Antioxidant activity of essential oils encapsulated in nanoemulsions

Ana Forgiarini1,2, Jimmy Rodríguez1, Laura Márquez1, Maria-Teresa Celis1,2 and Jean-Louis Salager1

1Laboratorio de Formulación, Interfases, Reología y Procesos (FIRP) 2Laboratorio de Polímeros y Coloides (POLYCOL)- Facultad de Ingeniería-Universidad de Los Andes- Mérida 5101–Venezuela.

Telf: (58) 274-2402954. Fax: (58) 274-2402957.

e-mail: anafor@ula.ve

Abstract

The encapsulation of essentials oils using nano-emulsified systems has potential application in personal care products for antioxidant delivery systems.

This work reports the formulation of oil-in-water nanoemulsions containing essential oils like lippia alba, rosemary and cypress in liquid paraffin.

Paraffin and essential oils were characterized by their EACN (Equivalent Alkane Carbon Number) using the SAD (Surfactant-Affinity-Difference)

generalized formulation concept. Nanoemulsions were prepared with a mixture of two nonionic surfactant calculated to adjust the proper SAD to

produce the required phase transitions to use a low energy emulsification method. Nanoemulsions were characterized by droplet size, transmittance

and stability. Antioxidant activity of pure essential oils and encapsulated in nanoemulsions and macroemulsion were studied by using the 2,2’-diphenyl-

1-picrylhydrazyl (DPPH) radical scavenging method. It was concluded that the antioxidant activity do not depend on the emulsion droplet size

distribution.

Keywords: Nanoemulsions, nanometric delivery system, essential oil, antioxidant activity

Introduction

Free radicals

Skin

Oxidative stress

Antioxidants

SOW systems

Naturals and synthetic

Essential oils

Naturals antioxidants

Factors:

Microemulsion

Liquid crystal

Emulsion/Nanoemulsion

Environmental

Biological

Social

Pathologies

Pharm. vehicle

Prophylaxis

Experimental

a. Emulsification

b. Antioxidant activity: DPPH method

a.1.- EACN

a.2.- Low energy emulsification

0 = σ + ln(S*) – k · EACN + at · ∆T + f(A)

300 340 380 420 460 500 540 580 620 660

1,4

1,2

1,0

0,8

0,6

0,4

0,2

0,0

Measurement 517 nm

DPPH

DPPH-H

Wavelength

Ab

so

rban

ce

DPPH DPPH-H

Results and discussion

Essential oil EACN

Lippia alba 6

Cypress 2,3 – 3,6

Rosemary 6

Droplet size of emulsions

Nanoemulsions Macroemulsions

20-100 nm 500-1000 nm

Calculated EACN of essentials oils

Nano and macroemulsions obtained: (A)

By dilution of liquid crystal (LC), and (B)

by a high energy method.

(B)

(A) (LC)

Om

Om+LC

O+Om

O+Wm

S

O W

50

60

70

80

90

100

110

0 20 40 60 80 100

%D

PP

H r

em

ain

ing

Time (min)

Nanoemulsions (First week)

Lippia alba

Cypress

Rosemary

50

60

70

80

90

100

110

0 20 40 60 80 100

%D

PP

H r

em

ain

ing

Time (min)

Nanoemulsions (Sixth week)

Lippia alba

Cypress

Rosemay

50

60

70

80

90

100

110

0 20 40 60 80 100 120

%D

PP

H r

em

ain

ing

Time (min)

Macroemulsions (First week)

Lippia alba

Cypress

Rosemary

50

60

70

80

90

100

110

0 20 40 60 80 100

%D

PP

H r

em

ain

ing

Time (min)

Macroemulsions (Sixth week)

Lippia alba

Cypress

Rosemay

Conclusions

The antioxidant activity of essential oils has been object of investigation due to their

potential as preservatives, cosmeceuticals or nutraceuticals in cosmetic or food

industries. In this study, results suggest that encapsulation of essentials oils in

emulsions or nano-emulsions could greatly enhance essentials oil´s chemical stability

during storage. The antioxidant activity of essential oils is independent of the droplet

size of emulsions oil in water in the studied time interval (6 weeks). In addition, the

essential oils studied (encapsulated), have a similar antioxidant activity (slightly higher in

the lippi alba). The advantage of encapsulated essential oils in the nanoemulsions

morphology is because these systems have high kinetic stability.

References

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S= Polisorbate 80/Sorbitan

monolaurate

O= Parafin/Essential oil 75/25

W= Water

HLB = 12,25

Temp = 30 °C

Antioxidant activity of essential oils encapsulated in nano and

macroemulsions, using the DPPH method.

SAD = α – EON + k · ACN – ϕ (A) + CT · (∆T)

Table 1.

Fig. 3 Fig. 4

Fig. 2 DPPH and antioxidant (AH) reaction / Absorption bands Fig. 1 Introductory scheme