Natural Medicine: In-Depth Exploration of Moringa oleifera’s Bioactive Compounds and Antimicrobial Effects

Abstract

The antimicrobial capabilities of Moringa oleifera have garnered significant scientific attention due to its rich array of bioactive compounds. This chapter provides a comprehensive examination of the antimicrobial activities exhibited by various components of the Moringa oleifera plant, including seeds, leaves, roots, fruits, and flowers. Notably, Moringa seeds, containing potent 4-(alpha-L-rhamanosyloxy) benzyl isothiocyanates, demonstrate strong antimicrobial effects against a broad spectrum of bacterial strains, including Bacillus cereus and Staphylococcus aureus, as well as fungi. Furthermore, lectins within Moringa seeds interact with bacterial membranes, impeding growth and viability. Moringa leaves exhibit pronounced antimicrobial actions against both Gram-positive and Gram-negative bacteria, facilitated by phenolic compounds that disrupt essential bacterial functions. Similarly, Moringa roots demonstrate antibacterial and antifungal properties, attributed to compounds like N-benzylethyl thioformate, presenting promising alternatives to conventional antibiotics. Additionally, Moringa fruits and flowers display significant antimicrobial efficacy, with bioactive compounds such as phenols and flavonoids demonstrating activity against common pathogens like Candida albicans and Escherichia coli. This in-depth analysis underscores the multifaceted antimicrobial potential of Moringa oleifera, highlighting pathways for further research and the development of novel antimicrobial agents and nutraceuticals.

1. Introduction

The Moringa oleifera plant is renowned for its nutritional density and medicinal versatility and is particularly known for its remarkable antimicrobial properties. This chapter delves into the antimicrobial attributes of various components of the Moringa oleifera plant, analyzing their mechanisms of action and potential therapeutic applications.

The seeds of Moringa oleifera emerge as potent antimicrobial agents, containing 4-(alpha-L-rhamanosyloxy) benzyl isothiocyanates that exhibit striking efficacy against a wide range of bacteria, including Bacillus cereus and Staphylococcus aureus, as well as certain fungi. Additionally, the presence of lectins in Moringa seeds enhances their antimicrobial effects, as they interact with bacterial membranes, ultimately inhibiting their growth and vitality. Moringa leaves also possess impressive antimicrobial activities, effectively defending against both Gram-positive and Gram-negative bacteria, thanks to the phenolic constituents that disrupt the bacterial mechanism. Similarly, Moringa roots display antibacterial and antifungal compounds, such as the indomitable N-benzylethyl thioformate, offering promising alternatives to conventional antibiotics. Furthermore, Moringa fruits contain bioactive compounds like phenols and flavonoids, which embark on campaigns against well-known microbial adversaries, including Candida albicans and Escherichia coli. This diverse array of antimicrobial prowess exhibited by Moringa oleifera calls for further exploration and innovation in the fields of antimicrobial therapeutics and nutraceuticals, promising to unlock new frontiers in the ongoing pathways against microbial infections (Figure 1) [1, 2, 3].

Figure 1.

The antimicrobial activities of various parts of the Moringa oleifera plant. Specifically, the leaves, seeds, roots, flowers, and pods all exhibit antimicrobial properties. Among these, the leaves stand out for their potent antimicrobial activity against Gram-negative bacteria, with Escherichia coli being particularly susceptible. Similarly, the seeds are recognized for their antimicrobial properties. Notably, the roots demonstrate good antibacterial activity against Escherichia coli, Bacillus subtilis, and Staphylococcus aureus, except for the lateral root. Additionally, the flowers and pods of the plant have been utilized as natural preservatives due to their antimicrobial effects. This comprehensive overview underscores the diverse antimicrobial potential inherent in different parts of the Moringa oleifera plan [1].

