C21 steroids from the roots of Marsdenia tenacissima.

A phytochemical investigation of the dichloromethane soluble fraction of the ethanolic extract obtained from the roots of Marsdenia tenacissima led to the discovery of the sixteen undescribed pregnane C21 steroids (1-16) and isolation of eleven known C21 steroidal analogues (17-27). Their chemical structures were elucidated by one- and two-dimensional nuclear magnetic resonance spectroscopy and, high resolution-electrospray ionization mass spectrometry and their absolute configurations were determined using electronic circular dichroism or single-crystal X-ray diffraction. The in vitro anti-proliferative effects of 1-16 were evaluated against HepG2 (human hepatocellular cancer), A549 (lung cancer), and MCF-7 (human breast cancer) cell lines. Even though some of them showed moderate cytotoxic activities, marsectohexol derivative 12 exhibited significant cytotoxicity against A549 cells with an IC50 value of 5.2 µM.

[Separation and authentication of tilianin and quality standards of semen of Dracocephalum moldavia].

Tilianin was separated and authenticated from the seeds of Dracocephalum moldavia, a Uygur medicine, by chromatographic technique and spectroscopic method. The purity of tilianin is more than 98% determined by HPLC area normalization method. Thin layer chromatography (TLC) method was used to separate tilianin from D. moldavia by mixture of chloroform-methanol (5: 1) as a developing solvent on high performance silicagel precoated plate (SGF254) and using aluminium trichloride as a chromogenic agent for qualitative identification of D. moldavia. To establish a HPLC method for quantitative analysis of D. moldavia, tilianin was used as a Quantitative marker and separated on a C18 (4.6 mm x 250 mm, 5 µm) column with acetonitrile-01% formic acid (25: 75) as the mobile phase and detected at 330 nm. The calibration curve of tilianin displayed ideal linearity over the range of 0.617 2-123.44 µg x mL(-1) with a regression equation of Y = 33.773X - 0.824 8 (r = 1). The average recovery of tilianin was 101.0% with RSD of 3.7%. The RSD values of intra-day and inter-day precision were less than 2%. The content of tilianin in 4 batches of the authenticated semen of D. Moldavia was between 0.016 and 0.187 mg x g(-1). The qualitative and quantitative method established is suitable for the quality evaluation and assessment of semen of D. Moldavia.

Screening of Chinese herbal medicines for antityrosinase activity in a cell free system and B16 cells.

AIM OF THE STUDY: Tyrosinase inhibitors are becoming increasingly important in controlling skin hyperpigmentation. We aimed to screen 50 extracts from traditional Chinese medicines (TCM) for tyrosinase activity-inhibiting agents. MATERIALS AND METHODS: The 50 herbal extracts were prepared from 32 herbs and 18 TCM formulas, which are used as folk skin whiteners in China and have not been investigated for their skin-whitening mechanisms. Each herb and formula was extracted with 30% ethanol and water, respectively, and followed by column chromatography for isolating bioactive substances such as saponins, flavonoids and alkaloids for the antityrosinase activity study. Every extract was tested using the cell free mushroom tyrosinase inhibitory assay at 2 mg/ml for the single herb extracts and 1mg/ml for formula extracts. Extracts showing greater than 50% inhibition against mushroom tyrosinase activity were further examined by cellular tyrosinase assay in mouse B16 cells. The cytotoxicity in B16 cells was measured by methyl thiazolyl tetrazolium bromide (MTT) assay. RESULTS: In the cell-free assay, 10 out of the 50 extracts demonstrated more than 50% inhibition against mushroom tyrosinase activity. These 10 extracts were further assessed by cellular tyrosinase assay, and 6 showed>50% inhibition with IC(50) values <1 mg/ml. The 6 extracts are from 3 herbs namely Ampelopsis japonica, Lindera aggregata, and Polygonatum odoratum, and 3 formulas namely Qian-wang-hong-bai-san, Qiong-yu-gao, and San-bai-tang. As compared with vitamin C, these 6 extracts showed similar or greater ratio of cell growth IC(50) to cellular tyrosinase IC(50). As compared with arbutin, extract from Ampelopsis japonica, Lindera aggregata, Qian-wang-hong-bai-san, or San-bai-tang had a similar, although extract from Polygonatum odoratum or Qiong-yu-gao had a greater, IC(50) value against murine tyrosinase activity. CONCLUSIONS: From the screening assays we identified three Chinese medicinal herbs and three TCM formulas that have appreciable antityrosinase activity. Further studies are warranted to develop them as skin-whitening agents with convenient dosage forms or to identify active constituents from the extracts as useful leads for the development of skin whiteners.