IR3535, the nature inspired repellent from Merckessentia.com.br/images/artigos/ativos-nov-2016/IR3535.pdf · IR3535, the nature inspired repellent from Merck Bohlmann 1AM , Broschard

IR3535, the nature inspired repellent from Merck

Bohlmann AM1, Broschard T2, Heider L1

International Conference on Biopesticides VI

Chiang Mai, Thailand 2011

1 Merck KGaA, Darmstadt Germany, 2 Merck KGaA, Institute of Toxicology

Introduction

International Conference on Biopesticides VI 2

1.0

2


First insect repellents were sourced from nature

Nature is an inexhaustible source of inspiration for

scientific and technological innovations.

Even the idea of repellent protection was adopted

from plants producing essential oils for own

protection against insect infestation. The transfer of

a simple natural protection mechanism to human

skin protection was the first innovative step.

The high evaporation rate of essential oils and the

correlated short protection times for personal

protection caused the demand to look for solutions

with long time protection.


ß-alanine is the natural prototype for IR3535

For the development of the topical Insect Repellent

3535 (Ethyl butylacetylaminopropionate), scientists

took again inspirations from nature with the

intention to create a molecule with optimized

protection times and low toxicity.

The naturally occurring amino acid ß-alanine was

used as basic module.

Poultry, beef and fish are

all rich sources of the

amino acide ß-alanine

N H 2 O H

O


ß-alanine is the natural prototype for IR3535

Selected end groups were chosen to avoid

toxicity and increase efficacy

O

N

O

OC 2 H 5

In 1997, US-EPA-OPP's

Biochemical Classification

Committee classified IR3535® as

a biochemical, based on facts

that it is functionally identical to

naturally occurring beta alanine in

that both repel insects, the basic

molecular structure is identical,

the end groups are not likely to

contribute to toxicity and it acts to

control the target pest via a non-

toxic mode of action.


Purpose of this presentation

This presentation will provide a review of efficiency

of this nature inspired scientific approach in

comparison to natural and pure synthetic repellent

solutions.

Example for synthetic approach:

DEET

Example for natural approach:

Citronella

Summary of Performance Comparison 2.0

International Conference on Biopesticides VI 7 7

Chemical quality and purity

DEET: synthetic substance with defined quality and high purity; > 95% of

N,N-diethyl-meta-toluamide

IR3535: synthetic substance with defined quality and high purity; > 98% of

Ethyl butylacetylaminopropionate

Oil of Citronella: Different types like “Java” and “Ceylong” are on the

market. Quality and purity depends on distillation and source. More than

80 compounds.

Performance comparison


Safety – US-EPA classification

DEET: Pesticide which will generally not cause unreasonable risks to

humans or the environment. EPA required improved label warnings than

DEET has been thought to be associated with incidents of seizure

IR3535: Biopesticide with non toxic mode of action

Oil of Citronella: Biopesticide with non toxic mode of action



Children use – US- EPA / CDC

DEET: “≤ 30% DEET should be used on children aged > 2 months.

Repellents with DEET should not be used on infants aged < 2 months” 1

IR3535: “Most repellents can be used on children aged > 2 months.

Repellent products must state any age restriction. If none is stated, the

Environmental Protection Agency has not required a restriction on the use

of the product” 1

Oil of Citronella: “Agency is requiring special precautionary labeling

relating to dermal sensitization and irritation for all product with use

directions for dermal applications” / “Use on children under 6 months of

age only with the advice of a physician.“ 2

1 CDC - Traveling Safely with Infants & Children, http://wwwnc.cdc.gov/travel/yellowbook/2012/chapter-7-

international-travel-infants-children/traveling-safely-with-infants-and-children.htm

2 EPA - REREGISTRATION ELIGIBILITY DECISION, Oil of Citronella, LIST C, CASE 3105



http://wwwnc.cdc.gov/travel/yellowbook/2012/chapter-7-international-travel-infants-children/traveling-safely-with-infants-and-children.htm





















Efficacy – US- EPA / CDC

DEET: “Products containing these active ingredients typically provide

reasonably long-lasting protection” (US-CDC)

IR3535: “Products containing these active ingredients typically provide

reasonably long-lasting protection” (US-CDC)

Oil of Citronella: In 1997, the EPA concluded that citronella-based insect

repellents must carry the following statement on their labels: "For

maximum repellent effectiveness of this product, repeat applications at

one hour interval."



