Phytotoxic Activity of p-Cresol, 2-Phenylethanol and 3-Phenyl-1-Propanol, Phenolic Compounds Present in Cistus ladanifer L.

Numerous studies about the leaf exudate of Cistus ladanifer highlight this Mediterranean shrub as an allelopathic species. Despite the very high diversity of secondary metabolites identified in its labdanum, only a few components have been evaluated. p-Cresol, 2-phenylethanol and 3-phenyl-1-propanol are three phenolic components present in the labdanum of C. ladanifer whose role has not been specified to date. The present study, through a static acute toxicity test, analyzed their activity, with respect to Allium cepa and Lactuca sativa. These three separate compounds and the mixture of all of them have a more or less phytotoxic activity depending on the medium, species and concentration tested. When the test is carried out on paper, the three pure allelochemicals and their mixture at 1 mM significantly inhibited the total germination, the germination rate and the development of the Allium cepa and Lactuca sativa seedlings to a lesser extent, but when the test performed in soil, the effects on the size of roots and cotyledons are attenuated. Furthermore, in the two species tested on paper, the joint action of the three compounds at 1 mM shows a significantly greater inhibition of the measured indices than each of the compounds separately.

Antibacterial and Antifungal Activities of the Leaf Exudate of Aloe megalacantha Baker

Infectious diseases caused by fungi and bacteria are among the major causes of illness and death worldwide. This is mainly implicated by the antimicrobial resistance of the current treatment regimens. Since plant products are house stores of bioactive compounds, it is essential to screen plant-based antimicrobials to come up with novel medicines that counter the grave consequences of antimicrobial resistance. In the folk medicine of Ethiopia, Aloe megalacantha is used for the treatment of wound, dandruff, malaria, diabetes, impotence, colon cleansing, amoeba, ascariasis, abdominal pain, urine retention, snake bite, and evil eye. Hence, the present study was aimed to evaluate the antibacterial and antifungal effects of the leaf exudate of Aloe megalacantha. Agar well diffusion was employed to determine the antibacterial and antifungal effects. Six bacterial strains, namely, S. aureus (standard), S. aureus (clinical isolate), E. coli ATCC 25922 (standard), E. coli (clinical isolate), K. pneumoniae (standard), and P. aeruginosa ATCC 27853 (standard), and four fungal strains such as C. albicans, C. glabrata, C. tropicalis, and C. krusei were studied. The leaf exudate showed the highest activity against C. krusei with an average zone diameter of 22.49 ± 0.47 mm at 400 mg/mL. Among the bacterial species, S. aureus ATCC 29213 (standard) was the most sensitive with an average zone of diameter of 16.63 ± 0.12 mm at 200 mg/mL. Thus, the present findings support the folklore use of Aloe megalacantha for the treatment of different microbial infections.

Aloe barbadensis Miller leaf exudate is a potential treatment for bovine mastitis

Background: Aloe barbadensis Miller, also known as Aloe vera is a well-known phytotherapeutic, and parts of its leaves are used for a wide range of medicinal purposes. This study seeks to assess the in vitro antimicrobial and cytotoxic effects of leaf exudate (LE) from A. barbadensis leaves against Staphylococcus aureus and MAC-T bovine mammary epithelial cells. Methods: Seasonal LE samples were collected, and the effect on total phenolic and aloin contents was determined. Antimicrobial activity of LE was evaluated using the broth microdilution method, and toxicity to MAC-T cells was determined by MTT assay. Results: Samples collected during different seasons of the year showed a seasonal effect on the chemical profile of LE (P<0.05). However, despite these chemical variations, we found no differences in antimicrobial activity against S. aureus. For all studied samples, the minimum inhibitory concentration (MIC) was 1,000 µg/mL. Furthermore, we found an elevated cytotoxic effect of LE on MAC-T cells with a significant reduction in cellular viability at 7.8 µg/mL (P<0.05) and an IC50 of 91.89 µg/mL. Conclusions: Despite the antimicrobial effects of LE, the high toxicity for MAC-T cells suggests that it is unsuitable for intramammary use, but does have potential as a topical antimicrobial.

Aloe barbadensis Miller leaf exudate is a potential treatment for bovine mastitis

Background: Aloe barbadensis Miller is a well-known phytotherapeutic, and parts of its leaves are used for a wide range of medicinal purposes. This study seeks to assess the in vitro antimicrobial and cytotoxic effects of leaf exudate (LE) from A. barbadensis leaves against Staphylococcus aureus and MAC-T bovine mammary epithelial cells. Methods: Seasonal LE samples were collected, and the effect on total phenolic and aloin contents was determined. Antimicrobial activity of LE was evaluated using the broth microdilution method, and toxicity to MAC-T cells was determined by MTT assay. Results: Samples collected during different seasons of the year showed a seasonal effect on the chemical profile of LE (P<0.05). However, despite these chemical variations, we found no differences in antimicrobial activity against S. aureus. For all studied samples, the minimum inhibitory concentration (MIC) was 1,000 µg/ml. Furthermore, we found an elevated cytotoxic effect of LE on MAC-T cells with a significant reduction in cellular viability at 7.8 µg/ml (P<0.05) and an IC50 of 91.89 µg/ml. Conclusions: Despite the antimicrobial effects of LE, the high toxicity for MAC-T cells suggests that it is unsuitable for intramammary use, but does have potential as a topical antimicrobial.