What have we learned?

Marty Mulvihill

Chris Vulpe

Marty’s Goals as a Chemist

• Know basic paradigms of toxicology- – Dose response – ADME – PBT

• Be able to find data • Build intuition for potential chemicals of concern.

– Electrophiles, reactive oxygen generators, persistent chemicals.

• Be able to understand and intuit basic mechanisms involved with ADMET – CYP450 – Transporters – Rules of thumb

There is data available: ToxNet

1. It is not organized in a way that makes comparisons easy.

2. The amount and quality of data varies widely across chemicals.

Persistence and Bioaccumulation

1. Relatively easy to qualitatively predict.

2. PBT Profiler easy to use, even if it is overly simplistic.

3. Can find the data/modeled data using EPI Suite (within chemspider or standalone).

Toxicophores

1. Electrophile

– Hard/soft

– Reactivity

2. ToxPredict on OpenTox.

QSARS: Need a program for chemists

• What are the important endpoints?

• What are the best training sets?

• How should the data be presented?

ADME: Adsorption and Distribution

Rules of thumb

Specific Mechanisms

ADME: Metabolism

• CYP predict

Testing

1. Still need to know endpoints?

2. What information is most useful?

3. When should that information be applied to the chemical design process?

Where to go from here: • User friendly QSAR risk assessment programs – interpret results • Consolidated information for green chemists – one stop website • ToxPi Risk analysis idea • Chemical search against nutrient transporters • Does fluorine groups actually increase or decrease Caco 2 absorption –

could be tested. • Guidance document on what simple toxicity assays to be used • Source of information on toxicity on most common reagents / solvents

used in chemistry • Modify ADME rules but for green chemistry – stress don’t just have to

make hydrophobic, ie. explore the hydrophilic side of the abosorbtion curve.

• Discuss minimum data set needed to choose between two chemicals. • Survey a class of reactants and rank safety similar to the solvent selection

guide and recent work from pharmaceutical • When should a chemist considered hazard? Design of a reaction? Design

of a molecule? What degree of certainty should they have? How should it be reported?

• Prioritize the results needed from QSAR analaysis to guide chemical design.

Summary of Findings Toxicology Basics

Adam Andrewjeski

Nancy Diaz

Katie McKinstry

"#$%&' ( )*!+, -!" , %. ( -&*, / !

Initial Assessment- PBT Profiler

• Half life of air is problematic for p-xylene & therephlalic acid

• Fish ChV is problematic for coumaryl alcohol and coumaric acid

Structure Modifications for Obtaining a Safer Chemical

• First changed coumaric acid: removed the double bond to prevent epoxide formation. – While easier to metabolize, we found that it had little effect on its

environmental fate (PBTprofiler).

– Became slightly more toxic to fish.

• We also changed xylene by turning the methyl groups into methoxy ones, which makes xylene dimethoxybenzene. – DMB is safer than xylene and is used in perfumes.

– This change to xylene might render it an ineffective solvent for most of its old applications because of its increased water solubility

Potential Modifications

• p-xylene most acutely toxic of four chemicals

• Possible substitution: dimethoxybenzene (less toxic to fish)

• Remove double bond in coumaryl alcohol, replace with hydrogen

• Result= no improvement

Predicting respiratory, dermal, and digestive absorption

p-xylene Digestive

Log P(ow) MW Phase Hydrogen Bonds

3.15 106.078247 liquid 0

Respiratory

Blood to Gas Partitioning MW

Vapor Pressure

11 106.078247 9 mmHg

Dermal

Log P(ow) MW Phase Polarity

3.15 106.078247 liquid no

Terephthalic Acid Digestive

Log P(ow) MW Phase Hydrogen Bonds

2 166.026611 solid 0

Respiratory

Blood to Gas Partitioning MW

Vapor Pressure

7.6 166.026611 0

Dermal

Log P(ow) MW Phase Polarity

2 166.026611 solid

Coumaryl Alcohol Digestive

Log P(ow) MW Phase Hydrogen Bonds

1.36 150.1 solid

Respiratory

Blood to Gas Partitioning MW

Vapor Pressure (mm Hg)

