Chemical Composition and Anti-Candida Activity of Mentha suaveolens Ehrh. Essential Oils Obtained by Different Distillation Processes

A comparative study on essential oils extracted from Mentha suaveolens Ehrh. from Italy is reported. Two extraction procedures were investigated: hydrodistillation and steam distillation, carried out as a continuous and fractionated procedure. Fresh and dried plant material from two harvests was used. The hydrodistillation method yielded a higher amount of essential oil. The dried plant was significantly richer in essential oil per kg of starting plant material. Gas chromatography-mass spectrometry analysis of 112 samples showed that the essential oils belong to the piperitenone oxide-rich chemotype. In addition, piperitenone, p-cymen-8-ol, and limonene were among the most abundant compounds in the different samples. A higher amount of piperitenone oxide was obtained by hydrodistillation, while steam distillation gave a higher percentage of piperitenone and limonene. The essential oils were characterized for their anti-Candida albicans activity; higher potency was observed for the samples rich in piperitenone oxide, with MIC values ranging from 0.39 to 0.78 mg·mL-1 (0.039% and 0.078% p/v). The results of this work provide a deep insight into the methodology of essential oil extraction and the associated chemical variability of M. suaveolens Ehrh. Some of the essential oils are potent against C. albicans and could be considered for potential use in therapy.

In Vitro Antioxidant and In Vivo Antigenotoxic Features of a Series of 61 Essential Oils and Quantitative Composition-Activity Relationships Modeled through Machine Learning Algorithms

The antioxidant activity of essential oils (EOs) is an important and frequently studied property, yet it is not sufficiently understood in terms of the contribution of EOs mixtures' constituents and biological properties. In this study, a series of 61 commercial EOs were first evaluated as antioxidants in vitro, following as closely as possible the cellular pathways of reactive oxygen species (ROS) generation. Hence, EOs were assessed for the ability either to chelate metal ions, thus interfering with ROS generation within the respiratory chain, or to neutralize 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and lipid peroxide radicals (LOO•), thereby halting lipid peroxidation, as well as to neutralize 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid cation radicals (ABTS•+) and hydroxyl radicals (OH•), thereby preventing the ROS species from damaging DNA nucleotides. Showing noteworthy potencies to neutralize all of the radicals at the ng/mL level, the active EOs were also characterized as protectors of DNA double strands from damage induced by peroxyl radicals (ROO•), emerging from 2,2'-azobis-2-methyl-propanimidamide (AAPH) as a source, and OH•, indicating some genome protectivity and antigenotoxicity effectiveness in vitro. The chemical compositions of the EOs associated with the obtained activities were then analyzed by means of machine learning (ML) classification algorithms to generate quantitative composition-activity relationships (QCARs) models (models published in the AI4EssOil database available online). The QCARs models enabled us to highlight the key features (EOSs' chemical compounds) for exerting the redox potencies and to define the partial dependencies of the features, viz. percentages in the mixture required to exert a given potency. The ML-based models explained either the positive or negative contribution of the most important chemical components: limonene, linalool, carvacrol, eucalyptol, α-pinene, thymol, caryophyllene, p-cymene, eugenol, and chrysanthone. Finally, the most potent EOs in vitro, Ylang-ylang (Cananga odorata (Lam.)) and Ceylon cinnamon peel (Cinnamomum verum J. Presl), were promptly administered in vivo to evaluate the rescue ability against redox damage caused by CCl4, thereby verifying their antioxidant and antigenotoxic properties either in the liver or in the kidney.

In Vivo Antiphytoviral and Aphid Repellency Activity of Essential Oils and Hydrosols from Mentha suaveolens and Foeniculum vulgare to Control Zucchini Yellow Mosaic Virus and Its Vector Aphis gossypii

In recent years, natural compounds have gained attention in many fields due to their wide-range biological activity. In particular, essential oils and their associated hydrosols are being screened to control plant pests, exerting antiviral, antimycotic and antiparasitic actions. They are more quickly and cheaply produced and are generally considered safer for the environment and non-target organisms than conventional pesticides. In this study, we report the evaluation of the biological activity of two essential oils and their corresponding hydrosols obtained from Mentha suaveolens and Foeniculum vulgare in the control of zucchini yellow mosaic virus and its vector, Aphis gossypii, in Cucurbita pepo plants. The control of the virus was ascertained with treatments applied either concurrently with or after virus infection; choice tests were performed to verify repellency activity against the aphid vector. The results indicated that treatments could decrease virus titer as measured using real-time RT-PCR, while the experiments on the vector showed that the compounds effectively repelled aphids. The extracts were also chemically characterized using gas chromatography-mass spectrometry. Mentha suaveolens and Foeniculum vulgare hydrosol extracts mainly comprised fenchone and decanenitrile, respectively, while essential oils analysis returned a more complex composition, as expected.

