Zinc oxide nanoparticles (ZnO-NPs) have piqued the curiosity of researchers all over the world due to their extensive biological activity. They are less toxic and biodegradable with the capacity to greatly boost pharmacophore bioactivity. ZnO-NPs are the most extensively used metal oxide nanoparticles in electronic and optoelectronics because of their distinctive optical and chemical properties which can be readily modified by altering the morphology and the wide bandgap. The biosynthesis of nanoparticles using extracts of therapeutic plants, fungi, bacteria, algae, etc., improves their stability and biocompatibility in many biological settings, and its biofabrication alters its physiochemical behavior, contributing to biological potency. As such, ZnO-NPs can be used as an effective nanocarrier for conventional drugs due to their cost-effectiveness and benefits of being biodegradable and biocompatible. This article covers a comprehensive review of different synthesis approaches of ZnO-NPs including physical, chemical, biochemical, and green synthesis techniques, and also emphasizes their biopotency through antibacterial, antifungal, anticancer, anti-inflammatory, antidiabetic, antioxidant, antiviral, wound healing, and cardioprotective activity. Green synthesis from plants, bacteria, and fungus is given special attention, with a particular emphasis on extraction techniques, precursors used for the synthesis and reaction conditions, characterization techniques, and surface morphology of the particles.

Citrus species of plants are among the most commercially cultivated crops, mainly for their fruit. Besides, the generally consumed flesh inside the fruit, the peel is quite important too. Essential oils extracted from the peel have a history of being used by humankind for centuries. These essential oils are rich in antioxidants and antimicrobial agents. Comparative investigation of volatile constituents, and antioxidant and antimicrobial activities were undertaken. The essential oils were evaluated through gas chromatography-mass spectrometry (GC–MS), and enantiomeric composition by chiral GC–MS. Similarly, the antioxidant properties were evaluated by 2,2-diphenyl-1-picrylhydrazyl scavenging assay, and antimicrobial activities were assayed using the disk diffusion method. The highest extraction yield of 1.83% was observed in Citrus sinensis Osbeck. GC–MS analysis showed limonene (63.76–89.15%), γ-terpinene (0.24–6.43%), β-pinene (0.15–6.09%), linalool (0.35–3.5%), sabinene (0.77–2.17%), myrcene (0.74–1.75%), α-terpineol (0.28–1.15%), and α-pinene (0.2–0.58%) as the major constituents of the essential oil of the Citrus species studied. For the first time, through our study, chiral terpenoids have been observed from Citrus grandis Osbeck essential oil. The order of antioxidant activity is as follows: Citrus grandis Osbeck red flesh > Citrus reticulata Blanco > Citrus sinensis Osbeck > Citrus grandis Osbeck white flesh. Except for Citrus grandis Osbeck white flesh (52.34 µL/mL), all samples demonstrated stronger antioxidant activities than those of the positive control, quercetin (5.60 µL/mL). Therefore, these essential oils can be used as a safe natural antioxidant to prevent product oxidation. Likewise, citrus peel essential oil showed antimicrobial activity against tested bacterial strains, albeit marginal.

Essential oils (EOs) from Citrus sinensis (Rutaceae) possess diverse biological activities. However, a comprehensive comparison of their chemical composition and bioactivity across different plant parts has not been studied yet. The current research comparatively assesses the yield, chemical composition, chiral distribution, antioxidant properties, and larvicidal activity of EOs extracted from the peels, leaves, and flowers of C. sinensis. EOs extracted via hydro-distillation (HD) and steam distillation (SD) were analyzed by gas chromatography–mass spectrometry (GC-MS) and chiral GC-MS to explore their chemical composition and enantiomeric distribution. In addition, their larvicidal and antioxidant potentials were evaluated following standard protocols. Peels of C. sinensis exhibited significantly higher oil content (1.75–2.25%) compared to its leaves (0.75–0.78%) and flowers (0.20–0.25%). The GC-MS analysis identified around 60 compounds, including terpenoids, sesquiterpenoids, and oxygenated terpenoids in the HD and SD extractions. Higher concentrations of sabinene were found in flower extract (38.05–39.89%) and leaf extract (32.30–36.91%), while peel extract contained more than 90% limonene. The larvicidal activity of peel oil was primarily attributed to limonene, with an LC₅₀ value of 0.0031 µL/mL. The current study reports the first chiral (GC-MS) analysis in the essential oil of the leaves and flowers of C. sinensis, paving the way for authenticity and purity. Furthermore, the chemical profiling of citrus EOs, particularly from the peel, demonstrates a safe and promising candidate for diverse biological applications.

Background: Diabetes has become a major health problem due to its high prevalence, morbidity, and mortality rate. Reducing postprandial hyperglycemia has become the main target in the treatment of diabetes mellitus. So, developing new drugs with fewer side effects has been a major priority. Objective: The main objective of this study is to investigate total phenolic and flavonoid content, antioxidant activity, α-glucosidase, and α-amylase inhibition activity of Persea Americana Mill (avocado) pulp and seed. Methods: The α-glucosidase and α-amylase inhibition activity were performed using substrates PNPG and CNPG3, respectively. DPPH free radical scavenging assay was used to perform the antioxidant activity. The total phenolic content was estimated using folin-ciocalu’s reagent. Likewise, the aluminium trichloride method was applied to find out the total flavonoid content. Results: The crude methanolic extract of avocado seed revealed potent α-glucosidase inhibition activity with an IC₅₀ 1.959±0.93μg/mL followed by the avocado pulp 308±2.36μg/mL. Similarly, the IC₅₀ for the α-amylase inhibition activity of avocado seed was found to be 120.3±1.382μg/mL. In addition, the avocado pulp and seed revealed a significant antioxidant activity with IC₅₀ values of 75.01±0.72μg/mL and 6.445±0.62μg/mL, respectively, compared to the standard quercetin 1.525±0.5μg/mL. The total phenolic content of avocado pulp and the seed was reported as 7.031±2.87 mg of GAE/g, and 142.96±1.589 mg of GAE/g, respectively. Similarly, the total flavonoid content of avocado pulp and the seed was found to be 6.313±1.301 mg of QE/g and 48.696±0.110 mg of GAE/g, respectively. Conclusion: The avocado seed of Nepali origin was found to inhibit the digestive enzyme significantly. These findings indicate that avocado fruit of Nepali origin has the potential to develop as an alternative food therapy for diabetic patients. Further research is required to find out the inhibitor compounds.