Mohideen M, Abidin N. S. I. Z, Idris M. I. H, Kamaruzaman N. A. An Overview of Antibacterial and Antifungal effects of Azadirachta indica Crude Extract: A Narrative Review. Biomed Pharmacol J 2022;15(1).

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Manuscript received on :07-11-2021
Manuscript accepted on :18-12-2021
Published online on: 30-03-2022

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Reviewed by: Dr. Pavani Laxmi
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Final Approval by: Dr. H Fai Poon

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Mazlin Mohideen^1*, Nor Syamimi Izzati Zainal Abidin¹, Mohamad Iqbal Hazmie Idris¹  and Nur Azzalia Kamaruzaman²

¹Faculty of Pharmacy and Health Sciences, Universiti Kuala Lumpur Royal College of Medicine Perak, 30450 Ipoh, Perak, Malaysia

²National Poison Centre, Universiti Sains Malaysia, 11800 Minden, Pulau Pinang, Malaysia

Corresponding Author E-mail: mazlin.mohideen@unikl.edu.my

DOI : https://dx.doi.org/10.13005/bpj/2391

Abstract

Azadirachta indica, commonly known as neem, or Margosa, originated in India. It is one of the species in the Azadirachta genus. It is native to South Asia's Indian subcontinent and dry areas such as India, Nepal, Sri Lanka, Bangladesh, Pakistan and the Maldives. The plant has long been used in Ayurvedic and folk medicine and it is now commonly used in cosmetics and organic agriculture. Several pharmacological activities were identified from the crude extract of Azadirachta indica, which have attracted a lot of research interest from scientists. This narrative review explores the vast potential of neem in eliciting antibacterial and antifungal effects. Furthermore, we highlight the various effects of different types of solvent and several parts of the neem plant on growth inhibition of bacteria and fungi by performing the inhibition zone technique using the disc diffusion method, one of the commonly used methods to measure bacterial, fungal growth.

Keywords

Azadirachta Indica; Antibacterial; Antifungal; Disc Diffusion; Inhibition Zone

Introduction

Herbal medicines have been known to man for centuries as records of their uses have been reported since ancient times.  The medicinal use of herbal remedies was first mentioned in ancient Hindu texts such as Vedas. These herbs formed an essential part of Indian culture’s medical science – Ayurveda (Rastogi et al., 2002).  Currently, practitioners of traditional medicines worldwide have described the therapeutic effects of many plant species for multiple disorders, either in the forms of natural herbs or their various extracts (Joshi & Sahu, 2014). The bulk of the population in developed countries also harness traditional folk medicines extracted from plant materials. Herbal medicines are a significant source of novel drugs which make up the ingredients in conventional medicinal systems, pharmaceutical intermediates, modern medicines, nutraceutical food supplements, lead compounds in synthetic drugs, and bioactive principles (Bijauliya et al., 2018). However, the significance and value of medicinal plants are still not recognized by many new generation people.

Neem (Azadirachta indica), an evergreen tree, is an extremely beneficial plant and was first discovered in Indonesia, a tropical climate (Saleem et al., 2018). Neem belongs to the Meliaceae family, a subfamily of Meloidae and the tribe of Melieae, and its botanical name is Azadirachta indica A. Juss. Neem is also generally known as ‘Indian lilac’ or ‘Margosa’ and could be found easily in India (Bhat & Girish, 2008). Some parts of neem plants can cure many diseases, including acute and chronic diseases (Chen et al., 2018). In addition, for thousands of years, people, especially from the Asian and African regions, have been using neem as a remedy for various types of diseases (Gupta et al., 2017). Neem plants are now grown in different countries worldwide, including Asian countries, the United States of America, Australia and African countries (Ghosh et al., 2016). The United Nations acknowledged the many advantages of the plant in treating various ailments that they referred neem as “trees of the 21^st century” and “a tree to solve global issues” (Kumar & Navaratnam, 2013).

Neem is a big tree (Figure 1) that can grow on dry and rocky soil, up to 700 m in height in various climatic conditions, and it can live for over 200 years. Neem plants often grow in rainfall regions with 450-1200 mm; pH varies from 4-10 and temperatures from 0-49 °C. In addition, neem could grow in very low-rain areas of 150-200 mm (Saleem et al., 2018). The tree becomes mature and productive within 10 years (Maragathavalli et al., 2012).

Figure 1: Tree of Azadirachta indica (adapted from    http://www.bothranursery.com/) Click here to view figure

The neem leaves (Figure 2a) can grow for up to 30 cm.  Each leaf contains 10-12 serrated leaflets, 7 cm long by 2.5 cm wide, mildly yellowish-green in color, odorless and bitter. In early summer, the tree produces delicate flowers (Figure 2b). The flowers (fragrant and white) have axillary arrangements, typically almost drooping panicles up to 25 cm long. Its fruit (Figure 2c) is semi-sweet and olive-sized. The bark of this tree (Figure 2d) varies considerably in thickness, depending on the age and sections of the tree from which it is taken; rusty-grey and fissured, rugged outer surface, foliaceous and yellowish laminated inner surface, crack, fibrous, odor, bitterness. The seed (Figure 2e) is rich in oil with significant therapeutic and botanical properties. Neem tree grows in almost all soil types, such as clay, saline soils, and alkaline, and it does not need much water and sunlight to grow (Ghosh et al., 2016).