Chemical Composition of Various Nepeta cataria Plant Organs’ Methanol Extracts Associated with In Vivo Hepatoprotective and Antigenotoxic Features as well as Molecular Modeling Investigations

This report summarizes the chemical composition analysis of Nepeta cataria L. flower, leaf, and stem methanol extracts (FME, LME, SME, respectively) as well as their hepatoprotective and antigenotoxic features in vivo and in silico. Herein, Wistar rat liver intoxication with CCl₄ resulted in the generation of trichloromethyl and trichloromethylperoxy radicals, causing lipid peroxidation within the hepatocyte membranes (viz. hepatotoxicity), as well as the subsequent formation of aberrant rDNA adducts and consequent double-strand break (namely genotoxicity). Examined FME, LME, and SME administered orally to Wistar rats before the injection of CCl₄ exerted the most notable pharmacological properties in the concentrations of 200, 100, and 50 mg/kg of body weight, respectively. Thus, the extracts’ hepatoprotective features were determined by monitoring the catalytic activities of enzymes and the concentrations of reactive oxidative species, modulating the liver redox status. Furthermore, the necrosis of hepatocytes was assessed by means of catalytic activities of liver toxicity markers. The extracts’ antigenotoxic features were quantified using the comet assay. Distinct pharmacological property features may be attributed to quercitrin (8406.31 μg/g), chlorogenic acid (1647.32 μg/g), and quinic acid (536.11 μg/g), found within the FME, rosmarinic acid (1056.14 μg/g), and chlorogenic acid (648.52 μg/g), occurring within the LME, and chlorogenic acid (1408.43 μg/g), the most abundant in SME. Hence, the plant’s secondary metabolites were individually administered similar to extracts, upon which their pharmacology in vivo was elucidated in silico by means of the structure-based studies within rat catalase, as a redox marker, and rat topoisomerase IIα, an enzyme catalyzing the rat DNA double-strand break. Conclusively, the examined N. cataria extracts in specified concentrations could be used in clinical therapy for the prevention of toxin-induced liver diseases.

In vivo Antiphytoviral Activity of Essential Oils and Hydrosols From Origanum vulgare, Thymus vulgaris, and Rosmarinus officinalis to Control Zucchini Yellow Mosaic Virus and Tomato Leaf Curl New Delhi Virus in Cucurbita pepo L

In the last decades, the interest in biological activity of natural compounds has been growing. In plant protection, essential oils have been reported to exhibit antiviral, antimycotic, and antiparasitic activities, and are regarded as promising for the formulation of safe antimicrobial agents. Attention has also been focused on hydrosols, the by-products of hydro-distillation of essential oils. Their production is easy, fast, and cheap, and they seem to arise less concern for human health than essential oils. Plant viruses represent a major concern for agricultural crops since no treatment compound is available for virus control. This work was aimed at evaluating the antiphytoviral effectiveness of treatments with three essential oils and corresponding hydrosols extracted from Origanum vulgare, Thymus vulgaris, and Rosmarinus officinalis on Cucurbita pepo plants infected by zucchini yellow mosaic virus or tomato leaf curl New Delhi virus. Treatments were applied either concurrently or after virus inoculation to ascertain an inhibition or curative activity, respectively. Symptoms were observed and samplings were performed weekly. Virus titer and expression levels of phenylalanine ammonia lyase gene (PAL) were measured on treated and untreated infected plants by real-time PCR. PAL gene plays an important role in plant defense response as it is involved in tolerance/resistance to phytopathogens. Results indicated that treatments were effective against tomato leaf curl New Delhi virus whether applied simultaneously with the inoculation or after. A major inhibition was observed with O. vulgare essential oil and hydrosol, resulting in 10^–4-fold decrease of virus titer 3 weeks after treatment. Curative activity gave maximum results with all three essential oils and T. vulgaris and R. officinalis hydrosols, recording from 10^–2-fold decrease to virus not detected 4 weeks after treatment. An induction of PAL gene expression was recorded at 12 d.p.i. and then was restored to the levels of untreated control. This allows to hypothesize an early plant defense response to virus infection, possibly boosted by treatments. Plant extracts’ composition was characterized by gas chromatography-mass spectrometry. Phenols were largely main components of O. vulgare and T. vulgaris extracts (carvacrol and thymol, respectively), while extracts from R. officinalis were based on monoterpene hydrocarbons (essential oil) and oxygenated monoterpenes (hydrosol).

