Biomedical subjects
Publications and source records attributed to P P But.
Two secoiridoid glucosides, lucidumosides A and B, as well as six known glucosides, oleoside dimethyl ester, ligustroside, oleuropein, nuezhenide, isonuezhenide, and neonuezhenide, were isolated from the fruits of Ligustrum lucidum. Their structures were elucidated by spectroscopic methods.
Two furanoditerpenoid lactones, were isolated from the seeds of Caesalpinia minax Hance. Their structures and stereochemistry have been established by spectral data and single crystal X-ray analysis.
A bioassay-guided study led to the isolation of five new cassane furanoditerpenes, designated as caesalmin C (1), D (2), E (3), F (4), and G (5), along with stigmasterol (6) from the seeds of Caesalpinia minax. The (1)H and (13)C NMR spectra were completely assigned by using a combination of 2D NMR analyses. The structures of all five furanoditerpenes were confirmed by X-ray analyses. The structure of 6 was verified by X-ray analysis for the first time. The bioassay results showed that the anti-Para3 virus activity of tetracyclic furanoditerpenoids 1-4 is more potent than that of the furanoditerpenoid lactone 5, which is in turn better than 6. As the major components of the plant possess significant potent activity, it may be feasible to develop new antiviral agents from this source.
The causal role of aristolochic acid (AA) in the so-called Chinese herbs nephropathy (CHN) has been conclusively demonstrated only in the Belgian epidemic. We report a biopsy-proven hypocellular interstitial fibrosing nephropathy in a Chinese patient who had ingested a Chinese herbal preparation bought in Shanghai. The identification of AA in the preparation and of AA-DNA adducts in the kidney tissue unequivocally demonstrates, for the first time, the causal role of AA outside the Belgian epidemic. Because the ingested preparation is very popular in China as an over-the-counter product, our observation raises the possibility that many such cases due to AA might be currently unrecognized in China. AA should be banned from herbal preparations worldwide. All cases of the so-called CHN, in which the causal role of AA has been thoroughly documented, should be further identified as aristolochic acid nephropathy (AAN). The term phytotherapy-associated interstitial nephritis (PAIN) might refer to the other cases associated with phytotherapy without identification, as yet, of the causal agent.
Herba Dendrobii (Shihu) is a commonly used Chinese medicine derived from the stem of several orchid species belonging to the genus Dendrobium. It is rather expensive and adulteration is frequent. Proper authentication of the medicinal species is necessary to protect consumers and support conservation measures. DNA sequences of the internal transcribed spacer 2 (ITS 2) of 16 Dendrobium species were shown to be significantly different from one another by an average of 12.4% and from non-orchids and Pholidota (an adulterant of Shihu) by 29.8% and 18.8%, respectively. The intra-specific variation among the Dendrobium species studied was only about 1%. Therefore, ITS 2 regions could be adopted as a molecular marker for differentiating medicinal Dendrobium species from one another and also from non-orchids and adulterants.
The method of direct amplification of length polymorphism (DALP) was applied to authenticate Panax ginseng and P. quinquefolius. A 636-bp DALP fragment was present in all P. ginseng but absent in all the P. quinquefolius cultivars examined. We have shown that the use of DALP and conversion of specific polymorphic band to sequence-tagged site (STS) for quick authentication may be applied to authenticate related medicinal materials.
A 420-bp RAPD fragment from Panax quinquefolius was converted to a sequence characterized amplified region (SCAR) marker. The main difference between the SCAR of P. quinquefolius and its homolog in P. ginseng is the presence of a 25 bp insertion in the latter. Primers derived from this sequence were successfully used to authenticate six Panax species and two common adulterants.
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Amentoflavone and three other flavonoids were isolated from the ethanol extract of Selaginella sinensis. Amentoflavone showed potent antiviral activity against respiratory syncytial virus (RSV), with an IC50 of 5.5 microg/ml. The contents of amentoflavone in nine species of Selaginella were determined by reversed-phase HPLC. S. sinensis showed a higher content of 1.13%.
Mikanin-3-O-sulfate (1), in the form of its potassium salt, together with mikanin (2) and alpinetin (3) were isolated from Mikania micrantha. The crystal structures of K(1) x CH3OH, 2 and 3 x H2O were established by X-ray crystallography. The potassium ions in K(1) x CHO3H are bridged by O5, O7 and O8 to form a chain of face-sharing KO8 coordination polyhedra, from which the aglycon units are outstretched to form a polymeric molecular column. Adjacent molecular columns are linked by pi-pi stacking between parallel, intercalating aglycon units to form layers matching the (101) family of planes, which are further interconnected into a three-dimensional supramolecular assembly. Sulfation at 3-OH induced better co-planarity and conjugation of the rings.
