Silk sericin was extracted from the cocoons of three Southern African wild silk moth species, namely Gonometapostica, G. rufobrunnae (Lepidoptera: Lasiocampidae), and Argema mimosae (Lepidoptera: Saturniidae); these three sericin extracts were analysed to determine the relationship that exists between their chemical structures and their functional properties. The relationship was investigated by utilising several methods that include the determination of the amino acid composition, and characterisation of the secondary structures with Fourier transformation infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The antibacterial properties of these three sericin extracts were evaluated by an agar well diffusion assay with three Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus, and Staphylococcus epidermidis) as test microorganisms; and, lastly, the antioxidant properties of the three sericin extracts were determined using several scavenging methods that include the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS˙⁺), and the ferric reducing antioxidant power (FRAP) assay. The amino acid composition in the silk sericin extracts from G. postica, G. rufobrunnea, and Argema mimosa in terms of the polar/non-polar ratio (P/NP) was found to be 65:35, 56:44, and 59:41, respectively. The FTIR spectra of these three silk sericin extracts showed distinct major bands such as amide A (3265 cm⁻¹), amide B (3062 cm⁻¹), amide I (1644 cm⁻¹), amide II (1538 cm⁻¹), and amide III (1244 cm⁻¹). The XRD patterns of the silk sericin extracts revealed both amorphous and α-helical structures, with small crystalline regions. All three silk sericin extracts presented potent antibacterial efficacy against the three Gram-positive bacteria and were found to have excellent antioxidant activities against the tested free radicals.

As part of our investigations to support the medicinal potential of Pontederia crassipes , an invasive water hyacinth plant, through the isolation of bioactive phytochemicals, we report the isolation and structural elucidation of two novel tetralin‐pentacyclic triterpenoid conjugates, designated Crassipeloyd A (A1‐10T) and Crassipeloyd B (WH‐E2), from the ethyl acetate fraction. Structurally, these compounds align more closely with pentacyclic friedelane‐type frameworks than with oleananes. Their structures were unambiguously elucidated using IR, ¹ H, ¹³ C, and HSQC NMR spectroscopy, alongside mass spectrometry. To explore their therapeutic relevance, we performed computational predictions of pharmacokinetics and HIV‐1 inhibitory activity using density functional theory (DFT)–optimized structures and molecular docking simulations. The HIV‐1 inhibitory profiles were conducted based on the structure–activity relationships of typical tetralin and pentacyclic triterpenoid derivatives. The in silico assessment predicted that compound A1‐10T exhibited the strongest binding affinity to HIV integrase (−8.5 kcal/mol), closely followed by WH‐E2 (−8.1 kcal/mol). These values compared favorably with reference inhibitors dolutegravir (−7.3 kcal/mol) and ritonavir (−7.0 kcal/mol). Meanwhile, ADMET modeling further suggested acceptable pharmacokinetic properties and low predicted systemic toxicity. These findings highlight A1‐10T and WH‐E2 as promising scaffolds with computationally predicted HIV‐1 inhibition. Importantly, the results represent theoretical models rather than experimental confirmation, warranting further experimental investigation into their potential use in treating HIV‐1 conditions and safety.

The application of silk sericin as a polymeric biomaterial has recently gained interest, although its film was found to be fragile, exhibiting brittleness when subjected to relatively slight stress, and it also displayed higher water solubility. This study focused on the enhanced physico-mechanical properties of the three films obtained by the crosslinking of sericin protein from three silkworm cocoons with poly (vinyl alcohol) (PVA) to reduce phase separation and solubilization of the films by promoting miscibility between sericin and PVA. The findings demonstrated how crosslinking with glutaraldehyde enhanced thermal stability and tensile strength and controlled the solubility of the three sericin–PVA films. The sericin from G. postica, G. rufobrunnea, and Argema mimosae is composed of serine, aspartic acid, and glutamic acid, which make up 80% of the total polar amino acids. X-ray diffraction (XRD) patterns showed that sericin–PVA films have semicrystalline features, representing amorphous and crystalline regions. The XRD results also indicated that the Saturniidae sericin–PVA film (Sat-SPF), Gonometa postica sericin–PVA film (GP-SPF), and Gonometa rufobrunnea sericin–PVA film (GR-SPF) have crystallinity percentages of 66.4%, 55.9%, and 17.7%, respectively. The moisture vapor transmission rate (MVTR) values observed in this study ranged from 991.2 to 5160 g/m²/24 h, indicating that these films can effectively regulate moisture levels in wounds. The swelling capacity of the three sericin–PVA composite films depends on the crosslinking density of their structures and was also found to be sensitive to the pH of the aqueous media, demonstrating their hydrophilic nature and potential use in drug delivery systems. The water vapor permeability of sericin–PVA films increased with higher environmental relative humidity (RH) and moisture content within the films. The elongation at break for GP-SPF (107.2% ± 3.1) and Sat-SPF (73.0% ± 4.1) was significantly higher than in GR-SPF (29.3% ± 2.3). However, their tensile strength and elastic modulus were lower than those of GR-SPF. These results show that the number of polar groups (amino and hydroxyl groups) from both sericin and PVA influences all the properties of the sericin–PVA composite films. The three sericin–PVA solutions were found to have antibacterial efficacy against three Gram-positive and one Gram-negative bacteria over 24 h. Scanning electron microscopy (SEM) images revealed a rough surface with a granular network pattern, which supports the potential use of sericin–PVA films for cell adhesion and proliferation, which are essential for biomedical wound dressing applications.