Performance Comparison of Safety 3.0


Safety

Acute toxicity oral rat (LD50) 2 170 mg/kg (EPA)

1 892 mg/kg (EU)

> 5 000 mg/kg > 5 000 mg/kg (EPA)

> 4 380 mg/kg (EPA)

Acute dermal toxicity rabbit or rat (LD50) 4 280 mg/kg (EPA)

> 5 000 (EU)

> 10 000 mg/kg > 2 000 mg/kg (EPA)

> 2 000 mg/kg (EPA)

Acute inhalation (LD50) 5.95 mg/l (EPA)

2.02 mg/I (EU)

> 5.1 mg/l > 5000 mg/kg (EPA)

> 3.1 mg/l (EPA)

Eye irritation rabbit Irritating to eye

(EPA + EU)

Slightly Irritating

cleared in 8 days or

less

Irritation cleared in 72

hours

Irritation cleared in 7

days or less

Skin sensitisation guinea pig no no Sensitizer

No

Dermal sensitisation human no no -

-

Subchronic dermal rat (NOAEL) 300 mg/kg/day (EPA)

1 000 mg/kg/day (EU)

3 000 mg/kg/day -

-

Developmental rat (NOAEL) 250 mg/kg/day

(EU + EPA)

1 000 mg/kg/day

(oral) -

-


Oil of Citronella

• Java

• Ceylon

DEET

IR3535

Ecological Toxicity Data Performance Comparison


DEET: Fish toxicity (rainbow trout) LC50 = 75 mg/L (slightly toxic)

Invertebrate toxicity (Daphnia magna) EC50 = 75 mg/L (slightly toxic) 1

IR3535: Fish toxicity (zebrafish, Danio rerio) LC50 > 100 mg/L

Invertebrate toxicity (Daphnia magna) EC50 > 100 mg/L 2

Oil of Citronella:

Fish toxicity (rainbow trout) LC50 = 17.3 mg/L (slightly toxic)

Invertebrate toxicity (Daphnia magna) EC50 = 26.4 mg/L (slightly toxic) 3

1 EPA - REREGISTRATION ELIGIBILITY DECISION DEET, LIST A, CASE 0002

2 Merck KGaA

3 EPA - REREGISTRATION ELIGIBILITY DECISION, Oil of Citronella, LIST C, CASE 3105


IR3535 Metabolism – The ester structure of the propionate provides essential advantages–

In case of penetration this molecule shows a

high safety level, because of a short

metabolic degradation and quick excretion

as a simple water soluble acid.

N O

O

O

N OH

O

O

IR3535(R)

N-acetyl-3-N-n-butylaminopropionic acid

Performance Comparison of Efficacy 4.0


Citronella EPA – Product Performance (Efficacy) Assessment


„Because of numerous public inquires regarding the effectiveness (efficacy)

of oil of citronella lotions, the Agency examined efficacy data associated

with oil of citronella insect repellent lotion products and determined that

product effectivesness diminishes rapidly over time; on the average,

rasonalbe effectiveness (efficacy) lasts for 1 to 2 hours.“


Performance comparison of IR3535® and DEET against Aedes aegypti

Method Formulation /

Concentration

Mean

Protection (h)

IR3535®

Mean

Protection (h)

DEET

Reference

Cage /

human

Ethanolic solution 10%

- 30%

4.2 – 7.3 5.0 - 6.3 Liebisch, 1981

Cage /

human

Ethanolic solution 10%

- 30%

1.1 – 3.6 1.6 -- 4.3 Shashin, 1998

Cage /

human

Cream

10% - 20%

1.9 – 3.0 2.2 -3.3 Cilek, 2004

Cage /

human

Pump Spray

10% - 20%

2.0 – 2.8 2.6 – 2.9 Cilek, 2004

Cage /

rabbits

Hydro gel

10%

5.6 5.1 Milutinovic, 2000

Cage /

human

Ethanolic solution 20% 9.8 9.7 Usavadee, 2001

Table 3: Mean Protection time results (h) of IR3535® and DEET against Aedes aegypti

In summary, an overall review of available data suggests rough repellency

equivalence for the two active ingredients


Performance comparison of IR3535® and DEET against Aedes albopictus

Method Formulation /

Concentration

Protection

IR3535®

Protection DEET Reference

Field /

2 tests

Aerosol

2.5%, 3%, 5%

100% for

5 / 6 h

100% for

5 / 6 h

1989 / 90

(Japan, Osaka)

Field Ethanolic solution

25%

100% / >90% for

4 h / 8h

100% / >90% for

6 h / 8h

Yap, 1998 (Malaysia),

Field/

2 tests

Ethanolic solution

20%

98.4% / 100%

for

8 h

97.4% / 100%

for

8 h

Usavadee, 2001

(Thailand)

Cage/

human

Ethanolic solution

25%

100% for

2 h

100% for

2 h

Yap, 1998

Table 3: % Protection and protection times (h) of IR3535® and DEET against Aedes albopictus

In summary, field and cage studies show strong similarity of protection times

for IR3535® vs. DEET against Aedes albopictus. Solutions of 20% - 25%

provided protection for up to 8 hours..


