To evaluate therapeutic efficacy of aldose reductase (AR) inhibition, the leaves of Aster yomena were tested for inhibition of AR. The stepwise polarity fractions of A. yomena were tested. Among them, the n-BuOH fraction showed highest activities against AR inhibition. Our results demonstrated that A. yomena could be a worthy natural source source for curing against diabetic complications.

Content analysis of loliolide in the leaves of Boehmeria nivea (Bn) collected from different region during four months (June, July, August, and September) was conducted by HPLC. The content of loliolide was detected in the leaves of B. nivea from Bns-2, -7, -10, -23, -38, -41, -67, -76, and -90 in June (5.02, 6.35, 6.93, 5.89, 4.31, 4.24, 4.91, 5.12, and 5.46 mg/g, respectively), July (4.32, 6.42, 7.72, 7.97, 4.05, 4.32, 5.65, 6.67, and 5.39 mg/g, respectively), August (3.52, 5.17, 3.90, 4.27, 3.26, 4.72, 3.82, 3.30, and 3.31 mg/g, respectively), and September (7.04, 7.25, 7.43, 7.86, 6.76, 6.38, 7.60, 6.79, and 4.77 mg/g, respectively). Among them, the highest content of loliolide was found in Bn-23 and in September. These results may be useful in determining the optimal harvest time at which phytochemical reaches a maximum level.

To evaluate therapeutic efficacy of aldose reductase (AR) inhibition, the seeds of Perilla frutescens var. japonica (PF) were tested for inhibition of AR. The stepwise polarity fractions of PF were tested. The CH2Cl2 and EtOAc fractions showed highest activities (IC50 5.47 and 3.63 μg/mL, respectively). Compounds 1-5 were isolated from the CH2Cl2 and EtOAc fractions by silica-gel and LH-20 Sephadex. Their structures were elucidated as β-sitosterol (1), diosmetin (2), kaempferol (3), luteolin (4), and apigenin (5). Compounds 1-5 were exhibited AR inhibitory. Among them, luteolin (4) and apigenin (5) exhibited AR inhibitory activities (IC50 0.40 and 1.10 μg/mL, respectively). Our results demonstrated that PF could be a worthy natural source for curing against diabetic complications.