A series of 16 novel prenylated chalcones (5A-5P) was synthesized by microwave-assisted green synthesis using 5-prenyloxy-2-hydroxyacetophenone and different benzaldehydes. Comparisons were also performed between the microwave and conventional methods in terms of the reaction times and yields of all compounds, where the reaction times in the microwave and conventional methods were 1–4 min and 12–48 h, respectively. The synthesized compounds were characterized using different spectroscopic techniques, including IR, ¹H-NMR, ¹³C-NMR, and LC-HRMS. The antifungal activities of all compounds were evaluated against Sclerotium rolfsii and Fusarium oxysporum under in vitro conditions and were additionally supported by structure–activity relationship (SAR) and molecular docking studies. Out of the 16 compounds screened, 2’-hydroxy-4-benzyloxy-5’-O-prenylchalcone (5P) showed the highest activity against both S. rolfsii and F. oxysporum, with ED₅₀ of 25.02 and 31.87 mg/L, respectively. The molecular docking studies of the prenylated chalcones within the active sites of the EF1α and RPB2 gene sequences and FoCut5a sequence as the respective receptors for S. rolfsii and F. oxysporum revealed the importance of the compounds, where the binding energies of the docked molecules ranged from −38.3538 to −26.6837 kcal/mol for S. rolfsii and −43.400 to −23.839 kcal/mol for F. oxysporum. Additional docking parameters showed that these compounds formed stable complexes with the protein molecules.

Piper longum L. (Piperaceae family), commonly known as long pepper, is used in traditional medicine and in recognized system of medicine in India for the treatment of inflammation, pain, epilepsy, arthritis, cancer, ulcer, and asthma in addition to pest control activity. Its fruits are rich in essential oil and possess different biological activities, but oil is not much explored against the root-knot nematodes. Thus, the essential oil from the fruits of P. longum was isolated by hydrodistillation method and analyzed by Gas chromatography-Flame ionisation detector and Mass spectrometry. Analysis showed that the oil is a complex mixture of volatile compounds. (Z)-β-Farnesene (25.08%), β-Caryophyllene (13.57%), α-Humulene (13.37%), 8-Heptadecene (9.28%), Heptadecane (7.07%), α-Patchoulene (5.44%), 3-Heptadecene (5.09%), γ-Elemene (4.37%), β-Humulene (3.69%) and Terpinen-4-ol (1.74%) were identified as main compounds in its oil. The essential oil was evaluated for its nematicidal activity against root-knot nematode at 62.5–1000 ppm concentrations in vitro conditions during 2020–21 at ICAR-Indian Agricultural Research Institute, New Delhi. Results showed promising nematicidal activity of the oil and have caused mortality of juvenile (J2), ranging from 2.33–88.0% after 24–96 hours of treatment compared to untreated control. The oil was further evaluated under the pot conditions in tomato (Solanum lycopercicum L.) (var. Pusa Ruby) at 3000 and 2000 ppm. Results showed a significant reduction in the number of galls/root of tomato with better plant growth in the essential oil based treatment as compared to the untreated control. These results suggest that the oil can be used for the development of nematicidal product for the protection of crops from the infestation of M. incognita.

Chalcones are known for their broad biological activities, which can be enhanced by incorporating heterocyclic moieties. Imidazole, recognized for its diverse properties, was introduced into a series of imidazolylchalcone derivatives (3a–3o) synthesized via Claisen-Schmidt condensation of benzaldehydes (2a–2o) and 4-(Imidazol-1-yl) acetophenone (1a) using ultrasonication as a green method. These compounds were characterized by spectroscopic techniques such as 1H-NMR, 13C-NMR, LC-HRMS and evaluated for fungicidal and nematicidal activity. Compound 3 h showed highest fungicidal activity against Rhizoctonia solani (ED₅₀ = 0.69 μg/mL), outperforming commercial hexaconazole (ED₅₀ = 3.57 μg/mL). Compound 3d exhibited the highest activity against Fusarium oxysporum (ED₅₀ = 119.22 μg/mL), while 3f was most effective against Meloidogyne incognita (LC₅₀ = 33.62 μg/mL), though less active than commercial Velum Prime (LC₅₀ = 3.46 μg/mL). The compounds potential activity may results from interactions of electronegative atom with enzyme active sites via hydrogen bonding. Docking studies against fungal cutinase and nematode acetylcholinesterase supported the in-vitro findings. Promising compounds will undergo further in-vivo and field trials for antifungal and antinemic applications and developed a potent molecule.