Insecticidal activity of forty-seven marine algae species from the Mediterranean, Aegean and Sea of Marmara in connection with their cholinesterase and tyrosinase inhibitory activity

Authors: KILIC, MEHTAP - Gazi University; ORHAN, ILKAY ERDOGAN - Gazi University; EREN, GOKCEN - Gazi University; OKUDAN, EMINE SUKRAN - Akdeniz University; Estep Iii, Alden; BECNEL, JAMES - Retired ARS Employee; Tabanca, Nurhayat

Submitted to: South African Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2021
Publication Date: 7/20/2021
Citation: Kilic, M., Orhan, I., Eren, G., Okudan, E., Estep Iii, A.S., Becnel, J.J., Tabanca, N. 2021. Insecticidal activity of forty-seven marine algae species from the Mediterranean, Aegean and Sea of Marmara in connection with their cholinesterase and tyrosinase inhibitory activity. South African Journal of Botany. https://doi.org/10.1016/j.sajb.2021.06.038.
DOI: https://doi.org/10.1016/j.sajb.2021.06.038

Interpretive Summary: Plants have provided many compounds of use as insecticides or as pharmaceuticals. Thie first step in the identification of potential products is to examine extracts of groups of plants for useful activities. Here we examined the algal species that are found in the waters off of Turkey. We tested 47 extracts and found limited enzymatic usefulness against hAche/hBche. A subset of these extracts did show very good insecticidal activity against the yellow fever mosquito and warrant further study to find the active components. This study demonstrates that common aquatic plants could be sources of useful insecticidal candidates.

Technical Abstract: Ethanolic extracts prepared from forty-seven macroalgae species collected from the Mediterranean Sea, Aegean Sea, and Sea of Marmara were screened for insecticidal and enzyme inhibitory activities. The extracts were tested at 200 'g/mL against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and tyrosinase (TYR), enzymes crucial for insect vivacity. The results obtained indicated that only one alga extract, e.g. Dictyota dichotoma var. intricata (C.Agardh) Greville 1830, had a notable inhibition of BChE (72.0 ± 0.07%), whereas the rest of the macroalgae possessed no or low inhibition of AChE (2.20 ± 0.39% - 14.20 ± 2.16%), BChE (0.62 ± 0.07% - 41.20 ± 3.07%), and TYR (< 10%). As D. dichotoma var. intricata extract was the only one exhibiting BChE inhibition over 50%, several known diterpenes (isoamijiol, 14-deoxyamijiol, amijidictyol, dictyodial, and 4'-acetoxydictyodial) found earlier in this species were proceeded to molecular docking experiments to figure out its interactions with BChE. Eleven of the 47 macroalgal extracts were selected based on sufficient availability for testing in larvicidal and adulticidal activity assays against female Aedes aegypti “Orlando1952,” the mosquito vector of yellow fever and dengue. The selected extracts displayed a high adulticidal activity ranging between 80-100% activity at 5 'g/mosquito. In contrast, only the ethanol extract of Ceramium siliquosum var. elegans showed larvicidal mortality of 93.3 ± 11.5% at 0.5 'g/mL. Our findings show that the macroalgae and their metabolites could be sources of novel insecticidal agents.