2. Antimicrobial seeds activities

Despite the flavonoid coat present in its seeds, Moringa oleifera demonstrates antibiofilm potential against Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans [4]which is discernible through the disc diffusion method [2, 5, 6, 7]. Additionally, antimicrobial peptides play a significant role in inhibiting essential enzymes and disrupting cell membranes [8]. Moreover, the Moringa oleifera seeds extract displays antimicrobial activity against Gram-negative bacteria [9, 10]and inhibits bacteriophage replication [11]. Additionally, its antibiotic activity corrects the pathogenic strain actions of Candida albicans, Staphylococcus aureus, and Enterococcus casseliflavus [12]. Besides, while this extract exhibits weaker effectiveness against Pseudomonas aeruginosa and E. coli compared to Bacillus cereus, it demonstrates strong inhibitory effects against Bacillus cereus, Staphylococcus aureus, Mucor species, and Aspergillus species, suggesting potential for treating the related infections caused by these organisms. It also shows inhibitory effects against bacteria such as Staphylococcus aureus [13]and Vibrio cholera [12, 14]. The antimicrobial effect of Moringa oleifera seeds is primarily attributed to its active components (to moringine, pterygospermine, and 4-(alpha-L-rhamanosyloxy) benzyl isothiocyanates [15]). Besides, two different isothiocyanate compounds exhibit a minimum inhibitory concentration of 1 mg/ml against all tested Gram-positive bacteria and dermatophytic fungi [16].

Lectins, carbohydrate-binding proteins present in Moringa seeds, exhibit diverse biological properties, notably antimicrobial activities. Isolated lectins from Moringa oleifera seeds interact with carbohydrates on bacterial membranes, causing damage particularly to species like Bacillus cereus, Bacillus megaterium, Micrococcus sp., Pseudomonas sp., Pseudomonas fluorescens,Pseudomonas stutzeri, and Serratia marcescens [16, 17, 18] thereby inhibiting cell growth and cell death (Figure 2). Moreover, these lectins and proteins bind specifically to carbohydrate motifs and peptidoglycan components in bacterial cell walls, resulting in membrane damage and disruption of structural integrity. Consequently, there is a leakage of cell contents and activation of apoptotic pathways in bacterial cells, which serves as a defence mechanism against pathogens and inhibits bacterial growth by disrupting essential cellular processes.

Figure 2.

Lectins SMO pathway’s actions on pathogenic bacteria. Moringa oleifera seeds contain lectins and proteins that bind to carbohydrates. These lectins target bacterial cell walls, specifically binding to carbohydrate motifs and peptidoglycan components. This interaction leads to membrane damage and disrupts the structural integrity of the cell wall, causing leakage of cell contents and activating apoptotic pathways in bacterial cells. This programmed cell death mechanism serves as a defence against pathogens and inhibits bacterial growth by disrupting essential cellular processes.

3. Antimicrobial leaves activities

Overall, this section highlights the multifaceted antibacterial properties of Moringa oleifera leaves, emphasizing their potential as natural antimicrobial agents with diverse mechanisms of action against bacterial pathogens.

Moringa oleifera leaves (MOL) exhibit significant antimicrobial effects against a wide range of bacterial species, including both Gram-positive (e.g., Staphylococcus aureus, Enterococcus faecalis) and Gram-negative (e.g., Escherichia coli, Pseudomonas aeruginosa) strains [19, 20]. This antimicrobial action is attributed to the inhibition zones generated by the disc diffusion method, indicative of the effectiveness of MOL against various organisms. The antimicrobial action of Moringa leaves is mediated by phytol, a component derived from chlorophyll that can be transformed into phytanic acid which contributes to the inhibition of bacteria such as Pseudomonas aeruginosa and Staphylococcus aureus [1]. A necrotrophic plant fungus are also inhibited at 99% within the methanolic leaves extract [2]. Besides, Moringa oleifera leaves are rich in phenolic compounds, known for their antioxidant and antibacterial properties. These compounds disrupt bacterial enzymatic activity, interfere with DNA structure, and impact bacterial membranes. Such interactions lead to compromised membrane integrity, cell content leakage, and eventual bacterial cell death. Additionally, plant polyphenols found in Moringa leaves act against bacterial cells through various mechanisms, including interaction with bacterial proteins and cell walls, alteration of membrane permeability, and inhibition of DNA synthesis. The amphipathic nature of polyphenolic compounds plays a significant role in their antibacterial activity (Figure 3). Moreover, methanolic extracts of Moringa leaves have shown potential in inhibiting urinary tract infections caused by both Gram-negative and Gram-positive bacteria, including Klebsiella pneumoniae, Escherichia coli, and Staphylococcus aureus.