Essential Oils Biofilm Modulation Activity and Machine Learning Analysis on Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients

The opportunistic pathogen Pseudomonas aeruginosa is often involved in airway infections of cystic fibrosis (CF) patients. It persists in the hostile CF lung environment, inducing chronic infections due to the production of several virulence factors. In this regard, the ability to form a biofilm plays a pivotal role in CF airway colonization by P. aeruginosa. Bacterial virulence mitigation and bacterial cell adhesion hampering and/or biofilm reduced formation could represent a major target for the development of new therapeutic treatments for infection control. Essential oils (EOs) are being considered as a potential alternative in clinical settings for the prevention, treatment, and control of infections sustained by microbial biofilms. EOs are complex mixtures of different classes of organic compounds, usually used for the treatment of upper respiratory tract infections in traditional medicine. Recently, a wide series of EOs were investigated for their ability to modulate biofilm production by different pathogens comprising S. aureus, S. epidermidis, and P. aeruginosa strains. Machine learning (ML) algorithms were applied to develop classification models in order to suggest a possible antibiofilm action for each chemical component of the studied EOs. In the present study, we assessed the biofilm growth modulation exerted by 61 commercial EOs on a selected number of P. aeruginosa strains isolated from CF patients. Furthermore, ML has been used to shed light on the EO chemical components likely responsible for the positive or negative modulation of bacterial biofilm formation.

Foeniculum vulgare Miller, a New Chemotype from Montenegro

Previous studies relating to prolonged and fractionated distillation procedures highlighted essential oils' (EOs) chemical composition to be significantly dependent on the extraction duration and harvesting time. As a continuation, a hydrodistillation procedure was applied to ripe fruit material of fennel, Foeniculum vulgare Miller (Apiaceae), collected from three localities in Montenegro (Podgorica, Nikšić, and Kotor) to furnish a total of 12 EOs. Liquid and vapor phases of the samples were analyzed by Gas Chromatography/Mass Spectrometry and Headspace-Gas Chromatography/Mass Spectrometry techniques, and 18 compounds have been identified. Although both quantitative and qualitative differences between the samples were notable, the phenylpropanoids anethole (ANE) and estragole and the monoterpenoids α-terpineol (TER) and fenchone (FEN) could be singled out as the most abundant constituents. The EOs from Podgorica belong to the most common ANE-rich chemotype, while the predominance of the monoterpenoid fraction is characteristic of the samples from Nikšić and Kotor. The latter is particularly rich in TER (up to 56.5%), with significant amounts of FEN and ANE. This chemical profile could represent a new chemotype of fennel EO. Vapor phases contained mainly monoterpenoids, with increased amounts of FEN and TER, while the number of phenylpropanoids was significantly decreased.

Machine Learning Data Augmentation as a Tool to Enhance Quantitative Composition-Activity Relationships of Complex Mixtures. A New Application to Dissect the Role of Main Chemical Components in Bioactive Essential Oils

Scientific investigation on essential oils composition and the related biological profile are continuously growing. Nevertheless, only a few studies have been performed on the relationships between chemical composition and biological data. Herein, the investigation of 61 assayed essential oils is reported focusing on their inhibition activity against Microsporum spp. including development of machine learning models with the aim of highlining the possible chemical components mainly related to the inhibitory potency. The application of machine learning and deep learning techniques for predictive and descriptive purposes have been applied successfully to many fields. Quantitative composition-activity relationships machine learning-based models were developed for the 61 essential oils tested as Microsporum spp. growth modulators. The models were built with in-house python scripts implementing data augmentation with the purpose of having a smoother flow between essential oils' chemical compositions and biological data. High statistical coefficient values (Accuracy, Matthews correlation coefficient and F1 score) were obtained and model inspection permitted to detect possible specific roles related to some components of essential oils' constituents. Robust machine learning models are far more useful tools to reveal data augmentation in comparison with raw data derived models. To the best of the authors knowledge this is the first report using data augmentation to highlight the role of complex mixture components, in particular a first application of these data will be for the development of ingredients in the dermo-cosmetic field investigating microbial species considering the urge for the use of natural preserving and acting antimicrobial agents.

