棉酚研究的新突破

自从发现棉酚的避孕作用以来,七十年代开始兴起了对棉酚研究的热潮,期望得到一个有效的男用避孕药物。然而由于它会引起低血钾症和难以恢复生育力的致命弱点,使它不能成为一个理想安全的男用避孕药而广泛应用。伦敦City大学的Stephen Matlin新近发现棉酚是光学活性化合物,存在二种对映异构体。在我国过去研究中的棉酚是这     

棉酚(+)、(-)异构体对小鼠体外间质细胞睾酮释放的抑制研究

棉酚是一种二聚倍半萜,存在于棉花的种子和皮中,50年代后期证实对人有抗生育作用,能抑制精子发生和精子活力,作为一种强效男用避孕药。然而在实际应用中发现有一些副作用,如低血钾、嗜睡和性欲减退,长期应用也可能产生对睾丸功能的不可逆性影响。许多学者提出经纯化的棉酚右旋异构体对田鼠抑制精子发生无效,而认为棉酚左旋     

棉酚发展为男性避孕药的局跟

棉酚是一种有希望的男用避孕药。但因低血钾及不可逆性精子发生障碍,影响了该药的广泛使用。本文报道使用纯品醋酸棉酚及棉酚与氯化钾合并使用,考察醋酸棉酚低血钾及可逆性抗生育作用。应用成年、体重为15～18kg的雄性1angur猴为实验动物,分笼喂养。研究过程分三个周期,即给药前30天、给药期120天及恢复期105天。动物分三组,每组5只。A组为对照,仅供给赋形剂;B     

近年国外对抗生育植物药研究概况

世界上民间传说和传统医学经验用于生育调节的植物已有200余种,据Farnsworth1975年报告经实验动物筛选有抗生育作用的植物达145种。从植物中寻找避孕药日益受到重视,仅印度就初筛了约400种,其中少数植物对大鼠有60%的抗生育活性。吴氏对国外的研究作过综述。但近年又有很大进展,现介绍如下。一、男用避孕植物药的研究棉酚:自80年代国外对棉酚主要从细胞水平研究其作用机制;从药代动力学和毒理学及分子或酶水平研究其生化作用机制。对后者研究结果有的尚不一致。棉酚的抗生育作用和对细胞的毒性依动物种属有所不同。除其本身的毒性外,所含杂质毒性也很大,棉酚在体外能抑制豚鼠精子获能,10~(-4)M棉     

棉酚在体外灭活人类免疫缺陷病毒

棉酚是一种口服有效的男用抗生育药。有研究提示用于阴道避孕时,棉酚是一种安全有效的杀精子/杀病毒药物。本研究表明在体外能灭活人类免疫缺陷病毒(HIV),从而增加了用于预防性传播病毒疾病的可能性。HIV贮备物为人类嗜T淋巴细胞三型病毒(HTLV-Ⅲ_B型),是从预先分装、置-70℃冷藏、已感染的H9细胞的澄清上清液中获     

棉酚对二种纯系小鼠精子计数的影响

由于近来发现棉酚在 Ames 试验中无致突变作用,体外实验中亦未发现其对淋巴细胞染色体的损伤,因此棉酚很有希望成为一种男用避孕药。动物对棉酚的反应有明显的种族特异性。棉酚对小鼠精子计数、睾丸及附性腺的影响各家报道亦不一致。为此,作者等研究了纯系 BALB/C/Ola 和 CBA/Gr 雄小鼠对醋酸棉酚的反应。取上述二种纯系雄小鼠(4～12周龄)随机分为用药及对照组,用药组每天以醋酸棉酚10或20mg/kg 灌胃,每周给药5天,连续3～5周,于末次给药后24小时杀死小鼠,取睾丸、附睾头、贮精囊称重,并作精子计数。结果表明二种纯系小鼠的体重和睾丸重量在用药组和对照组间无显著差异,但用药小鼠的附睾头     

