| dc.description.abstract | Emergence and spread of antimicrobial resistance (AMR), is of great concern to the global health, necessitating the search for new therapeutic agents. Candida albicans, Pseudomonas aeruginosa and Staphylococcus aureus are among the serious AMR pathogens worldwide. Furthermore, AMR infections are associated with higher levels of oxidative damage in the human cells which is linked to various diseases, including cancer and cardiovascular diseases. Medicinal plants are of significant importance worldwide, serving as alternatives to modern medicine. Plant extracts contain phytochemicals, such as phenolic compounds, which exhibit bioactivities including antioxidant and antimicrobial activities. Antioxidants prevent oxidative stress in human cells, aiding in the management of oxidative stress-related diseases whereas antimicrobials kill or inhibit the growth of microorganisms, helping in managing infectious diseases. Despite several benefits of medicinal plants in herbal medicine, there is insufficient scientific data to support the use of the herbal drugs. Though a lot of studies have dealt with the studies for antioxidant and antimicrobial drugs from plants, there is less information on antioxidant and antimicrobial activity especially from Adenia lobata, Ipomoea aquatica, and Rubia cordifolia against Candida albicans, Pseudomonas aeruginosa, and Staphylococcus aureus. This study was conducted at Maseno University and Kenya Marine and Fisheries Research Institute. The objectives of the study were to determine (i) the phytochemicals present in leaf, stem, and root extracts of the selected climbers; (ii) determine the antioxidant activity of the extracts and (iii) determine the effect of the extracts on the growth of the specified test organisms. A. lobata, I. aquatica, and R. cordifolia samples were collected using targeted random sampling method from Kisii (0°54'38.7"S 34°48'28.95"E), Lake Victoria shorelines-Kisumu City (0°7'33"S 34°44'33.6"E), and Maseno University farm (0°0'32.6"S 34°36'28.6"E) respectively. The samples were separated into leaf, stem and root parts which were air-dried in the shade, ground into powder and then soaked in methanol. Thereafter, filtration was done and the extracts concentrated. Phytochemical analysis was conducted to test the presence of saponins, tannins, terpenoids, steroids, flavonoids, alkaloids, cardiac glycosides, and anthraquinones. Thin layer chromatography (TLC), was conducted as a semi-quantitative phytochemical analysis. The antioxidant activity was assessed using 2, 2-diphenylpicryl-1-hydrazyl free radical scavenging method with ascorbic acid as reference standard. Microbial growth was assessed using the disc diffusion method at 25, 50, 75, and 100 mg/ml concentrations. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) were also determined. The antioxidant and antimicrobial assays were done in triplicates in a completely randomized design. Data collected was subjected to analysis of variance (ANOVA) followed by post hoc tests. Means were separated and compared using the least significant difference (LSD) at P≤0.05. Phytochemical analysis revealed presence of alkaloids, tannins, terpenoids, steroids, glycosides, saponins, flavonoids, and anthraquinones in the extracts. TLC analysis indicated R. cordifolia leaf extract had the highest number of phytochemical spots (14), while A. lobata and I. aquatica root extracts had the lowest spots (2). A. lobata root extract showed relatively high antioxidant activity with IC50 value of (116.25 μg/ml), and I. aquatica roots had lowest antioxidant activity of (355.16 μg/ml). The extracts significantly inhibited the growth of the three test organisms. The largest zones of inhibition were observed in 100 mg/ml R. cordifolia leaf extract against P. aeruginosa (21.00 mm), and S. aureus (15.57 mm), and 100 mg/ml in R. cordifolia root extract against C. albicans (11.67 mm). The extracts exhibited significant bacteriostatic and fungistatic activity. MIC values for R. cordifolia extracts against C. albicans was 5 mg/ml for both leaf and root extracts and 10 mg/ml for the stem whereas for both P. aeruginosa and S. aureus were all at 10 mg/ml. The study has demonstrated that A. lobata roots is a potential source of antioxidants. R. cordifolia has been shown to be active against C. albicans, P. aeruginosa and S. aureus. Bioactive activity in plants is primarily linked to phytochemicals. The study has revealed that the extracts from these climbing plants can be used as potential antioxidant and antimicrobial agents for the development of new drugs. With this evidence of bioactive secondary metabolites, there is need for further studies to isolate and characterize phytochemicals associated with these plants. | en_US |