Efficient adjustment sets in causal graphical models with hidden variables

We study the selection of adjustment sets for estimating the interventional mean under a point exposure dynamic treatment regime, that is, a treatment rule that depends on the subject’s covariates. We assume a nonparametric causal graphical model with, possibly, hidden variables and at least one adjustment set comprised of observable variables. We provide the definition of a valid adjustment set for a point exposure dynamic treatment regime, which generalizes the existing definition for a static intervention. We show that there exists an adjustment set, referred to as optimal minimal, that yields the nonparametric estimator of the interventional mean with the smallest asymptotic variance among those that are based on observable minimal adjustment sets. An observable minimal adjustment set is a valid adjustment set such that all its variables are observable and the removal of any of its variables destroys its validity. We provide similar optimality results for the class of observable minimum adjustment sets, that is, valid observable adjustment sets of minimum cardinality among the observable adjustment sets. Moreover, we show that if either no variables are hidden or if all the observable variables are ancestors of either treatment, outcome or the variables that are used to decide treatment, a globally optimal adjustment set exists. We provide polynomial-time algorithms to compute the globally optimal, optimal minimal and optimal minimum adjustment sets. Because static interventions can be viewed as a special case of dynamic regimes, all our results also apply for static interventions.

Essential Oils Biofilm Modulation Activity, Chemical and Machine Learning Analysis. Application on Staphylococcus aureus Isolates from Cystic Fibrosis Patients

Bacterial biofilm plays a pivotal role in chronic Staphylococcus aureus (S. aureus) infection and its inhibition may represent an important strategy to develop novel therapeutic agents. The scientific community is continuously searching for natural and “green alternatives” to chemotherapeutic drugs, including essential oils (EOs), assuming the latter not able to select resistant strains, likely due to their multicomponent nature and, hence, multitarget action. Here it is reported the biofilm production modulation exerted by 61 EOs, also investigated for their antibacterial activity on S. aureus strains, including reference and cystic fibrosis patients’ isolated strains. The EOs biofilm modulation was assessed by Christensen method on five S. aureus strains. Chemical composition, investigated by GC/MS analysis, of the tested EOs allowed a correlation between biofilm modulation potency and putative active components by means of machine learning algorithms application. Some EOs inhibited biofilm growth at 1.00% concentration, although lower concentrations revealed different biological profile. Experimental data led to select antibiofilm EOs based on their ability to inhibit S. aureus biofilm growth, which were characterized for their ability to alter the biofilm organization by means of SEM studies.

Co-transfer of embryos derived from cryopreserved and fresh natural cycle oocytes: a pilot study

Italian legislation regarding reproductive medicine prohibits embryo storage while allowing cryopreservation of supernumerary oocytes. This study evaluated the effect of fresh oocytes obtained from natural unstimulated cycles on the clinical success rates derived from the use of frozen-thawed (FR-TH) oocytes obtained following ovarian stimulation. For 36 women, intracytoplasmic sperm injection was performed on FR-TH oocytes supplemented by a fresh oocyte, if available, derived from a natural cycle in which gonadotrophin-releasing hormone-antagonist was used for premature LH surge control. The retrieval rate of fresh oocytes was 61.1% and survival rate of FR-TH oocytes was 43.6%. The fertilization rate of fresh and FR-TH oocytes was 70% and 52.5%, respectively. Fifty embryos were transferred, 14 of them developed from fresh oocytes and 36 from FR-TH oocytes. Six pregnancies occurred in 10 cycles in which the embryos developed from fresh and FR-TH oocytes (pregnancy rate 60.0%) and two in 12 patients in whom the embryos were obtained from only FR-TH oocytes (pregnancy rate 16.7%) (P < 0.05). In summary, the data demonstrate that the transfer of embryos derived from oocytes cryopreserved following a previous ovarian stimulation and an embryo developed from a fresh one retrieved in natural cycle ensures an excellent clinical outcome.

Hopes and facts about mild ovarian stimulation

Over the last two decades, easier and less expensive stimulation treatments have been largely replaced by more complex and more demanding protocols. Since the mid-nineties, long-term gonadotrophin-releasing hormone agonist stimulation protocols have been widely used. Such lengthy expensive regimens are not free from short- and long-term risks and complications. Mild stimulation protocols reduce the mean number of days of stimulation, the total amount of gonadotrophins used and the mean number of oocytes retrieved. The proportion of high quality and euploid embryos seems to be higher compared with conventional stimulation protocols and the pregnancy rate per embryo transfer is comparable. Moreover, the reduced costs, the better tolerability for patients and the less time needed to complete an IVF cycle make mild approaches clinically and cost-effective over a given period of time. However, further prospective randomized studies are needed to compare cumulative pregnancy rates between the two protocols. Natural cycle IVF, with minimal stimulation, has been recently proposed as an alternative to conventional stimulation protocols in normo- and poor responder patients. Although acceptable results have been reported, further large prospective randomized studies are needed to better evaluate the efficacy of these minimal regimens compared with conventional stimulation approaches.