Performance comparison of IR3535® and DEET against Anopheles species

Method Species Formul. / Conc. Protection IR3535® Protection DEET Reference

Field

gambiae and

funestus

Ethanolic solution

25%

96.3% for

6 h

99.3% for

6 h

Kuhlow, 1975

(West Africa)

Cage /

human

maculatus Ethanolic solution

25%

64% (1 h) /

70-40% (2-8 h)

100% (1 h) /

70-40% (2-8 h)

Yap, 1998

Field

(July)

hyrcanus minimus

sawad-wongporni

maculates

Ethanolic solution

20%

100% for 3 h

(99%, 5 h)

100% for 1 h

(98%, 5 h)

Usavadee, 2001

(Thailand)

Field

(August)

hyrcanus minimus

sawad-wongporni

maculates

Ethanolic solution

20%

100% for 4 h

(99%, 5 h)

100% for 2 h

(99%, 5 h)

Usavadee, 2001

(Thailand)

Cage /

human

dirus Ethanolic solution

20%

100% for 3.8 h 100% for 5.8 h Usavadee, 2001

(Thailand)

Field darlingi albitarsus

braziliensis

Pump spray

15%

100% / 90%

3.8 h / 4.5 h

- Hill, 2006

(Bolivian Amazon)


braziliensis

Lotion

15%

100% / 90%

6.9 h / 7.7 h

- Hill, 2006

(Bolivian Amazon)


braziliensis

Lotion

15%

100% / 90%

6.0 h / 6.9 h

- Hill, 2006

(Bolivian Amazon)

Table 5: % Protection and mean protection times (h) of IR3535® and DEET against Anopheles species

Anopheles species

In field studies at a concentration of 25%, IR3535® showed 5 hours

protection against Anopheles hyrcanus, An. minimus, An. sawad-

wongporni, and An. maculatus, similar to DEET.

However, DEET showed superior performance against Anopheles dirus in

cage studies.

In field studies, 15% formulations of IR3535® showed 5 hours protection

against Anopheles darlingi, An. albitarsus, and An. braziliensis.

Performance thus varies with formulation and species, and advanced

formulation can improve performance against Anopheles species.

Summary



Performance comparison of IR3535® and DEET against Culex species

Method Species Formulation /

Concentration

Mean

Protection

IR3535®

Mean

Protection

DEET

Reference

Cage /

human

pipiens Ethanolic solution

10% - 30%

100% for 1.9 –

5.0 h

100% for 2.5 –

5.9 h

Shashin, 1998

Cage /

human

quinque-fasciatus Cream

10% - 20%

100% for 5.7 –

6.6 h

100% for 5.7 –

6.2 h

Cilek, 2004

Cage /

human

quinque-fasciatus Pump Spray

10% - 20%

100% for 5.4 –

6.5 h

100% for 5.7 –

6.1 h

Cilek, 2004

Cage/

human

quinquefasciatus Ethanolic solution

20%

100% for

13.7 h

100% for

12.7 h

Usavadee, 2001

Cage/

human

tritaeniorhynchus Ethanolic solution

20%

100% for

14.8 h

100% for

14.5 h

Usavadee, 2001

Field quinquefasciatus Ethanolic solution

25%

>98% for

8h

>98% for

8h

Yap, 1998

(Malaysia),

Field

(April)

sitiens

tritaenio-rhynchus

Ethanolic solution

20%

100% for

5h

100% for

5h

Usavadee, 2001

(Thailand)

Field

(May)

gelidus

quinquefasciantus

tritaenio-rhynchus

Ethanolic solution

20%

100% for

5h

100% for

5h

Usavadee, 2001

(Thailand)

Field

(July)

tritaenio-rhynchus

sitiens

Ethanolic solution

20%

99% for

5h

100% for

5h

Usavadee, 2001

(Thailand)

Table 7: % Protection and protection times (h) of IR3535® and DEET against Culex species

Culex species

Review of available data indicates equivalent performance of IR3535®

and DEET against Culex species.

In cage tests, 20% ethanolic solutions of IR3535® provided protection

ranging from 3 – 13.7 hours,

while 20 – 25% ethanolic solutions provided at least 8 hours protection in

the field (Yap 1998; Usavadee 2001)

In cage tests, IR3535® protected against Culex species for twice as long

as Aedes species

Summary


Conclusion 4.0


Overall Conclusion

The ester structure of the propionate provides two essential advantages.

The evaporation is optimized to have a long lasting efficacy. In case of

penetration this molecule shows a high safety level, because of a short

metabolic degradation and quick excretion as a simple water soluble acid.

Learning from nature provided a molecule which shows impressive

performance in comparison to a natural and pure synthetic repellent

solution.

Nature inspired scientific approach in comparison to natural and pure

synthetic repellent solutions


Documents

IR3535, the nature inspired repellent from Merckessentia.com.br/images/artigos/ativos-nov-2016/IR3535.pdf · IR3535, the nature inspired repellent from Merck Bohlmann 1AM , Broschard