Antibacterial Activity of Kalanchoe mortagei and K. fedtschenkoi Against ESKAPE Pathogens

Abstract

Plants in the genus Kalanchoe (Family: Crassulaceae) are used in traditional medicine throughout the tropics for treating a variety of conditions. Two species, Kalanchoe mortagei and K. fedtschenkoi, have established ethnobotanical usage but have been neglected in previous research concerning their potential bioactivity. Here, we provide a thorough review of the reported antimicrobial activities of Kalanchoe genus and evaluate the in vitro antibacterial effects of two previously unexplored species against a panel of multidrug-resistant bacteria, the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter cloacae). Plant specimens were collected and voucher specimens deposited in the Emory University Herbarium. Dried plant material was ground into a powder and extracted as ethanolic macerations or as aqueous decoctions. Extracts were tested against the ESKAPE pathogens for growth inhibitory activity. Cytotoxicity to human cells was assessed via a lactate dehydrogenase assay of treated human keratinocytes (HaCaTs). K. fedtschenkoi extracts demonstrated growth inhibitory effects against two Gram-negative species, A. baumannii (strain CDC-33) and P. aeruginosa (AH-71), as well as S. aureus (UAMS-1). In these cases, growth inhibition greater than 50% (IC50) was generally observed at concentrations of 256 μg mL-1, though one K. fedtschenkoi extract (1465, prepared from stems) exhibited an IC50 against A. baumannii at 128 μg mL-1. All extracts were well tolerated by HaCaTs (LD50 ≥ 256 μg mL-1). Chemical characterization using HPLC and chemical standards established the presence of caffeic acid and quercetin in both plant species, as well as kaempferol in K. fedtschenkoi. These results reveal K. fedtschenkoi to be a plant of medicinal interest, and future research should aim to characterize the bioactivity of this species and its active constituents through bioassay-guide fractionation. Effects on bacterial biofilm formation and quorum-sensing are also research topics of interest for this genus.

From Ethnomedicine to Plant Biotechnology and Machine Learning: The Valorization of the Medicinal Plant Bryophyllum sp.

“…The antimicrobial activity attributed to Bryophyllum extracts was shown to present a high effectiveness against a wide range of both bacterial and fungal activities. In this sense, hydroethanolic extracts from B. fedtschenkoi showed a strong inhibitory effect against different antimicrobial resistant strains from the ESKAPE complex, including both Gram-negative and Gram-positive bacteria [37]. Similarly, the bactericidal effect of B. crenatum leaf juice against Bacillus subtilis and Klebsiella pneumoniae was also reported, as well as high effectiveness of methanol extracts from B. pinnatum to Gram-positive bacteria [34].…”

Antimicrobial Activity of Kalanchoe blossfeldiana and Paederia foetida Plant Leaves’ Extracts Against Some Selected Bacterial Strains

“…K. fedtschenkoi extract exhibited growth inhibition against two Gram-negative sp. A. baumannii (CDC-33) and P. aeruginosa (AH-71) as well as Gram-positive S. aureus [14]. Extract in other studies with S. aureus have always shown growth inhibition with the exception of the poor performance of a hexane fraction tested [15].…”

Evaluation of the Antibacterial Activity of Some Medicinal Plants Extract Against Some Human Pathogenic Bacteria

“…Enterococcus spp. and some air borne and food borne pathogenic bacteria at alarming stage (Bhatti et al, 2019;Richwagen et al, 2019;Chatham-Stephens et al, 2019;Mehboob and Abbas 2019;Naz & Pasha 2019;Irum et al, 2019). According to the published data, the mortality rate is about 0.7 million worldwide due to antimicrobial resistance pathogens, which will raise 10 million by 2050 (de Kraker et al, 2019) The data reported by Center of Disease and Control showed about 23,000 mortality rates due to infection caused by antimicrobial resistance annually (Lim et al, 2016).…”