Plant Derived Medicines

Plants are the source for medicines.

Fatty acids, volatile oils, alkaloids and saponins are important plant constituents.

Since their contribution to a plant’s medicinal potential is based on reaching the target receptor sites in the body, their solubility within membranes is essential.

Membrane permeability, solubility and absorption from the gastrointestinal tract are determined by the chemical structure of the plant compound.

Glycosides

Saponins or plant steroids are among the most commonly encountered medicinal agents found in plants.

These compounds when attached to sugar molecules are termed glycosides.

Glycosides are usually the pharmacologically active form of the medicinal compound.

Steroids

Naturally occurring steroid hormones owe their effect to their lipid solubility and ease of passing through membranes. Human steroids possess the ability to bind or cross lipid membranes due to their four-ringed non-polar structure.

Steroids are compounds that contain a backbone of four (tetracyclic) carbon ring structures fused along one side.

This is the classic steroid backbone from which a variety of sugars and small chains are draped.

The addition of these groups at different sites on the backbone leads to the limited variety of steroidal compounds.

Plant sterols are more diverse than their human counterparts, the steroids. and their basic structure (5 carbon rings) allows it to act very similar to the 4 carbon ring structure of human steroids.

In both sets of compounds, the carbon rings provide an organic matrix that gives them their chemical consistency.

It is this consistency that allows steroids and saponins to move through similarly structured materials (membranes).

Plant saponins structurally resemble steroid hormones but are built upon 5 carbon rings instead of 4.

This similarity explains why they cause similar effects. to steroids.

They both cross cell membranes without the need of carriers.

The additional cyclic group causes them to foam when mixed with water. These minor substitutions represent the only diversity permitted within steroid hormones. As steroids, their lipid solubility allows them access to the nucleus where they interact with DNA to produce their effects.

Saponins

Traditional Medicine is founded on the use of local plants. Village healers extracted substances from local plants and gave them to their villagers to restore harmony and balance. These plants contain a class of phytochemical known as saponins.

Saponins are named due to their tendency to form a lather. Saponins are a plant’s version of a steroid.

Steroids and saponins are both lipid soluble compounds that can cross the lipid rich barrier of membranes. They both bind with membrane receptors, steroid carriers and genes. Each of them is capable of producing effects on various processes. Saponins are lipid structures responsible for the effects of herbs.

Saponins or plant sterols are lipid soluble compounds that like human steroids have the ability to cross cell membranes. Once inside the cell, saponins act like steroids to direct DNA activity. Saponins bind with receptors to form complexes just as human steroid hormones.

The saponin complex, just as the steroid complex, interacts directly with genes (DNA) to produce their intended effects.

Unlike neurotransmitters or metabolic hormones, whose effects are instantaneous, steroids require time to produce their effects. The effects produced by saponins are likewise long term. For example, the use of the herb ginseng in males and dang qui in females provides longevity and resistance to illness only with long term, regular consumption. Some saponins, like those found in ginseng, interact with the adrenal cortex to promote hormonal efficiency. This helps cope with stress and is one of the reasons ginseng is so highly recommended. Plant saponins complexed with sugar molecules are termed glycosides. It is in this form that they are active. Since saponins and their glycosides are found in plants with no known function for the plant, it is believed that the actions of these substances are intended to ward off the plant’s natural predators. In other words, these compounds can be harmful but may also offer unknown medicinal benefits.

A saponin is classified on the basis of its carbohydrate content and its sapogenin or triterpene core core. The activity of any given molecule is dependent on its core structure while selectivity is a function of the sugar alignment as part of the whole complex. The core of a saponin is a structure made up of five carbon rings. A sapogenin’s core is the equivalent of the backbone of a steroid. From the sapogenin core, different sugars are complexed providing the plant with its library of similarly structured compounds. This determines the binding specificity of the molecule. Each member of the library is thus slightly unique and will therefore bind with a different membrane receptor.

Saponins are triterpene glycosides with varying number of sugar side chains. These compounds are synthesized by plants and are the basis for many wonder drugs such as the cardiac glycosides. A plant sterol is built upon its triterpene core. The triterpene and the steroid are remarkably similar in structure and function. Steroid diversity is limited while Saponins or plant steroids exist in a variety of conformations. They are part of nature’s library, a library of diversity.

Diversity in the library occurs by the addition of one or more sugar molecules to the sapogenin core. Plant Alkaloids The second important group of medicinal compounds found in plants are known as alkaloids.

Alkaloids represent a diverse group of cyclic organic compounds that contain nitrogen and exhibit alkaline activity. While steroids are restricted to four attached cyclic groups and saponins limited to a five-ringed structure, alkaloids are capable of assuming many complex combinations. Some alkaloids exert their effect by altering or mimicking natural neurotransmitters.

