PMC

¹H-NMR spectra of water extract of healthy C. roseus leaves (A) and phytoplasma (UDINESE)-infected C. roseus leaves (B) in the range of δ 6.0 to δ 8.0, and HMBC spectra of water fraction of phytoplasma (UDINESE)-infected (C) C. roseus leaves. In ¹H-NMR spectra (A and B): 1, H-7′ of chlorogenic acid; 2 and 3, H-3 of secologanin; 4, H-2′ of chlorogenic acid; 5, H-6′ of chlorogenic acid; 6, H-3 of loganic acid; 7, H-5′ of chlorogenic acid and aromatic signals of polyphenols; 8, fumaric acid; 9, H-8′ of chlorogenic acid; ^*, possible signals of chlorogenic acid derivatives. In HMBC spectra (C): 1, correlation of H-3 and C-5 of secologanin; 2, correlation of H-3 and C-1 of secologanin; 3, correlation of H-3 and C-4 of secologanin; 4, correlation of H-3 and carbonyl group of secologanin; 5, correlation of H-7′ and C-2′ of chlorogenic acid; 6, correlation of H-7′ and C-6′ of chlorogenic acid; 7, correlation of H-7′ and carbonyl group of chlorogenic acid; 8, correlation of H-3 and C-5 of loganic acid; 9, correlation of H-3 and C-1 of loganic acid; 10, correlation of H-3 and C-4 of loganic acid; 11, correlation of correlation of H-3 and carbonyl group of loganic acid; 12, correlation of H-2′ and C-1′ of chlorogenic acid; 13, correlation of H-2′ and C-3′; 14, correlation of H-2 and C-1 of gallic acid derivatives; 15, correlation of H-2 and C-3 of gallic acid derivatives; 16, correlation of H-2 and carbonyl group of fumaric acid; 17, correlation of H-8′ and C-1′ of chlorogenic acid; 18, correlation of H-8′ and carbonyl group of chlorogenic acid.

HPLC analysis. The HPLC profiles (a), (b), and (c) represent the identification of chlorogenic acid in water, methanolic and 70% ethanolic extracts from Flos Lonicerae respectively. The HPLC profile (d) represents purified chlorogenic acid from 70% ethanolic extract with HPLC. There are several contaminant constituents in the prepared chlorogenic acid fraction around chlorogenic acid peak which are caused by manual collection during purification. The peaks labelled with CGA are chlorogenic acid because the retention time was identical with that of chlorogenic acid standard (e) (13.97 min). Ten micrograms the samples (a), (b), (c), (d) were respectively loaded into the HPLC system except chlorogenic acid standard (5 μg)

A) Alignment of docked structures of chlorogenic acid on X-ray reference structure of A_2A receptor binding pocket. B) Pocket of A_2A receptor occupied by chlorogenic acid.

Expression of occludin, claudin-5, and ZO-1 with Western blot analysis. Occludin expression was decreased in diabetic rats, and restored with chlorogenic acid administration. Claudin-5 was decreased in diabetic rats, but did not increase to significant levels with chlorogenic acid administration. ZO-1 decreased in diabetic rats, but showed no change with chlorogenic acid administration. ^*P < 0.05 compared with control, ^†P < 0.05 compared with STZ. STZ, streptozotocin; CGA10, chlorogenic acid 10 mg/kg; CGA20, chlorogenic acid 20 mg/kg.