Figure 3.

Main Moringa’s phenolic compounds antibacterial mechanisms Moringa oleifera leaves are rich in phenolic compounds, renowned for their antioxidant and antibacterial properties. These compounds play a vital role in the leaves’ antibacterial mechanism by impeding bacterial enzymatic activity and interfering with DNA structure upon contact with bacterial cells. By inhibiting key enzymatic processes crucial for bacterial survival and replication, phenolic compounds disrupt vital cellular functions, hindering bacterial proliferation and inducing cellular stress. Moreover, they can directly interact with bacterial DNA, leading to structural alterations that compromise bacterial viability by impeding essential cellular processes like replication and transcription. Additionally, Moringa leaf extracts impact bacterial membranes by interacting with the lipid bilayer, causing destabilization and disruption. This leads to compromised membrane integrity, cell content leakage, and eventual bacterial cell death. Furthermore, interference with ribosomal function by phenolic compounds inhibits protein synthesis and disrupts bacterial translation, further contributing to the antibacterial effect of Moringa oleifera leaves.

In DNA, the molecule and hydrophobic core flatness means that polyphenols can penetrate the DNA helix during replication, recombination, and transcription. Moreover, polyphenols can also combine with metals such as CU²⁺ and form complexes that modify DNA stability. In fact, the inhibition mechanism depends on the polyphenol structure and bacterial species. The molecule’s favorable hydrophilic or hydrophobic characteristics depend on the action sites. So, the amphipathic phenolic compound action plays a major role in antibacterial activity. Additionally, phenolics also interact with synthetic pathways, such as inhibiting topoisomerase or DNA gyrase activity by polyphenols [21, 22].

4. Antimicrobial roots activities

In this section, the antimicrobial activities of Moringa oleifera roots will be investigated, and their potential as a natural remedy against infections will be explored. Thanks to their high content of antimicrobial compounds, such as flavonoids and alkaloids, MO root extracts can inhibit the growth of various harmful bacteria and fungi, including E. coli and Candida albicans. This famous fight against antibiotic-resistant bacterial strains makes these roots a potential alternative to conventional antibiotics.

Thanks to the presence of compounds, such as flavonoids and phenolic acids, which have been found to disrupt bacterial cell membranes and inhibit enzyme activity. The antimicrobial properties of MO roots make them a promising natural alternative for fighting infections.

Besides, Moringa oleifera roots (MOR) are rich in antimicrobial agents and antibacterial activities consequently, and this is due to the powerful antibacterial and fungicidal effects of an active antibiotic known as N-benzylethyl thioformate (an aglycone of deoxyniazimincin). Furthermore, MO’s bark (MOB) extract showed strong activity against Staphylococcus aureus (most sensitive), Bacillus megaterium, Pseudomonas fluorescens, and Citrobacter freundii. Also, the root bark Moringa’s antibacterial and antifungal activities are due to the aglycone of deoxy-niazimicine (N-benzyl, S-ethyl thioformate) [14]. Over and above that, the latter compound is found to be also responsible for these activities in MO root bark. In fact, an effect against Staphylococcus aureus was revealed in stem bark [23]. With further research and development, MO roots may be utilized in the future as a safe and effective treatment option for infections [24, 25].

In fact, some studies revealed that none of the elements extracted from Moringa roots were of concern for drinking water quality. Extracts from this miraculous plant are used not only in medicine but also in other industries such as water treatment [4].

5. Antimicrobial fruits activities

Research indicates that the bioactive compounds in Moringa oleifera fruits offer a range of health benefits, including anti-inflammatory properties and potential therapeutic applications against chronic diseases. The rich array of bioactive compounds underscores the nutritional and medicinal importance of Moringa oleifera as a valuable plant for human health and well-being.

