Inhibitory Effects of (2′R)‐2′,3′‐dihydro‐2′‐(1‐hydroxy‐1‐methylethyl)‐2,6′‐bibenzofuran‐6,4′‐diol on Mushroom Tyrosinase and Melanogenesis in B16‐F10 Melanoma Cells

(2′R)‐2′,3′‐Dihydro‐2′‐(1‐hydroxy‐1‐methylethyl)‐2,6′‐bibenzofuran‐6,4′‐diol (DHMB) is a natural compound extracted from Morus notabilis. It was found that DHMB acts as a competitive inhibitor against mushroom tyrosinase with a Ki value of 14.77 μM. Docking results further indicated that it could form strong interactions with one copper ion with a distance of 2.7 Å, suggesting the mechanism of inhibition might be due to chelating copper ions in the active site. Furthermore, melanin production in B16‐F10 murine melanoma cells was significantly inhibited by DHMB in a concentration‐dependent manner without cytotoxicity. The results of western blotting also showed that DHMB decreased 3‐isobuty‐1‐methxlzanthine‐induced mature tyrosinase expression. Taken together, these findings indicated that DHMB may be a new promising pigmentation‐altering agent for agriculture, cosmetic, and therapeutic applications. Copyright © 2015 John Wiley & Sons, Ltd.     

桑白皮各化学拆分组分化学成分研究

目的：研究桑白皮各化学拆分组分的化学成分。方法：利用Diaion HP-20、Toyopearl HW-40、Sephadex LH-20、MCI Gel CHP-20、硅胶柱等柱色谱技术以及制备液相技术,对桑白皮化学拆分组分进行分离纯化,并根据其理化性质和光谱数据鉴定化合物的结构。结果：从桑白皮各拆分组分中共分离并鉴定了23个化合物的结构,其中从30%乙醇组分中分离得到16个单体化合物,分别为：香草酸（1）,3,4-二甲氧基苯酚（2）,苯甲酸（3）,丁香酸（4）,kelampayoside A（5）,对羟基苯丙酸（6）,咖啡酸（7）,氢化阿魏酸（8）,6,7-二羟基香豆素（9）,5,7-二羟基香豆素（10）,桑色素-7-O-β-D-葡萄糖苷（11）,liriodendrin（12）,2,3-反式二氢桑色素（13）,2,3-顺式二氢桑色素（14）,2,3-反式二氢槲皮素（15）,2,3-顺式二氢槲皮素（16）;从50%乙醇组分中分离得到4个单体化合物,分别为：东莨菪亭（17）,桑色素（18）,山奈酚-7-O-β-D-葡萄糖苷（19）,伞形花内酯（20）;从80%乙醇组分中分离得到3个单体化合物,分别为：桑根酮R（21）,cis-mulberroside A（22）,白藜芦醇（23）。结论：化合物2,4-6,11,16,19为首次从该植物中分离得到。     

A new coumarin and a new norlignan from Ficus tsiangii

Chemical investigation of the stem bark of Ficus tsiangii led to the isolation of a new coumarin ficuscoumarin (1) and a new norlignan ficuslignan (2) by chromatographic methods. Their structures were elucidated on the basis of spectroscopic analyses.     

Isoprenylated phenolic compounds with tyrosinase inhibition from Morus nigra

A new isoprenylated sanggenon-type flavanone, nigrasin K (1), together with three known analogs (2–4) and five known Diels–Alder adducts (5–9), were isolated from the twigs of Morus nigra. Their structures were elucidated by spectroscopic methods. Sanggenon M (2), chalcomoracin (5), sorocein H (6), kuwanon J (7), sanggenon C (8), and sanggenon O (9) showed significant inhibitory effects on mushroom tyrosinase.     

Inhibition of Sanggenon G Isolated from Morus alba on the Metastasis of Cancer Cell

Objective An organic layer prepared from the cortex of Morus alba (Moraceae) was studied in order to identify the active compounds for heparinase. Methods Bioassay-guided fractionation resulted in the isolation of sanggenon G. Results The compound showed inhibitory activity with IC50 of 3.7 μmol/L on heparinase in vitro as well as 24 μmol/L in invasion assay using MDA-MB231 cells. Sanggenon G also had the moderate cytotoxicity at SW 620 (colon) and ACHN (kidney) cancer cell lines with IC50 of 10.96 and 13.44 μmol/L, respectively. Conclusion This is the first time that prenylated flavonoid sanggenon G is described as heparinase inhibitor. Besides, this flavonoid would be expected to be a metastasis inhibitor of cancer cells and also a valuable reagent to explore the mechanism of heparinase/heparanase-mediated metastasis.     

Antibacterial and Anti-Biofilm Activity of Flavonoids and Triterpenes Isolated from the Extracts of Ficus Sansibarica Warb. Subsp. Sansibarica (Moraceae) Extracts

Background

Ficus species are used in African traditional medicine in the treatment of a wide variety of ailments and diseases such as convulsive disorder, wound healing, gonorrhea, tuberculosis, diabetes, diarrhoeal infections, dysentery, malaria and HIV. The aim of this study was to isolate the phytochemical constituents in the plant and test them for their antibacterial activity.

