Characterizing Eckol as a Therapeutic Aid: A Systematic Review

Manandhar, Bandana; Paudel, Pradeep; Seong, Su Hui; Jung, Hyun Ah; Choi, Jae Sue

As outlined in the above review, eckol has been evaluated copiously for a broad spectrum of activities to establish it as a potential therapeutic agent. According to various experimental results, eckol possesses a wide array of therapeutic properties. Through various studies [42, 43] , eckol had been established as an antioxidant; however, the evidence of its usefulness in cell-based experiments is limited. Hence, the results of the cell-based experiments could act as future references for in vivo experiments to doubtlessly highlight antioxidant potential. Eckol has also shown promising results in diabetes suppression. Since diabetes is incurable and can only be suppressed over time, scientists are always on the verge of finding new compounds and pathways to cure this disease. As eckol has been evaluated for its role in the existing signaling pathways against diabetes, it would be interesting to see the effect of eckol on the newly discovered pathways other than the evaluated ones. Furthermore, eckol had contraindications for not being useful in hepatoprotection at the cellular level [92] , while it showed hepatoprotective activity in an in vivo model [48] . The possible reason for this discrepancy could be different toxicity-inducing agents employed in those studies, where eckol was ineffective against tacrine-induced toxicity in human liver cell line but exhibited a protective effect against CCl 4 -induced toxicity in mice model. Hence, why eckol failed to protect the liver cell against tacrine-induced toxicity needs further detailed research to know the exact mechanism involved. In neuroprotection, the GABA A -BZD receptor and dopamine receptors hold a good future for eckol due to its potent activity against these receptors [55, 56] . The high activity of eckol in AChE enzyme inhibition but not in BChE inhibition [26] explains its selective nature, including moderate hMAO-B inhibition [53] . Although these enzyme inhibition effects displays its neuroprotective nature, cell-based and in vivo experiments are imperative to show its actual therpeutics. In several diseases requiring radiation therapy, including cancer, radioprotection is of the utmost importance. Although the in vivo experiments showed eckol as a radioprotector [62] [63] [64] , there are still many complications and considerations while using it for human clinical trials, the correct dose of eckol required against the radiation being the utmost important part. Hence, these studies could be the references through which eckol could be further developed as a pharmaceutical product. Eckol showed a moderate protective role in skin cells against UV radiation [58, 60] by scavenging ROS and reducing intracellular oxidative damage induced by UVB radiation. Further, the in vivo experiment [59] also supported eckol as a UV protector against skin carcinogenesis. Hence, eckol could be a potent UV protector in pharmaceuticals or cosmeceuticals. Regarding its anticoagulative property [16, 120] , the dibenzo-1,4-dioxane skeleton (dibenzo-p-dioxin-I,3,6,8-tetraol) of eckol seems to be one of the major factors involved in the anticoagulative effect which requires further investigation. Although eckol showed potent anticoagulative effect via thrombin activity inhibition, the activity was reduced in whole plasma [16] most probably due to the plasma-protein binding affecting its efficacy. Hence, searching for alternatives to increase its bioavailability could be good future research. Similarl