The fruit of Moringa oleifera (MOF), rich in alkaloids, flavonoids, and steroids, exhibits a notable inhibitory impact on Candida albicans cultures, attributed to its steroidal ring structure. This inhibitory effect operates through mechanisms involving protein denaturation and inhibition of spore germination pathways [18]. The complex interaction of bioactive compounds within MOF underscores its potential as a formidable agent against Candida albicans, offering new insights into its therapeutic efficacy and prompting further research into its pharmaceutical applications.

The antimicrobial activities of Moringa oleifera fruits is an area of research exploring the potential of Moringa oleifera fruit extracts to inhibit the growth and activity of microorganisms. These extracts have shown promising antimicrobial properties against a range of bacteria and fungi, including Gram-positive and Gram-negative strains. Studies have identified bioactive compounds in Moringa oleifera fruit extracts that contribute to their antimicrobial activity. These compounds include phenols, flavonoids, alkaloids, and glucosinolates. They have been shown to be effective against a range of pathogens, including Staphylococcus aureus, Escherichia coli, and Aspergillus niger. This potential of Moringa oleifera fruit as a natural antimicrobial agent suggests its possible use in the development of new antimicrobial drugs or treatments.

6. Antimicrobial flowers activities

Mostly, this part emphasizes the significant therapeutic effects of Moringa oleifera flowers, in pharmaceutical and nutraceutical applications owing to their rich array of bioactive compounds. Compounds such as glucomoringin and benzyl glucosinolate are identified as common constituents found in various parts of the Moringa plant, including flowers, stems, pods, leaves, seeds, and roots, which highlights the widespread distribution of bioactive compounds throughout the plant, contributing to its therapeutic versatility.

Additionally, flowers are highlighted as a highly rich source of phenols, flavonoids, and minerals, distinguishing them for their potent antioxidant and antifungal properties [23, 26], which make their nutritional profiles comparable to Moringa oleifera leaves, but the creamy color and potentially greater acceptability of flower powder make them more used for food applications [21].

Moreover, emerging research suggests the efficacy of Moringa oleifera flowers as a natural remedy for urinary tract ailments, indicating their potential role in improving human health and combating antibiotic resistance [23, 27].

This section underscores also the diverse pharmacological effects of Moringa oleifera flowers, including antibacterial, antifungal, anti-inflammatory, and anticancer properties. Moreover, their antioxidant activity is highlighted, offering a safe and sustainable alternative to synthetic antibiotics.

Figure 4 summarizes the virtues of Moringa oleifera flowers.

Figure 4.

Moringa oleifera’s flowers composition, properties and health benefits.

7. Conclusion and future directions

In summation, the discerning analysis undertaken in this study underscores the promising antimicrobial attributes exhibited by Moringa oleifera across a spectrum of fungi. Extracts derived from the seeds, leaves, root bark, fruit, and flowers intricately showcase inhibitory effects on diverse pathogenic strains. The elucidation of specific active components, including 4-(alpha-L-rhamanosyloxy) benzyl isothiocyanates, lectins, phytol, and N-benzylethyl thioformate are paramount in comprehending the complex mechanisms underpinning these antimicrobial actions. This research accentuates the potential of Moringa oleifera as a reservoir of natural compounds, offering a fertile ground for the development of antimicrobial agents with tangible applications in the pharmaceutical landscape, thereby contributing substantively to the ongoing global initiatives aimed at combating fungal infections. Further exploration and refinement of these natural compounds stand as imperatives in the trajectory toward effective pharmaceutical solutions.

Moreover, according to previous studies, MO might also be used to prevent antibiotic toxicity. However, further extensive studies should be made to assess the relationship between infections to bring MO compounds to clinical trials as its potential for becoming an antimicrobial drug. Owing to their involvement in nutritional prevented routes, MO is considered as one of the best medicinal plants, providing a tremendous phytochemical effect. According to various studies oscillating from traditional medicine to a bioactive compound, an overview of some bacteria, fungi, and viruses has been listed. In alignment with the previously cited studies, Moringa’s full of nutriments and its major key prevention could be confirmed. Furthermore, a better understanding of microbial effects has been established.