Antifertility activity of volatile fraction of neem oil

Azadirachta indica A. Juss (neem) as a contraceptive: An evidence-based review on its pharmacological efficiency

BACKGROUND

Azadirachta indica A. Juss. is an Indian medicinal plant with innumerable pharmacological properties. Studies have proven that the phytochemicals from neem possess remarkable contraceptive abilities with limited knowledge on its mechanism of action.

PURPOSE

The present review aims to summarize the efficiency of A. indica treatment as a contraceptive.

METHODS

The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were used. Published scientific articles on antifertility, antispermatogenic, antiovulation, hormone altering, contraceptive, and abortifacient activities of A. indica were collected from reputed Journals from 1980 to 2020 using electronic databases. Specific keywords search was completed to collect numerous articles with unique experiment design and significant results. This was followed by the selection of the requisite articles based on the criteria designed by the authors. Data extraction was based on the common research elements included in the articles.

RESULTS

A total of 27 studies were considered for reviewing, which included key pharmacological investigations. In the beginning, authors evaluated a number of publications on the contraceptive properties of A. indica, in which it was revealed that most of the publications were made between 2005 and 2009. All the collected articles were categorised and reviewed as antifertility, antispermatogenic, antiovulation, hormone altering, contraceptive, and abortifacient. Authors also assessed studies based on the plant parts used for pharmacological evaluations including leaves, seeds, stem-bark, and flowers. The article was primarily divided into different sections based on the previous works of authors on phytochemistry and pharmacological review articles.

CONCLUSION

Although A. indica is not reported with the complete alleviation of reproductive system in both male and female animal models, studies have proven its efficacy as a contraceptive. Extracts and phytochemicals from neem neither reduced the libido nor retarded the growth of secondary sexual characters, thus indicating only a temporary and reversible contraceptive activity. However, there is a dearth for clinical studies to prove the efficacy of A. indica as a herbal contraceptive.

Harnessing the Phytotherapeutic Treasure Troves of the Ancient Medicinal Plant Azadirachta indica (Neem) and Associated Endophytic Microorganisms

Azadirachta indica, commonly known as neem, is an evergreen tree of the tropics and sub-tropics native to the Indian subcontinent with demonstrated ethnomedicinal value and importance in agriculture as well as in the pharmaceutical industry. This ancient medicinal tree, often called the "wonder tree", is regarded as a chemical factory of diverse and complex compounds with a plethora of structural scaffolds that is very difficult to mimic by chemical synthesis. Such multifaceted chemical diversity leads to a fantastic repertoire of functional traits, encompassing a wide variety of biological activity and unique modes of action against specific and generalist pathogens and pests. Until now, more than 400 compounds have been isolated from different parts of neem including important bioactive secondary metabolites such as azadirachtin, nimbidin, nimbin, nimbolide, gedunin, and many more. In addition to its insecticidal property, the plant is also known for antimicrobial, antimalarial, antiviral, anti-inflammatory, analgesic, antipyretic, hypoglycaemic, antiulcer, antifertility, anticarcinogenic, hepatoprotective, antioxidant, anxiolytic, molluscicidal, acaricidal, and antifilarial properties. Notwithstanding the chemical and biological virtuosity of neem, it has also been extensively explored for associated microorganisms, especially a class of mutualists called endophytic microorganisms (or endophytes). More than 30 compounds, including neem "mimetic" compounds, have been reported from endophytes harbored in the neem trees in different ecological niches. In this review, we provide an informative and in-depth overview of the topic that can serve as a point of reference for an understanding of the functions and applications of a medicinal plant such as neem, including associated endophytes, within the overall theme of phytopathology. Our review further exemplifies the already-noted current surge of interest in plant and microbial natural products for implications both within the ecological and clinical settings, for a more secure and sustainable future.

