High-molecular-weight poly(3-hydroxybutyrate) (PHB) has a low reactivity toward its terminal functional groups. Thus, the chemical reactivity of PHB was enhanced by the chemical degradation that occurred via β-elimination through the functionalization of PHB with ethylene glycol to give a low-molecular-weight PHB-diol. The reaction of PHB-diol with acryloyl chloride gave PHB-diacrylate, which was grafted by thiol compounds, such as ethane dithiol, 2-mercaptoethanol, ethane thiol, dithiothreitol, butane thiol, and thioglycolic acid, via a Michael-type addition reaction. The chemical and thermal properties of the functionalized PHB-thiol products were characterized with Fourier transform infrared spectroscopy, 1 H-NMR, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis techniques. X-ray diffraction showed that the PHB-thiol polymers had slight differences in crystallinity compared with neat PHB. The biological activities of the neat polymer and new PHB-thiol polymers, including the antibacterial and anticancer activities, were tested, and some of these products showed antibacterial and anticancer activities. These anticancer activities were attributed to the ability of these PHB-thiol polymers to induce apoptosis (as revealed by the higher expression of Bax and caspase 9 and the lower expression of Bcl2) and cell-cycle arrest in the G0/G1 phase, which is associated with the higher expression of p53 and p21 and the lower expression of the p53 inhibitor, MDM2. Thus, the anticancer effect of these PHB-thiol polymers may have been due to their ability to inhibit MDM2-p53 interactions.

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Polyvinyl alcohol (PVA), chitosan (CS), and cellulose (CL) are promising polymers for chemical functionalization and biomedical applications. This study aimed to synthesize folic acid (FA) conjugates with PVA, CS, and CL via chloroacetyl chloride, 2-bromopropionyl bromide, and epichlorohydrin to enhance it biomedical applications. The functionalized polymer conjugates were characterized by FT-IR, 1 H-NMR, GPC, and TGA techniques. FT-IR and 1 H-NMR revealed the main functional groups (O H, N H, C═O, C═N), the aromatic C H and N H protons of FA moieties. TGA illustrated two stages of decompositions of all-polymer conjugates. FA showed no antifungal activity, while two of the newly grafted polymer conjugates (chitosan bromopropionate-grafted FA and cellulose chloroacetate-grafted FA) illustrated antifungal activity against both Aspergillus fumigatus and Candida albicans. Polymer conjugates; poly(vinyl chloroacetate)-grafted FA and chitosan-EPCH-grafted FA revealed good antifungal effect on C. albicans and A. fumigatus, respectively. Most FA polymer conjugates showed significant antitumor activity against EAC-bearing mice. Among these conjugates, chitosan chloroacetate-grafted FA (P-2A) showed the highest antitumor effect against EAC-bearing mice via reduction in total tumor volume. Thus, these conjugates provided enhanced antifungal and antitumor activities as compared with FA itself. These conjugates may act as promising biologically active carrier systems for other applications such as drug delivery.

Guanosine (GU) is a purine nucleoside that has different biological applications. This study aimed to synthesize, characterize, and enhance the biological activities of GU through its covalently grafting on polyvinyl alcohol (PVA), chitosan (CS), and cellulose (CL). In this regard, the conjugation was constructed by different linkers such as chloroacetyl chloride, 2-bromopropionyl bromide, and epichlorohydrin (EPCH). The resulted novel conjugates were characterized by FT-IR, 1H-NMR, GPC, and TGA techniques. FT-IR spectra revealed the main characteristic groups, O–H, N–H, C=O and C=N of GU moieties. Furthermore, 1H-NMR spectra showed the aromatic C–H, O–H, and N–H protons of the grafted GU moieties. Two decomposition stages of grated polymers with high thermal stability are illustrated by TGA. GU showed no antifungal activity against Aspergillus fumigatus and Candida albicans. However, its conjugates: P-1A, P-1B, P-2A, P-2B, P-3A, and P-3B displayed significant antifungal effect with inhibitory zones in the range 8–11 mm. As compared to GU group, most of GU-polymer conjugates showed significant in vivo antitumor activity against EAC-bearing mice via the reduction in total tumor volume. In summary, these conjugates are biologically active macromolecules and may act as candidate carrier systems for other applications such as drug delivery.

Reaction of 2-mercapto-3-phenylquinazolin-4(3H)-one (MPQ) with both 4-vinyl benzyl chloride and allyl bromide furnished the reactive heterocyclic monomers 3-phenyl-2-((4-vinylbenzyl) thio) quinazolin-4(3H)-one (PVTQ) and 2-(allylthio)-3-phenylquinazolin-4(3H)-one (APQ), respectively. Copolymerization of PVTQ monomer with styrene and methyl methacrylate in the presence of 2,2′-azobisisobutyronitrile (AIBN) afforded the copolymers PS-co-PPVTQ and PMMA-co-PPVTQ, respectively. Similarly, copolymerization of monomer APQ with styrene and methyl methacrylate (MMA) afforded the copolymers PS-co-PAPQ and PMMA-co-PAPQ, respectively. The resulted copolymers were characterized by using FT-IR, 1H-NMR and GPC techniques. Silver nanocomposites of PS, PMMA, PS-co-PPVTQ, PMMA-co-PPVTQ, PS-co-PAPQ and PMMA-co-PAPQ were synthesized by the addition of silver nitrate into the polymer solution. The reduction of silver ions into silver nanoparticles was performed in DMF and water. Thermogravimetric (TGA) analysis was used to determine the thermal stability of the copolymers and their silver nanocomposites. The X-ray diffraction (XRD) analysis indicated the amorphous structures of the co-polymers and confirmed the formation of silver nanoparticles. The antitumor and antibacterial activities were screened for the copolymers and enhanced by the formation of their silver nanocomposites. In vivo antitumor activity in Ehrlich Ascitic Carcinoma (EAC) mice model showed that PS-co-PPVTQ/Ag NPs, PMMA-co-PPVTQ/Ag NPs, and PMMA-co-PAPQ/Ag NPs displayed promising inhibitory effects against EAC and induce apoptosis against MCF-7 cells.