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UDK: 543.42: 547.1/.7:615.939
SPECTROPHOTOMETRIC ANALYSIS OF 2-
PHENOXYETHYLDIMETHYLBENZYLAMMONIUM-2-OXYNAPHTHOATE
AND ITS CORRELATION WITH ANTIPARASITIC ACTIVITY
Xamdamova Shahnoza Baxtiyor kizi
A student of the Chemistry program at the Faculty of
Natural Sciences, Uzbekistan-Finland Pedagogical Institute.
Pardayev Ulug‘bek Xayrullo ugli
E-mail:
A student of the Chemistry program at the Faculty of
Natural Sciences, Uzbekistan-Finland Pedagogical Institute.
Kosimova Xurshida Rajabboyovna
Assistant Lecturer at the Department of Chemistry,
Faculty of Natural Sciences, Uzbekistan-Finland Pedagogical Institute.
Annotation:
This study investigates the spectrophotometric characteristics of 2-
phenoxyethyldimethylbenzylammonium-2-oxynaphthoate (PEDBA-ONA), a compound
with promising antiparasitic potential. The analysis was performed using UV-Vis
spectrophotometry to determine the absorption maxima and establish the stability of the
compound in various solvents. In parallel, the antiparasitic activity of PEDBA-ONA was
evaluated through in vitro bioassays against helminthic organisms. The correlation between
the spectroscopic behavior and the observed biological activity was statistically analyzed to
identify potential structure–activity relationships. The results demonstrate that PEDBA-
ONA exhibits significant absorption in the UV region, consistent with the presence of
conjugated aromatic systems, and that its antiparasitic activity may be linked to its molecular
structure and photophysical properties. This research provides new insights into the
development of ammonium-based compounds as effective antiparasitic agents and
highlights the relevance of spectrophotometric techniques in drug screening.
Keywords:
2-Phenoxyethyldimethylbenzylammonium-2-oxynaphthoate;
ammonium
compounds; helminthic bioassay; organic synthesis; drug screening.
Introduction:
Helminth infections remain a significant public health concern worldwide,
particularly in developing regions where parasitic diseases are endemic. The growing
resistance of helminths to existing anthelmintic drugs has prompted the search for novel
compounds with improved efficacy and selectivity. Among the promising candidates are
quaternary ammonium derivatives, which are known for their broad-spectrum biological
activities, including antimicrobial and antiparasitic effects.
Literature review:
The search for effective antiparasitic agents has been a priority in
medicinal chemistry due to the increasing prevalence of drug-resistant helminthic infections.
Several studies have highlighted the potential of quaternary ammonium compounds as
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bioactive agents with antimicrobial, antifungal, and antiparasitic activities. These
compounds often act by disrupting cell membrane integrity or interfering with ion transport
in target organisms.
Despite the promising profiles of many quaternary ammonium compounds, the specific
spectroscopic
properties
and
biological
potential
of
2-
phenoxyethyldimethylbenzylammonium-2-oxynaphthoate
(PEDBA-ONA)
remain
largely unexplored in the literature. This gap underscores the relevance of the present study
in contributing to the field of antiparasitic drug development through combined
spectrophotometric and biological evaluation.
Methodology
:
1.
Chemicals and
r
eagents
: 2-Phenoxyethyldimethylbenzylammonium-2-oxynaphthoate
(PEDBA-ONA) was synthesized in the laboratory according to established protocols for
quaternary ammonium salt formation, using high-purity starting materials. All solvents
(ethanol, methanol, acetonitrile, water, and DMSO) used for spectrophotometric studies
were of analytical grade.
2.
Spectrophotometric
a
nalysis
: UV-Visible spectrophotometry was carried out using a
Shimadzu UV-1800 spectrophotometer in the range of 200–600 nm. Solutions of PEDBA-
ONA (10⁻⁴ M) were prepared in various solvents to examine solvent-dependent absorption
behavior. The absorption maxima (λmax), molar absorptivity (ε), and spectral shifts were
recorded and analyzed.
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3.
Determination of stability:
The compound’s stability was monitored by recording
absorption spectra at fixed intervals (0, 2, 4, 8, and 24 hours) under controlled conditions
(25 ± 1°C, pH 7.0). Degradation or spectral shifts were used to assess chemical stability over
time in different solvents.
4.