棉酚对大小白鼠,家鼠抗生育作用的研究

世界各国消灭鼠害的药物和工具很多,但运用抗生育原理灭鼠未见报道。我们研制了一种抗生育药物——棉酚,又名绝鼠灵。该药原是一种男用节育药,国内外学者曾作过大量的研究工作,国内专家经过10余年的动物实验和临床验证,     

棉酚对雄兔的毒理作用及内分泌影响

引言棉酚(Gossypol)是从棉花籽、茎、根中分离出来的一种多酚化合物,在中国,它已被用作金地鼠等实验动物的雄性抗生育药物。曾报告应用高纯度的棉酚、醋酸棉酚以及甲酸棉酚进行了抗生育作用、作用部位、作用机制、药理动力学和毒理等一系列动物实验。在已研究的许多种属中,对抗生育作用最敏感的是大白鼠和猴,但不是没有毒性。这些动物不育的起效时间与剂量有关,在我们早先的报告,我们给家兔饲以剂     

体外比较(±)棉酚,(+)棉酚,(-)棉酚和棉酚酮的杀精子效力

自从证明了棉酚对人精子的体外杀精子效力后,将棉酚作为一种阴道避孕药应用的可能性近来已在非人灵长类和妇女中进行了评价。已有报导,棉酚有抑制人精子呼吸链和氧化磷酸化作用。且能干扰精子的能量代谢。这些棉酚的效应可能同精子的制动现象有关。但棉酚的杀精子机制至今仍不清楚。已经证明,主要由棉子类(GossypiumSpecies,Malvaceae)中分离出来的非旋光性(±)棉酚具有杀精子效力和抗生育作用。而由 Thepesia Populnea(Malva-ceae)植物中分离出来的旋光性(+)棉酚,     

棉酚引起酶失活和抑制

棉酚是从棉花作物中分离出来的一种淡黄色酚类化合物。中国首先发现食用粗制棉籽油可导致男性不育,且棉酚是其主要成分。临床上虽有过一些有关副作用的报道,但证明棉酚作为一种男性抗生育剂,其有效率达99.89%。为了阐明这种男性抗生育剂的作用机制,迄今曾在细胞及组织水平上研究了这些化合物的药理动力学和毒理学。然而,在     

Gossypol and Na+, K+ ATPase from human erythrocytes

The inhibition of Na+, K+ ATPase by gossypol has been proposed as a mechanism for the hypokalemia occurring in some patients receiving this drug. Gossypol acetic acid, 3 microM (higher concentration than present clinically), did not inhibit this enzyme prepared from erythrocytes from 5 humans. Thus, it is unlikely that gossypol inhibition of the usual form of this enzyme is the mechanism for the initiation of the hypokalemia.     

Effects of gossypol on the activity of kidney (Na+ + K+)-ATPase and the functions of erythrocyte membrane

Gossypol extracted from cottonseed oil, reputed to exert contraceptive action in males, may induce a side effect of hypokalemia. The cellular and molecular mechanisms by which gossypol produces hypokalemia are not quite understood. We have examined the inhibitory effect of gossypol on the activity of (Na+ + K+)-ATPase purified from the outer medulla of rabbit kidney, the half maximal inhibitory concentration (IC50) is 6.5 micron. The kinetic studies using this enzyme preparation show that gossypol is noncompetitive with ATP, Mg2+, Na+ and K+ with apparent Ki of 15.0, 13.0, 14.0 and 4.4 micron, respectively. On the other hand, in order to estimate the effects of gossypol on membrane transport of intact cells, we have investigated the effects of gossypol on the activity of (Na+ + K+)-ATPase, membrane integrity and permeability of human erythrocytes. It shows that gossypol inhibited the enzyme activity (greater than 5 micron) and expressed the hemolysis (greater than 50 micron) in vitro in a concentration-dependent manner, and increased the K+-efflux of the cells (10-40 micron). The above effects are antagonized by 1-2% bovine serum albumin. The data demonstrate that gossypol is a specific and potent membrane active agent. These results may be relevant to the in vivo actions of gossypol.     