Essential oils rich in monoterpenes are unsuitable as additives to boar semen extender

Despite the development of efficient boar semen extenders, there is still room for improvement of new formulas using new molecules that could increase fertilisation outcomes and substitute cryoprotectants and antibiotics. The goal of this work was to evaluate if the essential oils from the leaves of Myrrhinium atropurpureum and Cymbopogon citratus are suitable as additives in boar semen extender. The major compounds found in the essential oils from M. atropurpureum were 1,8-cineole (37.37%) and terpinolene (19.18%); and geranial (49.8%) and neral (33.24%) in essential oil of C. citratus. The addition of 1% and 0.1% of both essential oils to extended semen had immediate spermicidal effects (p < 0.05). Lower concentrations were tested and no cytotoxic effect was observed when M. atropurpureum essential oil was added at 0.001%. Differently, essential oil from C. citratus reduced sperm motility, membrane functionality and integrity and mitochondrial membrane potential even in concentrations as low as 0.001%. Also, addition of essential oils in low concentrations had no inhibitory effect against Escherichia coli and Pseudomonas aeruginosa growth. We conclude that the essential oils from C. citratus and M. atropurpureum, rich in monoterpenes, are cytotoxic to swine spermatozoa, therefore unsuitable as semen extender additives.

Azadirachta indica treatment on the congenital malformations of fetuses from rats

ETHNOPHARMACOLOGICAL RELEVANCE

Azadirachta indica A. Juss, popularly known as neem, presents medicinal and insecticide properties. However, the repercussions of the neem maternal treatment on fetal development should be investigated. Thus, the aim of this study was to evaluated the effects of Azadirachta indica (neem) on the frequency of congenital malformations in fetuses from rats.

MATERIALS AND METHODS

Pregnant rats were randomly distributed into three experimental groups: NT=non-treated; TOil=treated with neem seed oil (1.2 mL/day); TAP=treated with active principle of Azadirachta indica (azadirachtin-1.0 mg/mL/day). The neem oil (1.2 mL/day) or azadirachtin (1.0 mg/mL/day) treatments were orally administered throughout pregnancy. Blood samples were collected on days 0, 7, 14 and 20 of pregnancy. Oral glucose test tolerance (OGTT) was performed at day 17 of pregnancy for estimation of total area under the curve (AUC). At term, the fetuses were collected and external and internal (visceral and skeletal) malformations were analyzed.

RESULTS

The data showed that the dams treated with neem seed oil and Azadirachtin had no significant change in glucose levels and AUC. It was also verified that neem oil treatment contributed to increase the frequency of malformation/variation, in particular the visceral in their fetuses, while neither significant result was observed in TAP group.

CONCLUSION

In conclusion, neem seed oil treatment administered during pregnancy caused abnormalities in rat fetuses, showing teratogenic effect but the Azadirachtin (active principle) presented no impairment in the fetuses.

Potential antifertility agents from plants: a comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional medicines are practiced worldwide for regulation fertility since ancient times. This review provides a comprehensive summary of medicinal flora inhabitating throughout the world regarding their traditional usage by various tribes/ethnic groups for fertility regulation in females.

MATERIALS AND METHODS

Bibliographic investigation was carried out by analyzing classical text books and peer reviewed papers, consulting worldwide accepted scientific databases from the last six decades. Plants/their parts/extracts traditionally used for abortion, contraception, emmenagogue and sterilization purposes have been considered as antifertility agents. Research status of selected potential plant species has been discussed. Further, compounds isolated from plants with attributed fertility regulating potentials are also classified into three categories: (a) phytoconstituents with anti-implantation activity, (b) phytoconstituents with abortifacient activity and (c) phytoconstituents with contraceptive activity.

RESULTS

577 plant species belonging to 122 families, traditionally used in fertility regulation in females, have been recorded, of which 298 plants have been mentioned as abortifacients (42%), 188 as contraceptives (31%), 149 as emmenagogues (24%), and 17 as sterilizers. Among 122 plant families, fabaceae constitutes 49.2%, asteraceae 40.98%, euphorbiaceae 19.7%, apiaceae 16.4%, poaceae 12.3%, labiateae 11.5%, and others in lesser proportion. Various plant parts used in fertility regulation include leaves (25%), roots (22%), fruits (15%), seeds (12%), stem/stem bark (37%), and flowers (4%). Some active compounds, isolated from about various plant species, have been reported to possess significant antifertility potential.