Figure 2: (a) Leaves of A. indica; (b) Flowers of A. indica (adapted from http://keyserver.lucidcentral.org/weeds/ data/ media/ Images/ azadirachta_indica/ azadirachtaindica36.jpg; (c) Fruits of A. indica; (d) Stem bark of A. indica; (e) Seeds of A. indica Click here to view figure

Neem leaves have been reported to elicit various therapeutic effects such as antioxidant, anti-inflammatory, antimalarial, antiulcer, antihyperglycemic, antimutagenic, antidiabetic, anticarcinogenic, immunomodulatory and anticancer. Neem leaves and paste are also conventionally used to cure allergic skin reactions and treat smallpox and chickenpox (Hla et al., 2011). Furthermore, neem leaves have shown antifungal and antibacterial activities against various pathogenic microorganisms and antiviral effects for treating measles, Chikungunya, Vaccinia and Coxsackie B viruses (Gupta, 2016; Gupta et al., 2017). In addition, neem leaves have been reported for effects on antifertility (Saleem et al., 2018), spermicidal and contraception (Gupta, 2016), as this form of herbal contraception is non-hormonal and has reported no side effects (Tiwari et al., 2014). The diverse, active constituents contribute to the potential antifertility effect of neem leaves in the leaves (Hashmat et al., 2012). Women in the village of northwest Madagascar were reported to take neem leaves to avoid pregnancy. Women in villages in southwestern Madagascar chew neem leaves every day to prevent conception; in Gambia and Ghana, they drink tea prepared from neem leaves to induce abortion during the first 2-3 months of pregnancy (Ketkar et al., 2005). Besides that, most urban Bangladeshis, Nepalese and Indians have been using neem twigs to clean their teeth. The green juice of neem has also been used as a tonic to increase appetite and kill intestinal worms (Ghimeray et al., 2009). Other effects of neem include hypolipidemic, hypoglycaemic, hypotensive and hepatoprotective activities and reducing fever (Chaturvedi et al., 2011). The leaf extract has been used therapeutically for its antimicrobial effects against dental pathogens (Khan et al., 2010). Due to neem’s vast therapeutic applications, products from the plant were manufactured for various ailments such as cancer, digestive disorders, AIDS and skin diseases (Kumar & Navaratnam, 2013).

Neem Leaf’s Active Compounds

Indica (neem) contains several constituents with different therapeutics properties, whereby proteins, carbohydrates and fat derivatives are the main compounds. In contrast, A. Indica has secondary metabolites such as alkaloids, flavonoids, saponins, and steroids (Kumar et al., 2016). The active compounds of neem are divided into two major categories, isoprenoid and non-isoprenoid. Triterpenoid and diterpenoid are part of the isoprenoid group, named limonoid, gedunin, protomeliasin and azadiron. Non-isoprenoid compounds include sulfur, proteins, dihydrochalcone, carbohydrates, glycoside and polyphenols (Saleem et al., 2018). Azadirachtin is the essential constituent with Nimbin, nimbidol, nimbolinin, nimbidin, sodium nimbinate, salannin, quercetin and gedunin. The leaves also contain Nimbin, nimbandiol, 6-desacetylnimbine, nimbanene, nimbolide, n-hexacosanol, ascorbic acid, amino acid nimbiol, 17-hydroxyazadiradione, 7-desacetyl-7-benzoylgedunine and 7-desacetyl-7-benzoylazadiradione (Hossain et al., 2011). Quercetin and β-sitosterol, polyphenolic flavonoids, are purified from fresh neem leaves and possess antibacterial and antifungal effects (Govindachari et al., 1998).

With the rising phenomena of antimicrobial resistance, many medicinal plants were screened for their possible antimicrobial action. Furthermore, plants contain a wide range of biologically active molecules, making them rich sources of various medications; consequently, it is necessary to identify and evaluate such plants with potential antimicrobial activities. This narrative review provides pharmacological activities such as antibacterial and antifungal effects of neem and its medicinal uses.

Materials and Methods

This study utilized various types of literature databases, which included Springer Nature and ScienceDirect. A combination of several keywords used included ‘neem tree,’ ‘Azadirachta indica,’ ‘neem leaf active compounds,’ ‘phytochemical analysis of neem compound,’ ‘antibacterial and antifungal effects of neem leaf extract’ and ‘pharmacological activity of A. indica.’ Relevant articles have been selected to be reviewed for information collection purposes.

Literature Review on Pharmacological Activities of Neem

Neem and its components play a vital part in inhibiting the growth of various microbes, like bacteria and fungi. Antibacterial and antifungal activities of neem are described in the following sections.

Antibacterial effect of neem extract

Oil extracted from neem bark, leaves and seeds reveal its potent activity against organisms of gram-negative, gram-positive and mycobacterium tuberculosis (Srivastava et al., 2020). Neem oil extract yields four fractions of hexane in organic solvent methanol, such as methanol miscible for the first fraction (a), methanol immiscible for the second fraction (b), hexane miscible for the third fraction (c) and hexane immiscible for the fourth fraction (d). The first fraction displays a maximum antibacterial effect at 95%. The second and third fractions indicate 85% activity, and the fourth fraction exhibits 65% activity (Barman et al., 2009). Methanol, aqueous and petroleum ether extracts of the A. indica leaves have been screened for their antimicrobial properties using the cup plate agar well diffusion technique.  The evaluation was conducted on six types of bacteria, which were gram-positive bacteria, Bacillus subtilis (B. subtilis) and Staphylococcus aureus (S. aureus) and four gram-negative bacteria, Escherichia coli (E. coli), Proteus vulgaris (P. vulgaris), Pseudomonas aeruginosa (P. aeruginosa) and Salmonella typhi (S. typhi). It was found that the A. indica methanol extract showed marked action against B. subtilis with an inhibition zone around 28 mm (Grover et al., 2011).

