The Antibacterial, Antitumor Activities, and Bioactive Constituents’ Identification of Alectra sessiliflora Bacterial Endophytes

Abstract

Due to increased antimicrobial resistance against current drugs, new alternatives are sought. Endophytic bacteria associated with medicinal plants are recognized as valuable sources of novel secondary metabolites possessing antimicrobial, antitumor, insecticidal, and antiviral activities. In this study, five bacterial endophytes were isolated and identified from the medicinal plant, Alectra sessiliflora, and their antibacterial and antitumor activities were investigated. In addition, the crude extracts of the endophytes were analyzed using gas chromatography (GC) coupled with time-of-flight mass spectrometry (TOF-MS). The identified bacterial endophytes belong to three genera viz Lysinibacillus, Peribacillus, and Bacillus, with the latter as the dominant genus with three species. Ethyl acetate extracts from the endophytes were used for antimicrobial activity against eleven pathogenic strains through minimum inhibitory concentration (MIC). The antitumor activity against the Hela cervical, Hek 293 kidney, and A549 lung carcinoma cells was determined by the MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay. Lysinibacillus sp. strain AS_1 exhibited broad antibacterial activity against the pathogenic strains with MIC values ranging from 4 to 8 mg/ml, while Bacillus sp. strain AS_3 displayed MIC of 0.25 mg/ml. Crude extracts of Lysinibacillus sp. strain AS_1, Peribacillus sp. strain AS_2, and Bacillus sp. strain AS_3 showed growth inhibition of more than 90% against all the cancer cell lines at a concentration of 1,000 μg/ml. Untargeted secondary metabolite profiling of the crude extracts revealed the presence of compounds with reported biological activity, such as antimicrobial, antioxidant, anti-inflammatory, antitumor, and antidiabetic properties. This study reported for the first time, bacterial endophytes associated with A. sessiliflora with antibacterial and antitumor activities.

Endophytic microbes and their diverse beneficial aspects in various sectors: A critical insight

“…Endophytes associated with medicinal plants are considered as important sources of secondary metabolites which possess antidiabetic, antitumor, antiviral, antimicrobial, antioxidant, anti-inflammatory and insecticidal properties (93). In some cases, endophytes produce secondary metabolites similar to the host plant, making them equally efficient for drug development.…”

“…strain AS_2 and Lysinibacillus sp. strain AS_1 has been proven to exhibit growth inhibition of cancer cell lines at a concentration of 1,000 μg/ml (93). Pestalotiopsis microspora is important for the production of natural AOX Pestacin and Isopestacin (67,68).…”

Gas and Liquid Chromatography Mass Spectrometry as a Tool for Elucidating Volatile Organic Compounds (VOCs) and Metabolites in Maternal Milk: A Perspective on Infants’ Health Risk Assessment

“…Citronellol (GC-MS full-scan spectra in Figure S1), a terpenoid that is a common constituent of essential oils and cosmetic products but also categorized as a flavoring substance [49], was also detected in several samples. 4-Mercaptophenol, a phenol derivative, exhibiting substantial bioactivity [50,51], was identified in several samples (GC-MS full-scan spectra in Figure S2), adding further evidence of the beneficial chemical arsenal of maternal milk. However, the same compound is also reported as an impurity in hair dye of 1,2,4-trihydroxybenzene [52], implying another potential etiology for its presence.…”

GC Analysis, Anticancer, and Antibacterial Activities of Secondary Bioactive Compounds from Endosymbiotic Bacteria of Pomegranate Aphid and Its Predator and Protector

“…Interestingly, the EA-ME of Bacillus sp. was able to reduce the cell viability of A549 cells to 0 % at 100 µg/mL [ 65 ]. The activity of Bacillus sp.…”