Young-Hwa Kang

β-secretase (BACE1) inhibitors from Pomegranate (Punica granatum) husk

In the course of screening for anti-dementia agents from natural products, two β-secretase (BACE1) inhibitors were isolated from the husk of pomegranate(Punica granatum) by activity-guided purification. They were identified as ellagic acid and punicalagin with IC50 values of 3.9 x10-6 and 4.1x10-7 M andKi values of 2.4x10-5 and 5.9x10-7 M, respectively. The compounds were non-competitive inhibitors with a substrate in the Dixon plot. Ellagic acid and punicalagin were less inhibitory to α-secretase (TACE) and other serine proteases such as chymotrypsin, trypsin, and elastase, thus indicating that they were relatively specific inhibitors of BACE1.

β-Secretase (BACE1) inhibitors from Sanguisorbae Radix

In the course of screening anti-dementia agents from natural products, two β-secretase (BACE1) inhibitors were isolated from the ethyl acetate soluble fraction of Sanguisorbae Radix by the activity-guided purification using silica gel, Sephadex LH-20, and RP-HPLC. They were identified as 1,2,3-trigalloyl-4,6-hexahydroxydiphenoyl-β-d-glucopyranoside (Tellimagrandin II,1) and 1,2,3,4,6-pentagalloyl-β-d-glucopyranoside (2) and were shown to non-competitively inhibit β-secretase (BACE1) with the IC50 values of 3.10×10−6 M and 3.76×10−6 M, respectively. TheKi values of1 and2 were 6.84×10−6 M and 5.13×10−6 M. They were less inhibitory to α-secretase (TACE) and other serine proteases such as chymotrypsin, trypsin, and elastase, suggesting that they were relatively specific inhibitors of BACE1.

Comparative study of antioxidant effects of five Korean varieties red pepper (Capsicum annuum L) extracts from various parts including placenta, stalk, and pericarp

Methanol extracts from the placenta, stalk, and pricarp of 5 Korean varieties red pepper (Capsicum annuum L) were obtained and antioxidant constituents including total phenol, total flavonoids, and capsaicin were analyzed. Antioxidant effects were determined by ABTS, DPPH, and nitric oxide (NO) free radicals scavenging activities and superoxide dismutase (SOD)-like activity. All the extracts showed strong antioxidant activities in various bioassays. Chromatic parameters (L*, a*, b*, C*, and Ho) were responsible for the antioxidant capacity of red pepper pericarp extracts. Generally, stalk been considered as disposable part, exhibited not only strong scavenging activities against free radicals, but also high content of total phenols, total flavonoids, and capsaicin. In addition, positive correlations were also observed between antioxidant activities and constituents of phenolics, flavonoids, and capsaicin. It was concluded that red pepper, including stalk, can be functional food materials to enhance human health.

Antioxidant capacities and cytostatic effect of Korean red pepper ( Capsicum annuum L): a screening and in vitro study

Methanol extracts from 100 Korean varieties of red pepper (Capsicum annuum L) were obtained. Chromatic parameters (L*, a*, and b*) and total phenolic content were analyzed. By evaluation of total phenolic content and 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging based-antioxidant associated with surface color measurement, red pepper varieties were classified into four groups by hierarchical cluster analysis. Cultivars of ‘PR-Sangsaeng’, ‘PR-Jijon’, ‘PREowoolrim’, ‘PR-Chambut’, ‘PAK37’, and ‘Hojanggoonbigalim” had high quantity of pigments and high phenolic content. These six cultivars also with higher levels of antioxidant might give an advantage to local growers in Korea. For further cytostatic activity evaluation, extracts from various parts including pericarp, seed, and stalk of cultivar ‘PAK37’ and ‘Hojanggoonbigalim’ were prepared. Four human cancer cells (HepG2, AGS, MCF-7, and HT-29) were used. The tumor cell growth inhibitory effect was evaluated by in vitro MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. High capsaicin content and antioxidant activity-containing red pepper stalk extract showed the strongest cytostatic activity. Tumor cell growth inhibitory activity was positively correlated with the capsaicin content. The anticancer potentials of various red pepper parts were in the following order: stalk > seed > pericarp. The data suggest that red pepper parts might have a promising health benefit against liver cancer, colon cancer and gastric cancer more than breast cancer.