Study on Anti-cataract Drugs from Natural Sources. II. Effects of Buddlejae Flos on in Vitro Aldose Reductase Activity.

The inhibitory effects of nine crude drugs were tested on unpurified rat lens aldose reductase, an enzyme involved in the complications of diabetes. Among the crude drugs, a 70% methanolic extract of Buddlejae Flos (flower of Buddleja officinalis) exhibited the highest inhibition. Luteolin, luteolin-7-O-beta-D-glucopyranoside, apigenin and acacetin-7-O-alpha-L-rhamnopyranosyl-(6-1)-beta-D-glucopyranoside isolated from Buddlejae Flos showed the inhibitory activity, the IC50 (concentration of 50% inhibitory percentage) values of which were 0.21, 0.28, 0.58 and 0.75 microM, respectively. It is suggested that the inhibitory effect of Buddlejae Flos on aldose reductase is partially attributable to these flavonols or their glycosides.