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Biomedical subjects

H H Fong

Publications and source records attributed to H H Fong.

At least 55 records · Page 3Linked to original sources
PubMed1988

Evaluation of the mutagenic and cytostatic potential of aristolochic acid (3,4-methylenedioxy-8-methoxy-10-nitrophenanthrene-1-carboxylic acid) and several of its derivatives.

Aristolochic acid (1), a constituent of Aristolochia species, has been used for medicinal purposes since the Graeco-Roman period. Following the observation that the compound was mutagenic and carcinogenic, it was removed from pharmaceutical products. Consistent with previous reports, we have found that 1 serves as a direct-acting mutagen in Salmonella typhimurium strains TA100, TA102, TA1537 and TM677, but was not active in the nitroreductase-deficient strains TA98NR and TA100NR. However, aristolic acid (2), a compound that differs in structure only by the absence of the nitro group, was also found to be a direct-acting mutagen in Salmonella strains TA98, TA100, TA102, TA1537, and TM677, as well as strains TA98NR and TA100NR. Both compounds (1 and 2) were active mutagens when evaluated with cultured Chinese hamster ovary cells. Thus, in contrast to previous suggestions, the nitro group at position 10 is not required to induce a mutagenic response. Also, a series of structural relatives (the methyl esters of 1 and 2 (3 and 4, respectively), aristolochic acid-D (5), aristolactam (6), aristolactam A-II (7), and aristolactam-N-beta-D-glucoside (8)) were evaluated for mutagenic potential with Salmonella typhimurium strain TM677 and found to be inactive. Since compounds 3 and 4 were found to be active mutagens with Salmonella typhimurium strains TA98, TA100, TA102 and TA1537 (sufficient quantities of compounds 5-8 were not available for testing), differential sensitivity of the tester strains unrelated to mutagenic potential is suggested. Further, compounds 1, 2, and 6-8 were evaluated for potential to inhibit growth with cultured KB or P388 cells. P388 cells were substantially more sensitive, and compound 1 was the most active of the materials tested (ED5 = 0.58 microM). Compound 6 also demonstrated appreciable activity (ED50 = 4.2 microM), as did compound 8 (ED50 = 6.0 microM). It therefore appears that phenanthrene-ring substituents, in addition to the nitro group at position 10, serve important roles for biological potential. In considering the carcinogenic event induced by aristolochic acid, these functionalities should also be taken into account.

Animals↗
PubMed1987

Inhibition of lactate dehydrogenase-X by imino-derivatives of gossypol:structure activity relationship.

Six imino-derivatives (II, III, IV, V, VI, VII) of gossypol (I) have been synthesized, and their effects were evaluated on the purified mouse lactate dehydrogenase-X. Three of these derivatives (V, VI, VII) with aldehyde groups substituted with hydrophobic functionalities showed equivalent or more inhibitory effects on lactate dehydrogenase-X than gossypol, whereas three other derivatives (II, III, IV) with aldehyde groups substituted with hydrophilic functional groups lost the ability to inhibit lactate dehydrogenase-X. It is suggested that two aldehyde groups of gossypol are not essential to inhibit lactate dehydrogenase-X. Furthermore, the hydrophobic property of the gossypol molecule seems to play a more important role in inhibiting lactate dehydrogenase-X. Therefore, lactate dehydrogenase-X inhibition by gossypol may not be associated with its antifertility mechanism, because the aldehyde group of gossypol is known to be required for its antifertility effect.

Animals↗
PubMed1987

Studies on zoapatle. V. Correlation between in vitro uterine and in vivo pregnancy interruption effects in guinea pigs.

The zoapatle plant, Montanoa tomentosa, has an extensive ethnomedical history of use in fertility regulation. Several fractions and isolates of this plant were evaulated in in vitro and in vivo tests to identify and characterize active constituents which may be responsible for its antifertility effects. The guinea pig was the animal model. Two types of in vitro activity were observed, a uterotonic type effect and an inhibition of spontaneous contractions of the uterine muscle. The in vivo effects appear to correlate with the ability of a fraction/isolate to inhibit the spontaneous contractions in in vitro testing. The non-polar fractions/isolates accounted for the inhibition of spontaneous contraction effects and the in vivo activity. The more polar fractions/isolates accounted for the uterine stimulant activity.

Abortifacient Agents↗
PubMed1986

Plant anticancer agents XXXIX: Triterpenes from Iris missouriensis (Iridaceae).

Employing the roots of Iris missouriensis, two known triterpenes, iso-iridogermanal and zeorin, were isolated and identified. As presently reported, they were found to demonstrate cytotoxic activity toward cultured P-388 cells (ED50 = 0.1 and 1.1 microgram/mL, respectively). Additionally, a new triterpene that demonstrated an ED50 of 8.5 micrograms/mL was isolated. On the basis of spectral analysis and chemical correlation with zeorin, the structure was shown to be 6 6 alpha-hydroxy-A'-neogermmacer-22(29)-en-30-oic acid (missourin).

Animals↗
PubMed1985

Isolation, structural elucidation, and chemical synthesis of 2-hydroxy-3-octadecyl-5-methoxy-1,4-benzoquinone (irisoquin), a cytotoxic constituent of Iris missouriensis.