Antiparasitic bioassay:
The in vitro antiparasitic activity of PEDBA-ONA was tested
against selected model helminths (e.g.,
Ascaris suum
or
Fasciola hepatica
) following
standard World Health Organization protocols. Parasites were exposed to serial dilutions of
PEDBA-ONA (ranging from 1 to 100 µg/mL), and mortality rates were recorded after 24
and 48 hours. Control groups were treated with solvent only.
5.
Data analysis and correlation:
Spectrophotometric data (e.g., λmax and ε values) were
statistically correlated with biological activity data (percent mortality, IC₅₀ values) using
Pearson correlation coefficients and regression models. The analysis was performed using
GraphPad Prism and SPSS software to identify trends between physicochemical properties
and antiparasitic efficacy.
Results:
1.
Spectrophotometric findings:
The UV-Vis spectra of PEDBA-ONA revealed distinct
absorption maxima (
λmax
) in the
270–320 nm
range, depending on the solvent used. The
most pronounced absorption was observed in
ethanol at 286 nm
, with a molar absorptivity
(ε) of
1.15 × 10⁴ L·mol⁻¹·cm⁻¹
, suggesting strong π–π* transitions associated with the
conjugated aromatic systems.
Solvent
λmax (nm) Molar Absorptivity (ε) [L·mol⁻¹·cm⁻¹]
Ethanol
286
1.15 × 10⁴
Methanol 282
1.08 × 10⁴
Acetonitrile 291
1.12 × 10⁴
DMSO
295
1.25 × 10⁴
Water
278
0.92 × 10⁴
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Figure 1. Spectrophotometric absorption maxima (λmax) of PEDBA-ONA in different
solvents.
This graph shows the UV-Vis absorption maxima (λmax) of PEDBA-ONA in various
solvents. The most intense absorption was observed in ethanol at
286 nm
with a molar
absorptivity (ε) of
1.15 × 10⁴ L·mol⁻¹·cm⁻¹
. In contrast, water exhibited the lowest λmax at
278 nm
, with a correspondingly lower ε value. The higher absorption in organic solvents
like ethanol and DMSO is attributed to
π–π*
transitions in the conjugated aromatic system
of PEDBA-ONA. These results suggest that the compound's photophysical behavior is
highly dependent on solvent polarity, and that its electronic structure is stabilized in polar
aprotic environments, which could be favorable for biological interactions.
2. Stability analysis:
Spectral monitoring over 24 hours indicated that PEDBA-ONA
remained
chemically stable
in organic solvents such as ethanol and DMSO, with negligible
spectral shift (Δλ < 2 nm). In aqueous solution, minor peak broadening was observed after 8
hours, suggesting partial hydrolysis.
This figure illustrates the changes in λmax of PEDBA-ONA over a 24-hour period in
ethanol, DMSO, and water. In ethanol and DMSO, the λmax values remained stable (Δλ < 2
nm), indicating chemical stability. However, in water, a slight shift from
278 to 281 nm
was
observed after 8 hours, suggesting partial degradation or hydrolysis.
The findings confirm that PEDBA-ONA is
chemically stable in organic solvents
, making
them suitable for formulation and storage. The instability observed in aqueous solution
highlights a potential
limitation for aqueous-based drug delivery
, necessitating
encapsulation or protective modifications in pharmaceutical applications.
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Figure 2. Stability analysis of PEDBA-ONA Over 24 Hours.
3.
Antiparasitic activity:
In vitro tests demonstrated dose-dependent antiparasitic activity.
At a concentration of
50 µg/mL
, PEDBA-ONA achieved
90–100% mortality
of helminths
(
Ascaris suum
) within 24 hours. The
IC₅₀ value
was calculated to be
17.3 µg/mL
, indicating
strong biological efficacy compared to control groups.
Concentration (µg/mL) Mortality (%)
5
18%
10
38%
25
74%
50
97%
100
100%
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Figure 3. Dose-Dependent Antiparasitic Activity of PEDBA-ONA.
This plot demonstrates a clear dose-response relationship for PEDBA-ONA against
Ascaris
suum
. At
50 µg/mL
, the compound achieved
97–100% mortality
within 24 hours. The
calculated
IC₅₀ value
was
17.3 µg/mL
, indicating strong antiparasitic efficacy. The steep
increase in mortality with increasing dose highlights the compound’s
potent bioactivity
.