Materials and methods

The fruits, leaves and stem bark were extracted with organic solvents and the compounds in the extracts separated and purified by column chromatography before being identified by NMR spectroscopy and by comparison of the NMR data against values reported in the literature. The antibacterial activity of the pure compounds and extracts were tested using the disk diffusion method.

Results

Three triterpenes and three flavonoids: lupeol acetate (1); cycloart-23-ene-3,25-diol (2); β-sitosterol (3); 5,7,4′-trihydroxyflavan-3-ol (4); epicatechin (5); and isovitexin (6) were isolated in this study. Antimicrobial activity was observed at 8 mg mL⁻¹ for Staphylococcus aureus ATCC 29213 with four of the six isolated compounds, with no activity being observed at 1 – 4 mg mL⁻¹ against Escherichia coli ATCC 25922, E. coli ATCC 35218 and S. aureus ATCC 43300. Epicatechin (5) was found to decrease adhesion of E. coli ATCC 25922 and S. aureus ATCC 29213. Decreased adhesion of S. aureus ATCC 29213 was also observed with 5,7,4′-trihydroxyflavan-3-ol (4) and isovitexin (6).

Conclusions

The results of this study provide baseline information on F. sansibarica''s potential validity in the treatment of infections associated with Gram-positive microorganisms.     

Vitexin and isovitexin from the Leaves of Ficus deltoidea with in-vivo α-glucosidase inhibition

Ethnopharmacological relevance

The leaves of Ficus deltoidea are used as a traditional medicine by diabetes patients in Malaysia.

Aim of the study

The objective of the study is to identify and evaluate bioactive constituents with in vivo α-glucosidase inhibition.

Materials and Methods

The partitioned extracts, subfractions and pure bioactive constituents were subjected to α-glucosidase inhibition assay. The identified bioactive constituents were administered orally to sucrose loaded normoglycemic mice and induced diabetic rats. The postprandial blood glucose levels were monitored at 30 min interval. Acute toxicity was evaluated in both normoglycemic mice and induced diabetic rats.

Results

Bioactivity guided fractionation led to the isolation of both vitexin (1) and isovitexin (2). Oral administration of 1 mg/kg of either vitexin (1) or isovitexin (2) significantly (p<0.05) reduced the postprandial blood glucose level in sucrose loaded normoglycemic mice at 30 min. The percentage of postprandial blood glucose reduction was highest in sucrose loaded induced diabetic rats administered orally with 200 mg/kg of vitexin (1) or 100 mg/kg of isovitexin (2). Both vitexin (1) and isovitexin (2) did not exert any signs of toxicity at the highest dose of 2 g/kg administered orally to normoglycemic mice and induced diabetic rats.

Conclusion

Both the C-glycosyl bioflavonoids, namely, vitexin (1) and isovitexin (2) exhibited in vivo α-glucosidase inhibition.     

Melanin‐concentrating hormone‐1 receptor binding activity of pheophorbides isolated from morus alba leaves

The time‐resolved fluorescence technique based on melanin‐concentrating hormone (MCH) receptor subtype‐1 (MCH‐1 receptor) binding assay was adopted to carry out a bioassay‐guided fractionation of the methanol extract of Morus alba leaves. This fractionation and purification led to the isolation of two compounds identified as pheophorbide a methyl ester and 13²(S)‐hydroxypheophorbide a methyl ester. These active pheophorbides exhibited potent inhibitory activity in binding of europium‐labeled MCH to the human recombinant MCH‐1 receptor (IC₅₀ value; 4.03 and 0.33 ?M, respectively). Besides binding activity, the pheophorbides inhibited MCH‐mediated extracellular signal‐regulated kinase (ERK) phosphorylation in Chinese hamster ovary cells expressing human MCH‐1 receptor. These results suggest that pheophorbide a methyl ester and 13²(S)‐hydroxypheophorbide a methyl ester act as modulators of MCH‐1 receptor and MCH‐mediated ERK signaling. Copyright © 2009 John Wiley & Sons, Ltd.     

无花果果实中化学成分研究

目的研究桑科榕属植物无花果Ficus carica果实的化学成分。方法综合运用硅胶柱色谱、ODS柱色谱、Sephadex LH-20凝胶柱色谱以及制备型高效液相色谱等技术进行系统分离,根据化合物的理化性质及波谱数据鉴定化合物的化学结构。结果从无花果果实的90%乙醇提取物中分离得到了16个化合物,分别鉴定为怀特酮(1)、甘草宁G(2)、4′-羟基-5,7-二甲氧基-6-(3-甲基-丁烯基)-异黄酮(3)、猫尾草异黄酮(4)、indicanine C(5)、木豆素(6)、美迪紫檀素(7)、高丽槐素(8)、4-羟基-3-甲氧基-8,9-亚甲二氧基紫檀烷(9)、3-羟基-9,10-二甲氧基紫檀烷(10)、松脂素(11)、杜仲树脂酚(12)、丁香树脂醇(13)、8-羟基松脂醇(14)、3-羟基-1-(4-羟基-3-甲氧基苯)-1-丙酮(15)和4-羟基-3-甲氧基苯乙醇(16)。结论所有化合物均为首次从无花果中分离得到。