Antimicrobial activities of endophytic fungi residing in Aloe vera against diabetic wound pathogens

Aims@#Endophytic fungi are organisms that colonize living plant tissues without causing significant symptoms of diseases. They are known as the repository of bioactive compounds. This study was aimed to isolate endophytic fungi associated with Aloe vera and to assess their antimicrobial activity against the diabetic wound pathogens that result to lower limb amputations. @*Methodology and results@#In this study, 84 endophytic fungi were isolated from A. vera by using 5% sodium hypochlorite and 70% ethanol as surface sterilants. On preliminary antimicrobial screening by agar plug assay, 12 (14.3%) isolates showed significant antagonistic activity on the test microorganisms. Two of the endophytes were identified as Aspergillus flavus and Colletotrichum gloeosporioides through morphological and molecular techniques. The fungal cultures fermented in shake flask were extracted subsequently with hexane, dichloromethane, ethyl acetate, and n-butanol. Ethyl acetate and dichloromethane extracts of A. flavus and C. gloeosporioides inhibited all test bacteria. The compounds in the extracts were seemed to be semi-polar in nature. On broth microdilution assay, minimal inhibitory and minimal lethality concentration of ethyl acetate extracts of the fungi were found in the range of 0.63−2.50 and 1.25−5.00 mg/mL, respectively. @*Conclusion, significance and impact of study@#This study reveals that A. vera harbours a wide diversity of endophytic fungi. A. flavus and C. gloeosporioides showing broad spectrum antimicrobial activity on wound pathogens may be potential sources of bioactive compounds. Further investigations should be conducted to isolate and identify the antimicrobial compound produced by these fungal isolates.

Antimicrobial wound dressing film utilizing nano-cellulose and gelatin as drug delivery system for Garcinia mangostana L extract

Aims@#Diabetic patients with foot ulcer showed 150-fold increased risk of amputation, which is primarily caused by microbial infection. Silver ions are commonly incorporated into wound dressing to enhance the antimicrobial property. However, concerns have been expressed about the development of bacterial resistance to heavy metals. In this study, we extracted the nano-cellulose from medical cotton and reinforced with gelatin to develop a film for wound dressing. @*Methodology and results@#Garcinia mangostana L pericarp extract was incorporated into the nano-cellulose film as antimicrobial finishing. The efficacy of the developed nano-cellulose film was evaluated on diabetic wound microorganisms. We observed cellulose nano crystals with an average length of 133.71 nm under transmission electron microscope. The developed film showed gradual release of the extract over a period of 48 h and no burst effect was observed. The film exhibited significant inhibitory activity on three Gram positive bacteria, three Gram negative and all filamentous fungi tested. On Hohenstein challenge test, all test microorganisms showed significant growth reduction, with the treatment of the film. We also noticed that the antimicrobial activity of the film sustained even after 20 washes. @*Conclusion, significance and impact of study@#Our results indicate that the G. mangostana L pericarp extract loaded nano-cellulose films exhibited significant inhibitory activity on diabetic wound microorganisms. The developed film can be potentially used to prevent foot ulcer infection among diabetic patients.

Chemical Composition and Antimicrobial Efficiency of Swietenia macrophylla Seed Extract on Clinical Wound Pathogens

Microbial wound infection prolonged the hospitalization and increase the cost for wound management. Silver is commonly used as antimicrobial wound dressing. However, it causes several adverse side effects. Hence, this study was aimed to evaluate the antimicrobial efficiency of Swietenia macrophylla seed extract on clinical wound pathogens. Besides, the bioactive constituents of the seed extract were also determined. S. macrophylla seeds were extracted with methanol by maceration method. The seed extract inhibited 5 test bacteria and 1 yeast on disc diffusion assay. The antibacterial activity was broad spectrum, as the extract inhibited both Gram positive and Gram negative bacteria. On kill curve analysis, the antibacterial activity of the seed extract was concentration-dependent, the increase of extract concentration resulted in more reduction of bacterial growth. The extract also caused 99.9% growth reduction of Bacillus subtilis relative to control. A total of 21 compounds were detected in gas chromatography-mass spectrometry analysis. The predominant compounds present in the extract were oleic acid (18.56%) and linoleic acid (17.72%). In conclusion, the methanolic extract of S. macrophylla seeds exhibited significant antimicrobial activity on clinical wound pathogens. Further investigations should be conducted to purify other bioactive compounds from the seeds of S. macrophylla.

Chemical Composition and Antimicrobial Efficacy of Helminthostachys zeylanica against Foodborne Bacillus cereus

Helminthostachys zeylanica is a rare plant grows in lightly shaded areas. The fern was traditionally used as antipyretic and antiphlogistic agents. This study was aimed to evaluate the antibacterial potential of H. zeylanica on foodborne Bacillus cereus. The chemical composition of its ethanolic extract was also determined. The plant samples were collected at Kampung Kebun Relong, Kedah, Malaysia. The ethanolic extract showed significant inhibitory activity on B. cereus with a sizeable clear zone detected on disc diffusion assay. On broth microdilution assay, the MIC of the extract on B. cereus was 6.25 mg/ml and the MBC was 12.5 mg/ml. The inhibitory activity of the extract on B. cereus was bactericidal. In the growth dynamic study, the antibacterial efficacy of the extract was concentration dependent, where a lower colony forming unit count was obtained with increased extract concentration. The SEM micrograph of extract treated B. cereus cells showed invaginations of cell wall. The bacterial cell structure collapsed after 24 h exposure to the extract. The GCMS analysis of the extract showed that the major constituents of the extract were phenol (36.26%) and quercetin (29.70%). This study is important as it shows the potential use of H. zeylanica as an effective agent to control B. cereus related infections.

Antimicrobial Efficacy of Penicillium amestolkiae elv609 Extract Treated Cotton Fabric for Diabetic Wound Care

Diabetes mellitus is a chronic disorder which affects millions of population worldwide. Global estimates published in 2010 reported the world diabetic prevalence as 6.4%, affecting 285 million adults. Foot ulceration and wound infection are major forms of disabilities arising from diabetic diseases. This study was aimed to develop a natural antimicrobial finishing on medical grade textile that meets American Association of Textiles Chemists and Colorists (AATCC) standard. The textile samples were finished with the ethanolic extract of Penicillium amestolkiae elv609, an endophytic fungus isolated from Orthosiphon stamineus Benth (common name: cat's whiskers). Endophyte is defined as microorganism that reside in the living plant tissue, without causing apparent disease symptom to the host. The antimicrobial efficacy of the ethanolic extract of P. minioluteum was tested on clinical pathogens isolated from diabetic wound. The extract exhibited significant inhibitory activity against 4 bacteria and 1 yeast with the minimal inhibitory concentration ranged from 6.25 to 12.5 mg/mL. The results indicate different susceptibility levels of the test microorganism to the ethanolic extract. However, the killing activity of the extract was concentration-dependent. The finished medical textile showed excellent antimicrobial efficacy on AATCC test assays. All the microbial cultures treated with the textile sample displayed a growth reduction of 99.9% on Hoheinstein Challenge Test. The wash durability of the finished textile was found good even after 50 washes with commercial detergent. Besides, the gas chromatography mass spectrometry analysis showed that 6-octadecenoic acid and diethyl phthalate were the main bioactive constituents of the extract. In conclusion, the developed medical textile showed good antimicrobial efficacy on laboratory tests. This work can be extended to in vivo trials for developing healthcare textile products for antimicrobial applications.