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C H He

Publications and source records attributed to C H He.

At least 37 records · Page 2Linked to original sources
PubMed1991

[The structure and absolute configuration of isorupestonic acid from Artemisia rupestris L].

A new sesquiterpene compound named isorupestonic acid was isolated from Artemisia rupestris and its absolute stereostructure was elucidated as 3B by spectral and X-ray crystallographic methods. Interestingly, the isorupestonic acid is based upon an unusual 6, 7 membered ring skeleton differing from the 5, 7 membered ring rupestonic acid although both have the same absolute configuration at C-1. The biogenesis of isorupestonic acid most likely involves breaking the C4-C5 bond of rupestonic skeleton and forming the C5-C14 bond. The absolute configuration of rupestonic acid was also determined as 4C by X-ray analysis and CD data.

Azulenes↗
PubMed1990

Comparative cross-over pharmacokinetic study on two types of postcoital contraceptive tablets containing levonorgestrel.

A pharmaceutical and pharmacokinetic study was carried out on levonorgestrel tablets from two different sources (Hungarian- and Chinese-made). Both preparations contained 0.75 mg levonorgestrel and had been shown to have similar contraceptive efficacy and side effects when used for postcoital contraception. Absorption and bioavailability of the Hungarian-made tablets were greater as evidenced by higher serum concentrations of levonorgestrel, a greater area under the concentration-time curve during the first 24 hours, and a more marked suppressive effect on SHBG levels. These differences most probably reflect differences in their pharmaceutical formulation, in particular the extent of tablet dissolution and the degree of micronisation of levonorgestrel.

Absorption↗
PubMed1990

[Structure of pingbeimine C].

A new C-nor-D-homosteroid alkaloid, C27H43O6N, mp 171.5-173 degrees C, named pingbeimine C, was isolated from the bulb of Fritillaria ussuriensis Maxim. On the basis of IR, MS, 1HNMR and 13CNMR spectroscopic data, particularly X-ray crystallographic analysis, structure IV has been assigned to this alkaloid.

Alkaloids↗
PubMed1990

[Chemical constituents of Armillaria mellea mycelium. VI. Isolation and structure of armillaripin].

A new protoilludane sesquiterpenoid aromatic ester, named armillaripin, C24H30O6, mp 202-204 degrees C, [alpha]D15 + 130 degrees (c 0.055, CHCl3), was isolated from the petroleum ether extract of the artificially cultured mycelium of Armillaria mellea (Vahl. ex Fr.) Quel. (Tricolometaceae) by silica gel chromatography. On the basis of spectral (UV, IR, 1HNMR 13CNMR and MS) analysis its structure was deduced as I and confirmed by single-crystal X-ray analysis.

Agaricales↗
PubMed1989

Pharmacokinetic study of orally administered RU 486 in non-pregnant women.

A method based on HPLC was devised for the estimation of RU 486 in blood and utilised to study the pharmacokinetics of a single dose of 50 mg RU 486 administered orally to 12 women on day 7 of the cycle. The dose was rapidly absorbed with peak plasma concentration between 1 and 2 hours. Distribution was also rapid (mean t1/2 alpha: 1.4h), whereas elimination was slow (mean t1/2 beta: 28.3 h). RU 486 was still detectable in some women at 72 h after administration. The plasma concentrations fitted the equation for a two-compartment open model from which the pharmacokinetic parameters were calculated. The mean total plasma clearance was 3.0 l/h, and the comparison of our data with those published studies suggests that the pharmacokinetics of RU 486 in Chinese women are similar to those of other populations.

Administration, Oral↗
PubMed1989

[Studies on the chemical constituents of Curcuma kwangsiensis].

A new sesquiterpene lactone named gweicurculactone, along with beta-sitosterol, germacrone, daucosterin and palmitic acid, was isolated from Curcuma kwangsiensis. Its structure has been confirmed by means of spectral and X-ray diffraction analysis.

Azulenes↗
PubMed1989

[Coetsoidin A, a new diterpenoid from Rabdosia coetsoides C. Y. Wu].

From the leaves of Rabdosia coetsoides C. Y. Wu, a new diterpenoid, coetsoidin A (I) was isolated and its structure was established by spectroscopic and X-ray diffraction analysis. It is the first instance of a kaurene type diterpenoid possessing alpha,beta-unsaturated ketone functionality in ring B.

Chemical Phenomena↗
PubMed1989

[Chemical studies of flower buds of Tussilago farfara L].

We have studied the flower buds of Tussilago farfara L. collected from Yulin county Shaanxi Province and have isolated a new terpenoid compound I with the composition C23H34O5, M+ 390.2416, mp 100-101 degrees C. On basis of physical and chemical properties and spectroscopic analysis (UV, IR, 1HNMR, 13CNMR, 1H-1H-COSY, 13C-1H-COSY DEPT, EI-MS, FAB-MS, HR-MS) and X-ray, the structure of I has been elucidated as a novel sesquiterpenoid compound, which is named farfaratin.

