Isolation and characterization of cellulose nanocrystals and synthesis of bioplastic cellulose acetate from the invasive weed Senna didymobotrya using acid hydrolysis and acylation methods.

Two new powdery mildew species found in Mexico are described and illustrated based on morphological and molecular evidence. Phyllactinia passiflorae-adenopodae on Passiflora adenopoda, is characterized by having typically falciform to asymmetrically ellipsoid-ovoid or ellipsoid-lanceolate conidia. Phyllactinia sennae on Senna didymobotrya is characterized by having lanceolate to ellipsoid-lanceolate primary conidia, combined with clavate secondary conidia, and conidiophores with mainly helicoidal basal cells. Teleomorph was not observed in any of both fungi. Phylogenetic analyzes using nuclear rDNA ITS sequences showed that both powdery mildews form each an independent and strongly supported lineages, which enables their recognition as new species.

Leishmaniasis is a neglected tropical disease with high morbidity and mortality. Current treatments, such as pentavalent antimonials, are expensive, highly toxic, and face increasing parasite resistance. We evaluated the antileishmanial activity of methanolic leaf extracts of Senna didymobotrya as a potential complementary treatment. Leaves of S. didymobotrya were collected from Kabarak University Botanical Garden and extracted using methanol through cold maceration. Eight-week-old inbred BALB/c female mice were obtained from the Kenya Medical Research Institute (KEMRI) for macrophage assays. Leishmania major (Strain IDUB/94=NLB-144) parasites were cultured in Schneider’s insect medium (SIM) and used to infect macrophages. The infected macrophages were treated with varying concentrations of S. didymobotrya extract, while Pentostam served as a positive control and untreated infected macrophages as a negative control. A nitric oxide assay was conducted to assess immunomodulatory effects. The results indicated that S. didymobotrya extract exhibited antileishmanial activity, with a minimum inhibitory concentration (MIC) of 2 mg/ml, compared to Pentostam’s MIC of 250 μg/ml. The extract also demonstrated anti-amastigote activity by reducing parasite multiplication within macrophages. However, it did not significantly stimulate nitric oxide production compared to the standard treatment. In conclusion, methanolic leaf extracts of S. didymobotrya possess promising antileishmanial properties against L. major. Although its MIC value was higher than that of Pentostam, further research is needed to elucidate its mode of action and enhance its efficacy.

Abstract In this study, genetic information was obtained as evidence of proper identification to detect the divergence between the species belonging to the genus Senna.L, namely Senna alata (Linnaeus) Roxb and Senna didymobotrya (fresen) of the legume family Leguminosae (Fabaceae). Field work was carried out during the growing season of 10/1/2023. DNA was extracted from fresh leaves of the two plant species. We used the polymerase chain reaction - genomic reaction of the chloroplast DNA. The matK region of the chloroplast DNA was amplified using primers and the nucleotide sequences of each species were obtained. The results showed that the molecular weight of the band size for the two species was 902 Pb and according to the barcode classification, the entire genome is considered as a super barcode for the two samples under study. The matK gene sequence was obtained from the GenBank and used for analysis. The phylogenetic tree was designed to identify the ideal regions that can be used to determine the relationships between the two species.It was compared with the global plant sequences closest to the two species and the sequence was registered in the gene bank. The genetic tree showed that the species Senna didymobotrya deposited under the serial number MN243366.1 is the closest global species to the plant Senna didymobotrya under study in Iraq and is linked by up to 100% about the rest of the species. The research also showed that the most global plant related to the species Senna alata is the plant Senna alata registered under the serial number (LC385932.1) at a rate of 99%.

