Are humans really are Are humans really are what they eat?what they eat?

Complexity of human drug Complexity of human drug metabolismmetabolism

by Olga Trubetskoy

TerminologyTerminology Metabolism: (Gk: metabole: change)Metabolism: (Gk: metabole: change) Xenobiotics: xeno (Gk: foreign)… bioticsXenobiotics: xeno (Gk: foreign)… biotics Inhibition Inhibition (Latin inhibitus, ): to prohibit from (Latin inhibitus, ): to prohibit from

doing somethingdoing something Induction (Induction (Latin inducere): to induce: to Latin inducere): to induce: to

call forth or bring about by influence or call forth or bring about by influence or stimulationstimulation

Cytochrome P450s (CYPs)Cytochrome P450s (CYPs)

P450s is a weapon in plant-animal chemical P450s is a weapon in plant-animal chemical warfarewarfare

“We are continually under threat from chemical warfare in the guise of foreign compounds in our diet and environment, odorants, drugs and our bodies’ own waste chemicals. CYP450s are a vital part of defense system which reduce the toxicity of potentially damaging chemicals and facilitate their excretion”

- B. Burchell

Drug metabolism process (defense Drug metabolism process (defense mechanism against plants’ toxins)mechanism against plants’ toxins)

P450

Food

Toxin

Individual’s metabolic signatureIndividual’s metabolic signature An individual exposure to food and environmental An individual exposure to food and environmental

compounds leaves a “metabolic signature” in our compounds leaves a “metabolic signature” in our body, changing the way we are interacting with body, changing the way we are interacting with our environmentour environment

Many factors, including genetic, environmental, in Many factors, including genetic, environmental, in uterus exposure, life style, diet and eating habits uterus exposure, life style, diet and eating habits contribute to a “metabolic fingerprint map” unique contribute to a “metabolic fingerprint map” unique for each individual organismfor each individual organism

This “metabolic signature” may serve as a basis This “metabolic signature” may serve as a basis for the personalized drug therapyfor the personalized drug therapy

Why is it important to know you Why is it important to know you “metabolic signature”?“metabolic signature”?

Adverse reactions to prescription drugs Adverse reactions to prescription drugs are killing about 106,000 Americans each are killing about 106,000 Americans each year -- roughly three times as many as are year -- roughly three times as many as are killed by automobiles. killed by automobiles.

This makes prescription drugs the fourth This makes prescription drugs the fourth leading killer in the U.S., after heart leading killer in the U.S., after heart disease, cancer, and strokedisease, cancer, and stroke

What is behind adverse drug reactionsWhat is behind adverse drug reactions

+ +

Why do you need to know your metabolic Why do you need to know your metabolic profile (“metabolic signature”)?profile (“metabolic signature”)?

This information may save your life!!!!!This information may save your life!!!!! Drug-drug and drug/food interactions are one Drug-drug and drug/food interactions are one

of the leading cases of patients’ mortalityof the leading cases of patients’ mortality What drugs to prescribe/avoid and doseWhat drugs to prescribe/avoid and dose What combination of drugs to avoidWhat combination of drugs to avoid How your behavior affects your metabolismHow your behavior affects your metabolism Do you really need “a pill”?Do you really need “a pill”?

Get to know your P450s: body’s Get to know your P450s: body’s own biochemical weaponown biochemical weapon

““Weapon’s” design:Weapon’s” design:

P450s: where they are involved

Metabolism of xenobiotics*:• toxification• detoxification• production of intermediate metabolites (active, inactive, toxic)

* xenobiotics - non-biological compounds prevalent in the environment,including drugs, nutrients, herbal and plant food components, odorants, toxins, carcinogens and mutagens

Main P450s in drug metabolismMain P450s in drug metabolism Major classes of “weapons” (P450s)Major classes of “weapons” (P450s)

CYP3A, 2D6, 2C9, 2C19, 1A2, 2E1

CYP1 CYP2 CYP3

Families

Variability of drug clearance Variability of drug clearance (how fast drug is eliminated)(how fast drug is eliminated)

P450 enzyme

Extent of variability

1A ~40-folds 2C 25-100-folds

2D6 >1000-fold 2E1 ~20-fold 3A4 ~20-fold

Simulated effect of P450 inductionSimulated effect of P450 induction

Simulated effect of P450 inhibitionSimulated effect of P450 inhibition

Do we have control over our own Do we have control over our own weapons?weapons?