Alkaloids can thus stimulate or inhibit acetylcholine, norepinephrine, epinephrine, dopamine and neuropeptides. They can also interact with their receptors or the enzymes needed for their breakdown or re-formation. Alkaloids that are made of one cyclic carbon ring or aromatic group and contain nitrogen are structurally similar to brain neurotransmitters.

The amino acid tyrosine is the starting point in the formation of some neurotransmitters. Alkaloids are powerful drugs that interfere and alter normal brain activity. Alkaloids are active in the brain because they can pass through the blood-brain barrier, where they bind with neuronal receptors. Brain Chemistry Plant alkaloids, mood altering meds, diet drugs, painkillers, tranquilizers and even chocolate interact in some way with receptors in the brain.

Synapses are gaps between adjoining nerves. On either side of the gap, neurotransmitters are released and bound. Neurotransmitters cross the synaptic cleft to stimulate adjoining nerves. This instance of receptor binding relays the information from one neuron to another by causing the flow of ions thereby creating an electric gradient Neurotransmitters open or close ion channels Synaptic areas of nerves are the target of many drugs. These drugs, called psychotropic drugs work by stimulating or blocking the receptors in the synapse. These drugs structurally resemble the natural ligans and chemically bind with receptors as if they were. Natural transmitters relay information across the synapse. Drugs that prolong the effect of neurotransmitters create a feeling of euphoria.

Altered neurotransmitters produce depression while the accumulation of neuronal debris causes chronic brain diseases (Alzheimer, ALS, Parkinson). Altered receptors lose their selectivity. Receptors either no longer are able to bind with its natural ligans or they bind with different ligands. An excess of receptors characterizes addiction. Serotonin (5-hydroxytryptamine) is an amino acid style neurotransmitter.

Serotonin binds with serotonin receptors. Serotonin binding is linked to mood and sleeping patterns. The overall effect of this mood transmitter is to promote relaxation and sleepiness. Serotonin is a calmative transmitter that counters the effects of catecholamines and dopamine. Serotonin production is concentrated within the neurons of the Raphe nuclei of the brain. Serotonin produces its effect via second messenger activity that follows initial binding. Serotonin’s overall effect is inhibition. Serotonin is formed from the precursor amino acid tryptophan.

Tryptophan must cross the blood-brain barrier using what is called the large neutral amino acid transporter. This carrier also transports tyrosine where it is used in the synthesis of catecholamines (epinephrine). Use of this carrier after eating is responsible for the sleepiness that follows eating. Catecholamines are also neurotransmitters. The effect of catecholamines in the brain is stimulatory. Unlike serotonin, catecholamines bind to receptors outside the brain. Here, they are the neurotransmitter of choice for autonomic control. Inside the brain, catecholamines overall effect is stimulation. Catecholamines like epinephrine (adrenaline) are synthesized from the amino acid tyrosine while serotonin is derived from the amino acid tryptophan.

Tryptophan and tyrosine both compete for the receptor site on the ‘neutral amino transporter’ to gain entry to the brain. The effect that ultimately develops (relaxation vs activity) is determined by which precursor (tryptophan or tyrosine) has a higher concentration around the carrier’s receptor. These concentrations are linked to insulin and its ability to remove tryptophan competitors (tyrosine is a competitor) from the blood. Increased tryptophan is the blood, increases the likelihood that the transporter will pair up with tryptophan, leading to higher serotonin levels and the stimulation of serotonin receptors to produce relaxation. That is why certain meals cause sleepiness.

Tryptophan is the most limited amino acid in food. There are certain foods that contain higher amounts and include dairy and soy products, whole grains and beans as well as meat and fish. Increasing the level of serotonin is one of the two ways that psychopharmacological drugs work. They are known as SSRI (serotonin-specific re-uptake inhibitors), which block the serotonin pump from ending serotonin activity. Lack of tryptophan stores in the brain may be responsible for the blackouts suffered during alcohol binges. Tryptophan and supplements to increase GABA concentrations are innovative ideas to help alcoholics quit drinking.

Lysergic acid diethylamide (LSD)

Alkaloid compounds can affect the activity of serotonin due to their structural similarity and binding with serotonin receptors. Lysergic acid diethylamide (LSD), a derivative of morning glory seeds, has been used for centuries in carrying out sacred rituals or casting out evil demons. The mechanism of morning glory seeds and LSD’s hallucinatory action is thought to be the result of an interaction between serotonin receptors and the synapses involved in the visual cortex. The visual perceptions not received through the eyes, such as those experienced while dreaming, appear to originate by serotonin stimulation. LSD binding with serotonin receptors accounts for the hallucinatory state that occurs with LSD.