BackgroundAmongst all neoplastic diseases, breast cancer represents a major cause of death among the female population in developed and developing countries. Since alkaloid drugs are commonly used in chemotherapy to manage this disease, this study investigated the anti-proliferative effectiveness of alkaloid-rich fractions of Senna didymobotrya leaves only and with laser irradiation against MCF-7 breast cancer cells.Method and materialsA powdered sample of the plant leaves was extracted with 50% ethanol, filtered and their pH was adjusted with acid and base solution followed by partitioning with chloroform and ethyl acetate solvents. Cells were treated with 240 μg/mL of the respective extracts, while those in the photodynamic therapy groups, cells were exposed to laser (405 nm wavelength and 10 Jcm−2) irradiation 6 h post extracts' administration.ResultsTreatment with the S. didymobotrya leaves alkaloid extracts significantly decreased the ATP concentration and overall viability of the MCF-7 cells. Reactive oxygen species (ROS) levels in cell groups treated with the extracts and laser light were considerably higher than in experimental groups treated with only the extracts. Moreover, the molecular docking analysis revealed the involvement of only hydrophobic bonds in the interactions of the plant’s alkaloid-derived phytoconstituents’ with selected cancer protein biomarkers.ConclusionAlthough the in silico analysis suggests that the plant-identified alkaloid phytoconstituents inhibition of estrogen receptor-alpha, human epidermal growth factor receptor-2 and progesterone receptor proteins involved in breast cancer pathogenesis could explain a possible mechanism for the observed anticancer effect, more detailed in vitro molecular experiments are necessary to confirm these findings.

In this study, the synthesis of carboxymethyl cellulose (CMC) from nonusable invasive weed Senna didymobotrya cellulose was possible through response surface methodology (RSM)–guided alkalization and etherification methods. The RSM method indicates that the maximum CMC yield obtained, 0.85 gm or 85.6%, was achieved when 1 gm or 6 mol of anhydrous glucose unit (AGU) cellulose reacted with 1 gm or 3.24 mol of KOH/AGU and 1.1 gm or 2.05 mol of monochloroacetic acid (MCA)/AGU at 60°C with a total reaction time of 2 h. This finding opens a new avenue for saving chemicals while producing industrial chemicals. The RSM analysis also indicates that the method was significant and valid. This is because the factors and factor interactions used in this method were significant (p < 0.05) and the method was precise because the adequate precision (30.7) found was much higher than the expected precision value of 4. The factors used were alkalization, etherification, and temperature. The degree of substitution of synthesized CMC was 2.5 and comparable with the commercial CMC (2.9). The viscosity measurement of the synthesized and commercial CMC indicates that both materials showed non‐Newtonian pseudoplastic behavior. The viscosity of the synthesized CMC was 331.64 cP and the commercial CMC was 227.08 cP. This indicates that the synthesized CMC was more viscous than the commercial CMC. Hence, the synthesized CMC could be used as a good thickener in different factories. The FTIR, XRD peaks, and SEM images indicate that the CMC was synthesized from the isolated cellulose. The TGA/DTA analysis also indicates the CMC was thermally stable up to 380°C and exhibited heat resistance up to 800°C. Therefore, the two simplest, not time‐ and energy‐taking, methods used and the results of their characterizations with respect to commercial CMC indicate that our synthesized CMC from the weed Senna didymobotrya cellulose can be extended to large‐scale production of CMC and marketed locally and worldwide.

