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Alcohol preferring (P) rats, given "free choice" of water, exhibited daily intake of 60–75 g of water/kg of body weight. When given "free choice" of water and 15% ethanol, P rats consumed 7–13 g of alcohol/kg. Their water intake decreased proportionally to the alcohol intake, but total fluid intake did not differ significantly. Alcohol withdrawal after 50 days of alcohol drinking caused withdrawal symptoms such as hypersensitivity, poor coordination, and tremors. A daily 50 mg/kg dose of puerarin (PU) caused approximately 50% suppression in alcohol intake, but did not affect body weight and food and total fluid intake in P rats receiving "free choice" of water and 15% ethanol. Alcohol ingestion gradually returned to the control level despite consistent PU intake. However, alcohol intake following alcohol withdrawal was suppressed in PU-fed P rats. PU suppressed the severity of alcohol withdrawal symptoms. Thus, withdrawal symptoms do not occur in PU-fed rats even though their alcohol ingestion is comparable to that in control P rats. Brain, plasma, and liver samples were analyzed for the presence of kudzu root isoflavones, which are mostly PU (>90% of total isoflavones) and a trace amount of daidzin. Liver samples obtained from PU-fed P rats contained 20–30 μg/g of PU. An important observation was that plasma or brain samples obtained from PU-fed or alcohol + PU-fed rats did not contain PU. This study indicated that PU feeding transiently suppressed alcohol intake and abolished withdrawal symptoms at a time when alcohol intake had returned to the control level. The absence of PU in plasma and brain indicates the possibility that some nonspecific mechanism may be involved in the anti-alcoholism effects of PU in P rats.

Alcohol-preferring (P) rats, given free choice to drink water or 15% alcohol, drank 7–10 g of alcohol/kg/day, giving blood alcohol values ranging from 16 to 24 mg/dL. Body weight and food and total fluid intake values in control and alcohol-drinking P rats did not differ significantly, while water intake was inversely related to the amount of alcohol consumed. Alcohol withdrawal after 50 days of alcohol drinking caused withdrawal symptoms such as hypersensitivity, poor landing coordination, and tremors. A daily 0.5, 0.75, and 1.0 g/kg dose of kudzu root (KdR) did not affect body weight and food and water intake values in control (no alcohol) P rats. Subchronic feeding of relatively higher KdR doses (0.75 and 1.0 g/kg) caused a 25–30% reduction in weight gain. The 0.5 g/kg KdR dose caused a 50–60% reduction in alcohol consumption, abolished the development of alcohol withdrawal symptoms, but did not affect blood alcohol levels. The higher KdR doses did not further reduce alcohol consumption. Alcohol suppressed the weight-reducing effects of KdR. The KdR extract used in this study contained 150 mg/g of puerarin, 13 mg/g of daidzin, 4 mg/g of daidzein, 3 mg/g of genistin, 0.2 mg/g of genistein, and 1 mg/g of glycetin. Blood and liver samples contained mostly puerarin and a trace amount of daidzein that may have been formed by the hydrolysis of daidzin by liver enzymes. An important observation was that brain samples obtained from KdR-fed or alcohol + KdR-fed rats did not contain any of the KdR isoflavones. Thus, KdR isoflavones suppressed alcohol drinking and withdrawal symptoms without entering the brain.

Kudzu-root and soy phytoestrogens have been associated with anti-cancer and anti-intoxication activities. Sales of capsules containing kudzu-root and soy extracts through health food stores and the Internet are unregulated. To compare efficacy, the amount of phytoestrogens present in commercial preparations and their fate in biological samples must be determined. In this study, the levels and composition of phytoestrogens in kudzu-root and soy extracts were studied using high-performance liquid chromatography with ultraviolet light detection. The bioavailability of phytoestrogens was studied by measuring red blood cell (RBC) uptake and serum protein binding ability. Phytoestrogen levels in acidified kudzu-root samples were 5- to 10-fold greater than those in nonacidified samples. Puerarin accounted for 80% of total phytoestrogens in kudzu-root. In soy extract, puerarin was absent while genistin, glycetein, and daidzin or daidzein were the major phytoestrogens. The RBC uptake depended on the phytoestrogen's polarity and molecular length. When serum was dialyzed with phytoestrogen standards in a buffer, the protein binding of phytoestrogens correlated negatively with their polarity. However, when serum was dialyzed with kudzu-root or soy extract, almost all of the phytoestrogens present in the extract bound to serum protein. Therefore, this study suggests differences in the bioavailability of phytoestrogens when they are ingested as purified compounds compared with crude plant extract. The differential composition of phytoestrogens in kudzu-root and soy may account for the differences in their therapeutic activities.