White Kwao Krua [Pueraria candollei Grah. ex Benth. var. mirifica (A.Shaw and Suvatabandhu)
Niyomdham] is a Thai native medicinal plant with a long record of traditional medicinal consumption
among menopausal women for the purposes of rejuvenation and estrogen replacement. It is attracting
great interests due to the antioxidant and estrogen-like properties of some of its natural products.
The antioxidant activities of puerarin and genistin in White Kwao Krua (WKK) that were treated
with elicitors, and their antihyperglycemic effect on rats (Rattus norvegicus) were investigated. Eight
combinations of chitosan, CuCl2 and salicylic acid (SA) were applied over two months to forty eight
plants of WKK grown in a growth chamber. The results showed that all combinations of additives had
statistically significant effects on antioxidant activities and the amount of genistein and puerarin
produced. The combination of chitosan (1000 mg/L) + CuCl2 (200 mg/L) + salicylic acid (100 mg/L)
gave the highest antioxidant activities [IC50 value = 2482 µg/ml for DPPH, FRAP value = 45.5 µmol
Fe2+/g dry weight (dw)], while the combination of chitosan (1000 mg/L) + CuCl2 (200 mg/L) gave the
highest amount of genistein (423 µg/g dw) and puerarin (22.6 µg/g dw). WKK crude extract could
reduce blood sugar level in streptozotocin (STZ)-diabetic rats. The results showed that the elicitors
used can increase the amount of puerarin and genistein and their antioxidant activities in WKK.
Furthermore, WKK crude extract pronounced an antihyperglycemic effect in STZ-diabetic rats also.