Medicinal plants are affordable and accessible, but documentation and evidence of their effectiveness is limited. A study was conducted in Kieni forest, Kiambu County with the aim of documenting the therapeutic plants, exploring their phytochemical properties and potential antimicrobial properties. Semi-structured questionnaires administered via the snowball technique was used in the survey. Phytochemical investigations was carried out using standard methods while disc diffusion method was used to evaluate antimicrobial properties. The study identified 28 medicinal plants from 25 families. The most common conditions treated by the plants were noted to be skin infections (31 %). The primary sources of medicinal plant knowledge were from parents and grandparents (63%). Plant parts that were most utilized were the leaves (27%), while only 2% of the seeds were used. Qualitative analysis of methanol extracts from Croton macrostachyus, Cordia africana, Elaeodendron buchananii, Senna didymobotrya, and Coleus barbatus identified phytochemicals such as terpenoids, flavonoids and tannins. The microbial sensitivity assay showed that the plant extracts displayed efficacy against Gram-positive bacteria, such as Bacillus subtilis, Streptococcus pyogenes and Staphylococcus aureus. However, limited efficacy was observed against isolates of Salmonella typhi and Escherichia coli although the former exhibited susceptibility to E. buchananii leaves extracts. All the tested plant extracts were unable to inhibit the growth of Candida albicans. E. buchananii emerged as the most effective species against tested microorganisms with a mean zone of inhibition of 9.90 (SD 0.391), while C. macrostachyus and C. africana were relatively less effective. Minimum Inhibitory Concentration (MIC) revealed S. pyogenes as the most susceptible microorganism, with an average MIC of 65.63 mg/ml. S. aureus and B. subtilis had a MIC of 81.25 mg/ml and 125.00 mg/ml respectively. Conducting further research on isolated phytochemical compounds and properties could potentially lead to the development of cost-effective and less toxic drugs for managing microbial infections.

Attractant and repellent properties of Senna didymobotrya plant extracts to Amblyomma variegatum and Rhipicephalus appendiculatus

Due to the dearth of extremely capable, sensitive, and stable catalysts, the efficient detection and catalytic removal of 4-nitrophenol (4-NP) in industrial wastewater remains a serious challenge. The detection and determination of 4-nitrophenol (4-NP) presence in the environment is a matter of paramount importance because it is a high-priority hazardous pollutant that can affect people, animals, and plants. Here, we present a promising and economically viable green synthetic route for fabricating CuFe2O4 and CuFe2O4@Ag hybrid nanocomposites from the leaf extract of Senna didymobotrya. The UV–Vis, FTIR, XRD, FE-SEM, EDXA, BET and VSM analysis were performed to characterize the synthesis of CuFe2O4@Ag nanocomposite. To evaluate the electrocatalytic capacity of CuFe2O4@Ag, electrochemical sensing stratergy was performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The modified CuFe2O4@Ag glassy carbon electrode (GCE) (CuFe2O4@Ag/GCE) demonstrated a linear response in the range of 0.01-15 μg/ml (71 nm-107 μM) and the ability to detect 4-NP at low concentration (0.006 μg/ml (43 nM)). Due to the increased surface area of CuFe2O4@Ag/GCE by ̴ 1.5-fold, a greater cathodic current response (-16 μA/cm2) at a low potential of -0.81 V was observed compared to CuFe2O4/GCE alone for the detection of 4-NP. Additonally, CuFe2O4@Ag showed excellent reduction ability towards 4-NP using NaBH4 with an efficiency of 96.4 % which was higher than the CuFe2O4 (only 87.3 %) in 12 min due to the synergistic relationship among Ag NPs and CuFe2O4 nanostructures. The outcomes from this study shows that the bi-functional electrocatalyst holds vast potential for environmental remediation.

Senna didymobotrya is one of the emerging invasive weeds in East and South Africa. One of the solutions for weed management involves isolating cellulose and converting it into valuable materials. In this research, the isolation of cellulose was optimized by the Plackett‐Burman design (PBD) and response surface methodology using Box‐Behnken design (BBD), both of which are statistical empirical models. The maximum isolated cellulose yield was 37.5% (w/w) using sulfuric acid 1.75% (w/v), sodium chlorite 3% (w/v) at pH of 3.5, and potassium hydroxide 6% (w/v) treatment. Each chemical treatment was done by heating the mixture at 90°C for 2 hrs. The cellulose yield obtained (37.5% (w/w)) was higher than the preoptimized value of 35.5% (w/w). The dewaxed powder of the weed, isolated cellulose, and commercial cellulose was characterized side by side for comparison using FTIR, XRD, SEM, and TGA/DTA. All the characterizing methods indicated that the isolated material was cellulose. Even though the intensity of FTIR and XRD graphs of the isolated cellulose was higher than the commercial cellulose, the crystallinity index calculated from XRD analysis showed that the commercial cellulose (83%) was higher than the isolated cellulose (78%). The TGA/DTA indicates that the isolated cellulose and commercial cellulose had comparable thermal stability, both stable at up to 360°C. Therefore, using this optimized method, cellulose isolation from S. didymobotrya opens avenues for converting cellulose into valuable materials like carboxymethyl cellulose, cellulose hydrogel, and cellulose nanocrystals.