Drugs also operate by binding or interfering with membrane bound receptors. Botanical compounds bind with these receptors to produce their effects. Most plants contain a library of these compounds, each one capable of binding with a different receptor. The effect of these bindings is the result of this combination and not solely the result of the predominate compound. Natural medicine is based on plants. Whole plants produce conflicting and opposing effects. This phenomena is best described as adaptogenic. These plant compounds are a group of medically effective substances that heightened one’s resistance to stress.

Adaptogenic substances produced different effects depending upon the person it was administered to. Adaptogens are substances that promote a non-specific increase in resistance against a variety of stressful conditions.

GABA Gamma amino butyric acid (GABA) is the major inhibitory neurotransmitter in the brain. GABA is synthesized in the brain from the amino acid glutamate. GABA prevents overactivity. Lack of GABA results in anxiety and overactivity. The GABA receptor is composed of five different subunits of proteins (alpha, beta, gamma, delta, epsilon and pi). The substructure of these subunits determines the sensitivity to various addictive compounds. Each subunit has its own receptor site and is specific for the ligans it accepts The subunits are assembled to form a membrane pore through which chloride ions flow when the receptor is bound. GABA receptors bind to drugs like alcohol, benzodiazepines (valium) and barbiturates as well as steroids.

GABA receptor stimulation causes relaxation.

Activities such as movement, memory, reasoning, and respiration are controlled in areas, high in GABA receptors.

This program has emphasized the importance of exercise and colorful carbohydrates in the diet. It argues that the damaging effects of free radicals attacks are the primary cause of most chronic diseases. Most non-infectious diseases are chronic diseases. This includes disorders of lipid and carbohydrate metabolism (atherosclerosis and diabetes) as well as overreaction by the inflammatory system (arthritis) and dysfunction in immunological processes (allergies).

In addition, high blood pressure, cancer, dementia even aging itself can be attributed to free radical attack.

The chronic nature of these diseases indicates that there is an opportunity to prevent their inception or at the least, retard their progress. Since this program requires exercise. it anticipates the free radicals that result from exercise and recommends the right foods and supplements to thwart that danger.

Free radical attack uses a wide and varied set of agents to attack and alter cell structures. Fortunately for humankind nature has showered the earth with a variety of plants that contain a library of naturally occurring antioxidants.

In addition to protecting the plant from the sun, these antioxidants offer protection to humans from the harmful effects of oxidative damage to cells. Doctors recommend the minimal combination of vitamins E and C together with beta-carotene and the trace mineral selenium. This pogram further recommends others embedded in the fibers of colorful foods. These foods include the cruciferous vegetables (broccoli, arugula, cabbage and cauliflower) as well as pigmented fruit (grapes, tomatoes and berries) and herbs.

CAROTENOIDS

The carotenoids are lipid-soluble antioxidants that are involved in the normal maintenance of mucus membranes and pigments in the eye. Consuming foods rich in carotenoids can lower the risk of colon and bladder cancer. Beta-carotene is the best-known carotene due to its importance as a vitamin A precursor. There are over 600 carotenoid pigments documented and over 50 can be metabolized to active vitamin A. Carotenoids are the primary pigments found in red, yellow, and orange colored plants (fruits and vegetables).

Lycopene is a carotenoid and is the principal pigment found in bright red fruits (tomatoes), spices (paprika) and pink grapefruit. Structurally, lycopene resembles but is a much more powerful antioxidant than beta-carotene. Lycopene however lacks vitamin A activity. Lycopene is considered cancer-preventive. Once lycopene enters the blood it preferentially targets the prostate gland, lungs and eye. Its antioxidant activity is thought to prevent prostate cancer. Lutein is another carotenoid found in pigmented plants. Dark green, leafy vegetables contain a high concentration of this pigment. Lutein is important for eyesight and is preferentially deposited in the macula and the rods of the retina.

Lutein is a yellow pigment that absorbs blue light and may prevent excessive oxidative damage to the eye. Beta-carotene is a precursor of the active form of vitamin A and prevents lipid peroxidation. Beta-carotene lacks the toxicity associated with vitamin A. Beta-carotene is an excellent quencher of singlet oxygen free radicals and is primarily carried in the blood by LDL. Beta-carotene is believed to be a safe supplement and certainly supplements containing 10-12 mg are completely safe. Nevertheless, there have been reports that high doses of beta-carotene among smokers increased their incidence of contracting lung cancer.

Vitamin E is the antioxidant vitamin. Vitamin E are a group of related fat-soluble compounds. They are divided between tocopheherols and tocotrienols.

 

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