2.1. Effects of Beverages on Concentrations of Ethanol and Acetaldehyde in Blood
The levels of blood alcohol and acetaldehyde are rapidly elevated 2 h after alcohol consumption when compared with the normal group (untreated group) (Table 1
). The blood ethanol levels ranged between 1300 and 2200 mg/L. The majority of these beverages did not markedly affect the content of ethanol in blood except that one beverage called honey citron tea (1332.72 ± 249.50 mg/L, p
< 0.05) could significantly decrease the concentration in blood. The levels of blood acetaldehyde ranged between 58 and 87 mg/L. Honey citron tea (84.88 ± 16.75 mg/L, p
< 0.05), red bull (76.12 ± 2.60 mg/L), plum juice (84.66 ± 5.37 mg/L), and fresh orange juice (86.48 ± 8.27 mg/L) dramatically increased the concentration of acetaldehyde in blood, while there was no beverage that could significantly decrease the level of acetaldehyde.
The treatment of honey citron tea significantly decreased the concentration of ethanol in blood of intoxicated mice, and increased the acetaldehyde level in blood significantly, which means that honey citron tea could accelerate the speed of first pass of ethanol metabolism. That is, ethanol could be metabolized rapidly to acetaldehyde, but the acetaldehyde is slowly metabolized to acetic acid. In addition, red bull, fresh orange juice, and plum juice weakly decreased the content of ethanol and apparently increased the acetaldehyde in blood. It was suggested that the second phase of ethanol metabolism was inhibited more potently than the first phase, which led to the accumulation of acetaldehyde in blood. It is well established that acetaldehyde plays a key role in the toxic effects of ethanol [11
]. People would get drunk and have hangover symptoms more easily with higher level of acetaldehyde in blood. In addition, the mechanism of a beverage leading to acetaldehyde accumulation was similar to that of a drug therapy for alcohol dependence. Disulfiram, an aldehyde dehydrogenase inhibitor, was approved by the FDA in 1951 as an aversive therapy for treating alcohol dependence. It could block the oxidation of ingested alcohol at the acetaldehyde stage, preventing its rapid and efficient metabolism to acetic acid. As a result, acetaldehyde accumulation caused unpleasant symptoms such as tachycardia, hypotension, diaphoresis, flushing, dyspnea, nausea, and vomiting, acting as a deterrent to alcohol ingestion [15
]. Therefore, those beverages which could increase the level of acetaldehyde could be developed to diet supplements to treat alcohol dependency.
2.2. Effects of Beverages on Hepatic ADH and ALDH Activities
The ADH and ALDH are two key catalytic enzymes in the alcohol metabolism in liver. As can be seen from Table 2
, most of the beverages did not markedly affect the activities of ADH and ALDH in liver. Green tea (14.26% ± 1.24%, p
< 0.05) and honey chrysanthemum tea (7.78% ± 0.41%, p
< 0.05) obviously increased the activity of ADH in liver. Iced black tea (21.20% ± 1.79%, p
< 0.05) and soda water (21.43% ± 3.16%, p
< 0.05) remarkably boosted the activity of ALDH in liver, while coca cola (−29.98% ± 10.27%, p
< 0.05), water chestnut juice (−30.90% ± 3.56%, p
< 0.05), jasmine tea (−41.56% ± 17.17%, p
< 0.05), and fresh orange juice (−43.71% ± 10.12%, p
< 0.05) notably inhibited the activity of ALDH in liver.
As above, ethanol was oxidized to acetaldehyde by ADH, mainly in liver; and acetaldehyde was metabolized into non-toxic acetic acid by ALDH. When the ADH activity was boosted, it could accelerate the oxidation of ethanol to acetaldehyde, the ethanol level would decrease and the acetaldehyde level would increase accordingly. When the ALDH activity was inhibited, the speed of acetaldehyde oxidative into acetic acid was slowed, thus the acetaldehyde could be accumulated in the body system, leading to serious hangover symptoms. In brief, the concentrations of ethanol and acetaldehyde in blood were dependent on the relative reaction rate of two major catalyzing enzymes in liver, ADH, and ALDH.
The ADH activity was markedly increased by green tea and honey chrysanthemum tea, which means that they could promote the first pass of alcohol oxidation. In addition, iced black tea and soda water significantly increased the activity of ALDH in liver. Acetaldehyde, the metabolite of ethanol, was transferred to acetic acid by ALDH in many tissues. Agents which could boost the activity of ALDH have the potential to accelerate conversion of acetaldehyde to acetic acid, which has protective health effects. Therefore, green tea, honey chrysanthemum tea, iced black tea, and soda water might provide potential health benefits after excessive alcohol consumption. On the contrary, coca cola, water chestnut juice, jasmine tea, and fresh orange juice evidently inhibited the activity of ALDH, which might contribute to the acetaldehyde accumulation in blood.