BackgroundInfectious diseases are a major global public health concern as antimicrobial resistance (AMR) currently accounts for more than 700,000 deaths per year worldwide. The emergence and spread of resistant bacterial pathogens remain a key challenge in antibacterial chemotherapy. This study aims to investigate the antibacterial activity of combined extracts of various Kenyan medicinal plants against selected microorganisms of medical significance.MethodsThe antibacterial activity of various extract combinations of Aloe secundiflora, Toddalia asiatica, Senna didymobotrya and Camelia sinensis against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Methicillin Resistant Staphylococcus aureus was assessed using the agar well diffusion and the minimum inhibitory concentration in-vitro assays. The checkerboard method was used to evaluate the interactions between the various extract combinations. ANOVA test followed by Tukey’s post hoc multiple comparison test was used to determine statistically significant differences in activity (P < 0.05).ResultsAt concentrations of 100 mg/ml (10,000 µg/well), the different combinations of the aqueous, methanol, dichloromethane and petroleum ether extracts of the selected Kenyan medicinal plants revealed diverse activity against all the test bacteria. The combination of methanolic C. sinensis and A. secundiflora was the most active against E. coli (14.17 ± 0.22 mm, diameter of zones of inhibition (DZI); MIC 2500 µg/well). The combination of methanolic C. sinensis and S. didymobotrya was the most active against S. aureus (16.43 ± 0.10 mm; MIC 1250 µg/well), K. pneumonia (14.93 ± 0.35 mm, DZI; MIC 1250 µg/well), P. aeruginosa (17.22 ± 0.41 mm, DZI; MIC 156.25 µg/well) and MRSA (19.91 ± 0.31 mm, DZI; MIC 1250 µg/well). The Minimum Inhibitory Concentration of the different plant extract combinations ranged from 10,000 µg/ well to 156.25 µg/well. The ANOVA test indicated statistically significant differences (P < 0.05) between single extracts and their combinations. The fractional inhibitory concentration indices (FICI) showed that the interactions were either synergistic (10.5%), additive (31.6%), indifferent (52.6%), or antagonistic (5.3%) for the selected combinations.ConclusionThis study findings validate the ethnopractice of selectively combining medicinal plants in the management of some bacterial infections in traditional medicine.

Phytochemicals constitute reliable sources of antifungal and antioxidant compounds with low toxicity to mammals and safe to the environment which may serve as substitutes for synthetically produced chemicals. The present work aims at screening, and investigating the antimycotic and antioxidant activities of six medicinal plants, namely Croton macrostachyus (Euphorbiaceae), Clerodendrum (Rotheca) myricoides (Lamiaceae), Erucastrum arabicum (Brassicaceae), Melanthera scandens (Asteraceae), Senecio mannii (Asteraceae), and Senna didymobotrya (Fabaceae). A qualitative phytochemical screening was conducted by appropriate chemical methods. Antioxidant activity of 18 aqueous extracts has been tested by bleaching the solution of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Antimycotic activity of all extracts was measured by the disc diffusion method on a potato dextrose agar plate against five fungal strains viz. Rhizopus stolonifer, Aspergillus niger, Aspergillus flavus, Aspergillus parasiticus and Fusarium oxysporum. The study revealed that the main phytochemical constituents of leaf, stem and root bark extracts were terpenoids, tannins, saponins, alkaloids. Furthermore, the results showed that leaf extracts were richer in antioxidant potentials than the rest of the plant parts tested. However, scavenging capacity of leaf extract was lower than that of the ascorbic acid for all extracts except C. macrostachyus and M. scandens which exhibited approximately the same values as ascorbic acid. The leaf extracts displayed the highest inhibition zone average for most of the fungi. The strong antimycotic activity ranged from 14 to 27 mm and was observed mainly in leaf extracts. The leaf extract of M. scandens was the strongest against F. oxysporum with 27.0 mm inhibition zone diameter. The root extract displayed the lowest average zones of inhibition such as 2.0 mm for E. arabicum extract against R. stolonifer and 3.0 mm for S. didymobotrya extract against A. niger. Antioxidant and antimycotic activities were probably attributed to the presence of different groups of phytochemicals as such as terpenoids, flavonoids, and tannins. From the results of this study, plant extracts with higher antioxidant and antimycotic activity could be further studied and eventually be used in the development of natural antioxidants and food preservatives that could replace the synthetic compounds.