Levels of complexityLevels of complexity in drug metabolism in drug metabolism response:response:

GeneticsGenetics EpigeneticEpigenetic

In uterus exposureIn uterus exposure Age, sex, diseaseAge, sex, disease Diet and nutritionDiet and nutrition Exposure to environmental toxinsExposure to environmental toxins

Psychological factorsPsychological factors

Control over sources of variability Control over sources of variability ((onon//offoff switch programming) switch programming)

Genes - individual, ethnic (initial conditions) Physiology:

age, sex, diseases (uncontrolled conditions) nutrition and diet, alcohol and smoking, style of

life (partial control) Environment (environmental toxins, mutagens

carcinogens) (partial control?) Psychology– anything will work in 40%

cases (placebo effect) – may be?

Genetics: P450 polymorphism

CYP2D6

PM (poor metabolizer) - inactive or absent enzyme

EM (extensive metabolizer) - at least 1 functional allele

UM (ultrarapid metabolizer) - multiple copies (up to 13) of CYP2D6 gene

Frequency of PM phenotype:

Caucasian ~12 %

African-American ~1 - 3%

Asian <1 %

Frequency of EM phenotype:

Ethiopian ~13 %

Spanish ~3.5 %

Can you influence your genes?

The most interesting example: high expression of CYP2D6 in many persons of Ethiopian and Saudi Arabian origin. 2D6 is not inducible, so these people have developed a different strategy to cope with the (presumed) high load of toxic alkaloids in their diet - multiple copies of the gene (up to……) Changing the diet (moving to Sweden) changed their CYP2D6 phenotype to (not genotype).

Effect of fast metabolism may be dual - many antidepressants and neuroleptics are quickly become ineffective. Conversely, prodrugs will be extensively activated - codeine will be turned into morphine almost immediately.

Others: through induction CYP2C9, 2D6, 2C19, 3A4

1

13

Interplay between nuclear receptors (NR), their Interplay between nuclear receptors (NR), their ligands and CYP450sligands and CYP450s

XO, EOX, EP450 genes

NRs

Other genes

metabolitesXeno-,Endo-biotics

On off

On off

P450

How dietary composition can modulate on/off switch

Unlike that of other animal species, the human diet is extremely variable among individuals.

The compositions of diets vary according to availability, religion and the method of preparation

Which P450 enzymes are being Which P450 enzymes are being affectedaffected

Nutrition 1A1; 1A2; 2E1; 3A4, 5

Smoking 1A1; 1A2

Alcohol 2E1

Drugs 1A1; 1A2; 2A6; 2B6; 2C; 2D6; 3A3, 3A4,5

Enviroment 1A1; 1A2; 2A6; 1B; 2E1; 3A3, 3A4,5

Genetic Polymorphism

1A1; 2A6; 2C9, 19; 2D6; 2E1

Does it matter if you had a glass of Does it matter if you had a glass of coffee, grapefruit juice or milk for coffee, grapefruit juice or milk for

breakfast? breakfast? What else?What else? Spices (saffron, cumin, ginger)Spices (saffron, cumin, ginger) Flavonoids (soy, red wine)Flavonoids (soy, red wine) Fruits (bergamottin – grapefruit juice)Fruits (bergamottin – grapefruit juice) Other herbs: St. John’s WortOther herbs: St. John’s Wort Cruciferable vegetables (sprouts, cabbage) due Cruciferable vegetables (sprouts, cabbage) due

to a presence of indolsto a presence of indols CaffeineCaffeine Smoking (benzopyrene)Smoking (benzopyrene)

CYP1A induction by flavonoidsCYP1A induction by flavonoids

Red wine (good wine stored in brown bottle)

1 bottle

2 glasses

Curry

Food/spices modulate P450 activityFood/spices modulate P450 activity

Hot pepper

Onion , garlic

Root beer

CYP3A4

CYP2E1

Cooking style modulates P450 Cooking style modulates P450 activityactivity

Individuals who ate a charcoal-broiled 8-ounce hamburger at lunch and a 6-ounce steak for dinner each day for 4 days had >80% lower plasma concentrations of

phenacetin compared with those who ate their usual home dietA high-protein–low carbohydrate diet for 2 weeks increases the metabolism of caffeine and aminopyrine

