1. Control group (oral administered 0.3ml and 0.9% sodium chloride)
2. Treated group (oral administered with different concentrations of purple yam extract)

Visible benefits

The results showed that food intake, fasting blood glucose level and body weight were significantly reduced when compared with the control group.

Table 1: Comparison of food intake in the difference between difference experimental groups

Table 2: Comparison of fasting blood glucose in the difference between difference experimental groups.

Table 3: Comparison of body weight changes in the difference between difference experimental groups.

1. Determination of Total Phenolic Compound
2. Total Antioxidant Activity

Visible benefits

• Phenolic content of yam ranges from 15.9 to 421.8 mg gallic acid/100g sample.
• Total antioxidant activity by ferric thiocyanate method at 50 mg/mL was between 92.0-95.6%.
• All taro samples were found to exhibit better radical scavenging activity and reducing power on a µg analyte basis than α-tocopherol.

Table 1: Total phenolic content of yam samples.

Table 2: Antioxidant activity of yam samples.

*radical scavenging activity of α-tocopherol (EC50 = 23 µg mL-1)
reducing power of α-tocopherol (EC50 = 94 µg mL-1)

1. Control group (Casein diet)
2. Treated group (casein diet supplemented with 10% lyophilized or with hot-air dried yam)

Visible benefits

• Results of passive and active shuttle avoidance tests showed the mice fed with the diet containing yam had significantly better learning and memory ability than the control group.
• Brain morphology of mice revealed less spongy degeneration and low percentages of cells with lipofuscin in the hippocampus.

Figure 1: Mean number of successful active avoidance among 20 trials per day of shuttle avoidance test in SAMP8 mice fed with control or yam diets for 12 weeks.

Table 2: The spongiosis numbers and lipofuscin f the hippocampus in SAMP8 mice fed with the control or yam diets for 12 weeks.

• The senescence-prone inbred series (SAMP) is a murine model system that has a shorter life span than normal mouse, and it shows many characteristics of mammalian aging.
• The supplementation of the diet with yam could improve the learning and memory ability whilst reducing the brain morphology changes in mice.

orally administered to the SHRs

1. Alcohol-insoluble-solids (AIS) and hot air drying (HAD) = 40 or 60 mg/kg of SHR
2. Steam-cooked once (SCO) / Steam-cooked twice (SCT) and hot air drying (HAD) = 80 mg/kg of SHR
3. Water extracts = 154.4 mg of protein/kg of SHR

Visible benefits

Yam products were found to have antihypertensive properties in SHRs.

Figure 1: Effects of water extract Yam tuber heated at 90 degree celcius for 10min (WEY90H) on systolic blood pressure of spontaneously hypertensive rats by oral administration (1 ml/kg of SHR) once a day for 30 days.