Tomato is one of the most important vegetables in the world. Ralstonia solanacearum causes a devastating bacterial wilt that is wide-spread throughout tropical environments that has been difficult to control with chemicals and African cultural practices in poor regions of the world. This study was initiated to determine the inhibitory effect of methanolic root extract of Senna didymobotrya and Moringa oleifera seed extracts on growth and development of R. solanacearum. The study was conducted both in the Laboratory and in the green house in Maseno from where S. didymobotrya and M. oleifera specimens used were collected from the University Botanic Garden, dried under shade for 30 days, before being ground into a fine powder. 1000 grams of the plant powder was later transferred into a conical flask and covered with 250mls of methanol. Filtration was done and the extracts concentrated. Ten diseased tomato plants showing bacterial wilt symptoms earlier collected from Maseno, Mariwa, Seme and Holo all within Kisumu county (Kenya) were cut to obtain plant sections (0.5–1cm) that were later plated onto Triphenyltetrazolium chloride media. Bacteriostatic activity of the extracts was determined by the disc diffusion method on Mueller Hinton agar. In vivo evaluations were conducted in a green house using tomato seedlings. Data collected was subjected to analysis of variance and means separated were compared using least significance difference (P≤ 0.05). Both plants extracts showed inhibitory activity against R. solanacearum pathogen (M. Oleifera; 8.5 and S. didymobotrya 9.2). Based on the outcome of this study, S. didymobotrya is recommended as a potential botanical agent suitable for future trials and use in the control of R. solanacerum by tomato farmers in Maseno region Kisumu county.

Globally, approximately 13% of all deaths annually are attributed to cancer. Surgery, radiation and chemotherapy are the current treatment techniques for cancer; however, these methods are expensive, have high failure rates and have been associated with detrimental side effects. Plant derived products could be good candidates in alleviating challenges being experienced with these current methods. This study aimed at evaluating the phytochemistry, antiproliferation potential, and probable mechanism of action of Albizia gummifera, Rhamnus staddo and Senna didymobotrya plant extracts. The 3– (4, 5-dimethylthiazol-2-yl) -2, 5-diphenyltetrazolium (MTT) assay dye was used in the determination of the antiproliferative activity of the extracts. Extracts induction potential of p53 (apoptosis) and VEGF (angiogenesis) genes’ expression was evaluated using Real Time PCR. Phytochemical screening was done as per standard procedures. Several plant extracts exhibited antiproliferative activity against the cancerous cell lines tested showing selective toxicity to cancer cells while sparing the normal cells (SI ≥ 3). An upregulation of p53 and down-regulation VEGF genes was observed. Phytochemical screening revealed presence of pharmacologically important phytochemicals in the plant’s extracts. The study findings suggest exploitation of these plant extracts as potential candidates for development of drugs for the management of breast and prostate cancer.