460 150.1 0.000161

Dermal

Log P(ow) MW Phase Polarity

1.36 150.1 solid

P-Coumaric Acid Digestive

Log P(ow) MW Phase Hydrogen Bonds

1.59 164.0 solid

Respiratory

Blood to Gas Partitioning MW

Vapor Pressure (mm Hg)

127 164.0 0.00000121

Dermal

Log P(ow) MW Phase Polarity

1.59 164.0 solid

In Vitro Assays Useful for Studies

• Example assays available to measure [T. Riss et al. 2003]: – Number of dead cells (cytotoxicity

assay),

– Number of live cells (viability assay),

– Total number of cells

– Mechanism of cell death (e.g., apoptosis)

• Endpoints from EPA Phase I – Cell cytotoxicity (High Content

Screening)

– Cell free assays of protein function

– Cell-based transcriptional reporter assays

– Gene expression in primary human cell cultures

– Developmental assays in zebrafish embryos

T. Riss et al. 2003

Summary for Chem 298

Tom McDonald

Sara Thoi

Least to Most Harmful Chemicals

> > >

- Not readily adsorbed in the body and are removed fairly quickly

- Mild irritant

- Limited health effects due to extended exposure for rodents.

Least to Most Harmful Chemicals

> > >

- Not readily adsorbed in the body and are removed fairly quickly

- Mild irritant

- Limited health effects due to extended exposure for rodents.

- A liquid with high vapor pressure

- Adsorbed in the body more easily than the other 3 chemicals.

- Reacts with Cyt P450

Least to Most Harmful Chemicals

- Some toxicity to fish,

- Limited adsorption in the human body

- Electrophilic components that may make them reactive toxicphores.

- Ferulic acid has had a positive effect against cancer in rodents.

> > >

- Not readily adsorbed in the body and are removed fairly quickly

- Mild irritant

- Limited health effects due to extended exposure for rodents.

- A liquid with high vapor pressure

- Adsorbed in the body more easily than the other 3 chemicals.

- Reacts with Cyt P450

Potential Modifications

Methylation increases the steric bulk and accessibility to reactive carbons for oxidation, as well as decrease the electrophilicity of the olefins and its ability to make a toxicphore

Assays

• There is a need to develop assays for developmental and immunological effects of these compounds

• High throughput screening for ecotoxicity, particularly for aquatic systems, would be most efficient

What we’ve learned

• How to use tools for predicting toxicities for different endpoints

• Ways to modify molecules to make them less toxic/reactive

• Toxicology is really hard!

Bio-based vs. Petroleum-Based Solvents

GROUP 5

Solvents

• Toluene, Anisole, Furfuryl Alcohol, Beta-Propiolactone

Beta-Propiolactone

• OpenTox: – Carcinogen: produces local tumors

in mice – Mutagen: Direct-acting alkylating

agent that forms DNA adducts – Genotoxic: Exerted at the

diakinesis/metaphase-I or metaphase-II stages of meiosis

ToxPredict: Low level human health

effects from Cramer rules: Class I. UM-BBD: most water soluble, least

bio-accumulative compound

Most likely metabolite From SmartCyp:

Furfuryl Alcohol

• OpenTox: – Damages Central Nervous

System: can cause paralysis and death

– Pulmonary damage: larger doses depress respiration, reduce body temperature, produce nausea, salivation, diarrhea, dizziness, and diuresis

– Not a carcinogen or genotoxic ToxPredict: carcinogenic, high

level human health effects from Cramer rules: Class III.

UM-BBD: Third least bio-accumulative compound

Most likely metabolite From SmartCyp:

Toluene

• OpenTox: – Central nervous system (CNS) effects:

depressant or excitatory, with euphoria followed by disorientation, tremulousness, mood lability, convulsions, and coma.

– Important cause of encephalopathy (brain disease) in children (aged 8 - 14 years): may lead to permanent neurological damage.

– Not a carcinogen. No effect on reproduction.

ToxPredict: Low level human health effects

from Cramer rules: Class I. UM-BBD: Second least bio-accumulative

compound

Most likely metabolite From SmartCyp:

Anisole

Most likely metabolite From SmartCyp:

• OpenTox: – Least toxic compound: LD50 of 3700 mg/kg

in rats – Found in many natural and synthetic

fragrances. – Can become carcinogenic when adding

substituents (particularly, an allyl group). – BHA (butylated hydroxyanisole): shown to

cause slight reproductive problems like slow weight gain in the fetus (of pigs); but overall, anisole has no birth defects.

