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At least 19 recordsLinked to original sources
PubMed1992

Effect of quassin on the metabolism of catecholamines in different life cycle stages of Culex quinquefasciatus.

Quassin, a mosquito larvicide isolated from Quassia amara, inhibits tyrosinase activity in the larvae of Culex quinquefasciatus. Since tyrosinase is directly involved in sclerotisation of the cuticle, it is suggested that quassin, as a larvicide, inhibits development of the cuticle. In presence of quassin phenylalanine, tyrosine and L-dopa levels were increased in larvae. In the larval stages, mosquitoes have a high concentration of phenylalanine and tyrosine with the level of the latter being very high just before pupation and then declines sharply. Monoamine oxidase (MAO), an enzyme directly involved in the metabolism of catecholamines, remained unaffected by quassin, in fact the level of adrenaline also remained unchanged in larvae during quassin poisoning. MAO showed high variation in its activity between synthetic and natural substrates. Tyramine is not a substrate for MAO. Tyrosinase activity was high in developing stages and negligibly low in adults and showed specificity to L-dopa. Phenylalanine and tyramine are unaffected by tyrosinase. Blood feeding did not influence the activity of both these enzymes.

Animals↗
PubMed1991

Larvicidal efficacy of Quassin against Culex quinquefasciatus.

Crushed aqueous extracts of leaf, wood, bark and flowers of Quassia amara showed antilarval activity against C quinquefasciatus. Quassin has been identified to be the antilarval principle present in this plant and was effective against mosquito larvae at a concentration of 6 ppm. Quassin was present to the extent of 0.1 to 0.14 per cent (average 0.12%) on a dry weight basis in wood of Q. amara. This compound is an unsaturated lactone and it gave a positive response to the Legal test, characteristic of unsaturated lactones. Quassin lost its antilarval activity on treatment with strong alkalies. Quassin was over five times as active as carbaryl, a synthetic antilarval agent.

Animals↗
PubMed1984

An enzyme-linked immunosorbent assay for quassin and closely related metabolites.

A microtitration plate enzyme-linked immunosorbent assay has been developed for quassin and closely related seco-triterpenes. The method is much more sensitive than conventional chromatographic techniques and enables the routine analysis of large numbers of samples with a detection limit of 5 ng quassin. Antibody production was elicited by injecting a conjugate of iso-quassinic acid linked to bovine serum albumin into rabbits. Important features of the technique are (a) the use of a double-antibody, noncompetitive enzyme-linked immunosorbent assay for a low-molecular-weight, nonantigenic compound using microtitration plates; and (b) that the initial incubation of samples with primary antiserum can be carried out in buffer containing up to 20% (v/v) methanol with minimal loss of sensitivity. The structural requirements for recognition of the hapten by the antiserum are considered based on the levels of cross-reaction found with a wide range of other quassinoids.

Chemical Phenomena↗
PubMed2000

Total synthesis of (+)-quassin.

A total synthesis of (+)-quassin from naturally occurring (S)-(+)-carvone is described. The total number of steps was 28, and the overall yield was about 2.6%. The synthetic strategy for the construction of the tetracyclic carbon framework was based on a C-->ABC-->ABCD ring annulation sequence, involving an aldol reaction, an intramolecular Diels-Alder reaction, and an intramolecular acylation as the key steps. Subsequent functionalization of ring A and ring C then afforded the target (+)-quassin.

Antineoplastic Agents, Phytogenic↗
PubMed2003

Enhancement of the antiplasmodial activity of quassin by transformation into a gamma-lactone.

The naturally occurring bitter principle quassin (1) was converted chemically into the gamma-lactone quassilactone (13) in an attempt to enhance its antiplasmodial activity. The in vitro antiplasmodial activity of 13 against Plasmodium falciparum (K1) (IC(50) = 23 microM) was 40-fold greater than that of 1. However, one of the intermediates, compound 8, the 15beta-hydroxy,16-O-m-chlorobenzoyl analogue of 1, was 506-fold more active than 1 against P. falciparum (IC(50) = 1.8 microM) and only 3-fold less potent than chloroquine. In addition, 8 displayed the best cytotoxic/antiplasmodial ratio (112) of all of the compounds tested. In the course of this work a dimer, neoquassin ether (6), linked at C-16 was also prepared; 6 was found to have weak antiplasmodial activity (IC(50) = 9.7 microM).

Animals↗
PubMed1981

[Antiamebic properties of some derivatives of ailantone and quassin].

Owing to its high toxicity, ailanthone, one of the most potent in vivo amoebicidal drugs of natural origin, cannot be safely employed in clinical trials. With the aim of obtaining a compound with a better therapeutic index and of studying possible relationships between biological activity and chemical structure, many derivatives of ailanthone and of the chemically related, although biologically inactive, quassin have been prepared and tested.