Bio-synthesised silver nanoparticles are effective in controlling several micro-organisms. They are correspondingly environmentally friendly, affordable, and easy to synthesise when compared with chemically synthesised silver nanoparticles. This study investigated the efficacy of biosynthesized silver nanoparticles against the fungus Sporisorium scitamineum, the causal agent of sugarcane smut. The reduction of silver nitrate upon mixing with the plants&rsquo; crude extracts was evidenced by the change in colour of the mixture to dark brown. Optimization of the mixtures using ultraviolet-visual spectroscopy showed peaks in the range of 340 to 450 nm. The Fourier transform infrared spectroscopy analysis identified proteins to be essential capping agents, and reducing sugars were responsible for the reduction of silver nitrate to nanoparticles and stabilizing the nanoparticles. The transmission electron microscope analysis showed the sizes of the nanoparticles to vary between 3 and 70 nm. Carissa spinarum and Melia azedarach had the most antifungal activity against S. scitamineum as observed from the inhibition-zone assay. Silver nanoparticles were successfully synthesized using the selected botanicals. All the synthesized nanoparticles showed varying antifungal effects against the S. scitamineum. C. spinarum and M. azedarach exhibited the highest antifungal activity, while Azadirachta indica showed the least. &nbsp; Key words: Sporisorium scitamineum, Acacia nilotica, Carissa spinarum, Senna didymobotrya, Warburgia ugandensis, Melia azedarach, Azadirachta indica, bio-synthesised silver nanoparticles, antifungal activity.

Kenya's vision 2030 partly aims at ensuring adequate health care for all, and the integration of traditional healthcare practices into the national healthcare system would present a more rapid alternative towards the realization of universal health coverage in Kenya. Currently, research on Kenyan medicinal plants with potential antibacterial activity remains vastly fragmented across numerous literature studies and databases; thus, it is imperative to collate and appraise these data for the ease of future research and possible clinical application. Objective. This review aims at exploring and compiling research evidence on medicinal plants used in the management of bacterial infections in Kenya, with a focus on their efficacy and safety. Methodology. A comprehensive web-based systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was executed to highlight the Kenyan medicinal plants used for the management of bacterial infections in Kenya. This review includes studies published until January 2021 from the PubMed, Science Direct, AJOL, and Google Scholar databases. Results. A total of 105 Kenyan medicinal plants belonging to 43 families have their in vitro activity against various human pathogenic bacteria evaluated. Plants from the Lamiaceae, Rutaceae, and Fabaceae families were the most commonly studied. Aloe secundiflora, Toddalia asiatica, Senna didymobotrya, Warbugia ugandensis, Tithonia diversifolia, Fuerstia africana, Olea africana, and Harrisonia abyssinica were the plants frequently evaluated within Kenya. The plants with the strongest antimicrobial activities were Toddalia asiatica, Hagenia abyssinica, Ocimum gratissimum, Harrisonia abyssinica, Senna didymobotrya, Olea Africana, Camellia sinensis, and Tarmarindus indica. Conclusion. Based on a published work, it is evident that traditional medicine is seemingly an acceptable and efficient system among Kenyan communities in the management of bacterial infections. Kenya's rich biodiversity with diverse secondary metabolites presents a promising source of new therapeutic alternatives with possibly different mechanisms of action against bacteria.

Praziquantel (PZQ) remains the only drug of choice for the treatment of schistosomiasis, caused by parasitic flatworms. The widespread use of PZQ in schistosomiasis endemic areas for about four decades raises concerns about the emergence of resistance of Schistosoma spp. to PZQ under drug selection pressure. This reinforces the urgency in finding alternative therapeutic options that could replace or complement PZQ. We explored the potential of medicinal plants commonly used by indigenes in Kenya for the treatment of various ailments including malaria, pneumonia, and diarrhoea for their antischistosomal properties. Employing the Soxhlet extraction method with different solvents, seven medicinal plants Artemisia annua, Ajuga remota, Bredilia micranta, Cordia africana, Physalis peruviana, Prunus africana and Senna didymobotrya were extracted. Qualitative phytochemical screening was performed to determine the presence of various phytochemicals in the plant extracts. Extracts were tested against Schistosoma mansoni newly transformed schistosomula (NTS) and adult worms and the schistosomicidal activity was determined by using the adenosine triphosphate quantitation assay. Phytochemical analysis of the extracts showed different classes of compounds such as alkaloids, tannins, terpenes, etc., in plant extracts active against S. mansoni worms. Seven extracts out of 22 resulted in <20% viability against NTS in 24 h at 100 μg/ml. Five of the extracts with inhibitory activity against NTS showed >69.7% and ≥72.4% reduction in viability against adult worms after exposure for 24 and 48 h, respectively. This study provides encouraging preliminary evidence that extracts of Kenyan medicinal plants deserve further study as potential alternative therapeutics that may form the basis for the development of the new treatments for schistosomiasis.

