New sugar-mimic alkaloids from the pods of Angylocalyx pynaertii

Chromatographic separation of the pod extract of Angylocalyx pynaertii resulted in the isolation of 13 sugar-mimic alkaloids (1-13). The structures of the new alkaloids were elucidated by spectroscopic methods as the 6-O-beta-D-glucoside (10) and N-hydroxyethyl derivative (11) of 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) (1), 1,6-dideoxynojirimycin (12), and 1,3,4-trideoxynojirimycin (13). 2,5-Imino-1,2,5-trideoxy-L-glucitol (7), 2,5-dideoxy-2,5-imino-D-fucitol (8), and beta-homofuconojirimycin (9), isolated from the pods as well as the bark, were very specific inhibitors of alpha-L-fucosidase with no significant inhibitory activity toward other glycosidases. In this work, 1,4-dideoxy-1,4-imino-D-ribitol (6) was found to be a better inhibitor of lysosomal beta-mannosidase than 2,5-imino-1,2,5-trideoxy-D-mannitol (2). N-Hydroxyethyl-1-deoxynojirimycin (miglitol), which is commercially available for the treatment of diabetes, retained its inhibitory potential toward rat intestinal maltase and sucrase, whereas 11 and the synthetic N-hydroxyethyl derivative of 2,5-dideoxy-2,5-imino-D-mannitol markedly lowered or abolished their inhibition toward all enzymes tested.     

A cytotoxic and antifungal 1,4-naphthoquinone and related compounds from a New Zealand brown algae, Landsburgia quercifolia.

The bioactivity-directed isolation of deoxylapachol [I] from a New Zealand brown alga, Landsburgia quercifolia, is described. Compound I was active against P-388 leukemia cells (IC50 0.6 microgm/ml) and was also antifungal. 1,4-Dimethoxy-2-(3-methyl-2-butenyl)-naphthalene [3] was the major low polarity component of extracts of this seaweed, which also contained 2,3-dihydro-2,2-bis(3-methyl-2-butenyl)-1,4-naphthalenedione [6] and 2-(3-methyl-2-butenyl)-2,3-epoxy- 1,4-naphthalenedione 4,4-dimethoxy ketal [7]. Compound 7 was converted to the 2,3-epoxide of I, which had biological activities similar to those of I.     

长穗桑中的α-葡萄糖苷酶抑制剂成分研究

 目的 研究长穗桑中具有α-葡萄糖苷酶抑制活性的化学成分。方法 采用各种离子交换树脂对长穗桑水提取物进行分离纯化,通过NMR、MS等波谱分析手段鉴定化合物结构。结果 从长穗桑水提取物中分离到11个化合物,其中7个多羟基生物碱类化合物,2个酰胺类化合物,1个氨基酸以及甜菜碱。分别鉴定为1-deoxynojirimycin (1),fagomine (2),3-epi-fagomine (3),1,4-dideoxy-1,4-imino-D-arabinitol (4),2-O-α-D-galactopyranosyl-1-deoxynojirimycin (5),4-O-β-D-glucopyranosyl-fagomine (6),1,4-dideoxy-1,4-imino-(2-O-β-D-glucopyranosyl)-D-arabinitol (7),(2S)-citrullinamide (8),grateloupinamide (9),天冬氨酸(10),甜菜碱(11)。化合物1~10分别进行了α-葡萄糖苷酶抑制活性筛选。结论 化合物1~11均为首次从该植物中分离得到。4个多羟基生物碱(1,5~7)以及1个酰胺类化合物(9)有较强的α-葡萄糖苷酶抑制活性,其中化合物1的IC₅₀为0.07 μmol·L^-1;化合物5的IC₅₀为0.39 μmol·L^-1,与阳性对照阿卡波糖(acarbose,IC₅₀=0.52 μmol·L^-1)相当;化合物6,7,9的IC₅₀值在1~5 μmol·L^-1。     

Iminosugar-producing Thai medicinal plants

Alpha-1-C-hydroxymethylfagomine (7), 3-O-beta-D-glucopyranosyl-DMDP (12), and 2,5-dideoxy-2,5-imino-D-glucitol (13) were isolated from the Thai traditional crude drug "Non tai yak" (Stemona tuberosa), which also contains a high concentration level of alpha-homonojirimycin (0.1% dry weight). "Thopthaep" (Connarus ferrugineus) and "Cha em thai" (Albizia myriophylla) contained 1-deoxymannojirimycin (DMJ) (10) at levels of 0.083% (dry weight) and 0.17% (dry weight), respectively. 2-O-alpha-D-Galactopyranosyl-DMJ (20), 3-O-beta-D-glucopyranosyl-DMJ (21), 1,4-dideoxymannojirimycin (17), 1,4-dideoxyallonojirimycin (18), and 1,4-dideoxyaltronojirimycin (19) from C. ferrugineus and 2-O-beta-D-glucopyranosyl-DMJ (22) and 4-O-beta-D-glucopyranosyl-DMJ (23) from A. myriophylla were isolated as new compounds.     

