Contribution of endophytes towards improving plant bioactive metabolites: a rescue option against red-taping of medicinal plants

Abstract

Medicinal plants remain a valuable source for natural drug bioprospecting owing to their multi-target spectrum. However, their use as raw materials for novel drug synthesis has been greatly limited by unsustainable harvesting leading to decimation of their wild populations coupled with inherent low concentrations of constituent secondary metabolites per unit mass. Thus, adding value to the medicinal plants research dynamics calls for adequate attention. In light of this, medicinal plants harbour endophytes which are believed to be contributing towards the host plant survival and bioactive metabolites through series of physiological interference. Stimulating secondary metabolite production in medicinal plants by using endophytes as plant growth regulators has been demonstrated to be one of the most effective methods for increasing metabolite syntheses. Use of endophytes as plant growth promotors could help to ensure continuous supply of medicinal plants, and mitigate issues with fear of extinction. Endophytes minimize heavy metal toxicity in medicinal plants. It has been hypothesized that when medicinal plants are exposed to harsh conditions, associated endophytes are the primary signalling channels that induce defensive reactions. Endophytes go through different biochemical processes which lead to activation of defence mechanisms in the host plants. Thus, through signal transduction pathways, endophytic microorganisms influence genes involved in the generation of secondary metabolites by plant cells. Additionally, elucidating the role of gene clusters in production of secondary metabolites could expose factors associated with low secondary metabolites by medicinal plants. Promising endophyte strains can be manipulated for enhanced production of metabolites, hence, better probability of novel bioactive metabolites through strain improvement, mutagenesis, co-cultivation, and media adjustment.

Impact of Heavy Metal Pollution in the Environment on the Metabolic Profile of Medicinal Plants and Their Therapeutic Potential

“…Within plant cells, heavy metals may be bound to proteins, such as metallothioneins, or chelated by compounds like phytochelatins. These mechanisms serve as the plant’s defense strategy, sequestering and reducing the toxicity of heavy metals [ 83 , 84 ]. However, the effectiveness of these mechanisms varies among plant species.…”

“…Heavy metals, acting as catalysts, induce the formation of ROS, including superoxide radicals and hydrogen peroxide. These molecular entities play dual roles as both signaling molecules and instigators of cellular damage, setting the stage for oxidative stress within the plant [ 44 , 45 , 83 , 84 ].…”

“…Medicinal plants can respond to heavy metal stress by producing metal-chelating compounds. These compounds, like phytochelatins and metallothioneins, act as defenders, binding to heavy metals and preventing them from causing harm within the plant [ 83 , 84 , 125 ]. Understanding the role of these chelating compounds sheds light on the ingenious ways herbs shield themselves from the adverse effects of metal exposure.…”

The Indiscriminate Chemical Makeup of Secondary Metabolites Derived from Endophytes Harvested from Aloe barbadensis Miller in South Africa’s Limpopo Region

“…The use of medicinal plants to address human health problems dates back many years, and the benefits of medicinal plants in the health care system are undeniable. Plants are important and reliable reservoirs of bioactive compounds, as evidenced by their prolonged and continuous use in addressing the pressing issues in human health [ 4 ]. Aloe barbadensis Miller, commonly known as aloe vera, Artemisia afra , known as wormwood, and Moringa oleifera , generally named drumstick tree, are three important medicinal plants used in South Africa to address various clinical conditions.…”

“…Instances of such interactions encompass the synthesis of bioactive secondary metabolites. It is worth noting that these metabolites exhibit variable degrees of specificity, wherein certain metabolites exhibit a broad-spectrum effect by targeting a large range of molecular targets, while others exhibit a narrow-spectrum effect by targeting a more limited scope of molecular targets [ 4 ]. The exploration of endophytic secondary metabolites with bioactive properties has gained increasing attention, owing to their various bioactive capabilities and wide range of structural categories.…”