Antifertility, spermicidal and ultrastructural effects of gossypol and derivatives administered orally and by intratesticular injections

Because there are problems, in men, associated with the use of gossypol related to reversibility and, infrequently, hypokalemia, several laboratories around the world have resorted to the synthesis and evaluation of experimental analogs and optical isomers of gossypol in an attempt to find a compound which retains its pharmacologically desirable antifertility effects while eliminating its suboptimal ones. The present study documents: (a) the effects of fourteen new, orally-administered synthetic analogs of gossypol on testicular ultrastructure and fertility in hamsters, (b) the in vitro effects of these compounds as well as of the optical isomers of gossypol against hamster and human sperm, and (c) the morphological and antifertility effects of intratesticular injections of gossypol-PVP and its optimal isomers in the rat. The results of the study demonstrate that these new analogs are not effective as male antifertility agents and that their in vitro activity is unrelated to their in vivo contraceptive potential. In addition, this report establishes the validity of the intratesticular injection model for the analysis of the mechanism of action of gossypol and its analogs by making these compounds directly available at the testicular site. The significance of these findings is discussed.     

与棉酚有关低血钾症不同发病地区自然人群钾摄入量和血清钾水平

在与棉酚有关低血钾症的高发区上海,中发区四川和不发区山东进行了自然人群钾摄入量和血清钾水平的调查,结果表明,自然人群钾摄入量以上海为最高,山东次之,四川最低,分別为60.1±16.6,58.7±11.1和54.6±13.4mmol/人/日,三地血清钾水平上海为4.2±0.3mmol/L,山东为4.2±0.4mmol/L,四川为4.0±0.3mmol/L。这些结果说明高发病区的上海和不发病区的山东两地钾摄入量和血清钾没有显著差别,与棉酚有关低血钾症的发病可能与当地钾摄入量和血清钾的本底水平无关。     

Limitations in developing cossypol acetic acid as a male contraceptive

Highly purified gossypol acetic acid (5 mg/day; oral) alone and in combination with potassium chloride (0.25 mg/day; oral) was tested in adult male langurs for 120 days to evaluate reversibility of its antifertility action and possible hypokalemia. The treatment resulted in severe oligospermia with impairment of sperm motility. Sperm morphological defects were evident. The functional activities of accessory sex glands and libido remained unimpaired. Occurrence of hypokalemia was found more pronounced in the gossypol alone group. Extensive renal potassium loss was evident and conversely the renal excretion of sodium decreased markedly. The activities of serum transaminases increased significantly. Other parameters of blood and of urine did not show any marked alterations. Complete reversal of the above changes was evident following 90 to 105 days of withdrawal of treatment. In conclusion, the oligospermia achieved was reversible and the hypokalemic response of langurs is similar to human and not related to impurity of the drug.     

Spermatotoxicity of a protein isolated from the root of Achyranthes aspera: a comparative study with gossypol

Background

A previous study showed that 50% ethanolic extracts of the roots of Achyranthes aspera possess spermatotoxic effects.

Study Design

A 58-kDa protein (Ap) was isolated, and its spermatotoxic effects were studied in comparison with gossypol. Ap (25 mg/kg body weight a day) and gossypol (40 mg/kg body weight a day) were administered orally to Swiss male albino mice for 35 days. Sperm motility, sperm count, sperm abnormality, toxicity markers such as aspartate aminotransferase (AST), alanine aminotransferase (ALT) in the liver and serum, testicular activities of hydroxyl methyl glutaryl CoA reductase (HMG CoA reductase), 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase(17β-HSD), glucose-6-phosphate dehydrogenase, cholesterol level and serum testosterone were assayed. Spermicidal action of the proteolytic digests of Ap was also studied in vitro.

Results

Treated mice showed significant spermatotoxicity. Significant differences were also observed in the testicular activities of HMG CoA reductase, 3β-HSD, 17β-HSD and glucose-6-phosphate dehydrogenase and in the levels of cholesterol and serum testosterone. The nontoxic nature of Ap was indicated by the insignificant alterations in the activities of AST and ALT. Ap possessed spermicidal activity even after proteolysis.