Grapefruit juice modulates (inhibits) Grapefruit juice modulates (inhibits) CYP3A4 activityCYP3A4 activity

Drug clearance (felodipine)

No GP 1 glass GP juice0

250

500

%

Effect of bergamottin onCYP3A4

0.0 1.0 10.0 100.00

50

100

Bergamottin, uM

% r

emai

ning

CY

P3A

4ac

tivi

ty

Bergamottin (present in grapefruit skin only)

Diet modulate P450 activityDiet modulate P450 activity

Alcohol modulates P450 activityAlcohol modulates P450 activity Alcohol (dual effect– beneficial from red wine Alcohol (dual effect– beneficial from red wine

flavonoids and induction from ethanol exposure)flavonoids and induction from ethanol exposure) Alcohol – induced toxicity of acetaminophen Alcohol – induced toxicity of acetaminophen

(Tylenol) Acetaminophen in small amounts is (Tylenol) Acetaminophen in small amounts is metabolized by glucuronidation and sulfation. metabolized by glucuronidation and sulfation. Larger ingestions result in production of a toxic Larger ingestions result in production of a toxic metabolite N-acetyl-p-benzoquinoneimine (NAPQI) metabolite N-acetyl-p-benzoquinoneimine (NAPQI) by P450. The NAPQI is normally detoxified by by P450. The NAPQI is normally detoxified by glutathione. However, chronic alcoholism depletes glutathione. However, chronic alcoholism depletes glutathione, and also induces P450 to increase glutathione, and also induces P450 to increase toxicity. Thus, previous chronic alcohol ingestion toxicity. Thus, previous chronic alcohol ingestion increases the risk for acetaminophen toxicity.increases the risk for acetaminophen toxicity.

Smoking modulates P450 activitySmoking modulates P450 activity

Polycyclic hydrocarbons in cigarette smoke induce the metabolism of CYP1A substrates as a result of CYP1A induction

The average content of CYP1A in the liver biopsies from smokers (16.3 pmol/mg of protein) was significantly higher than that from nonsmokers (4.7)

Theophylline, caffeine, fluvoxamine, clozapine, and olanzapine clearance is significantly increased in smokers compared with nonsmokers

Herbal supplements modulate Herbal supplements modulate P450 activityP450 activity

St. John’s Wort (Hypericum perforatum) St. John’s Wort (Hypericum perforatum) extracts, preparations that are used in the extracts, preparations that are used in the treatment of depression, inhibit CYP1A2, treatment of depression, inhibit CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4CYP2C9, CYP2C19, CYP2D6, and CYP3A4

Ginseng (CYP1A1, 1A2, 1B1)-inhibitionGinseng (CYP1A1, 1A2, 1B1)-inhibition The Licorice Root derived Isoflavan Glabridin The Licorice Root derived Isoflavan Glabridin

inhibits P450s 3A4, 2B6, and 2C9inhibits P450s 3A4, 2B6, and 2C9

Multiple drug interactions modulate Multiple drug interactions modulate P450 activityP450 activity

A 63 year old man receiving medication for major depression showed he boarded a plane in Toronto to fly to London. On arrival he was unrousable. In his Carry-on bag he had Mefadazone (for depression), Ketoconazole (for fungal infection) and Triazolam (an antipsychotic also used for insomnia). All three of these drugs bind to CYP3A4. Ketoconazole inhibits CYP3A4 and caused the other two drugs to become overdosed during 6 hr flight (sitting still is a factor).

CYP3A4

Triazolam

Ketoconazole

Mefadazone+ +

Overdose

Do our eating (and other) habits Do our eating (and other) habits leave marks (metabolic signatures) leave marks (metabolic signatures) in our drug metabolism landscape?in our drug metabolism landscape?

Prescriptions based on genotype or Prescriptions based on genotype or phenotype?phenotype?

E.g., do we need to know only initial E.g., do we need to know only initial conditions (your genes) or the final picture conditions (your genes) or the final picture (on/off switch)?(on/off switch)?

Can we regulate this complex picture?Can we regulate this complex picture? To a what degree?To a what degree? And if we can, then….And if we can, then….

Can one do things right just for Can one do things right just for himself?himself?

Presence of drug metabolites in soil and Presence of drug metabolites in soil and underground waters (contamination)underground waters (contamination)

Global environmental exposureGlobal environmental exposure Are all these factors triggers for human Are all these factors triggers for human

adaptation?adaptation?