GnRH antagonists in ovarian stimulation for ICSI with oocyte restriction: a matched, controlled study

Italian legislation regarding reproductive medicine limits the number of embryos transferred per attempt to three. Thus, in order to achieve pregnancy, more IVF cycles may be required, generating a need for methods of ovarian stimulation with fewer side effects. The gonadotrophin-releasing hormone (GnRH) antagonists have several advantages in this respect, but there is a debate regarding a possible lower pregnancy rate from resulting cycles. This study evaluated the clinical applicability of GnRH antagonists for ovarian stimulation in young women undergoing intracytoplasmic sperm injection (ICSI) in which only three oocytes can be fertilized. The 200 women treated with GnRH antagonist had a significantly shorter stimulation and lower gonadotrophin consumption, oestradiol concentration, total and mature oocyte recovery as compared with 200 matched controls treated with GnRH agonist. No differences were found between the groups in the number of normal zygotes, total cleaved, transferred and high quality embryos, or in the clinical outcomes. Thus, the previously reported lower pregnancy rate in GnRH antagonist cycles may be related to the oocyte characteristics. Finally, under conditions of oocyte number restriction, the GnRH antagonist-based cycles may be proposed as an efficacious, safe and minimally invasive alternative to GnRH agonist in a standard long protocol.

Management of poor responders in IVF

Correct controlled ovarian stimulation is of paramount importance in assisted reproductive technologies. Therefore, analysis of the ovarian reserve of the patient is mandatory to tailor the best ovarian stimulation regimen. When the ovarian reserve is reduced, the induction of a multifollicular growth remains a challenge. Several factors could be associated with reduced ovarian response. However, reduced ovarian reserve either in older patients or in young patients represents the most frequent aetiological factor. Whatever is the aetiology, one of the main problems is how to predict a reduced ovarian response, and although several tests have been suggested, no very accurate predictive test is available. A variety of different stimulation protocols have been suggested but the lack of any large-scale, prospective, randomized, controlled trials of the different management strategies and the lack of a uniform definition of the population may result in comparisons of heterogeneous groups of patients, making it difficult to draw any definitive conclusions. Natural cycle IVF may represent an easy and cheap approach in the management of this group of patients. Although no controlled large prospective randomized studies are available to compare the natural IVF procedure with ovarian stimulation IVF in poor responder patients, the efficacy of natural cycle IVF is hampered by high cancellation rates mainly due to untimely LH surge. The use of gonadotrophin-releasing hormone antagonists in the late follicular phase, which reduces the premature LH rise rate, and the improvements in laboratory conditions and fertilization techniques, increase the embryo transfer rates, making this procedure more cost-effective.

Cumulative pregnancy rates after transfer of fresh and thawed embryos

Frozen-thawed embryo transfer is an effective procedure that allows further possibilities of pregnancy in addition to those obtained after the fresh in vitro fertilization (IVF). In our follow-up study we analysed all fresh embryo transfer procedures and every frozen-thawed embryo transfer performed from January 2000 to December 2001 evaluating the cumulative pregnancy rates. The study population was divided into two groups according to the female age: <38 years (group I) and >38 years (group II). All the best embryos were chosen for transfer and all the supernumerary good quality embryos were cryopreserved on the day of transfer. The embryos were then thawed and manipulated using a new technique. In group I, 527 patients (619 cycles) underwent fresh embryo transfer and in 232 of them (238 cycles) the embryos were frozen (44% per patients and 38.4% per cycle). In group II, 156 patients (193 cycles) underwent fresh embryo transfer and in 14 of them (15 cycles) the embryos were frozen (9% per patient and 7.8% per cycle). The pregnancy rate of group I patients that had their supernumerary embryos frozen (232 patients and 238 cycles) was 47.4% per cycle and 48.7% per patient whereas in the same population of group II patients (14 patients and 15 cycles) the clinical pregnancy rate was 35.7% per cycle and 38.5% per patients. The cumulative clinical pregnancy rate after transfer of fresh and thawed embryos was: group I, 74% per cycle and 76% per patients; group II, 42.8% per cycle and 46.1% per patient. Frozen-thawed embryo transfer is a cost-effective practice.

