| The chemical constituents of both Pogostemon cablin (Blanco.) Benth. and Dendrobium aurantiacum Rchb.f. var. denneanum (Kerr.) Z. H. Tsi have been reported in this dissertation. A total of thirty-two compounds including sixteen new ones and two new natural products have been isolated and identified.Pogostemon cablin (Blanco.) Benth., a member of genus Pogostemon (Lamiaceae), has been used as Chinese herbal medicine to remove dampness, relieve summer-heat, exterior syndrome, stop vomiting and stimulate the appetite. In addition to being used in prescription, P. cablin is also an important material of more than forty Chinese patent medicines. For discovering more functional substances, we studied the chemical constituents of the essential oil of P. cablin systematically. Sixteen sesquiterpenoids including two patchoulol (1,2#), four nor-β-patchoulene (3*-6#), two caryolane (7,8*),four zizaane (9*-12*), three guaiane (13*-15*) and one cyperane (16*) compounds have been isolated and identified.By means of spectroscopic and chemical methods, twelve new compounds named 14-mor-β-patchoul-1 (5)-ene-2,4-dione (3*),2β-methoxy-14-nor-β-patchoul-1 (5)-ene-4-one (4*),14-nor-β-patchoul-1(5),2-diene-4-one (5*),1-methoxy-senecrassidiol (8*), 4β-methoxyzizaane-5-ene-2α-ol (9*),13-methoxyzizaane-5-ene-2a-ol (10*),2a-hydroxyzizaane-5-ene-6-al (11*),12,12-dimethoxyzizaane-2,5-diene-4-one (12*), guaia-1(10),3,11-triene-2-one (13*), la,10a-epoxyguaia-4,11-diene-3-one (14*), guaia-1,10(15),11-triene-9a-ol (15*) and 4-oxocyperan-6-ene-3a-ol (16*), together with two new natural products named (±)-patchouli alcohol methyl ether (2*) and 14-nor-β-Patchoul-1(5)-ene -4-one (6#), and two known compounds patchouli alcohol (1) and senecrassidiol (7) were determined.In in vitro bioassays, the new compound 5* showed weak cytotoxic activities against NCI-H1975 and HePG-2 with IC50 values of 49.9 mg/mL and 56.0 mg/mL respectively, while the ICso value of compound 6# against acute myeloid leukemia cell line MV4-11 was 56.0 mg/mL.In China, D. aurantiacum var. denneanum, which belongs to the genus Dendrobium (Orchidaceae), is mainly distributed and cultivated in Taiwan, Hainan, Guangxi, Yunnan and Guizhou province. It has been used in traditional Chinese medicine for recovery of gastric motility and promoting gastric acid secretion in the stomach, as well as promoting secretion of saliva, improving eyesight, and reducing fever. In the course of searching for more bioactive natural products from D. aurantiacum var. Denneanum, the 95% ethanol extract of the stems was systematically investigated to afford sixteen compounds, including eleven lignan glycosides (1*-11), four phenylpropanoid glycosides (12-15) and one flavone C-glycoside (16).The compounds were elucidated as (-)-(7S,8R,7’E)-4-hydroxy-3,3’,5,5’-tetramethoxy-8,4’-oxyneolign-7’-ene-7,9,9’-triol 7,9’-bis-O-β-D-glucopyranoside (1*), (ï¼)-(8R,7’E)-4-hydroxy-3,3’,5,5’-tetramethoxy-8,4’-oxyneolign-7’-ene-9,9’-diol 4,9-bis-O-β-D-glucopyranoside (2*), (-)-(8S;7’E)-4-hydroxy-3,3’,5,5’-tetramethoxy-8,4’-oxyneolign-7’-ene-9,9’-diol 4,9-bis-O-β-D-glucopyranoside (3*), (-)-(8R,7’E)-4-hydroxy-3,3’,5,5’,9’-pentamethoxy-8,4’-oxyneolign-7’-ene-9-ol 4,9-bis-O-β-D-glucopyranoside (4*), picraquassioside C (5), (±)-5,5’-dimethoxylariciresinol 4’-O-β-D-glucopyranoside (6), lariciresion-4’-O-β-D-glucoside (7), mangliesides E (8), (-)-syringaresinol-4,4’-bis-O-β-D-glucopyranoside (9), syringaresinol-4’-O-β-D-glucopyranoside (10), (-)-secoisolariciresinol 4-O-β-D-glucopyranoside (11), shashenoside I (12), syringin (13),4-(β-D-glucopyranosyloxy)-3,5-dimethoxyphenyl-propanone (14),2’-O-β-D-glucosylrosine (15), and vicenin-2 (16). 1*-4* were new compounds.In the in vitro screenings of pure compounds, compound 1* and 9 showed evident activity against glutamate-induced neurotoxicity in PC 12 cells, with the relative protection of 25.7±2.2% and 19.3±5.6% at a concentration of 10 10μM, respectively. Compound 12 showed a selective cytotoxic activity with the IC50 value of 4.17 μM against the acute myeloid leukemia cell line MV4-11. |