In this study, the relationships between the content of ethanol in blood and the activity of ADH in liver as well as acetaldehyde content and ALDH activity as influenced by the 20 selected beverages were obtained and were exhibited in Figure 1
. The correlation was analyzed by statistic software SPSS 20.0. As shown in Figure 1
b, a moderate negative correlation between acetaldehyde content and ALDH activity was obtained with the correlation coefficient of −0.447 (p
< 0.05), suggesting that the content of acetaldehyde in blood could be different from the activity of ALDH influenced by beverages. The content of acetaldehyde in blood was decreased when ALDH activity was boosted; on the contrary, the content of acetaldehyde in blood was increased when ALDH activity was inhibited by beverages. Chronic alcohol consumption reduced the activity of ALDH significantly which led to accumulation of acetaldehyde in blood and brain [16
]. Acetaldehyde might play an important role in mediating the neuropharmacological and behavioral effects of ethanol.
However, there was no significant correlation between the content of ethanol in blood and the activity of ADH (r
= 0.224, p >
0.05), which indicated that ADH activity in liver might not be responsible for content of blood ethanol after drinking alcohol and these beverages. There are three major enzymes involved in the metabolism of alcohol, that is ADH, catalase (peroxisomes), and P450 2E1 (microsomes) [17
]. The ADH metabolized the bulk of ethanol within the liver, and the others also contributed to the production of acetaldehyde from ethanol oxidation. The results suggested that these beverages that influenced the concentrations of ethanol and acetaldehyde in blood were not by means of changing ADH and ALDH activities, but through other ways, such as non-enzymatic ways, which could inhibit the absorption of ethanol in the stomach and intestine or accelerate the excretion of ethanol through breath and urine.
Therefore, beverages such as iced black tea and soda water which could boost the ALDH activity so as to decrease the content of acetaldehyde in blood might possess the capacity of accelerating the metabolism of alcohol and be beneficial in reducing the harm from excessive alcohol consumption. On the contrary, due to the evident inhibition of ALDH activity, the groups of coca cola, honey citron tea, water chestnut juice, jasmine tea, and fresh orange juice showed higher level of acetaldehyde in blood than the control. The results suggested that these beverages might increase the potency of the acetaldehyde toxicity. Red bull and plum juice markedly increased the acetaldehyde in blood might through other mechanism such as inhibition of other enzymatic pathways or non-enzymatic pathways [8
]. These beverages could disturb the metabolism of ethanol and accumulated toxic acetaldehyde in blood, causing harmful effects on human health.
2.3. Effects of Beverages on ALT and AST Levels in Serum
The liver damage was evaluated by measuring the activities of AST and ALT in serum. As showed in Table 3
, there was a significant rise of levels of AST and ALT in serum 6 h after alcohol consumption (control group) when compared with the normal group. In the literature [18
], 6 h were usually adopted for evaluation of AST and ALT levels, and some researchers even found that the level of ALT was the highest among 1.5, 3, 6, 12 h [21
]. For treatment groups, ban sha herbal infusion, sprite, and fresh orange juice obviously increased the level of AST, while green tea, honey chrysanthemum tea, jasmine tea, and soda water markedly decreased the level of AST in serum. In addition, red bull and fresh orange juice notably increased the level of ALT, while green tea, honey chrysanthemum tea, fructus cannabis herbal infusion, and soda water dramatically lowered the level of ALT in serum.
AST and ALT are enzymes with high concentrations in the cytoplasm. When liver cells were injured, these enzymes leaked into the blood stream and their levels in serum were significantly elevated. Assessment of liver function could be performed by measuring the activities of serum enzymes. ALT mainly presents in liver, whereas AST can be found in liver, skeletal muscle, and cardiac muscle. As a result, ALT is more specific for hepatic damage with respect to AST. The elevated levels of AST and ALT in serum were significantly reduced in the animals groups treated with green tea, honey chrysanthemum tea, and soda water, which suggested that these beverages could provide a protection to alcohol-induced liver damage. Conversely, fresh orange juice caused a marked increase in both serum AST and ALT activities, which indicated that it could aggravate liver injury caused by alcohol. Red bull obviously increased the level of ALT, while ban sha herbal infusion and sprite increased the level of AST. Due to ALT could reflect the liver damage more specific than AST, red bull would do more harm to liver than ban sha herbal infusion and sprite. In addition, jasmine tea decreased the level of AST, and fructus cannabis herbal infusion decreased the level of ALT, suggesting that they might provide some protection from liver injury caused by alcohol.