CONCLUSION

This review clearly indicates that it is time to increase the number of experimental studies to find out novel potential chemical entities from such a vast array of unexploited plants having traditional role in fertility regulation. Also, the mechanisms of action by which plant extracts and their active compounds exert antifertility effects remain to be studied.

Contraceptive efficacy and safety of HerbOshield™ vaginal gel in rats

BACKGROUND

Spermicides represent one of the methods of contraception. The synthetic agents available as spermicides produce severe side effects. Hence, there is a need to replace these agents with safe and effective agents such as plant-based contraceptive agents.

STUDY DESIGN

The objective of the present study was to develop and evaluate a stable, safe, effective and easily acceptable contraceptive delivery system containing herbal drug. Efforts were made to evaluate the contraceptive potential of the hydroalcoholic extract from the seeds of Annona squamosa Linn. and the vaginal gel HerbOshield™ containing the extract.

RESULTS

Spermicidal effect was evaluated in vitro using healthy human spermatozoa and in vivo in rats. The in vitro results demonstrated that HerbOshield™ vaginal gel is an effective spermicide. At a 100-mg/mL dose, complete immobilization of human spermatozoa was observed within 20 s. None of the treated animals conceived, indicating 100% contraceptive effect as compared to Gynol II, a nonoxynol-9-containing marketed formulation, which showed only 67% contraceptive effect in vivo. HerbOshield™ vaginal gel was found to be safe in animals during a 14-day toxicity study.

CONCLUSIONS

HerbOshield™ vaginal gel was found to be safe and effective in rats and could be developed as a potential vaginal contraceptive for future use in humans.

Spermicidal activity of Azadirachta indica (neem) leaf extract

The present study was carried out to evaluate the effective concentration of aqueous extract of old and tender Azadirachta indica (neem) leaves to immobilize and kill 100% human spermatozoa within 20 s. Sander-Cramer test was used to study the spermicidal activity of neem leaf extract. Under the test conditions, minimum effective spermicidal concentrations for tender and old leaf extracts were 2.91 +/- 0.669 mg/million sperm and 2.75 +/- 0.754 mg/million sperm, respectively. The effect of extracts on morphology and viability of sperm was also studied and no change was observed in morphology of head, mid-piece and tail and no viable sperm seen. The leaf extracts were found to be water soluble and carbohydrate in nature. The effect of different concentrations of extracts (old and tender) on percentage motility of the sperm was also studied. With an increase in concentration, there is a linear decrease in percentage motility, becoming zero at a 3-mg dose within 20 s.

Spermicidal activity of the crude ethanol extract of Sedum praealtum in mice

Ethanol extract of Sedum praealtum in intravaginal doses of 10, 20, 40, 50, 100 and 150 mg/kg body weight showed a toxic effect in spermatozoa viability after 24h of administration. Spermatozoa viability was 94, 83, 58 and 24%, respectively, for extract doses of 10, 20, 40 and 50mg/kg body weight, while only dead spermatozoa were found in the vagina of the treated female mice with doses of 100 and 150 mg/kg body weight.

Spermicidal activity of seed oil of Pongamia glabra

The medicinal properties of seed oil of Pongamia glabra are well known in traditional Indian medicine. It has antimicrobial activity against several organisms. It is used in the treatment of herpes and scabies and, systemically, it is also used in the treatment of dyspepsia with sluggish liver. The present study demonstrates that in vitro, Pongamia oil has strong spermicidal activity.

Anti-microbial activity of a new vaginal contraceptive NIM-76 from neem oil (Azadirachta indica)

Efficacy of NIM-76, a spermicidal fraction from neem oil, was investigated for its antimicrobial action against certain bacteria, fungi and Polio virus as compared to whole neem oil. The NIM-76 preparation showed stronger anti-microbial activity than the whole neem oil. It inhibited growth of various pathogens tested including Escherichia coli and Kleibsiella pneumoniae which were not affected by the whole neem oil. NIM-76 also exhibited antifungal activity against Candida albicans and antiviral activity against Polio virus replication in vero cell lines. It also protected mice from systemic candidiasis as revealed by enhanced % survival and reduced colony forming units of C. albicans in various tissues. This shows that NIM-76 has a potent broad spectrum anti-microbial activity.

