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Examining the Potential of Eucalyptus Oil Nanoemulsion Against Pulmonary Inflammation in a Biomedical Sciences News and Activities
Held at the Dr. A.A. Made
Djelantik Meeting Room (4th Floor, Faculty of Medicine Building, Udayana
University, Denpasar, Bali), the Doctoral Study Program in Biomedical Sciences
at the Udayana University Faculty of Medicine conducted a public doctoral defense
for candidate I Nyoman Gede Tri Sutrisna, S.Farm., Apt., M.Farm. The
dissertation is titled "Development of Inhalable Eucalyptus Oil
Nanoemulsion through Formulation Optimization, Stability Evaluation, and
Preclinical Validation in a Pulmonary Inflammation Model." (September 24,
2026)
Pulmonary inflammation caused by
cigarette smoke exposure is a complex response involving cellular changes and
inflammatory mediators. Eucalyptol, a key bioactive component of eucalyptus
oil, has been reported to possess various biological activities relevant to the
respiratory system. A systematic review of 35 articles and a bibliometric
analysis revealed that research on eucalyptol in respiratory diseases has
evolved around three main themes: antimicrobial activity, anti-inflammatory and
antioxidant activity, and clinical applications for respiratory diseases. The
review also highlighted the need for further development, particularly
regarding formulation, stability, and delivery systems. Based on these
findings, this study aimed to develop and optimize an inhalable eucalyptus oil
nanoemulsion, evaluate its physicochemical characteristics and stability, and
conduct preclinical validation using a model of acute pulmonary inflammation
induced by cigarette smoke exposure.
The nanoemulsion was developed
using a Quality by Design (QbD) approach, employing a Full Factorial Design
(2?) to evaluate the effects of surfactant and co-surfactant proportions and
types on transmittance and viscosity. Sixteen formulas were tested, and the
optimum formula was determined using a desirability function. This optimum
formula was subsequently characterized based on droplet size, polydispersity
index (PDI), zeta potential, pH, transmittance, viscosity, emulsion type, and
visual stability. Physicochemical stability was evaluated over three months
under accelerated storage conditions (40 ± 2°C and 75 ± 5% RH), while the
chemical stability of eucalyptol was assessed using GC-MS. Preclinical
validation was conducted on 42 male Wistar rats divided into a normal control
group (N), a negative control group (KN), a budesonide positive control group
(KKP), and three nanoemulsion groups receiving nominal volumes of 400, 800, and
1600 µL/day (KKU1, KKU2, and KKU3). A pulmonary inflammation model was induced
via cigarette smoke exposure over five days. Biological responses were
evaluated based on TNF-? and IL-1? levels in serum and lung tissue, as well as
neutrophil infiltration observed during histopathological examination.
Optimization results indicated
that the optimum formula consisted of 3% eucalyptus oil, 7% PEG 40 HCO, 4% PEG
400, and purified water up to 100 g. This formula yielded predicted values ??of 92.41% for transmittance and
27.59 cPs for viscosity, with an overall desirability of 0.972. Experimental
results showed a transmittance of 94.11% and a viscosity of 24.13 cPs. During
three months of accelerated storage, droplet size remained within the 22–25 nm range with a PDI < 0.30. The pH value remained
relatively stable, and no phase separation, creaming, or sedimentation was
observed. However, this physicochemical stability was not fully mirrored by the
chemical stability of the eucalyptol. GC-MS analysis revealed a decrease in the
relative eucalyptol content of approximately 25–40% after three months of
storage. Given that the method's linearity yielded an R² value of 0.8481, these
changes were used to illustrate relative trends during storage rather than to
determine absolute content.
In the preclinical validation,
the KN group exhibited higher neutrophil infiltration compared to the N group.