Variation in antibacterial and anti-inflammatory activity of different growth forms of Malva parviflora and evidence for synergism of the anti-inflammatory compounds

Malva parviflora leaves and roots were collected from five sites within the Qacha's Nek District in Lesotho. These plants had two distinct growth forms--upright and prostrate. Hexane, methanol and water extracts were made from the plant material and tested for antibacterial and anti-inflammatory activity using the disc diffusion and cyclooxygenase-1 (Cox-1) bioassays, respectively. Hexane, methanol and water extracts made from Malva parviflora with a prostrate growth form inhibited the growth of Gram-positive and Gram-negative bacteria, while extracts made from plants with an upright growth form inhibited the growth of Gram-positive bacteria only. Cox-1 anti-inflammatory activity of hexane, methanol and water extracts did not show any variation between the two growth forms. The hexane extracts of both the leaves and roots were the most inhibitory. The water extracts had the least inhibitory activity. Bioassay-guided fractionation of the root dichloromethane extract showed that Cox-1 anti-inflammatory activity was caused by at least two compounds that acted synergistically to produce the biological effect.     

Manadosterols A and B, Sulfonated Sterol Dimers Inhibiting the Ubc13-Uev1A Interaction, Isolated from the Marine Sponge Lissodendryx fibrosa

Two new dimeric sterols, manadosterols A (1) and B (2), were isolated from the marine sponge Lissodendryx fibrosa collected in Indonesia. The two compounds are comprised of two sulfonated sterol cores connected through the respective side chains. Manadosterols A (1) and B (2) inhibited the Ubc13-Uev1A interaction with IC(50) values of 0.09 and 0.13 μM, respectively. They are the second and third natural compounds showing inhibitory activities against the Ubc13-Uev1A interaction and are more potent than leucettamol A (IC(50), 106 μM), the first such inhibitor, isolated from another marine sponge.     

New butenolides from two marine streptomycetes

Chemical examination of two marine Streptomycetes has resulted in the isolation of four new butenolides, namely 4, 10-dihydroxy-10-methyl-dodec-2-en-1,4-olide (1), two diastereomeric 4,11-dihydroxy-10-methyl-dodec-2-en-1,4-olides (2/3), and 4-hydroxy-10-methyl-11-oxo-dodec-2-en-1,4-olide (4). The structures were identified by interpretation of the 2D NMR and mass spectral data.     

Trisphaerolide A,a novel polyketide from the Dominican sponge Erylus trisphaerus

The structure of trisphaerolide A (1), a mildly cytotoxic metabolite isolated from extracts of the marine sponge Erylus trisphaerus collected in Dominica, has been elucidated by detailed analysis of spectroscopic data. Trisphaerolide A (1) has a putative polyketide biogenesis, incorporating a rare variant on the standard pathway, which involves the addition of methyl branches arising from C-2 carbons of acetate units to chain carbons that arise from C-1 of acetate units.     

Pharmacological and phytochemical screening of two Hyacinthaceae species: Scilla natalensis and Ledebouria ovatifolia

Aqueous, ethanolic, dichloromethane and n-hexane extracts of Scilla natalensis Planch. and Ledebouria ovatifolia (Bak.) Jessop bulbs (Hyacinthaceae) were screened for antibacterial, anti-inflammatory, antischistosomic, anticancer and anthelmintic activity. Poor antibacterial activity against both Gram-positive and Gram-negative bacteria was shown with S. natalensis extracts. Good antibacterial activity was shown by the ethanolic and dichloromethane extracts of L. ovatifolia against Gram-positive bacteria. In the anti-inflammatory screening, the dichloromethane and hexane extracts of S. natalensis resulted in good inhibition against both COX-1 and COX-2. Ethanolic extracts had the highest inhibitory effect against nematodes in the anthelmintic assays. Poor anti-inflammatory and anthelmintic activity was found with L. ovatifolia. Aqueous extracts of S. natalensis had good activity against Schistosoma haematobium, with a minimum inhibitory concentration of 0.4 mg ml(-1). Aqueous extracts of fresh L. ovatifolia bulb material were found to be lethal to S. haematobium at a concentration of 1.6 mg ml(-1). The phytochemical screening of S. natalensis bulbs revealed the presence of saponins and bufadienolides within the bulbs. Bulbs of L. ovatifolia contained bufadienolides.     

大黄和生首乌鞣质含量对小鼠小肠推进的影响

目的研究大黄和生首乌70%乙醇提取物中鞣质含量对小鼠在体小肠推进的影响。方法用紫外分光光法测定浸膏中鞣质含量,小鼠小肠炭末推进法测定大黄及生首乌醇提物去除鞣质前后小肠的推进率。结果大黄和生首乌醇提物对小鼠小肠炭末的推进无明显影响,但去除鞣质后则呈现明显的促进作用。结论鞣质的存在明显抑制了小鼠小肠炭末的推进率,且其含量与抑制的强度呈正相关。