Amebicides↗
PubMed2003

[Analysis of constituents in Jamaica quassia extract, a natural bittering agent].

Jamaica quassia extract, a natural bittering agent, is described as "a substance extracted from bark of Jamaica quassia (Quassia excelsa Sw.)" in the List of Existing Food Additives in Japan. The constituents in Jamaica quassia extract product were investigated as a part of an ongoing study to evaluate its quality and safety as a food additive. The main constituents of the extract were identified as quassin and two isomers of neoquassin by using LC/MS. The main constituent, quassin, was isolated and the structure was determined by spectral means. The quantification of their main constituents was performed by HPLC using quassin as a standard, and the concentrations of quassin and total of neoquassin isomers were 21.4% and 55.5%. In addition, it was confirmed that Jamaica quassia extract was different from quassia extract, which is extracted from bark of Picrasma quassioides Benn. belonging to the same family as Q. excelsa, by comparing their HPLC profiles.

Chromatography, High Pressure Liquid↗
PubMed1997

Antifertility activity of Quassia amara in male rats - in vivo study.

The crude methanol extract of the stem wood of Quassia amara. L. (A-1) significantly caused a reduction in the weight of the testis, epididymis and seminal vesicle, but an increase in that of the anterior pituitary gland. Epididymal sperm counts, serum levels of testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH) were significantly reduced when the rats were treated with the extract. Furthermore the basal and LH-stimulated testosterone secretion of Leydig cells isolated from rats pretreated with the extract was inhibited. These changes seemed to be restored eight weeks after the withdrawal from extract treatments. Two compounds - quassin and 2-methoxycanthin-6-one were isolated after fractionation of A-1. Quassin produced similar biological actions as the crude extract while the effects of 2-methoxycanthin-6-one did not seem to differ from those of the control. Quassin appears to be the antifertility principle of Quassia amara.

Animals↗
PubMed2002

Antiviral activity of simalikalactone D, a quassinoid from Quassia africana.

After removing lipophilic material, the ground root bark of Quassia africana Baill. (Simaroubaceae) was extracted with ethanol 95 %. Partitioning between chloroform, ethyl acetate and water yielded three crude extracts. Pronounced activities were shown by the chloroform and ethyl acetate crude extracts against Herpes simplex, Semliki forest, Coxsackie and Vesicular stomatitis viruses. By repeated column chromatography and preparative thin layer chromatography on silica gel, two quassinoids, i. e., quassin and simalikalactone D were isolated. Structures of the pure compounds were established primarily using NMR spectroscopy. Mass spectral information confirmed the assigned structures. Simalikalactone D was responsible, at least in part, for the high antiviral activity observed for the chloroform crude extract. Quassin showed no activity. For quassinoids the ester group at C-15 and the epoxymethano bridge between C-8 and C-13 appeared to be important structural features in order to exhibit a pronounced antiviral activity.

Antineoplastic Agents, Phytogenic↗
PubMed2003

Quassinoids from Picrasma crenata.

From woods of Picrasma crenata, a new stereoisomer dihydronorneoquassin was obtained together with others well knowns dihydronorneoquassin, parain, alpha-neoquassin, beta-neoquassin and quassin. The structures were determined by spectroscopic data and chemical evidence.

Picrasma↗
PubMed1997

[Weitz' aminium salt initiated electron transfer reactions and application to the synthesis of natural products].

A stable cation radical Weitz' aminium salt, tris(4-bromophenyl)aminium hexachloroantimonate (BAHA) initiated electron transfer has been found to efficiently promote a great variety of reactions on electron-rich substrates: e.g. the cation radical pericyclic reactions, the chain-induced cation radical oxygenation of strained olefines and dienes, and several other intriguing reactions on a great variety of electron-rich substrate. The discovery of the Weitz' aminium salt catalysed Diels-Alder reaction has stimulated interest in cation radical chemistry and facilitated the development of a wide range of cation radical pericyclic chemistry. Applications of the method to the synthesis of natural products utilizing BAHA are also presented. Reaction of a lignan precursor, cinnamyl alcohols with BAHA in tetrahydrofuran (THF) gave a furofuran lignan, (+/-)-sesamin in one step. Podophyllum lignans, (+/-)-isopodophyllotoxin and (+/-)-isopicropodophyllin were synthesized by a biomimetic procedure from the doubly unsaturated esters by means of the BAHA induced cation-radical cycloaddition reaction. A new general synthesis for (+/-)-dibenzocyclooctadiene lignans was established utilizing novel synthetic method for quinone derivatives by oxidation with BAHA. Reactions of phenol derivatives using BAHA gave the corresponding quinone derivatives, which may be useful synthon for obtaining quassinoids such as quassin.

Antimony↗