Artemisia absinthium and Psidium guajava are powerful sources of secondary metabolites, some of them with potential allelopathic activity. Both the species grow together in India with a weed (Parthenium hysterophorus) that is becoming extremely invasive. The aim of the present research was to test the allelopathic effect of A. absinthium and P. guajava aqueous leaf extracts on seed germination, seedling growth (shoot and root length), as well as some biochemical parameters (enzymatic and non-enzymatic antioxidants, photosynthetic pigments, osmolytes, and malondialdehyde by-products) of P. hysterophorus plants. Leaf extracts of both A. absinthium and P. guajava constrained the germination and seedling development (root and shoot length), affected pigment content (chlorophylls, carotenoids), stimulated the activity of antioxidant enzymes, and increased the level of malondialdehyde by-products of P. hysterophorus plants. Non-enzymatic antioxidants (glutathione and ascorbic acid) in P. hysterophorus leaves were, conversely, negatively affected by both leaf extracts tested in the present experiment. Although A. absinthium was more effective than P. guajava in impacting some biochemical parameters of P. hysterophorus leaves (including a higher EC50 for seed germination), P. guajava extract showed a higher EC50 in terms of root inhibition of P. hysterophorus seedlings. The present study provides the evidence that A. absinthium and P. guajava extract could be proficiently exploited as a botanical herbicide against P. hysterophorus.

Nanotechnology holds significant ameliorative potential against neurodegenerative diseases, as it can protect the therapeutic substance and allow for its sustained release. In this study, the reducing and capping agents of Urtica dioica (UD), Matricaria chamomilla (MC), and Murraya koenigii (MK) extracts were used to synthesize bio-mediated zinc oxide nanoparticles (ZnO-NPs) against bacteria (Staphylococcus aureus and Escherichia coli) and against rotenone-induced toxicities in D. melanogaster for the first time. Their optical and structural properties were analyzed via FT-IR, DLS, XRD, EDS, SEM, UV–Vis, and zeta potential. The antioxidant and antimicrobial properties of the fabricated ZnO-NPs were evaluated employing cell-free models (DPPH and ABTS) and the well diffusion method, respectively. Rotenone (500 µM) was administered to Drosophila third instar larvae and freshly emerged flies for 24–120 h, either alone or in combination with plant extracts (UD, MC, an MK) and their biogenic ZnO-NPs. A comparative study on the protective effects of synthesized NPs was undertaken against rotenone-induced neurotoxic, cytotoxic, and behavioral alterations using an acetylcholinesterase inhibition assay, dye exclusion test, and locomotor parameters. The findings revealed that among the plant-derived ZnO-NPs, MK-ZnO NPs exhibit strong antimicrobial and antioxidant activities, followed by UD-ZnO NPs and MC-ZnO NPs. In this regard, ethno-nano medicinal therapeutic uses mimic similar effects in D. melanogaster by suppressing oxidative stress by restoring biochemical parameters (AchE and proteotoxicity activity) and lower cellular toxicity. These findings suggest that green-engineered ZnO-NPs have the potential to significantly enhance outcomes, with the promise of effective therapies for neurodegeneration, and could be used as a great alternative for clinical development.

Cancer is defined as a multifactorial disease because it exhibits the continuous proliferation of malignant cells. It is one of the principal causes of death worldwide, with breast cancer occurrence being the highest among women and lung cancer being the highest among men. Hydroxyflavanones come under the category of flavonones and are further classified as 2′-hydroxyflavanone, 4′-hydroxyflavanone, 6-hydroxyflavanone, 7-hydroxyflavanone, etc. Flavonoids constitute approximately 60% of the total dietary polyphenols. Dietary components such as vegetables, fruits, cereals, soybeans, and tea are the chief sources of flavonoids, while citrus fruits contain a high amount of hydroxyflavanones. 2′-Hydroxyflavanone is known to have anti-inflammatory, antimutagenic, and anticancer activities. Hence, it is being investigated as a treatment for various diseases, especially cancer. 2′-Hydroxyflavanone can act as a chemotherapeutic agent in cancer. It restricts the signal transducer and activator of the transcription 3 pathway (STAT3) in some forms of cancer.

Black tea is one of the most popular beverages consumed in the world. It is stronger in taste as well as in flavour compared to other less oxidized teas. It is made from the leaves of the shrub Camellia sinensis var. assamica. Black tea can be supplemented with other plant parts to enhance its flavour and health-promoting properties. In India, Ocimum spp. leaves have been used for their medicinal properties since ancient times. These leaves can be added during black tea preparation to enhance their aroma and healing activities. O. gratissimum, known as “Scent Leaf”, is traditionally used for the management of many diseases, such as the common cold and cough. This work was designed to evaluate the antioxidant interaction between black tea and O. gratissimum (leaves) at five different ratios (1:1, 1:2, 1:3, 2:1, and 3:1). To determine the antioxidant activity, chemical-based methods and ex vivo assays were conducted. The total phenolic and flavonoid contents were calculated by Folin’s reagent and aluminium chloride colorimetric assays, respectively. The antioxidant interactions were determined by the combination index (CI), using CompuSyn software. The black tea exhibited higher radical quenching activity (DPPH, ABTS, and NO) and antihaemolytic and anti-lipid peroxidation potential compared to the Ocimum gratissimum infusion. Variation in the antioxidant capability was observed for various ratios of the black tea and O. gratissimum (BT+OG) combination. The antioxidant interaction between BT and OG ranged from nearly additive to antagonistic. The total phenolic content was higher for O. gratissimum, whereas the total flavonoid content was high in black tea. The binary mixture of BT+OG at all ratios (3:1, 2:1, 1:1, 1:2, and 1:3) expressed similar phenolic and flavonoid levels. Overall, black tea and O. gratissimum displayed additive antioxidant interaction and the highest free radical scavenging potential at a 3:1 proportion in all the performed parameters.