In this study, procyanidins fractions of dimers and trimers (F1–F2) from the Leucosidea sericea total extract (LSTE) were investigated for their chemical constituents. The total extract and the procyanidins were employed in the synthesis of gold nanoparticles (Au NPs) and fully characterized. Au NPs of 6, 24 and 21 nm were obtained using LSTE, F1 and F2 respectively. Zeta potential and in vitro stability studies confirmed the stability of the particles. The enzymatic activity of LSTE, F1, F2 and their corresponding Au NPs showed strong inhibitory alpha-amylase activity where F1 Au NPs demonstrated the highest with IC₅₀ of 1.88 µg/mL. On the other hand, F2 Au NPs displayed the strongest alpha-glucosidase activity at 4.5 µg/mL. F2 and F2 Au NPs also demonstrated the highest antioxidant activity, 1834.0 ± 4.7 μM AAE/g and 1521.9 ± 3.0 μM TE/g respectively. The study revealed not only the ability of procyanidins dimers (F1 and F2) in forming biostable and bioactive Au NPs but also, a significant enhancement of the natural products activities, which could improve the smart delivery in future biomedical applications.

In this study, procyanidin dimers and Leucosidea sericea total extract (LSTE) were employed in the synthesis of silver nanoparticles (AgNPs) and characterized by ultraviolet-visible (UV-Visible) spectroscopy, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), and dynamic light scattering (DLS) techniques. AgNPs of about 2–7 nm were obtained. DLS and stability evaluations confirmed that the AgNPs/procyanidins conjugates were stable. The formed nanoparticles exhibited good inhibitory activities against the two enzymes studied. The IC₅₀ values against the amylase enzyme were 14.92 ± 1.0, 13.24 ± 0.2, and 19.13 ± 0.8 µg/mL for AgNPs coordinated with LSTE, F1, and F2, respectively. The corresponding values for the glucosidase enzyme were 21.48 ± 0.9, 18.76 ± 1.0, and 8.75 ± 0.7 µg/mL. The antioxidant activities were comparable to those of the intact fractions. The AgNPs also demonstrated bacterial inhibitory activities against six bacterial species. While the minimum inhibitory concentrations (MIC) of F1-AgNPs against Pseudomonas aeruginosa and Staphylococcus aureus were 31.25 and 15.63 µg/mL respectively, those of LSTE-AgNPs and F2-AgNPs against these organisms were both 62.50 µg/mL. The F1-AgNPs demonstrated a better bactericidal effect and may be useful in food packaging. This research also showed the involvement of the procyanidins as reducing and capping agents in the formation of stable AgNPs with potential biological applications.

The reducing potential of plant extracts in the green synthesis of nanoparticles has been associated with their phytochemicals. Although pharmacologically inactive, a norlignan diglucoside “hypoxoside” (HP) occurs in large quantities in the extract of Hypoxis hemerocallidea (HE). In this work, HP was isolated from HE where both were used in the biosynthesis of the corresponding silver nanoparticles (HP-AgNPs and HE-AgNPs). The AgNPs were fully characterized using various physicochemical techniques and their antimicrobial and anticancer properties were evaluated. Transmission electron microscopy (TEM) revealed sizes of 24.3 ± 4 nm for the HE-AgNPs and 3.9 ± 1.6 nm for the HP-AgNPs. The HE-AgNPs demonstrated enhanced anti-bactericidal effects on Escherichia coli and Salmonella enterica with a minimum inhibitory concentration (MIC) value of 1.95 µg/mL, competing well with the standard drug. The cytotoxic activity showed that the HE-AgNPs reduced cell viability with an IC50 of 0.81 and 4.0 µg/mL, respectively, for the U87 and U251 cells, while the HP-AgNPs displayed 0.20 and 0.55 µg/mL for both cell lines, respectively. Furthermore, while the HE-AgNPs were selective to U87 alone, the HP-AgNPs were selective to both glioblastoma cells tested. The study demonstrated the ability of a single phytoconstituent (hypoxoside), not only as the chief bioreductant in the extract, but also as a standalone reducing and capping agent, producing ultra-small, spherical, and monodispersed AgNPs with enhanced biological properties.

Pathogenic microorganisms develop incessant resistance toward antibiotics through various cellular defense mechanisms, thereby creating a search for chemotherapeutic alternatives, the potentials of which metal complexes of small-molecule drugs offer. In this study, Cu(II) and Co(II) complexes of mixed piperaquine and diclofenac were synthesized and characterized via magnetic moment determination, elemental analysis, FTIR, UV-Visible, 1D 1H NMR, 13C NMR spectroscopy and powder XRD, then evaluated for biological activities in silico and in vitro. The results provide evidence of coordination of the metal ions to ligands through N, COO and Cl groups with proposed octahedral geometry, low spin, paramagnetic, polycrystalline complexes. The physicochemical and pharmacokinetic parameters predicted in silico support bio-functionality and safety of the complexes. The complexes demonstrate strong inhibition against bacterial strains especially Staphylococcus aureus in vitro. Specifically, Cu(II) complex at 1% w/w inhibited a zone of 100 mm which is in multi-folds of the effects of piperaquine and diclofenac with 32 and 25 mm respectively, and better than ciprofloxacin with 92 mm. On DPPH assay, both complexes display better antioxidant potentials with respective IC50 of 165.09 and 382.7 µg/mL compared to ascorbic acid with 7526 µg/mL. Thus, the complexes represent therapeutic models for overcoming antibacterial resistance upon further study.

Diabetes has continued to affect the well-being of millions of individuals all over the world. More than seventy percent of Africans have undiagnosed diabetes mellitus, with Nigeria among the list of the African countries recording most undiagnosed cases. Biologically synthesized gold nanoparticles using the extracts of plants have continued to gain grounds in the treatment of diabetes. In the present research, a straightforward green method was used to form gold nanoparticles (AuNPs) from Mangifera indica leaf extract. Transmission electron microscopy (TEM), dynamic light scattering (DLS), ultraviolet visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and selected area electron diffraction (SAED) were used to characterize the nanoparticles. Using XRD and SAED, the AuNPs' crystallinity was ascertained. The TEM revealed particles of various morphologies, and the UV-Vis revealed a surface plasmon resonance (SPR) at 539 nm. The stability of the colloidal suspension was implied by the DLS measurement, which revealed a hydrodynamic size of 31.74 nm and a zeta potential of -23.7 mV. With percentage inhibitions that were about equivalent to that of acarbose, the conventional medication, the AuNPs demonstrated strong antidiabetic efficacy against the alpha-glucosidase and alpha-amylase enzymes. The research revealed the potential of Mangifera indica leaf extract-mediated gold nanoparticles in treatment of diabetes.