Beyond Melanization: Phenoloxidase Responses across Caffeic Acid Concentrations in Galleria mellonella (Lepidoptera: Pyralidae)
Abstract
Caffeic acid is a naturally occurring hydroxycinnamic acid with antioxidant and immunomodulatory properties, but its effects on phenoloxidase (PO), a key component of insect humoral immunity and melanization, remain poorly understood. This study investigated PO activity in Galleria mellonella larvae following administration of caffeic acid at 0.1, 0.25, 0.5, 1, 2.5, and 5 mg/mL. Caffeic acid was prepared in 20 % ethanol, which served as the primary vehicle control, and untreated larvae were included as a negative control. Each larva received 5 µL of the corresponding solution, and PO activity was determined 24 h after treatment using DL-DOPA as substrate. Treatment had a significant overall effect on PO activity (HC3 robust linear model, F(7, 86) = 4.12, p < 0.001). However, planned comparisons with Holm adjustment showed that none of the caffeic acid concentrations differed significantly from the ethanol vehicle (all adjusted p > 0.05). PO activity was significantly lower in untreated larvae than in the vehicle group (adjusted p < 0.001), indicating a marked response associated with the vehicle/injection condition. Although mean PO activity tended to be lower at several higher caffeic acid concentrations, this pattern was not statistically significant and did not support a concentration-dependent inhibitory effect. These findings demonstrate that caffeic acid does not significantly modify circulating PO activity relative to its vehicle at 24 h and emphasize the importance of appropriate vehicle controls when evaluating phytochemical effects on insect immunity.
Keywords
Supporting Institution
This research received no specific grant or financial support from any funding agency or institution.
Ethical Statement
Ethical approval was not required for this study because Galleria mellonella is an invertebrate species and is not subject to institutional ethical approval requirements for animal experimentation.
Thanks
OpenAI ChatGPT (GPT-5.6 Sol) was used to assist with English-language editing, grammatical correction, improvement of readability and narrative clarity, and manuscript formatting. The authors independently reviewed and approved all revisions and are fully responsible for the scientific content, interpretation, accuracy, and integrity of the manuscript. No generative AI tool was used to generate research data, perform the statistical analyses, or create or verify references.
References
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Details
Primary Language
English
Subjects
Enzymes, Medicinal Plants
Journal Section
Research Article
Early Pub Date
September 29, 2026
Publication Date
-
Submission Date
September 19, 2026
Acceptance Date
September 27, 2026
Published in Issue
Year 2026 Number: Advanced Online Publication
APA
Er, A., & Kaya, S. (2026). Beyond Melanization: Phenoloxidase Responses across Caffeic Acid Concentrations in Galleria mellonella (Lepidoptera: Pyralidae). International Journal of Nature and Life Sciences, Advanced Online Publication. https://izlik.org/JA83RU42ZS
AMA
1.Er A, Kaya S. Beyond Melanization: Phenoloxidase Responses across Caffeic Acid Concentrations in Galleria mellonella (Lepidoptera: Pyralidae). Int J Nature Life Sci. 2026;(Advanced Online Publication). https://izlik.org/JA83RU42ZS
Chicago
Er, Aylin, and Serhat Kaya. 2026. “Beyond Melanization: Phenoloxidase Responses across Caffeic Acid Concentrations in Galleria Mellonella (Lepidoptera: Pyralidae)”. International Journal of Nature and Life Sciences, no. Advanced Online Publication. https://izlik.org/JA83RU42ZS.
EndNote
Er A, Kaya S (September 1, 2026) Beyond Melanization: Phenoloxidase Responses across Caffeic Acid Concentrations in Galleria mellonella (Lepidoptera: Pyralidae). International Journal of Nature and Life Sciences Advanced Online Publication
IEEE
[1]A. Er and S. Kaya, “Beyond Melanization: Phenoloxidase Responses across Caffeic Acid Concentrations in Galleria mellonella (Lepidoptera: Pyralidae)”, Int J Nature Life Sci, no. Advanced Online Publication, Sept. 2026, [Online]. Available: https://izlik.org/JA83RU42ZS
ISNAD
Er, Aylin - Kaya, Serhat. “Beyond Melanization: Phenoloxidase Responses across Caffeic Acid Concentrations in Galleria Mellonella (Lepidoptera: Pyralidae)”. International Journal of Nature and Life Sciences. Advanced Online Publication (September 1, 2026). https://izlik.org/JA83RU42ZS.
JAMA
1.Er A, Kaya S. Beyond Melanization: Phenoloxidase Responses across Caffeic Acid Concentrations in Galleria mellonella (Lepidoptera: Pyralidae). Int J Nature Life Sci. 2026. Available at https://izlik.org/JA83RU42ZS.
MLA
Er, Aylin, and Serhat Kaya. “Beyond Melanization: Phenoloxidase Responses across Caffeic Acid Concentrations in Galleria Mellonella (Lepidoptera: Pyralidae)”. International Journal of Nature and Life Sciences, no. Advanced Online Publication, Sept. 2026, https://izlik.org/JA83RU42ZS.
Vancouver
1.Aylin Er, Serhat Kaya. Beyond Melanization: Phenoloxidase Responses across Caffeic Acid Concentrations in Galleria mellonella (Lepidoptera: Pyralidae). Int J Nature Life Sci [Internet]. 2026 Sep. 1;(Advanced Online Publication). Available from: https://izlik.org/JA83RU42ZS