Another study was conducted by Muhammad et al. (2019) were investigated the antibacterial activity of neem leaf extract against specific clinical isolates, which were E. coli, Klebsiella pneumonia (K. pneumonia) and S. aureus. The phytoconstituents in neem were extracted using ethanol as a solvent; a Soxhlet extractor was used to evaluate the extract using standard techniques. Some of the studied bioactive compounds were saponin and alkaloids, flavonoids, phenols and tannins. Compared with gram-positive S. aureus, the extract was much more efficient in inhibiting the growth of gram-negative K. pneumonia and E. coli. The extract inhibition zones at the 125 mg/ml concentration were 21 mm and 16 mm, respectively, for gram-positive and gram-negative bacteria. The means of the minimum inhibitory concentrations (MICs) of A. indica leaf extracts in-vitro were shown to be at a significantly lower concentration of 50 mg/ml for E. coli relative to 100 mg/ml for S. aureus. Meanwhile, the minimum bactericidal concentrations (MBCs) of A. indica leaf extract indicated that the extract has bacteriostatic activity against gram-negative bacteria but a static effect against gram-positive bacteria.

A review was conducted to assess the antimicrobial sufficiency of herbal substitutes as endodontic irritants and differentiated with generic irritant sodium hypochlorite (Giri et al., 2019; Ahmad et al., 2019). The result verified that neem leaf extract demonstrated profound inhibition zones of indicated antibacterial activity. It was also found that neem leaf extract exhibited more specific inhibition zones than 3% sodium hypochlorite (Ghonmode et al., 2013). Furthermore, the antibacterial efficacy of neem extracts toward 21 strains of foodborne pathogens was tested. The examination findings suggested that extracts produced compounds with an antibacterial activity that could be important in inhibiting the growth of foodborne pathogens and other life forms of deterioration (Hoque et al., 2007).

Further research was conducted by Ghonmode et al. (2013) to evaluate the antibacterial efficacy of A. indica seed, fruit, bark and leaf extracts on bacteria isolated from the adult mouth. The results displayed that leaf and bark extracts exhibited antibacterial effects against all of the tested microorganisms. Moreover, fruit and seed extracts exhibited higher concentrations of antibacterial activities. Results also indicated that neem bark extract blocked the herpex simplex virus (HSV-1) entry into cells at 50 and 100 μg/ml (Yerima et al., 2012).

In one study by Bijauliya et al. (2018). A. indica methanolic leaf extract was evaluated for its antibacterial, antihemorrhagic and antisecretory effects against Vibrio cholera (Thakurta et al., 2007). In addition, methanol, chloroform and hexane extracts of A. indica were tested for antibacterial effects against K. pneumonia, E. coli, Micrococcus luteus, Enterococcus faecalis, P. Vulgaris, B. subtilis and Streptococcus faecalis.

Another study by Koona & Budida (2011) concluded that methanol neem extract exhibited the highest antibacterial activity, while chloroform extract exhibited moderately active antibacterial activity. Hexane extract exhibited the lowest antibacterial activity against several types of bacteria.

Neem leaf, bark and seed oil extracts provided a wide range of antibacterial effects against gram-negative and gram-positive microorganisms, including streptomycin-resistant strains and Mycobacterium tuberculosis. Active compounds including alkaloids, flavonoids, tannins, saponins, steroids and crude glycosides of the neem plant were screened against pathogenic strains of S. aureus, E. coli and Corynebacterium bovis for antibacterial activity (Aslam et al., 2009).

Hymete et al. (2005) also supported the outcomes and conveyed FIGUREthat flavonoids possess antimicrobial properties. A study by Hafiza et al. (2002) also showed that saponins inhibited the growth of microbes. Acetone and methanol extracts of A. indica leaves have been evaluated for antibacterial properties against two distinct bacterial strains, which were B. subtilus and E. coli, and methanol extracts have been reported to have higher antibacterial properties compared with acetone extracts (Lall et al., 2013).

Another research was conducted by Bassey and colleagues (2016) using the agar diffusion technique to conduct in vitro analysis of the antibacterial capability of acetonic, ethanolic and methanolic extracts of bark and leaves of the neem plant. These extracts had been prepared and tested for the presence of various phytochemicals. The findings revealed that both bark and leaf extracts contained an alkaloid, reducing sugar, flavonoid, tannin, polyphenol and saponin. The neem plant’s methanolic, ethanolic, and acetonic bark and leaf extracts have been screened against selected pathogens, including S. aureus, E. coli, P. aeruginosa, Aspergillus fumigatus, Candida albicans, and Aspergillus niger by agar well diffusion method. The MIC for stem bark extract was 6.25 mg/ml, while the MBC for stem bark extract was 25 mg/ml. Analysis indicated that the bark extract elicited more robust antimicrobial activity toward fungi and bacteria at different concentrations when compared with the leaf extract. The zone of inhibition for acetonic stem bark extract was 22 mm, a maximum antibacterial activity.