Effects of composite root extract on histological structures of graffian follicle and endometrial epithelium in albino rat

This study attempted in vivo testing of a group of plant root extracts in composite form on the reproductive organs of the female albino rat. These roots in composite form have been used by the folk women of Assam to prevent pregnancy. Firsthand knowledge revealed that the dry powder of these roots in composite form can induce sterility in women temporarily (reversible) or permanently which is dose-dependent when taken through oral route. The study revealed that administration of ethanolic crude extract of these composite roots in a dose of 1000 mg/kg/day, consecutively for 12 days, can modulate histological changes in the structures of ovary and uterus. This dose has previously been detected as the threshold dose to induce sterility (reversible) in albino rat. The ovarian follicle showed structural disparity in thecal cells and granulosa cells, and formation of zona pellucida. In the uterus, the endometrial epithelium on the luminal surface showed pseudostratification, vacuolation of the cells, and irregular desquamation from the stroma. Infiltration of a large number of polymorphs in the endometrial stroma and necrosis of endometrial gland tissues indicated structural and functional aberrations of the uterus.

Immunocontraceptive activity guided fractionation and characterization of active constituents of neem (Azadirachta indica) seed extracts

A novel approach for immunocontraception by intervention of local cell mediated immunity in the reproductive system by using single intrauterine application of neem oil has been described earlier. The reversible block in fertility was reported to last for 107-180 days in female Wistar rats (Upadhyay et al., 1990. Antifertility effects of neem oil by single intrauterine administration: A novel method of contraception. Proceedings Of The Royal Society Of London B 242, 175-180) and 7-11 months in monkeys (Upadhyay et al., 1994. Long term contraceptive effects of intrauterine neem treatment (IUNT) in bonnet monkeys: An alternative to intrauterine contraceptive devices. Contraception 49, 161-167). The present study, describes the identification and characterization of the biologically active fraction from neem seeds (Azadirachta indica A. Juss. Family Meliaceae), responsible for the above activity in adult female Wistar rats. Initial studies with the mechanically extracted oil and solvent extracts of neem seeds have revealed that the antifertility activity was present in constituents of low to intermediate polarity. A hexane extract of neem seeds was reported to be biologically active (Garg et al., 1994. Comparison of extraction procedures on the immunocontraceptive activity of neem seed extracts. Journal of Ethnopharmacology 22, 87-92). Subsequently, hexane extract was sequentially fractionated through the last active fraction using various separation techniques and tested for antifertility activity at each step. Preparative HPLC was used for isolating individual components of the active fraction in quantities, sufficient for characterization. An analytical HPLC method was developed for standardization of the fraction. The active fraction was identified to be a mixture of six components, which comprises of saturated, mono and di-unsaturated free fatty acids and their methyl esters. Dose response study was performed with the last active fractions. The antifertility activity with the active fraction was reversible in nature and it was completely active until 5% concentration. There was no systemic toxic effect following the administration of the active fraction. This study, for the first time, proposes an active fraction from neem seeds, responsible for long term and reversible blocking of fertility after a single intrauterine administration with high efficacy.

Mechanism of action of NIM-76: a novel vaginal contraceptive from neem oil

The present study was undertaken to elucidate the mechanism of spermicidal action of NIM-76, a fraction isolated from neem oil. The spermicidal activity of NIM-76 was confirmed using a fluorescent staining technique. NIM-76 was found to affect the motility of the sperm in a dose-dependent manner. Supplementation of pentoxifylline, which is known to enhance the motility of the sperm, could not prevent the spermicidal action of NIM-76. There was a gradual leakage of cytosolic LDH from the sperm in the presence of NIM-76. Electron microscopic studies revealed the formation of pores and vesicles over the sperm head, indicating the damage to the cell membrane. Membrane fluidization studies did not reveal any significant change in the fluidity of sperm cell membrane structure.

