chiclets used chicle gum), but gums are now more commonly found
in paints and erasers. The aloe vera you use on burns is a type of mucilage, rich in glycoproteins. But
many plants, especially coniferous trees, exude resins when they are under attack or are damaged.
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Amber
is fossilized resin. Scientists learn much from organisms
caught
in it and thus preserved. Recent evidence also
shows that amber can
help us track bug attacks on plants from the days of dinosaurs.
Gum is semi-solid, and rubbery.
The gum shown is chicle, used
for many years in Chiclets
gum. Mucilage is produced by
many pants, including
as a treat and trap for insects in carnivorous
plants
like this sundew. Maple sap is clear and dilute when tapped
from
a tree. It must be boiled for hours to reduce it to
syrup. Latex rubber is
naturally white. The first car and bicycle tires were all white, not
just white-walled. |
Gums can also be used for defense, but are made directly
from disintegrating internal plant material. They harden to a certain degree
after being exuded from the plant tissue, but are more known for their ability
to increase the viscosity of a liquid, due to their long polysaccharide
molecules. Bacterial agar plates use a gum from seaweed to grow microorganisms.
Sap is the sugary fluid that travels up and down in
the xylem of vascular plants, providing the different structures with
carbohydrate to produce ATP at the cellular level. Therefore, sap is a
nutritive liquid and all trees produce it – but not all taste good.
Mucilage is similar to sap. It also contains
glycoproteins and other carbohydrate-containing molecules, and is important for
food and water storage in almost all plants, especially cacti. However, mucilage can
be used for other purposes, like luring insects into carnivorous plant traps,
such as the flypaper plant.
People used to lick mucilage everyday, but technology has
reduced its role in our lives. When mixed with water, mucilage is an adhesive,
like on the backs of stamps. You don’t have to lick your computer screen to
send an e-mail, so mucilage is less important to us in these modern times.
Resins become definite solids when exposed to air. They
are not nutritive, and contain primarily the byproducts and secondary
metabolites of other cellular processes. While gums and saps are soluble (will
dissolve) in water or fat, resins are stable in water but will dissolve in
alcohol.
The reason for resin production is not fully understood. They
may play a role in defense or tissue injury, but may instead serve to rid the
plant of unneeded or unwanted waste products. Indeed, when trees are cut to
harvest frankincense, the first resin produced is discarded, because it
contains many toxins and foul smelling chemicals.
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The
Boswellia sacra tree grows in a harsh
environment.
The roots can grip onto stones and
they grow out of the ground as buttresses to keep
the
tree stable on the cliff sides.
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B. sacra grows
only in the middle eastern countries of Yemen and Oman, and possibly in Somalia.
The tree is only 2-7 meters (6-23 ft.) when fully grown, and starts producing
resin at a fairly young age of 8-10 years. Its small stature may be due in part
to the arid climate that it lives in; there is so little water to be had that B. sacra survives only on the moisture
it absorbs from fog.
However uninviting its environment might seem, B. sacra is well adapted to this area
and is very finicky in growing anywhere else. In fact, a recent study indicates
that they are more finicky than even previously believed. Though living in two
different areas (Oman/Yemen vs. Somalia), it had been accepted that these plants
were the same species. But based on chemical evaluation of the essential oils of the resins from trees in these two regions, the Oman/Yemen trees of B.
sacra are truly different than the B.
carterii trees of Somalia.
Initial gas chromatography-mass spectrum analysis did not
show significant differences in the kinds of volatile molecules present, but
there were large differences in the amounts of the individual compounds in the
resin from each species of tree. Later experiments also showed chemical
differences in the same compounds from each species.
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Yemen
and Oman are side by side and Somalia is
just
across the Gulf of Aden. But recent studies show
that
the frankincense trees that grow in Yemen and
Oman
are distinctly different from those in Somalia.
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Add goats grazing on the existing trees, global warming, fires,
and low genetic diversity in individual stands of trees to the low rate of
propagation and this spells trouble for the B.
sacra species. Estimates are as dire as a 50% decrease in frankincense
production in the next 15 years, to a 90% loss of trees in the next 50 years –
but there is hope.
A recent DNA study shows that trees from different parts of the Dhofar region are
genetically distinct, and that there is a low level of heterozygosity in the
trees of a single area. This low level of genetic diversity results in trees
less able to survive changes in environment or biology (genetic diversity is
key to natural selection). But some stands show more genetic diversity and
arguments are now being made to initiate conservation efforts for the diverse
stands, while increasing cross-pollination of the least genetically diverse
trees. It is hoped that these efforts, as well as attempts to grow B. sacra in the Sonora Desert of North
America, could stave off extinction of B.
sacra.
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The
hippocampus is important in your sense of well-
being.
Studies have shown that in people with
depression,
the hippocampus is smaller, perhaps from
poor
neurogenesis or from increased
cell death. Why
the
seahorse? In Greek, hippocampus means, “horse sea
monster.”
I can see the resemblance.
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We mentioned above that IA (incensole acetate) of
frankincense acts on the brain to increase feelings of well-being. Mice bred to
be submissive and to give up (quit) earlier in a test of depressive activity show a much stronger will to live and more positive behaviors when given IA. Recent research in Israel shows that IA
influences brain molecular biology, especially in the hippocampus, altering
depressive behaviors as much as other chemical interventions. It is hoped that
IA may be a viable anti-depressant drug in the future.
This same group showed in 2008 that IA was a significant anti-inflammatory agent,
through its inhibitor action on an important transcription factor (called NF-kB) that stimulates expression of
inflammatory proteins. In mice with traumatic brain injuries, IA administration
resulted in reduced inflammation and pressure on the brain, reduced neuron
degeneration, and prevented loss of cognitive function. Their more recent study also
indicates that IA is protective in stroke and in the damage that can come after
strokes by reintroducing oxygen into the damage part of the brain (when blood
flow resumes).
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Boswellic
acid is also of use in myeloid leukemia, a type
of
cancer of the white blood cells. It seems that BA can
induce
the cancer cells to commit suicide, and die after a
period
of time like most cells do. BA trigger apoptosis by
stimulating
the release of important compounds from the
mitochondria,
suggesting to the cell that its energy making
organelles
are irreparably damaged.
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Cancer is the result of mutations in genes that code
for the production of proteins that keep cells living, growing, and dividing forever.
BA stops the synthesis of some of these proteins. It turns out that BA
stimulates production of a micro RNA (miRNA, a short RNA molecule of about 22
nucleotides) that can bind to the messages transcribed from DNA that would be
translated into pro-cancer proteins and stop the proteins from being made. Do you think the three kings had any idea
that they were giving a gift that can stop inflammation, depression, and cancer
– or they did they just think it smelled nice?
Next week – The third of the original gifts, myrrh. There's a biologic reason frankincense and myrrh were given together as gifts, but science didn't figure it out until just a couple of years ago.
Takahashi, M., Sung, B., Shen, Y., Hur, K., Link, A., Boland, C., Aggarwal, B., & Goel, A. (2012). Boswellic acid exerts antitumor effects in colorectal cancer cells by modulating expression of the let-7 and miR-200 microRNA family Carcinogenesis, 33 (12), 2441-2449 DOI: 10.1093/carcin/bgs286
For
more information, see:
Resin
–
Sap
–
Gum
–
Latex
–
Mucilage
–
Boswellia
sacra –
http://www.iucnredlist.org/details/34533/0
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