The methanol stem bark extract had maximum antifungal activity, with an inhibition zone of 22.50 mm. In contrast, ethanol extract from the stem bark reported an inhibition zone of 21 mm. Therefore, the results indicated some bioactive compounds and antimicrobial properties in leaf and stem bark extracts (Bassey et al., 2016).

An in vitro study by Francine et al. (2015) was performed to examine the antimicrobial effect of bark and leaf extracts of A. indica. Aqueous and ethanol extract of barks and leaves were screened against E. coli and S. aureus, which are known to be resilient to numerous antibiotics. Using the agar disc diffusion technique, the effectiveness of the extracts of various concentrations was observed on two cultivated bacterial strains. Aqueous and ethanol extracts were extracted from the fresh and dried barks and leaves of neem. Results suggested that fresh neem materials caused significant effects on S. aureus and E. coli compared to dry extracts. In addition, ethanol extracts were found with higher antibacterial activity compared to aqueous extracts. The findings demonstrated that the efficiency of the extracts relied on the concentration used; therefore, an increase in the concentration of the extracts increased the zone of inhibition (Francine et al., 2015).

The susceptibility of the pathogenic microorganisms to the leaves extracts has been contrasted with one another and chosen antibiotics (Chhibber & Sharma, 2014). A. indica methanol extract showed marked action against B. subtilis with an inhibition zone around 28 mm (Dholi et al., 2011). The preparation of neem oil has been reported to elicit effective inhibitory activity against a broad spectrum of bacteria viz., B. cereus, B. pumilus, E. coli, P. Vulgaris, S. aureus, M. tuberculosis, S. Typhi, K. pneumonia, Salmonella dysentery, E. faecalis, Streptococcus mutants, Streptococcus sanguis, Streptococcus mitis, Streptococcus salivarius and even Streptomycin resistant strains (Mehrota et al., 2010; Sarmiento et al., 2011; Rosaline et al., 2013). A. indica leaf extract has good antibacterial activity, thereby validating the enormous potential of phytoconstituents and justifying the usage of this plant in primary health care (Koona & Budida, 2011). Besides that, neem oil possesses an antiplaque effect (Elavarasu et al., 2012), while neem leaf extract inhibits the growth of P. aeruginosa by obstructing the biofilm formation in this bacteria strain (Harjai et al., 2013).

El-Mahmood et al. (2010) reported the antibacterial activity of neem seed crude extracts against microorganisms involved in the eye and ear infection. Pure methanol, acetone and ethanol extracts of neem seeds were tested against bacterial strains such as E. coli, S. typhus, B. subtilis, S. aureus, K. pneumonia and Staphylococcus epidermis. Irshad et al. (2011) also reported that acetone neem extracts exhibited maximum antibacterial effect relative to other solvent extracts. Another study reported that neem seed oil showed bactericidal action against 14 pathogenic bacterial strains (Baswa et al., 2001). Furthermore, crude aqueous and solvent extracts of A. indica were tested against 20 pathogenic bacterial strains, wherein crude extracts showed better outcomes (Srinivasan et al., 2001). Ethanolic neem leaf extracts and bark of the neem plant were tested for antibacterial effects on S. mutants. It was found that neem stick extracts possessed more antibacterial activity than leaf extracts (Siswomihardjo et al., 2007).

Neem leaf extracts were screened against Vibrio alginolyticus (V. alginolyticus) and Vibrio parahaemolyticus (V. parahaemolyticus), isolated from shrimps. Aqueous leaf extract produced no inhibitory zone. In contrast, neem juice produced an inhibitory zone which demonstrated a linear relationship to neem juice concentration on both bacteria. The MICs were 6.25 and 3.13 mg/ml for V. parahaemolyticus and V. alginolyticus, respectively. At the same time, the MBCs were 25.00 and 12.50 mg/ml for V. parahaemolyticus and V. alginolyticus, respectively. Thus, neem juice could be concluded as an antibacterial agent and is beneficial for the vibrios inhibitors in shrimp (Banerjee et al., 2013). The methanolic extract of neem has the most potent growth-inhibitory action on both clinical and standard isolated strains of P. aeroginosa. Ethanol and ethyl acetate extracts showed a growth inhibitory effect on both standard isolated strains of S. aureus. In the case of E. faecalis, methanol and ethanol extracts revealed maximum growth inhibitory effects against the clinical and standard strains, respectively. Based on the MIC index effects, methanolic extract possessed bactericidal effect against both standard and nosocomial strains of P. aeroginosa and S. aureus and bacteriostatic effect against the nosocomial strain E. faecalis. The ethanolic extract exhibited bactericidal activity towards both standard and nosocomial strains of P. aeroginosa and E. faecalis and bacteriostatic activity against the nosocomial strain of S. aureus. Ethyl acetate extract had revealed bactericidal activity against standard strains of P. aeroginosa and S. aureus and bacteriostatic against the standard strain of E. faecalis and nosocomial strain of S. aureus. Thus, neem can be an effective therapeutic agent to fight antibiotic-resistant bacteria (Maleki et al., 2018).

Antifungal effect of neem extracts

Alcoholic extract of neem leaves is beneficial in retarding Aspergillus and Rizopous fungal species (Srivastava et al., 2020). The antifungal properties of neem could also be found in oil and bark extracts and the other parts of neem extracts (Mahmoud et al., 2011).