The aim of the study was to compare glade and forest-glade edge plant community attributes for man-made, upper and lower natural glades. Two plots were set up in twelve glades at 2.5, 12.5 m and three plots in thirteen glades at 2.5, 12.5 and 22.5 m depending on the size of the glade. The results showed that plants total abundance, percentage basal cover, species richness and species diversity for upper and lower natural glades differed significantly p -4.51, p χ2 = 15.95, df = 4, p Eleusine jaegeri, Heterogon contortus, Senna mimisoides, Digitaria scalarum, Clutia abyssinica) were habitat indicators for disturbed areas, wet humid grey/black clay soils for upper natural glades and three (Solanum incanum, Senna didymobotrya, and Pennistem mezianum, were indicators of overgrazed areas and black clay soils for man-made glades. In conclusion, plant species abundance, richness and diversity were highest at the forest-glade edge and decreased towards the glade interior, while plant species composition differed significantly between the three-glade types. The plant growth form for lower natural glades was associated with forest-glade edge and glade interior.

The economic burden and high mortality associated with multidrug-resistant bacteria is a major public health concern. Biosynthesized copper nanoparticles (CuNPs) could be a potential alternative to combat bacterial resistance to conventional medicine. This study for the first time aimed at optimizing the synthesis conditions (concentration of copper ions, temperature, and pH) to obtain the smallest size of CuNPs, characterizing and testing the antibacterial efficacy of CuNPs prepared from Senna didymobotrya (S. didymobotrya) roots. Extraction was done by the Soxhlet method using methanol as the solvent. Gas chromatography-mass spectrometry (GC-MS) analysis was performed to identify compounds in S. didymobotrya root extracts. Box–Behnken design was used to obtain optimal synthesis conditions as determined using a particle analyzer. Characterization was done using ultraviolet-visible (UV-Vis), particle size analyzer, X-ray diffraction, zeta potentiometer, and Fourier transform infrared (FT-IR). Bioassay was conducted using the Kirby–Bauer disk diffusion susceptibility test. The major compounds identified by GC-MS in reference to the NIST library were benzoic acid, thymol, N-benzyl-2-phenethylamine, benzaldehyde, vanillin, phenylacetic acid, and benzothiazole. UV-Vis spectrum showed a characteristic peak at 570 nm indicating the formation of CuNPs. The optimum synthesis conditions were temperature of 80°C, pH 3.0, and copper ion concentration of 0.0125 M. The FT-IR spectrum showed absorptions in the range 3500–3400 cm−1 (N-H stretch), 3400–2400 cm−1 (O-H stretch), and 988–830 cm−1 (C-H bend) and peak at 1612 cm−1 (C=C stretch), and 1271 cm−1 (C-O bend). Cu nanoparticle sizes were 5.55–63.60 nm. The zeta potential value was −69.4 mV indicating that they were stable. The biosynthesized nanoparticles exhibited significant antimicrobial activity on Escherichia coli and Staphylococcus aureus with the zone of inhibition diameters of 26.00 ± 0.58 mm and 30.00 ± 0.58 mm compared to amoxicillin clavulanate (standard) with inhibition diameters of 20 ± 0.58 mm and 28.00 ± 0.58 mm, respectively.

The distribution of selected woody invasive alien species in small towns in the Eastern Cape, South Africa