Six secoiridoid glucosides, lucidumoside C (1), oleoside dimethylester (2), neonuezhenide (3), oleuropein (4), ligustroside (5) and lucidumoside A (6), isolated from the fruits of Ligustrum lucidum (Oleaceae), were examined in vitro for their activities against four strains of pathogenic viruses, namely herpes simplex type I virus (HSV-1), influenza type A virus (Flu A), respiratory syncytial virus (RSV) and parainfluenza type 3 virus (Para 3). Antiviral activities were evaluated by the cytopathic effect (CPE) inhibitory assay. The purpose was to check if the antioxidative potency of these glucosides correlated with their antiviral potency. Results showed that none of the glucosides had any significant activity against HSV-1 and Flu A. Oleuropein, however, showed significant antiviral activities against RSV and Para 3 with IC50 value of 23.4 and 11.7 microg/ml, respectively. Lucidumoside C, oleoside dimethylester and ligustroside showed potent or moderate antiviral activities against Para 3 with IC50 values of 15.6-20.8 microg/ml. These results also documented that the anti-oxidative potency of these secoiriodoid glucosides was not directly related to their antiviral effects.
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Methanolic extract and two purified compounds (brazilin and hematoxylin) from Caesalpinia sappan were examined for their relaxant effects in isolated rat thoracic aorta. The methanolic extract significantly and dose-dependently relaxed the alpha1-receptor agonist phenylephrine-precontracted aortic rings, without affecting passive tension of these vessels. Removal of the vascular endothelium, inhibition of nitric oxide (NO) synthase with 0.1 mM Nomega-nitro-L-arginine and of cGMP biosynthesis with 10 microM methylene blue abolished the vasorelaxant effects of the herbal extract at doses up to 30 microg/ml. Similar vasorelaxant effects were observed with brazilin and hematoxylin. Therefore, these results suggest that brazilin and hematoxylin may be responsible for the vascular relaxant effects of C. sappan, via endogenous NO and subsequent cGMP formation. The vascular relaxant effects of the plant may contribute to its therapeutic actions.
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An LC/MS-based method is established for the differentiation and authentication of specimens and commercial samples of Panax ginseng (Oriental ginseng) and Panax quinquefolius (American ginseng). This method is based on the separation of ginsenosides present in the ginseng methanolic extracts using high-performance liquid chromatography (HPLC), followed by detection with electrospray mass spectrometry. Differentiation of ginsenosides is achieved through simultaneous detection of intact ginsenoside molecular ions and the ions of their characteristic thermal degradation products. An important parameter used for differentiating P. ginseng and P. quinquefolius is the presence of ginsenoside Rf and 24-(R)-pseudoginsenoside F11 in the RICs of Oriental and American ginsengs, respectively. It is important to stress that ginsenoside Rf and 24(R)-pseudoginsenoside F11, which possess the same molecular weight and were found to have similar retention times under most LC conditions, can be unambiguously distinguished in the present HPLC/MS method. The method developed is robust, reliable, reproducible, and highly sensitive down to the nanogram level.
Chinese traditional medicine is used extensively in Chinese populations, and other Asian countries employ similar therapies. Herbal treatments have a major role in these systems, and although most have a well-established safety record, occasional adverse effects are seen. Problems arise when toxic herbs are used in excessive doses, with improper preparation, or when they are substituted erroneously. There may also be adulteration with Western drugs or heavy metals, and interactions between herbs and Western drugs may also occur. It is always prudent to obtain a complete history of the use of herbal medications during any clinical assessment, particularly in Asian patients.
Twenty-nine flavonoids and six hydrolyzable tannins were studied for their inhibitory activity against human immunodeficiency virus (HIV)-1 protease using fluorescence and HPLC assays. Among the flavonoids, flavones, flavanones, flavonols, catechols and chalcones, the flavonols were the most active category while flavanones and catechols displayed low activity. Quercetin was the most potent inhibitor of the target enzyme with an IC50 value of 58.8 microM, while butein and luteolin showed moderate activity. Of the hydrolyzable tannins tested, three ellagitannins which contain a hexahydroxvdiphenoyl (HHDP) unit linked to the O-3 and 0-6 positions of the sugar, were found to strongly inhibit HIV-1 protease. The IC50 values of corilagin and repandusinic acid on HIV-1 protease were 20.7 and 12.5 microM, respectively.
A new cytotoxic polyhydroxysterol, 23,24-dimethylcholest-16(17)-E-en-3beta,5alpha,6beta,2 0(S)-tetraol (2), together with nine known compounds was isolated from the soft coral Sarcophyton trocheliophorum. Their structures were determined by spectroscopic methods. Compound 2 showed potent growth inhibitory activity against human HL60 leukemia, M14 skin melanoma, and MCF7 breast carcinoma cells with EC50 values of 2.8, 4.3, and 4.9 microg/ml, respectively, and exhibited minimal toxicity to normal human peripheral blood lymphocytes.