Another study was conducted to determine antifungal activity of various neem leaf concentrates on seed-borne parasites such as Aspergillus and Rhizopus; the findings showed that the growth of both infectious species was profoundly depressed and regulated by aqueous and alcoholic extracts (Giri et al., 2019). Moreover, an alcoholic neem leaf extract was tested. Leaves and seed kernels of neem were utilized as antifungal agents (Ahmad et al., 2019). Neem seed kernel extract decreases significantly (P<0.05) on post-harvest diseases, pathogens of Penicillium expansum, Monilinia fructicola, Alternaria and Trichothecium Roseum alternate in-vitro (Singh & Purohit, 2011). It could also be observed that ethanolic, aqueous. Ethyl acetate neem leaf extracts (5, 10, 15 and 20%) inhibited human pathogens (A. niger, Aspergillus flavus, A. fumigatus, A. terreus, C. Albicans and M. gypsum).

Antidermatophytic activity against dermatophyte isolates has been demonstrated using the agar dilution method to produce aqueous and ethanolic neem leaf extracts (Bijauliya et al., 2018). Ethanol extract exhibited more visible activity than aqueous extract (Venugopal & Venugopal, 1994). Antifungal properties were also screened using acetone and methanolic extracts of A. indica against two distinct fungal strains, such as A. fumigatus and A. niger. It was stated that methanolic neem extract exhibited extreme antifungal effects compared to acetonic extracts (Lall et al., 2013).

In vitro antifungal activity of different concentrations of ethyl acetone and aqueous ethanolic extracts of neem leaves was investigated on a few human pathogens (C. Albicans, A. flavus, A. fumigates, A. niger, A. terreus, and M. gypsum). It was documented that these extracts helped to prevent the growth of the tested pathogenic organisms, and the effect improved significantly as the concentrations increased (Mahmoud et al., 2011). Gedunin segregated from neem seed oil has conveyed antifungal properties. Mohanty et al. (2008) conducted a study to evaluate the antifungal effect of neem against Metarhizium anisopliae (M. anisopliae) and Lagenidium giganteum (L. giganteum) in Emerson’s Yeast Soluble Starch (YpSs) and Peptone Yeast Extract Glucose Broth (PYG) agar media. A higher MIC value of neem oil was reported for L. giganteum compared to M. anisopliae. For both fungi, a less fungicidal concentration of neem oil was observed in the PYG medium than YpSs (Mohanty et al., 2008). Another study examined antifungal properties of neem leaf extract against three fungal species – Cladosporium, Alternaria solani and A. flavus. Methanolic and ethanolic extracts in distinct concentrations (25, 50, 75 and 100%) were screened against test organisms using the disc diffusion technique. Ketoconazole was a positive control to relate neem leaf extract’s toxicity against its antifungal properties (Shrivastava & Swarnkar, 2014).

Another experiment by Alzohairy (2016) was conducted to determine the effectiveness of different neem leaf extracts inhibiting the growth of seed-borne fungi. Results confirmed that the growth of Rhizopus and Aspergillus was substantially controlled and inhibited by both alcoholic and water extracts. Furthermore, alcoholic leaf extract was more effective than aqueous extract to retard the growth of both fungal species (Mondali et al., 2009). Other findings displayed the antimicrobial role of aqueous extracts of neem by inhibiting spore germination against three sporulating fungi, including H. pennisetti, C. lunata and C. gloeosporioides f. sp. mangiferae (Kumari et al., 2013), while results of another study demonstrated that ethanol and methanol extracts of A. indica displayed growth inhibition against Cladosporium, A. solani and A. flavus (Shrivastava & Swarnkar, 2014). Aqueous extracts of neem oil and its main principles possess antifungal properties conveyed by earlier investigators (Lloyd et al., 2005). An experiment was undertaken to observe the antifungal effect of A. indica against A. solani. The findings showed that the ethyl acetate fraction was most effective in retarding fungal growth with a MIC of 0.19 mg. This fraction was also significant than fungicide (metalaxyl and mancozeb) as the fungicide has a MIC of 0.78 mg (Jabeen et al., 2013).

Conclusion

This review paper presented an overview of the antibacterial and antifungal effects of Azadirachta indica neem Extract. Neem is a powerful medicinal plant endowed with potential therapeutic benefits, mainly for antibacterial and antifungal properties. In addition, industrial and medicinal sectors prepare countless formulations of neem through potent clinical uses in developing novel drugs to treat different ailments due to their effectiveness against pathogens. Thus, these past few decades have shown a progressively growing interest in neem research in chemistry exploration and therapeutic discovery. Even with this establishment, it is still imperative that research on neem’s clinical importance and value is actively continued for enhanced economic and medicinal applications.

Acknowledgements

The authors gratefully acknowledge the Faculty Pharmacy and Health Sciences, Universiti Kuala Lumpur – Royal College of Medicine Perak for Final Year Project financial support.

Conflict of Interest 

We declare that we have no conflict of interest.

Funding Sources

There is no funding source.