Conclusion

The 58-kDa protein isolated from A. aspera possesses spermatotoxic effects comparable to gossypol.     

Effects of gossypol on the kidney with special emphasis on potassium (K) excretion

The overall and renal toxicity of racemic gossypol acetic acid was assessed in 6 mongrel dogs. Oral racemic gossypol acetic acid was given orally at doses increasing from 10 to 40 mg/d for a total of 6 weeks in 3 female dogs and from 40 to 80 mg/d for a total of 4 weeks in 3 male dogs. The animals were then sacrificed. Drug tolerance was excellent. Pathological examination of the liver and heart was normal. Renal function remained normal. The renal excretion of K, Mg, phosphate and acid remained normal. Serum K remained within the range appropriate for animals on a K-free diet. Pathological examination of the kidney disclosed mild proximal tubule vacuolization similar to that observed in animals on a K-free diet and small brownish pigment deposits in a few tubular cells. Spermatogenesis was arrested in the testes of one of the 3 male dogs. We conclude that short exposure to 10 to 80 mg/day of gossypol does not result in detectable toxic effect. Neither significant hypokalemia nor a tubular K leak were observed.     

The effects of gossypol on nuclear protein in rat testes. II. The synthesis of histones and testis-specific proteins after gossypol treatment

This communication is to report the effects of gossypol on the synthesis of chromosomal basic proteins in the spermiogenic cells. A double-labelling experiment has been performed. The control rats received 14C-arginine, whereas the gossypol-treated rats received a 3H-arginine injection. An equal volume of the tissues (from control and gossypol-treated) were combined, and the total nuclear basic proteins (TNBP) from round spermatids (RS) and elongating spermatids (ES) were extracted for electrophoretic separation. By studying the ratio of 3H/14C, it was indicated that the synthesis of H1, H3, H2B plus H2A and TP1 in the RS was reduced by gossypol. The amount of inhibition of these proteins were 48%, 19%, 27%, and 11%, respectively. In the ES, the synthesis of H1, H3, H2B plus H2A, H4 plus TP2, TP3, and TP1 was reduced by gossypol, the reduction was 33%, 22%, 26%, 14%, 33%, and 8%, respectively. The synthesis of S1 protein was not inhibited by gossypol in both RS and ES.     

Gossypol: a contraceptive for men

Gossypol is a polyphenol isolated from the seed, roots, and stem of the cotton plant (Gossypium sp.). The substance, a yellow pigment similar to flavonoids, is present in cottonseed oil. In the plant, it acts as a natural defensive agent against predators, provoking infertility in insects. In most animals, gossypol provokes infertility, and in man it causes spermatogenesis arrest at relatively low doses. Studies carried out in China, Africa, and Brazil have shown that the substance is well tolerated, causing no side effects that lead to discontinuation. The reported hypokalemia of early studies has not been confirmed in the latest trials. The only concern at present appears to be lack of reversibility in over 20% of subjects. Gossypol should be prescribed preferably to men who have completed their families or for those who would accept permanent infertility after a few years of use.     

Vaginal contraception with gossypol: A clinical study

A clinical study concerning the vaginal contraceptive efficacy of gossypol acetic acid was performed. Fifteen women who had undergone tubal sterilization volunteered for the study. The effect of vaginal gossypol-containing gel on spermatozoa was determined by postcoital tests performed in subjects without and after using gossypol gel. After gossypol application, the number of spermatozoa found in cervical mucus was greatly decreased and, in eleven of the fifteen women, all spermatozoa seen were immobilized. In four cases a few poorly motile spermatozoa were seen but they showed no forward progression. We have previously reported that gossypol has an inhibitory effect on herpes simplex virus type 2 $\text{in vitro}$. This antiviral property of gossypol makes it particularly attractive as a topical barrier contraceptive. The present study shows that gossypol is also promising as a vaginal contraceptive agent in human $\text{in vivo}$ experiments.