The KKU1, KKU2, and KKU3 groups showed a significant reduction in neutrophil
infiltration compared to the KN group (p = 0.009, p = 0.004, and p < 0.001,
respectively). The KKU3 group displayed the lowest level of neutrophil
infiltration, differing significantly from KKU1 (p = 0.025), whereas the
difference between KKU2 and KKU3 was not significant (p = 0.052). Thus, the
reduction in neutrophil infiltration was the most consistent change in the
cellular inflammatory response, although this pattern did not yet demonstrate a
linear dose-response relationship. Serum TNF-? levels did not differ
significantly among the groups. Lung tissue TNF-? levels showed a non-linear
pattern, with the highest levels observed in KKU1, while levels in KKU2 and
KKU3 did not differ significantly from those in KN. Serum IL-1? levels also
showed no significant differences among groups; however, lung tissue IL-1?
levels in the KKU1, KKU2, and KKU3 groups were significantly higher than in the
KN group. The discrepancy between histopathological responses and cytokine
biomarker levels indicates that changes in the inflammatory response did not
occur uniformly across all parameters evaluated.
Overall, an inhaled eucalyptus
oil nanoemulsion was successfully developed and optimized, exhibiting
relatively good physicochemical characteristics that were maintained throughout
three months of accelerated storage. However, the decrease in relative eucalyptol
content indicates that chemical stability remains an aspect requiring
optimization. In an acute lung inflammation model induced by cigarette smoke
exposure, the most consistent response observed following nanoemulsion
administration was a reduction in neutrophil infiltration, whereas TNF-? and
IL-1? levels did not show a consistent pattern of change. Differences in
responses across parameters may be related to the specific characteristics and
temporal dynamics of each parameter; however, this could not be confirmed as
sampling was performed at only a single time point. Furthermore, this study did
not determine the specific dose of nanoemulsion or eucalyptol deposited in the
lungs, the molecular mechanisms underlying the biological responses, a definitive
dose-response relationship, lung function, or specific inhalation safety
profiles. Thus, the inhaled eucalyptus oil nanoemulsion can be positioned as a
candidate inhalation formulation with preliminary preclinical evidence for
modulating lung inflammation, particularly based on histopathological findings
of reduced neutrophil infiltration. Further development is required, involving
the optimization of chemical stability, characterization of aerosols and lung
deposition, evaluation of biological mechanisms, safety studies, and research
incorporating multiple observation time points.
The examination was chaired by
the Vice Dean for Academic Affairs and Planning at the Faculty of Medicine,
Udayana University, Prof. dr. I Made Ady Wirawan, S.Ked., MPH, Ph.D., with an
examination team comprising:
1. Prof. Dr. rer. Nat. Drs. I
Made Agus Gelgel Wirasuta, Apt., M.Si. (Promoter)
2. Prof. Dr. dr. Ni Made
Linawati, S.Ked., M.Si. (Co-promoter I)
3. Prof. Dr. dr. Dyah Kanya Wati,
Sp.A. SubSp.ETIA(K) (Co-promoter II)
4. Prof. Dr. dr. Ketut Suryana,
Sp.PDKAI., FINASIM
5. Prof. Dr. dr. Desak Made
Wihandani, M.Kes
6. Prof. Dr. dr. I Made Jawi,
M.Kes
7. Dr.rer.nat. dr. Ni Nyoman Ayu
Dewi, M.Si
8. Dr. dr. Dewa Ayu Agus Sri
Laksemi, M.Sc
9. Dr. apt. Ketut Agus Adrianta,
S.Farm., M.Biomed
With academic invitees:
1. Dr. apt. Dewa Ayu Swastini,
S.F., M.Farm
2. Dr. apt. I Gusti Ngurah Jemmy
Anton Prasetia, M.Si.
3. Dr. apt. Putu Oka Samirana,
S.Farm., M.Sc
4. apt. Made Ary Sarasmita,
S.Farm.Klin., Ph.D
5. Dr. apt. I Gusti Ayu Rai
Widowati, S.Si., M.Kes., M.H., CMC.
In this examination, Dr. I Nyoman Gede Tri Sutrisna, S.Farm., Apt., M.Farm., was declared to have passed, becoming the 509th graduate of the Doctoral Program in Biomedical Sciences at the Faculty of Medicine, Udayana University, with the distinction of *Cum Laude*
UDAYANA UNIVERSITY