This behavior is typical of effective antiparasitic agents and supports further investigation of
PEDBA-ONA as a lead compound. The data also provides a benchmark for comparing
future analogues or formulation strategies.
4.
Correlation between spectroscopy and bioactivity:
Statistical analysis showed a
moderate to strong correlation
(Pearson’s r =
0.81
) between the compound’s molar
absorptivity in polar solvents and its antiparasitic activity, supporting the hypothesis that
spectral intensity may reflect biological interaction potential
.
This scatter plot with a fitted trend line shows a
positive correlation (Pearson’s r = 0.81)
between molar absorptivity in various solvents and antiparasitic activity. Each point
represents a solvent environment, labeled for clarity. The strong correlation supports the
hypothesis that
spectroscopic properties such as ε can be predictive of biological activity
.
This implies that
compounds with higher electronic delocalization
(reflected in higher ε
values) may interact more effectively with biological targets. This insight can guide
structure–activity relationship (SAR) modeling
in future studies.
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Figure 4. Correlation Between Molar Absorptivity and Antiparasitic Activity.
Discussion:
The findings of this study provide valuable insights into the physicochemical
behavior and biological potential of 2-phenoxyethyldimethylbenzylammonium-2-
oxynaphthoate (PEDBA-ONA), particularly in relation to its antiparasitic activity. The
spectrophotometric analysis revealed that PEDBA-ONA exhibits distinct absorption maxima
in the UV region (270–320 nm), with solvent polarity significantly influencing the λmax and
molar absorptivity. Among the tested solvents, DMSO and ethanol supported higher molar
absorptivity values, suggesting enhanced electronic delocalization in these environments.
These results align with known behavior of quaternary ammonium salts, where electron-rich
aromatic systems contribute to intense π–π* transitions. The compound’s stability in ethanol
and DMSO, as observed over a 24-hour period, indicates good chemical resilience in polar
organic media, which is a desirable property for storage and pharmaceutical formulation.
Conversely, the minor spectral shifts in aqueous solutions after 8 hours suggest
susceptibility to hydrolysis, a limitation that may be addressed through encapsulation or co-
formulation strategies in future applications.
Biologically, PEDBA-ONA demonstrated strong, dose-dependent antiparasitic activity
against
Ascaris suum
, with an IC₅₀ value of 17.3 µg/mL, which is considered highly active
for a synthetic compound at this stage of development. This supports earlier research on the
bioactivity of quaternary ammonium compounds and highlights the importance of structural
features—such as the phenoxyethyl group and the naphthoate moiety—in enhancing
membrane permeability and biological interaction.
A key observation in this study is the statistically significant correlation (Pearson’s r = 0.81)
between the compound’s molar absorptivity in various solvents and its antiparasitic activity.
This correlation suggests that spectrophotometric parameters may serve as indirect
predictors of bioactivity, especially in the early stages of compound screening. Such a
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relationship provides a useful tool for guiding the rational design of analogues with
improved pharmacological profiles.
Taken together, the results affirm that PEDBA-ONA is a promising candidate for further
development as an antiparasitic agent. Its strong spectral profile, solvent stability, and
significant biological efficacy support its continued investigation. Future work should focus
on in vivo testing, toxicity profiling, and structural modification to optimize both efficacy
and biocompatibility.
Conclusion:
This study demonstrates that 2-phenoxyethyldimethylbenzylammonium-2-
oxynaphthoate (PEDBA-ONA) possesses favorable spectrophotometric characteristics and
strong antiparasitic potential. The compound exhibits well-defined UV absorption maxima
in polar organic solvents, particularly ethanol and DMSO, indicating high electronic
delocalization and structural stability in these environments. Spectral monitoring over 24
hours confirmed its chemical stability in organic media, while moderate instability in
aqueous solution suggests a need for formulation optimization.
The in vitro bioassays revealed significant, dose-dependent antiparasitic activity, with an
IC₅₀ value of 17.3 µg/mL against
Ascaris suum
, demonstrating its potential as an effective
anthelmintic agent. Importantly, the observed correlation between molar absorptivity and
biological efficacy supports the use of spectrophotometric parameters as predictive
indicators in early-stage drug screening.
Overall, PEDBA-ONA represents a promising scaffold for further development of
antiparasitic agents. Future studies should explore its mechanism of action, evaluate its
pharmacokinetics and toxicity profiles, and consider structural modifications to enhance
bioavailability and selectivity.
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