ToxPredict: Low level human health effects from Cramer rules: Class I.

UM-BBD: Most bio-accumulative compound (perhaps most hydrophobic)

The End.

Toluene vs. Furfuryl Alcohol

Meera A.

4/30/12

Chemical Properties

Toluene:

• Molar Mass: 92 g/mol • LogPow: 2.73 • H-bond donors: 0 • H-bond acceptors: 0 • Polar surface area: 0 A2 • Physical state (liquid or solid): liquid • Vapor pressure: 27.7 mmHg ( 25 °C) • # Freely rotating bonds: 0 • Polar? – no • Kow: 537 • Kaw: 0.2716 • Pbg = 10.6

Furfuryl Alcohol:

• Molar Mass: 98 g/mol • LogPow: 0.28 • H-bond donors: 1 • H-bond acceptors: 2 • Polar surface area: 33.37 Å2 • Physical state (liquid or solid): solid • Vapor pressure: 1 mmHg at 25°C • # Freely rotating bonds: 2 • Polar? - yes • Kow: 1.9 • Kaw: 3.21x10-6 • Pbg = 313241

Accumulation in the Environment

Toluene

• Air

• Water

• Soil

• 2.6 mg/L toxicity

• More likely to bioaccumulate

Furfuryl Alcohol

• Water

• Soil

• 26 mg/L toxicity

Absorption

Toluene

• Hydrophobic

• Non-polar

• High vapor pressure

• Risk for absorption into the skin and digestive tract

Furfuryl Alcohol

• Polar

• Low vapor pressure

• Risk for absorption into the blood

Conclusions

• Overall, toluene (from petroleum) seems to be “more toxic” than furfuryl alcohol (from renewable, biological sources).

Chemical fate and toxicity of phthalate and alternative plasticizers

Ben Greenfield CEE217 Final Project Presentation

May 1, 2012

Additional Contributions

• Leah Rubin, Chemistry Grad Student

• Martin Mulvihill, ED, Berkeley Center for Green Chemistry

Outline

• Background and concerns regarding phthalates

• Method: Case study approach

• Results

– Fate and partitioning

– Degradation

– Toxicity

• Conclusions: Are there differences?

Exposure:

Food containers

Water pipes

Skincare products

Distribution: Rapid via blood to liver, kidneys

Target organs: Liver and reproductive (e.g., testes)

Metabolism I: Remove alkyl group II: Glucuronidation of alkyl group Elim

inatio

n: R

apid

urin

ary excretion

. Fecal egestio

n o

f com

po

un

d n

ot ab

sorb

ed.

Bioenergy: alternative chemical production pathways

Source: Martin Mulvihill

Phthalate esters

(general structure)

Important industrial precursors

Terephthalic acid

(TPA)

Dimethyl

terephthalate

(DMT)

Di-2-ethylhexyl

terephthalate

(DEHT)

Diethyl phthalate

(DEP)

Dibutyl phthalate

(DBP)

Common phthalate esters

Butyl benzyl

phthalate (BBzP)

Diethylhexyl

phthalate (DEHP) Diisononyl

phthalate (DINP)

Monobutyl phthalate

(MBP)

OR

OR

Gluc I: Remove alkyl group II: Glucuronidation of alkyl group

Metabolism:

Two phthalates vs. two alternatives

Likely degradation products All compounds have easily hydrolyzed ester linkages, forming the molecules below:

Likely degradation products

Comparison of Plasticizers

April 30, 2012

Leah Rubin

The Molecules

Experimental Data

No data available Suspected human carcinogens, possible endocrine disruptors Lots of literature and testing for carcinogenicity

PBT Profiler

Longer half-lives in all compartments, partition primarily into sediment, may accumulate there

DEHP expected to bioaccumulate, BBP fish toxicity exceeds EPA limits

Biodegradation All compounds have easily hydrolyzed ester linkages, forming the molecules below:

ToxPredict

No alerts, structural alert for epoxides

Structural alert for phthalates

Absorption

Similar for all four – reasonable absorption by ingestion or skin contact, less good by inhalation. Kow ranges from 4 to 9.

Overall