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

Abstract

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.

Medicinal Plants and Their Bacterial Microbiota: A Review on Antimicrobial Compounds Production for Plant and Human Health

“…In some cases, MPs have been shown to harbor endophytes potentially involved in the biosynthesis of phytoconstituents and/or to be able to synthesize bioactive compounds. Among MPs adopted in clinical studies, an example is the plant neem (Azadirachta indica), which is an evergreen tree of the tropics and sub-tropics, native to the Indian subcontinent, with a demonstrated ethnomedicinal value and importance in agriculture as well as in the pharmaceutical industry [4]. In a clinical study, the impact of neem-containing mouthwash on plaque and gingivitis was investigated, demonstrating that it can be used for maintain-ing oral hygiene and that it might have a better impact in the prevention of oral diseases, as it is both cost-effective and easily available [5].…”

“…In a clinical study, the impact of neem-containing mouthwash on plaque and gingivitis was investigated, demonstrating that it can be used for maintain-ing oral hygiene and that it might have a better impact in the prevention of oral diseases, as it is both cost-effective and easily available [5]. So far, more than 400 compounds have been isolated from different parts of neem, including important bioactive secondary metabolites, and more than 30 compounds have been isolated from neem endophytes [4].…”

Bioprospecting of endophytes in medicinal plants of Thar Desert: An attractive resource for biopharmaceuticals

“…Varieties of such bioactive molecules with therapeutic value have been identified to date, for example, paclitaxel (also known as Taxol), camptothecin, azadirachtin, deoxypodophyllotoxin, and podophyllotoxin [ 70 ]. The secondary metabolites synthesized by endophytes not only have ecological importance but also support a scientific handle to investigate the biochemical and molecular frameworks associated with their synthesis [ 173 ].…”

In vitro effectiveness of an aqueous extract of Neem (Azadirachta indica A. Juss) leaves on bacteria causing healthcare associated infection in Valledupar

“…This plant has active natural substances in leaves and seeds against multiple pathogens, including bacteria, fungi, and viruses (8). Its extract has been demonstrated to contain relevant properties at the health level (9,10), with antibacterial, anti-inflammatory, antiviral, hypoglycemic, and antiulcer activity, among others (11).…”