This work presents the evaluation of iron oxide nanoparticles obtained from the aqueous extract of Eucalyptus grandis. Twenty-three experiments were carried out where the synthesis of nanoparticles was performed by using the aqueous extract together with salts of iron (II) chloride tetrahydrate and iron (III) chloride hexahydrate. A characterization was carried out by IR, TEM and BET, where bands were presented at 3,440.77, 1,559.26 and 445.31 cm⁻¹, indicating the presence of iron oxide nanoparticles. A relatively high monodispersity was evidenced with particles around 9 nm. By means of BET analysis it was found to present a surface area of 131.897 m²/g. Obtaining nanoparticles by this green method presents yield values of 98%, with application in nanotechnology, biomedicine, environmental treatment, among others, making them highly versatile and their production cost is relatively low.

The enormous biological potential of herbal products is one of the main reasons for their frequent use in the production of dietary supplements and functional foods, which, in addition to their nutritional properties, have pharmacological and physiological effects. New scientific knowledge on the isolation of pharmacologically active compounds from complex matrices has led to significant advances in this field. Today, the process of extraction plays a significant scientific role, with “green” technologies occupying a special place in today’s science. Herbal medicine is one of the oldest human skills, which has worn off with its centuries-old application in the path of modern medicine. Microwave-assisted extraction, or more simply, microwave extraction, is a new extraction technique that combines traditional extraction solvents and microwaves. The mentioned method takes less time, consumes less energy, and has strong penetration power into the plant matrix to obtain more oils, but it can also reduce production costs. This can eventually increase the quality of the final product and reduce the product price at the consumer level. Microwave-assisted extraction could be useful to the herbal industry for oil extraction as well as other pharmaceutically important plant components. Based on a comparison and study of published literature, this research examines the present state of extraction procedures. This review includes a detailed discussion of the most important extraction techniques.

Water splitting has been one of the potential techniques as a clean and renewable energy resource for the fulfillment of world energy demands. One of the major aspects of this procedure is the exploitation of efficient and inexpensive electrocatalysts due to the fact that the water oxidation procedure is accompanied by a delayed reaction. In this research, ZnO-CoFe₂O₄ nanostructure was successfully synthesized via the green method and green resources from cardamom seeds and ginger peels for oxygen evolution reaction (OER). The modified Glassy carbon electrode (GCE) with ZnO-CoFe₂O₄ is effective for the electrochemical water oxidation interaction since it has sufficient electrical strength and excellent catalytic performance. The creation of rice-like and small granular structures of ZnO-CoFe₂O₄ nano-catalysts was confirmed by characterization methods such as XRD, FESEM, EDS and MAP. According to the achieved results, in the electrolysis of water, with in-cell voltage of 1.40 V and 50 mA cm^–2 for current density in a 0.1 M KOH electrolyte and OER only has 170 mV overpotentials.

Zero-valent iron is a moderately reducing reagent that is both non-toxic and affordable. In the present work, iron nanoparticles were synthesized using bitter guard leaf extract (Momordica charantia L.) (BGL-Fe NP). Using leaf samples from bitter protectant extract, iron nanoparticles were synthesized with secondary metabolites such as flavonoids and polyphenols acting as capping and reducing agents. Polyphenols reduce Fe²⁺/Fe³⁺ to nanovalent iron or iron nanoparticles. Iron nanoparticles were synthesized by reducing iron chloride as a precursor with bitter protective leaf extract in an alkaline environment. The obtained BGL-Fe NPs were calcined for 4 h at various temperatures of 400 °C, 500 °C, and 600 °C. The obtained samples were coded as BGL-Fe NPs-4, BGL-Fe NPs-5, and BGL-Fe NPs-6, respectively. The synthesized BGL-Fe NPs were systematically characterized by XRD, SEM, FTIR, UV-Vis and TG-DTA analysis. The obtained BGL-Fe NPs were then used as an adsorbent to remove the aqueous solution of basic methylene blue (MB) dye. MB concentration was monitored using UV-Vis spectroscopy.

Yam (Dioscorea sp.) is a popular tuber in Cameroon, where it is grown for both food and income. One of the most challenging aspects of the long-term storage of yam tubers is post-harvest spoilage, often caused by fungi. The use of post-harvest chemicals on yam tubers is not a matter of course. The present study evaluated the efficacy of aqueous extract and powder of Zingiber officinale against fungi associated with the storage rot of yam. The fungi were isolated from two yam cultivars, “Calabar” and “Ghana”, from three localities in Cameroon. The antifungal activity of the aqueous extract and ginger powder was studied in vivo on slices of yam tubers. The results obtained showed that eight fungi were associated with yam tubers and exhibited typical rotting symptoms. The most prevalent and virulent fungus was Penicillium sp., which caused decay volumes of 12.76 cm³ and 8.74 cm³ for “Calabar” and “Ghana” cultivars, respectively. Fungal spoilage was greatly reduced by the application of aqueous extract and ginger powder. The aqueous extract tested at the 30% dose was more effective with up to 80% inhibition. However, the ginger powder was more effective against Penicillium sp., Aspergillus niger, and Colletotrichum sp. associated with rot in the variety “Ghana” with total inhibition (100%). Therefore, the aqueous extracts and powder of Zingiber officinale can be used as a bio fungicide to improve the shelf life of yam tubers.