Minor and trace elemental determination in the Indian herbal and other medicinal preparations

Medicinal plants described in the Indian "Ayurvedic" literature viz. Tulsi (Ocimum sanctum), Gulvel (Tinospora cardifolia), bitter Neem (Azadirachta indica), Kanher (Nerium Andicum), Vekhand (Acorus calamus), and Peacock's feather (ash) were analyzed for minor and trace elements by instrumental neutron activation analysis. The samples and the standards from the National Institute of Standards and Technology, USA and IAEA, Vienna were irradiated for 5 min, 1 h, 5 h, and 10 h with thermal neutrons at a flux of 10(12)-10(13) n cm-2 s-1 in APSARA and CIRUS reactor at BARC, Bombay. High resolution gamma ray spectrometry was performed using a 45 cm3 HPGe detector and a 4096 MCA system. Concentrations of 13 elements were determined. Zinc, manganese, and sodium were significantly higher in Tulsi leaves while zinc is higher in Neem leaves. Peacock's feathers were found to be rich in manganese, iron, copper, and zinc. A high concentration of mercury was also found in the peacock's feather ash. The therapeutic significance in restoring ionic balance is discussed.

Comparison of extraction procedures on the immunocontraceptive activity of neem seed extracts

Azadirachta indica (Neem) seed extracts are known to activate the local cell-mediated immune reactions after a single intrauterine administration, leading to a long term reversible block of fertility. In order to identify and characterize the active fraction responsible for this activity, neem seeds were extracted by both mechanical expression and solvent extraction using a range of polar to non-polar solvents which yielded 3 broad fractions. The mechanically expressed oil was fractionated using different approaches and studied for antifertility activity. The hexane extract and a corresponding column fraction showed potent and reproducible antifertility activity. Other fractions were less stable with regard to reproducibility of effects and composition. It is our conclusion that for subsequent fractionation to reach the last active fraction, the hexane extract is the most useful starting material.

Neem oil inhibits two-cell embryo development and trophectoderm attachment and proliferation in vitro

PURPOSE

The in vitro effect of neem oil was studied on the development of mouse two-cell embryos and trophectodermal cell attachment and proliferation.

METHOD

Female mice were primed with gonadotropins for superovulation and caged with male mice. Early embryos, at the two-cell and the blastocyst stages, were recovered at 40 and 88 hr post-hCG from the oviducts and the uteri, respectively. In the first experiment, two-cell embryos were exposed to culture medium containing different concentrations of neem oil for 1, 12, and 24 hr and then grown in neem oil-free culture medium and assessed for the formation of total and hatching blastocysts at 96 hr. In the second experiment, partially hatching blastocysts were cocultured with human endometrial stromal cell monolayers in culture medium containing different concentrations of neem oil and assessed for the attachment and proliferation of trophectodermal cells at 96 hr.

RESULTS

Exposure of two-cell embryos to neem oil concentrations of 0.050-0.500% for 1 hr, 0.010-0.250% for 12 hr, and 0.005-0.100% for 24 hr caused significant inhibition of the formation of total and hatching blastocysts, in a dose-dependent manner. Neem oil at 0.050-0.100% concentrations inhibited, in a dose-dependent manner, the in vitro attachment and proliferation of trophectodermal cells of partially hatching blastocysts cocultured with human endometrial stromal cells monolayers.

CONCLUSION

Neem oil inhibits the development of two-cell embryos and attachment and proliferation of the trophectodermal cells of partially hatching blastocysts in vitro. The study encourages the use of this herbal product as a postcoital contraceptive that warrants further research.

Synergistic spermicidal activity of neem seed extract, reetha saponins and quinine hydrochloride

In order to identify potent spermicidal agents which are free from the side effects of currently available agents, spermicidal activity of purified neem seeds extract (Praneem), reetha saponins and quinine hydrochloride was studied individually and in combination. Sander-Cramer test was used to assess the activity on human sperm. Under the test conditions, minimum effective spermicidal concentrations for Praneem, reetha saponins and quinine hydrochloride were 25%, 0.05% and 0.346%, respectively. At these concentrations, 100% of the sperm were immobilised within 20 seconds. A positive synergistic effect in the spermicidal activity of these components, if used in combination, was observed which implies the use of reduced concentrations of each to bring about the desired action. The selected combination formulated into a suitable dosage form is likely to offer dual benefit of a potent contraceptive and an antimicrobial preparation.