2.4. Effects of Beverages on SOD and MDA Levels in Liver
The effects of the 20 selected beverages on the levels of SOD and MDA in liver were showed in Table 4
. In comparison with normal group, there was a significant increase in the level of MDA in control group, suggesting the development of peroxidation in liver tissue. Generally, the majority of these beverages did not obviously affect the levels of MDA and SOD in liver. As can be seen in Table 4
, the treatment of soda water, honey chrysanthemum tea, he qi zheng herbal infusion and semen coicis herbal infusion significantly prevented the increase of the MDA level in liver. Jia duo bao herbal infusion and semen coicis herbal infusion decreased the level of hepatic SOD.
Oxidative stress is considered to play a critical role in the pathogenesis of various liver disorders [22
]. The formation of acetaldehyde in alcohol metabolism is associated with an increase in reactive oxygen species formation, leading to the development of oxidative stress in the liver. Free radicals derived from oxygen were an important factor to liver injury. The content of malondialdehyde in liver tissues reflex the oxidative stress associated with the ingestion of alcohol, which could be used as an indirect measurement of cellular oxidative injury. Soda water, honey chrysanthemum tea, he qi zheng herbal infusion, and semen coicis herbal infusion significantly decreased the level of MDA in liver, suggesting that these beverages could attenuate alcohol-induced oxidative stress. There was no marked change of SOD in most groups except that jia duo bao herbal infusion and semen coicis herbal infusion lowered the level of SOD. Their antioxidant capacity might be declined by excessive alcohol consumption.
The concentration of ethanol and acetaldehyde in blood as well as the activities of ADH and ALDH in liver are major indicators of the metabolism of alcohol. The reduction in levels of AST and ALT by the beverages is an indication of repair of hepatic tissue damage caused by alcohol, and the levels of MDA and SOD could reflect the extent of peroxidation damage. Over-consumption of alcohol could increase the activities of AST and ALT as well as the content of MDA (Table 3
and Table 4
). Three (soda water, honey chrysanthemum tea and green tea) out of the 20 kinds of beverages were recommended to consume after excessive alcohol drinking due to their protection from alcohol-induced injuries. Soda water could significantly decrease the levels of AST, ALT, and MDA, and remarkably increase the activity of ALDH. Honey chrysanthemum tea could significantly decrease the levels of AST, ALT, and MDA and markedly increase the activity of ADH. Green tea could significantly decrease the activities of AST and ALT, increase the activity of ADH. Tea (Camellia sinensis
) is the most consumed beverage in China. Soda water is an alkalescent soft drink, which is widely used by people for drinking. A study has demonstrated the alkalescent electrolyzed-reduced water has an effect of alcohol detoxification through its antioxidant capacity and has potentiality for relief of ethanol-induced hangover symptoms in Sprague-Dawley rats, such as lowering the levels of AST and ALT in serum, significantly increased the levels of glutathione, glutathione peroxidase, glutathione-S-transferase, Cu/Zn-superoxide dismutase, and catalase in liver [23
]. Green tea possessed a strong antioxidant capacity owing to abundant of polyphenols, such as catechin, epicatechin and gallate [24
]. Fu et al.
] have evaluated the total phenolic contents and antioxidant capacities of herbal and tea infusions, and the results showed that green tea had high FRAP values (12.722 ± 0.698 g GAE/L), TEAC values (7.853 ± 0.126 g GAE/L) and total phenolic contents (0.660 ± 0.016 g GAE/L). Ingestion of green tea with solid contents 2.0 g/L significantly increased reducing power in plasma [26
]. Green tea lowered the AST and ALT in this study, which was in accordance with the literature. A cross sectional study in a Japanese population showed that green tea consumption was significantly associated with lower circulating levels of aminotransferases [28
Two out of the 20 kinds of beverages were not recommended to consume after alcohol drinking. Fresh orange juice significantly increased the content of acetaldehyde in blood as well as the activities of AST and ALT, and remarkably inhibited the activity of ALDH. Red bull could significantly increase the concentration of acetaldehyde in blood and the activity of ALT. It would be better not to drink these beverages simultaneously after alcohol consumption. Studies have confirmed that combining energy drinks (such as red bull) with alcohol could mask the signs of alcohol intoxication, resulting in greater levels of alcohol intake, dehydration, more severe and prolonged hangovers, and alcohol poisoning [29