Chemical Phenomena↗
PubMed1989

[The structure of versicolactone D].

The extracts of Aristolochia versicolar S.M. Huang root afforded a new dimeric sesquiterpene lactone, versicolactone D, with a novel skeleton. Its structure was established by spectroscopic methods, mainly X-ray and 2D-NMR.

Chemical Phenomena↗
PubMed1989

[Studies on the chemical constituents of the root of Desmos cochinchinensis Lour].

Desmos cochinchinensis as a folk medicine is used for treatment of malaria in China. Pharmacological studies showed that the petroleum ether extract of the root of the plant exhibited anti-malarial activity. Three flavonoids were isolated from this extract, of which two were identified as lawinal and isounonal. Compound III is a new flavanol. On the basis of spectroscopic analyses (UV, IR, MS, 1HNMR, 13CNMR and X-RD) the structure was established as 4,7-dihydroxyl-5-methoxyl-6-methyl-8-formyl-flavan. I and II were found from this plant for the first time.

Antimalarials↗
PubMed1989

[The isolation and structure identification of triptotriterpenic acid C].

A new ursolic-type acid named triptotriterpenic acid C was obtained from the total glycosides extracted from the root of Tripterygium wilfordii Hook.f. Its structure was inferred from chemical reaction, IR, 1HNMR, 13CNMR and MS spectral data. The structure and stereochemistry of this compound was confirmed to be 3 beta,22 alpha-dihydroxy-delta 12-ursene-30-oic acid by X-ray crystallo-diffraction analysis of its methyl ester.

Chemical Phenomena↗
PubMed1989

[Studies on the chemical constituents of Aquilaria sinensis (Lour) Gilg. III. Elucidation of the structure of isobaimuxinol and isolation and identification of the constituents of lower boiling fraction of the volatile oil].

A new sesquiterpenoid, named isobaimuxinol, C15H26O2, mp 73-75 degrees C, [a]D12-68(0) (c 0.10, CHCl3), was isolated from the volatile oil of Aquilaria sinensis (Lour), Gilg. (Thymeleaceae). Based on spectral (IR, 1H-NMR, 13C-NMR and 2D-NMR as well as MS) analysis its structure was identified as isobaimuxinol. The relative stereochemistry of isobaimuxinol was determined by X-ray crystallograhy. In addition, four known compounds, benzylacetone, p-methoxybenzylacetone, anisic acid and beta-agarofuran were isolated and identified from the lower boiling fraction of the volatile oil of this plant. These compounds were obtained for the first time from this plant.

Chemical Phenomena↗
PubMed1988

Pharmacokinetic study of levonorgestrel used as a postcoital agent.

The pharmacokinetics and pharmacodynamics of levonorgestrel (LNG) were studied in six women given 0.75 mg LNG orally for seven days during the periovulatory phase of the menstrual cycle. Steady-state concentrations of LNG were reached within three days and serum LNG concentrations at various times on day 7 were generally lower than on day 1, presumably due to a reduced serum level of SHBG. On day 7 the volume of distribution was significantly increased and Co significantly decreased and both the clearance and elimination half-life were higher on day 7 than on day 1. Half-lives varied from 5.6 to 25.1 hours. The day-to-day intra-subject variations in serum LNG concentrations ranged from 23% to 80%. Serum concentrations of pituitary and ovarian hormones suggested that ovulation was not inhibited in four of the six subjects and was delayed in the remaining two. No significant changes in serum prolactin levels were observed.

Absorption↗
PubMed1987

Pharmacokinetics of norethisterone in humans.

The pharmacokinetics of a dose of 1mg norethisterone administered with 50 micrograms ethynyloestradiol was studied in 83 subjects. The dose was rapidly absorbed and there were wide variations in the serum NET concentrations at any particular time after dosing; the concentrations at 24 h varied from 100 to 1700 pg/ml. There was a significant negative correlation between the serum NET concentration and the time after dosing in all women. There were large inter-subject variations in the pharmacokinetic parameters, the elimination half-life and bioavailability showing 3- and 5- fold variability, respectively. Mean values for the parameters were t1/2, 7.6 h; bioavailability, 53.6 ng/ml/h; C max, 4.63 ng/ml; clearance, 22.6 l/h; and Vd 2361. There were a number of statistically significant correlations between the pharmacokinetic parameters and analysis of the correlations suggested that clearance was an important determinant of the bioavailability and of C max whereas the elimination half-life was the determinant of the NET concentration at 24 h. The pharmacokinetics of NET are compared with those of ethynyloestradiol. The wide variation in pharmacokinetics is likely to be important in determining inter-subject variations in efficacy and, particularly, side-effects of oral contraceptives especially now that low-dose formulations are widely used.

Biological Availability↗