Table 3.
Mechanisms of hydrogen biology in hydrogen medicine and hydrogen agronomy
| Process | Mechanism of action | Reference |
| Hydrogen medicine | ||
| Hydrogen-mediated oxidative stress | H2 can attenuate severe burn-induced early AKI by regulating the MAPKs, Akt, and NF-κB signaling pathway | Guo et al., 2015 |
| H2 can increase the antioxidant effect by activating the Nrf2 transcription system | Kawamura et al., 2013 | |
| Hydrogen-regulated metabolic diseases and neurodegenerative diseases | H2 can improve Alzheimer’s disease caused by apolipoprotein ApoE4 mutation | Nishimaki et al., 2018 |
| HRW can reduce the damage of type 2 diabetes mellitus patients to glucose tolerance to a certain extent | Kajiyama et al., 2008 | |
| Hydrogen-regulated autophagy | Hydrogen-rich saline can enhance anti-apoptosis of cells by regulating Bax/Bcl-2 ratio and ASK-1/JNK pathway | Liu et al., 2015 |
| H2 can increase the expression of phosphorylated p-AMPK, AIF, Caspase 3, etc., thereby enhancing the 5-fluorouracil-induced apoptosis of cancer cells | Runtuwene et al., 2015 | |
| Hydrogen agronomy | ||
| Hydrogen-mediated ROS signaling | H2 can reduce the accumulation of cadmium and mercury, improve the antioxidant capacity of plant seedlings, and reduce the accumulation of ROS | Cui et al., 2014; Dai et al., 2017 |
| H2 can maintain a low-ROS level, thereby extending the shelf life of kiwifruit | Hu et al., 2014 | |
| Interaction of hydrogen and NO | H2 mobilizes NO signaling to promote stomata closure, thereby improving its drought tolerance | Xie et al., 2014 |
| H2 enhances the resistance of tomato fruits to Botrytis cinerea by increasing the activity of polyphenol oxidase and NO content | Lu et al., 2017 | |
| Interaction of hydrogen and CO | H2 regulates CO, a downstream signaling molecule that depends on heme oxygenase-1, thereby improving alfalfa’s drought tolerance | Jin et al., 2013 |
| H2 modulates target gene expression related to adventitious root development and auxin signaling pathway through the CO pathway, thereby promoting the development of cucumber adventitious roots | Lin et al., 2014 |
ROS, reactive oxygen species; NO, nitric oxide; CO, carbon monoxide; AKI, acute kidney injury; MAPK, mitogen-activated protein kinase; NF-κB, nuclear factor-κB; Nrf2, nuclear factor erythroid 2-related factor 2; ApoE4, apolipoprotein E4; HRW, hydrogen-rich water; Bcl-2, B cell lymphoma-2; ASK-1, apoptosis signal-regulating kinase 1; JNK, c-Jun N-terminal kinase; p-AMPK, phospho-adenosine monophosphate (AMP)-activated protein kinase; AIF, apoptosis-inducing factor