Implantation in patients over 40 and raising FSH levels--a review

There is an evident decline of female fertility with age. This decline is mainly due to increased risk of pregnancy termination either after conception or after embryo implantation. Very likely the major cause of this embryo and pregnancy loss is chromosomal aneuploidies caused mostly by increasing rates of 'poor quality' oocytes. This phenomenon can be explained either by an age dependent accumulation of damage and/or by the hypothesis that the defective oocytes are there in the ovaries from the fetal life. 'Good quality' oocytes are ovulated first, leaving 'poor quality' oocytes to be ovulated later in life. Besides the quality of the oocytes which is mainly responsible of the embryo quality (we have not to forget a paternal effect) the process of implantation is dependent upon two variables: the probability of a viable embryo and that of a receptive uterine environment. From the oocyte donation model it seems that the endometrium also plays a minor role in human reproductive ageing as it does in some laboratory animals. However, besides some macroscopic possible causes which may play a role in the reduction of the age-related endometrial receptivity, there are so many endometrial factors possibly related to its receptivity which need to be further studied especially in older women.

Semen parameters and conception rates after intraperitoneal insemination

OBJECTIVE

To analyze the reproductive outcome in infertile couples which underwent intraperitoneal insemination (IPI).

METHODS

We analyzed a series of 216 couples who underwent IPI. Indications for treatment were unexplained infertility in 51 couples and male factor in 165. The 51 couples with unexplained infertility underwent a total of 71 cycles (20 couples underwent a second IPI cycle). The 165 couples with male factor underwent 243 cycles (165 first cycles and 78 second cycles).

RESULTS

Out of the 314 cycles performed, a total of 41 clinical pregnancies were observed, with a corresponding conception rate of 13.1%. The values of conception rates for unexplained and male factor infertility were 21.1 (based on 15 pregnancies) and 10.7% (based on 26 pregnancies), respectively. Out of the 41 pregnant women, 26 gave birth to a child, thus the overall livebirth rate was 8.3% (12.7 and 7.0%, respectively, for unexplained infertility and male factor diagnostic subgroups). Considering the couples with unexplained infertility, the conception rates were 9.0, 30.8 and 20.0% for strata of < 5, 5-10 and > or = 10 millions of inseminated spermatozoa. The corresponding values were 6.8, 12.5 and 18.5%, respectively, in couples with male factor infertility (chi(2)1 trend p < 0.05).

CONCLUSION

In conclusion, this series provides quantitative estimates of pregnancy rates after IPI in Italian couples with unexplained infertility or male infertility and suggested that the number of motile sperm inseminated is a determinant of pregnancy with this technique.

An auto-controlled study in in-vitro fertilization reveals the benefit of Percoll centrifugation to swim-up in the preparation of poor-quality semen

The efficiency of spermatozoa prepared by swim-up or by Percoll centrifugation was assessed in an in-vitro fertilization programme on 71 semen samples of a well-defined quality [total number of type A (WHO criteria) motile spermatozoa]: category I (n = 21) with > 100 x 10(6), II (n = 31) with 15-100 x 10(6), III (n = 11) with 5-15 x 10(6) and IV (n = 8) with < 5 x 10(6) type A motile spermatozoa. Oocytes were inseminated 4 h after oocyte retrieval, alternately with spermatozoa derived from swim-up and Percoll preparation. Both selection procedures resulted in a significantly higher (P < 0.001) percentage motility as compared to fresh semen. For low-quality samples (III and IV), however, swim-up was more effective in selecting highly motile (P = 0.004) and morphologically normal spermatozoa (P < 0.05). For high-quality samples, this difference might have been masked by introducing a swim-up step to remove Percoll particles. Regardless of the initial sperm quality, the mean fertilization rate was significantly higher (P = 0.003) when Percoll-treated spermatozoa were used for insemination (51.3 versus 37.8%). For semen of groups I and II, no difference in fertilization capacity was observed according to the sperm preparation method. Despite the lower percentage motility and normal morphology for the Percoll compared to the swim-up treatment in groups III and IV, fertilizing capacity was significantly (P < 0.001) in favour of this selection method (65.3 versus 26.5% in group III, 47.6 versus 11.6% in group IV).(ABSTRACT TRUNCATED AT 250 WORDS)