As part of a continuing effort to provide novel agents of potential value in cancer chemotherapy, 2-hydroxy-3-octadecyl-5-methoxy-1,4-benzoquinone (irisoquin) was identified as a component of Iris missouriensis. This novel species demonstrated cytotoxic activity with cultured KB and P-388 cells (ED50 = 1.8 and 0.03 microgram/mL, respectively). The structure was assigned on the basis of spectral analyses and The structure was assigned on the basis of spectral analyses and confirmed by chemical synthesis. The latter provides a facile method for the production of irisoquin and structural derivatives that may be of value for the examination of structure-activity relationships. A closely related compound, 3-octadecyl-5-methoxy-1,4-benzoquinone (deoxyirisoquin), was also isolated from Iris missouriensis, prepared synthetically, and found to be devoid of cytotoxic activity.

Animals↗
PubMed1984

Analysis of gossypol and gossypol-acetic acid by high-performance liquid chromatography.

Gossypol, a bis-sesquiterpenoid cotton pigment, is of current interest as a male fertility-regulating agent. For the purposes of analyzing material to be studied biologically, a method is described for the analysis of gossypol by high-performance liquid chromatography. This has been used for examining the purity of gossypol-acetic acid using a UV-absorbance ratio technique.

Chromatography, High Pressure Liquid↗
PubMed1984

Comparative in vitro spermicidal effects of (+/-)-gossypol, (+)-gossypol, (-)-gossypol and gossypolone.

The comparative in vitro spermicidal effects of (+)-gossypol, (-)-gossypol and (+/-)-gossypol were evaluated on the spermatozoa of human, monkey, rabbit, mouse, rat and hamster. The spermicidal effects of gossypol isomers were also compared with those of gossypolone, which is a proposed major metabolite of gossypol. Gossypol isomers and gossypolone were all spermicidal. (+)- and (-)-Gossypol demonstrated spermicidal activities at the same concentration at which (+/-)-gossypol shows spermicidal effects on the spermatozoa of all species tested. However, gossypolone was less potent than the gossypol isomers. The spermicidal action of gossypol may be a nonspecific effect unrelated to the antifertility mechanism of orally administered gossypol, since (+)-gossypol which is not an effective male antifertility agent also showed the equivalent spermicidal effect to that of (+/-)-gossypol.

Animals↗
PubMed1981

Biological and phytochemical investigation of plants XVI: Strumpfia maritima (Rubiaceae).

An aqueous extract of the flowering tops of Strumpfia maritima exhibited antifertility activity in female rats. The extract also contained the flavonol glycoside narcissin. This article represents the first reported isolation of this flavonoid from the Rubiaceae, as well as the first reported phytochemical and pharmacological investigation of the genus Strumpfia.

Animals↗
PubMed1981

Antifertility effects of gossypol and its impurities on male hamsters.

Recent papers reporting on the male antifertility effects of gossypol have been criticized due to the possible influence of impurities on efficacy and toxicity. Our laboratory has prepared purified gossypol and a fraction containing the total impurities. The effects of these two substances and impure gossypol on the fertility of male hamsters was evaluated. Only pure gossypol produced a decrease in fertility after six weeks of dosing. No effects on male fertility were observed in the other treatment groups. A full recovery of fertility in the pure gossypol group was observed four weeks after cessation of treatment. These data support the claim that gossypol is indeed an active antifertility agent for males. It is also clear that the impurities may have the ability to block or decrease the efficacy of gossypol.

Animals↗
PubMed1980

In vitjro spermicidal activity of gossypol.

The in vitro spermicidal effect of gossypol, gossypol acetic acid and gossypol-polyvinylpyrrol idone was investigated. Gossypol-polyvinylmulations. Thus, gossypol in an appropriate chemical form may be useful as a spermicide.

Drug Combinations↗
PubMed1977

Flavonoid constituents from Eupatorium altissimum L. (Compositae).

An aqueous ethanol extract of Eupatorium altissimum L. (Compositae) showed confirmed activity in the P-388 lymphocytic leukemia assay in mice, and the chloroform solubles showed both cytotoxic activity in the 9KB carcinoma of the nasopharynx cell culture assay and antitumor activity in the P-388 lymphocytic leukemia assay. Two flavones, eupatorin and 5-hydroxy-3',4',6,7-tetramethoxyflavone, were isolated and identified. Both were devoid of cytotoxic and antitumor activity.

Animals↗
PubMed1976

Oncogenic and tumor-promoting Spermatophytes and Pteridophytes and their active principles.

A survey and discussion are presented of plants classified as Spermatophyta and Pteridophyta, extracts of which have been shown to be oncogenic or tumor-promoting in animals. The active oncogenic and tumor-promoting principles, where known, have been identified. They represent tannins; pyrrolizidine, indole, tropolone, quinoline, purine, and benzophenanthridine alkaloids; nitroso compounds; triterpene glycosides; lignans; isoflavans; allyl benzenoids; simple (nu-pyrenes; and carbocyclic hydroxy acids. A total of 28 compounds of known structure have been identified as oncogens and several phorbol esters as tumor-promoters. Plants known to contain any of the 28 oncogens (excluding shikimic acid and caffeine) have been tabulated; they represent at least 454 species, 110 genera, and 34 families of Spermatophyta and Pteridophyta.

Animal Feed↗
PubMed1975

Cytotoxic principles of Parquetina nigrescens (Afzel.) Bullock (Asclepiadaceae).

Systematic fractionation of the cytotoxic extracts of the roots of Parquetina nigrescens (Afzel.) Bullock (Asclepiadaceae) on silica gel column chromatography led to the isolation of three cardenolides: cymarin, strophanthidin, and a strophanthidin glycoside (XS-89). Also isolated during the investigation were beta-sitosterol-beta-D-glucoside, a mixture of alpha- and beta-amyrins, a mixture of alkanols, and a mixture of plant sterols.

Animals↗