Plants generally secrete secondary metabolites in response to stress. These secondary metabolites are very useful for humankind as they possess a wide range of therapeutic activities. Secondary metabolites produced by plants include alkaloids, flavonoids, terpenoids, and steroids. Flavonoids are one of the classes of secondary metabolites of plants found mainly in edible plant parts such as fruits, vegetables, stems, grains, and bark. They are synthesized by the phenylpropanoid pathway. Flavonoids possess antibacterial, antiviral, antioxidant, anti‐inflammatory, antimutagenic, and anticarcinogenic properties. Due to their various therapeutic applications, various pharmaceutical companies have exploited different plants for the production of flavonoids. To overcome this situation, various biotechnological strategies have been incorporated to improve the production of different types of flavonoids. In this review, we have highlighted the various types of flavonoids, their biosynthesis, properties, and different strategies to enhance the production of flavonoids.

The field of nanotechnology is concerned with the creation and application of materials having a nanoscale spatial dimensioning. Having a considerable surface area to volume ratio, nanoparticles have particularly unique properties. Several chemical and physical strategies have been used to prepare zinc oxide nanoparticles (ZnO-NPs). Still, biological methods using green or natural routes in various underlying substances (e.g., plant extracts, enzymes, and microorganisms) can be more environmentally friendly and cost-effective than chemical and/or physical methods in the long run. ZnO-NPs are now being studied as antibacterial agents in nanoscale and microscale formulations. The purpose of this study is to analyze the prevalent traditional method of generating ZnO-NPs, as well as its harmful side effects, and how it might be addressed utilizing an eco-friendly green approach. The study’s primary focus is on the potential biomedical applications of green synthesized ZnO-NPs. Biocompatibility and biomedical qualities have been improved in green-synthesized ZnO-NPs over their traditionally produced counterparts, making them excellent antibacterial and cancer-fighting drugs. Additionally, these ZnO-NPs are beneficial when combined with the healing processes of wounds and biosensing components to trace small portions of biomarkers linked with various disorders. It has also been discovered that ZnO-NPs can distribute and sense drugs. Green-synthesized ZnO-NPs are compared to traditionally synthesized ones in this review, which shows that they have outstanding potential as a potent biological agent, as well as related hazardous properties.

Today, environmental contamination is a big concern for both developing and developed countries. The primary sources of contamination of land, water, and air are extensive industrialization and intense agricultural activities. Various traditional methods are available for the treatment of different pollutants in the environment, but all have some limitations. Due to this, an alternative method is required which is effective and less toxic and provides better outcomes. Nanomaterials have attracted a lot of interest in terms of environmental remediation. Because of their huge surface area and related high reactivity, nanomaterials perform better in environmental clean-up than other conventional approaches. They can be modified for specific uses to provide novel features. Due to the large surface-area-to-volume ratio and the presence of a larger number of reactive sites, nanoscale materials can be extremely reactive. These characteristics allow for higher interaction with contaminants, leading to a quick reduction of contaminant concentration. In the present review, an overview of different nanomaterials that are potential in the remediation of environmental pollutants has been discussed.

Nutraceuticals are dietary supplements, utilized to ameliorate health, delay senescence, prevent diseases, and support the proper functioning of the human body. Currently, nutraceuticals are gaining substantial attention due to nutrition and therapeutic potentials. Based on their sources, they are categorized as dietary supplements and herbal bioactive compounds. The global market for nutraceutical is huge i.e. approximately USD 117 billion. Herbal nutraceutical helps in maintaining health and promoting optimal health, longevity, and quality of life. Studies have shown promising results of nutraceuticals to treat several diseases, such as cancer, neurodegenerative diseases, cardiovascular diseases, etc. In the present review, an overview of various bioactive ingredients that act as nutraceuticals (carbohydrates, lipids, edible flowers, alkaloids, medicinal plants, etc.) and their role in health benefits, has been discussed. Further application of nutraceuticals in the prevention of various diseases has also been discussed.

The manipulation of matter at the atomic level (nanotechnology) has experienced an explosion in research interest in recent years. Bimetallic nanoparticles are vital due to their high biocompatibility, stability and comparatively less toxicity. The synthesis methods that include physical, chemical and biological methods are explored and explained in detail, along with their advantages. They have a wide range of applications due to their synergistic properties including biological applications (in medicine and agriculture), environmental application (in water treatment and removal of toxic contaminants), engineering application (in nanosensors, nanochips and nano-semiconductors) and chemical and physical application (in optics, catalysis and paints). The green synthesis approach is a promising method of synthesis that can give rise to more biocompatible and less toxic bimetallic nanoparticles due to increasing environmental pollution. However, despite these interesting attributes of bimetallic nanoparticle, there is still much work to be done to improve the biocompatibility of bimetallic nanoparticles because of their toxicity and potentially hazardous effects.

As Allium cepa is one of the most important condiment plants grown and consumed all over the world, various therapeutic and pharmacological effects of A. cepa were reviewed. Onion (Allium cepa) is a high dietary fiber-rich perennial herb that is placed under the family Amaryllidaceae. It contains high concentration of folic acid, vitamin B6, magnesium, calcium, potassium, and phosphorus as well as vitamins and minerals. It is widely used as an antimicrobial agent, but it showed anticancer, antidiabetic, antioxidant, antiplatelet, antihypertensive, and antidepressant effects and neuroprotective, anti-inflammatory, and antiparasitic effects and so on. It is said to have beneficial effects on the digestive, circulatory, and respiratory systems, as well as on the immune system. This review article was devoted to discussing many health benefits and traditional uses of onions in pharmacological perspectives, as well as the safety/toxicological profile. If more detailed research on this perennial herb is conducted, it will open the door to an infinite number of possibilities.