References

1. Ahmad S, Maqbool A, Srivastava A and Gogoi S. Biological detail and therapeutic effect of Azadirachta Indica (neem tree) products – a review. Journal of Evidence-Based Medicine, 2019; 6(22): 1607-1612.
   CrossRef
2. Alzohairy M. A. Therapeutics Role of Azadirachta indica (Neem) and Their Active Constituents in Diseases Prevention and Treatment. Evidence-Based Complementary & Alternative Medicine, 2016; 11.
   CrossRef
3. Aslam F, Khalil-ur-Rehman, Asghar M and Sarwar M. Antibacterial Activity of Various Phytoconstituents of Neem. Pakistan Journal of Agriculture Sciences, 2009; 46(3): 209-213.
4. Banerjee S, Kim L. M, Shariff M, Khatoon H and Yusoff F. M. Antibacterial Activity of Neem (Azadirachta indica) Leaves on Vibrio spp. Isolated from Cultured Shrimp. Asian Journal of Animal & Veterinary Advances, 2013; 8(2): 355-361.
   CrossRef
5. Barman P, Yadav M. C, Kumar H, Meur S. K and Rawat M. Antibacterial efficacy of neem oil fractions on clinical isolates of endometriotic cows. Indian Journal of Animal Sciences, 2009; 79(7): 665-668.
6. Bassey E. E, Mohammed G. A, Bala H. M, Ogonna U. S, Yawuri B. B and Maduchi O. C. Phytochemical Analysis and Antimicrobial Activity of Methanolic, Ethanolic and Acetonic Extracts of Stem Bark and Leaf of Neem Plant (Azadirachta indica). Journal of Diseases & Medicinal Plants, 2016; 2(3): 14-25.
   CrossRef
7. Baswa M, Rath C. C, Dash S. K and Mishra R. K. Antibacterial activity of Karanj (Pongamia pinnata) and Neem (Azadirachta indica) seed oil: a preliminary report. Microbios, 2001; 105(412): 183-189.
8. Bhat S. S and Girish K. Neem – A green treasure. Electronic journal of biology, 2008; 4: 102-111.
9. Bijauliya R. K, Alok S, Chanchal D. K, Sabharwal M and Singh M. An Updated Review of Pharmacological Studies on Azadirachta Indica (Neem). International Journal of Pharmaceutical Sciences & Research, 2018; 9(7): 2645-2655.
10. Chaturvedi P, Bag A, Rawat V, Jyala N. S, Satyavali V and Jha P. K. Antibacterial Effects of Azadirachta indica Leaf and Bark Extracts in Clinical Isolates of. National Journal of Integrated Research in Medicine, 2011; 2(1): 5-9.
11. Chen J, Fan X, Zhu J, Song L, Li Z, Lin F, Yu R, Xu H and Zi J. Limonoids from seeds of Azadirachta indica A. Juss. and their cytotoxic activity. Acta Pharmaceutica Sinica B, 2018; 8(4): 639-644.
    CrossRef
12. Chhibber S and Sharma N. Medicinal and Therapeutical potential of Neem (Azadirachta Indica): A review. International Journal of Scientific & Research Publications, 2014; 4(5): 1-5
13. Dholi S. K, Raparla R, Mankala S. K and Nagappan K. Invivo Antidiabetic evaluation of Neem leaf extract in alloxan-induced rats. Journal of Applied Pharmaceutical Science, 2011; 1(4): 100-105.
14. Elavarasu S, Abinaya P, Elanchezhiyan S, Thangakumaran, Vennila K and Naziya K. B. Evaluation of antiplaque microbial activity of Azadirachta indica (neem oil) in vitro: A pilot study. Journal of Pharmacy Bioallied Sciences, 2012; 4(2): S394-S396.
    CrossRef
15. El-Mahmood A. M, De N and Alo A. B. Susceptibility of nosocomial Staphylococcus aureus, Escherichia coli and Candida albicans to some antimicrobial drugs routinely used in Adamawa State Hospitals, Nigeria. Journal of Clinical Medicine & Research, 2010; 2(8): 125-134.
16. Francine U, Jeannette U and Pierre R. J. Assessment of antibacterial activity of Neem plant (Azadirachta indica) on Staphylococcus aureus and Escherichia coli. Journal of Medicinal Plants Studies, 2015; 3(4): 85-91.
17. Ghimeray A. K, Jin C. -W, Ghimire B. K and Cho D. H. Antioxidant activity and quantitative estimation of azadirachtin and Nimbin in Azadirachta Indica A. Juss grown in foothills of Nepal. African Journal of Biotechnology, 2009; 8(13): 3084-3091.
18. Ghonmode W. N, Balsaraf O. D, Tambe V. H, Saujanya K. P, Patil A. K and Kakde D. D. Comparison of the antibacterial efficiency of neem leaf extracts, grape seed extracts and 3% sodium hypochlorite against E. feacalis – An in vitro study. Journal of International Oral Health, 2013; 5(6): 61-66.
19. Ghosh A. l, Sugumar S, Mukherjee A and Chandrasekaran N. Chapter 67 – Neem (Azadirachta indica) Oils. Essential Oils in Food Preservation, Flavor & Safety, 2016; 593-599.
    CrossRef
20. Giri R. P, Gangawane A. K and Giri S. G. Neem the Wonder Herb: A Short Review. International Journal of Trend in Scientific Research & Development, 2019; 3(3): 962-967.
    CrossRef
21. Govindachari T. R, Suresh G, Gopalakrishnan G, Banumathy B and Masilamani S. Identification of antifungal compounds from the seed oil of Azadirachta Indica. Phytoparasitica, 1998; 26: 109-116.
    CrossRef
22. Grover A, Bhandari B. S and Rai N. Antimicrobial activity of medicinal plants-Azadirachta indica A. Juss, Allium cepa L. and Aloe vera L. Journal of Pharm Tech Research, 2011; 3(2): 1059-1065.
23. Gupta R. C. Nutraceuticals: efficacy, safety and toxicity (1 ed.). Elsevier Academic Press, 2016
24. Gupta S. C, Prasad S, Tyagi A. K, Kunnumakkara A. B and Aggarwal B. B. Neem (Azadirachta indica): An Indian traditional panacea with modern molecular basis. Phytomedicine, 2017; 34: 14-20.
    CrossRef
25. Hafiza M. A, Parveen B, Ahmad R and Hamid K. Phytochemical and Antifungal Screening of Medicago sativa and Zinnia elegans. Journal of Biological Sciences, 2002; 2(2): 130-132.
26. Harjai K, Bala A, Gupta R. K and Sharma R. Leaf Extract of Azadirachta Indica (Neem): A Potential Antibiofilm Agent for Pseudomonas Aeruginosa. Pathogens and Disease, 2013; 69(1): 62-65.
    CrossRef
27. Hashmat I, Azad H and Ahmed A. Neem (Azadirachta indica A. Juss) – A Nature’s Drugstore: An overview. International Research Journal of Biological Sciences, 2012; 1(6): 76-79.
28. Hla K. K, Aye M. M and Ngwe M. H. Some Chemical Analyses and Determination of Antioxidant Property of Neem Leaf (Azadirachta indica A.Juss). Universities Research Journal, 2011; 4(3): 1-9.
29. Hoque M. M, Bari M. L, Inatsu Y, Vijay K. J and Kawamoto S. Antibacterial Activity of Guava (Psidium guajava L.) and Neem (Azadirachta indica A. Juss.) Extracts Against Foodborne Pathogens and Spoilage Bacteria. Foodborne Pathogens and Disease, 2007; 4(4): 481-488.
    CrossRef
30. Hossain M. A, Shah M. D and Sakari M. Gas chromatography-mass spectrometry analysis of various organic extracts of Merremia borneensis from Sabah. Asian Pacific Journal of Tropical Medicine, 2011; 4(8): 637-641.
    CrossRef
31. Hymete A, Iversen T. H, Rohloff J and Erko B. Screening of Echinops Ellenbeckii and Echinops Longisetus for Biological Activities and Chemical Constituents. Phytomedicine, 2005; 12(9): 675-679.
    CrossRef
32. Irshad S, Butt M and Younus H. In-Vitro Antibacterial Activity of Two Medicinal Plants Neem (Azadirachta indica) and Peppermint. International Research Journal of Pharmaceuticals, 2011; 1(1): 9-14.
33. Jabeen K, Hanif S, Naz S and Iqbal S. Antifungal Activity of Azadirachta Indica against Alternaria Solani. Journal of Life Sciences and Technologies, 2013; 1(1): 89-93.
    CrossRef
34. Joshi J and Sahu O. Azadirachta Indica Leaves as Antibacterial Treatment on Drinking Water. International Journal of Clinical Nutrition, 2014; 2(2): 36-40.
35. Ketkar A. Y, Ketkar C. M, Jacobson M, Ketkar M. S and Schmutterer H. Various Uses of Neem Products. The Neem Tree, 2005; 518-558.
    CrossRef
36. Khan I, Srikakolupu S. R, Darsipudi S, Gotteti S. D and Amaranadh H. Phytochemical studies and screening of leaf extracts of Azadirachta indica for its antimicrobial activity against dental pathogens. Archives of Applied Science Research, 2010; 2(2): 246-250.
37. Koona S and Budida S. Antibacterial Potential of the Extracts of the Leaves of Azadirachta indica Linn. Notulae Scientia Biologicae, 2011; 3(1): 65-69.
    CrossRef
38. Kumar D, Rahal A and Malik J. K. Neutraceuticals, Efficacy, Safety and Toxicity. London: Academic Press, 2016.
39. Kumar V. S and Navaratnam V. Neem (Azadirachta indica): Prehistory to contemporary medicinal uses to humankind. Asian Pacific Journal of Tropical Biomedicine, 2013; 3(7): 505-514.
    CrossRef
40. Kumari A, Kumar R, Maurya S and Choudhary J. S. Antifungal efficacy of aqueous extracts of neem cake, karanj cake and vermicompost against some phytopathogenic fungi. An International Quarterly Journal of Life Sciences, 2013; 8(2): 671-674.
41. Lall W. S, Charan A. A and Bind A. Antimicrobial Activity of Methanolic and Acetonic Extracts of Azadirachta Indica, Saraca Asoca and Curcuma Longa. International Journal of Medicine & Pharmaceutical Sciences, 2013; 3(2): 79-86.
42. Lloyd C. A, Menon T and Umamaheshwari K. Anticandidal activity of Azadirachta indica. Indian Journal of Pharmacology, 2005; 37(6): 386-389.
    CrossRef
43. Mahmoud D. A, Hassanein N. M, Youssef K. A and Zeid M. A. Antifungal Activity of Different Neem Leaf Extracts and the Nimonol Against Some Important Human Pathogens. Brazilian Journal of Microbiology, 2011; 42(3): 1007-1016.
    CrossRef
44. Maleki L, Sadeghian-Rizi T, Ghannadian M, Sanati M. H, Shafizadegan S and Sadeghi-Aliabadi H. Antibacterial Activity of Azadirachta indica Leaf Extracts Against Some Pathogenic Standards and Clinical Bacterial Isolates. Avicenna Journal of Clinical Microbiology and Infection, 2018; 5(1): e12987.
    CrossRef
45. Maragathavalli S, Brindha S, Kaviyarasi N. S, Annadurai B. B and Gangwar S. K.  Antimicrobial Activity in Leaf Extract of Neem (Azadirachta Indica Linn.). International Journal of Science and Nature, 2012; 3(1): 110-113.
46. Mehrotra S, Srivastava A. K and Nandi S. P. Comparative antimicrobial activities of Neem, Amla, Aloe, Assam tea and Clove extracts against Vibrio cholera, Staphylococcus aureus and Pseudomonas aeruginosa. Journal of Medicinal Plants Research, 2010; 4(23): 2473-2478.
47. Mohanty S. S, Raghavendra K and Dash A. P. Influence of growth medium on antifungal activity of neem oil (Azadirachta indica) against Lagenidium giganteum and Metarhizium anisopliae. Mycoscience, 2008; 49(5): 318-320.
    CrossRef
48. Mondali N. K, Mojumdar A, Chatterje S. K, Banerjee A, Datta J. K and Gupta S. Antifungal activities and chemical characterization of Neem leaf extracts on the growth of some selected fungal species in vitro culture medium. Journal of Applied Sciences and Environmental Management, 2009; 13(1): 49-53.
49. Muhammad A, Lawan I. M, Abubakar A and Dangora I. I. Antimicrobial Activity of Azadirachta indica (Neem) Leaves Extract Against Some Clinical Isolates. Dutse Journal of Pure & Applied Sciences, 2019; 5(1b): 97-104.
50. Rastogi R. P, Mehrotra B. N, Sinha S, Pant P and Seth R. Compendium of Indian medicinal plants, 2002; (3 ed., Vols. 1-6).
51. Rosaline H, Kandaswamy D, Gogulnath D and Rubin M. I. Influence of various herbal irrigants as a final rinse on the adherence of Enterococcus faecalis by fluorescence confocal laser scanning microscope. Journal of Conservative Dentistry, 2013; 16(4): 352-355.
    CrossRef
52. Saleem S, Muhammad G, Hussain M. A and Bukhari S. N. A Comprehensive Review of Phytochemical Profile, Bioactives for Pharmaceuticals, and Pharmacological Attributes of Azadirachta Indica. Phytotherapy Research, 2018; 32(7): 1241-1272.
    CrossRef
53. Sarmiento W. C, Maramba C. C and Gonzales M. L. An in-vitro study on the antibacterial effect of Neem (Azadirachta indica) leaf extract on methicillin-sensitive and Methicillin-resistant Staphylococcus aureus. PIDSP Journal, 2011; 12(1): 40-45.
54. Shrivastava D. K and Swarnkar K. Antifungal Activity of leaf extract of Neem (Azadirachta Indica Linn). International Journal of Current Microbiology & Applied Sciences, 2014; 3(5): 305-308.
55. Singh A and Purohit B. Tooth Brushing, Oil Pulling and Tissue Regeneration: A Review of Holistic Approaches to Oral Health. Journal of Ayurveda and Integrative Medicine, 2011; 2(2): 64-68.
    CrossRef
56. Siswomihardjo W, Sunarintyas S, Nishimura M and Hamada T. The Different of antibacterial effects of neem leaves and stick extracts. International Chinese Journal of Dentistry, 2007; 7(1): 27-29.
57. Srinivasan D, Nathan S, Suresh T and Lakshmanaperumalsamy P. Antibacterial activity of neem (Azadirachta indica) and tamarind (Tamarindus indica) leaves. Asian Journal of Microbiology, Biotechnology & Environmental Sciences, 2001; 3(1): 67-73.
58. Srivastava S. K, Agrawal B, Kumar A and Pandey A. Phytochemicals of Azadirachta Indica Source of Active Medicinal Constituent Used for Cure of Various Diseases: A Review. Journal of Scientific Research, 2020; 64(1): 285-290.
    CrossRef
59. Thakurta P, Bhowmik P, Mukherjee S, Hajra T. K, Patra A and Bag P. K. Antibacterial, antisecretory and antihemorrhagic activity of Azadirachta indica used to treat cholera and diarrhoea in India. Journal of Ethnopharmacology, 2007; 111(3): 607-612.
60. Tiwari R, Verma A. K, Chakraborty S, Dhama K and Singh S. V. Neem (Azadirachta indica) and its Potential for Safeguarding Health of Animals and Humans: A Review. Journal of Biological Sciences, 2014; 14(2): 110-123.
    CrossRef
61. Venugopal P and Venugopal T. Antidermatophytic activity of neem (Azadirachta indica) leaves in vitro. Indian Journal of Pharmacology, 1994; 26(2): 141-143.
62. Yerima M. B, Jodi S. M, Oyinbo K, Maishanu H. M, Farouq A. A, Junaidu A. U, Al-Mustapa M. N and Shinkafi A. L. Effect of Neem Extracts (Azadirachta indica) on Bacteria Isolated from Adult Mouth. Nigerian Journal of Basic & Applied Science, 2012; 20(1): 64-67.