Phytochemical Evaluation of Terminalia canescens DC. Radlk. Extracts with Antibacterial and Antibiotic Potentiation Activities against Selected ß-Lactam Drug-Resistant Bacteria.

Terminalia canescens DC. Radlk. (family: Combretaceae) is native to northern Australia. Species of the genus Terminalia are widely used as traditional medicines to treat diverse ailments, including bacterial infections. However, we were unable to find any studies that had examined the antimicrobial activity of T. canescens. In this study, T. canescens was screened against a panel of bacterial pathogens, including multi-antibiotic-resistant strains. Solvents with different polarities were used to extract different complements of phytochemicals from T. canescens leaves. Methanolic and aqueous extracts exhibited substantial antimicrobial activity against various pathogens, including those that are multidrug-resistant strains. When combined with some selected clinical antibiotics, some extracts potentiated the antibacterial inhibitory activity. This study identified two synergistic, eleven additive, eleven non-interactive and eight antagonistic interactions. The toxicities of the plant extracts were examined in the Artemia franciscana nauplii assay and were found to be non-toxic, except the aqueous extract, which showed toxicity. Metabolomic liquid chromatography-mass spectrometry (LC-MS) analyses highlighted and identified several flavonoids, including vitexin, quercetin, orientin and kaempferol, as well as the tannins ellagic acid and pyrogallol, which may contribute to the antibacterial activities observed herein. The possible mechanism of action of these extracts was further explored in this study.

Selected Australian Terminalia Species Extracts Inhibit ß-Lactam Drug-Resistant Bacteria Growth and Potentiate the Activity of Conventional Antibiotics: Bioactivities and Phytochemistry.

Terminalia ferdinandiana Exell, Terminalia grandiflora Benth., Terminalia microcarpa Decne., and Terminalia muelleri Benth. (family: Combretaceae) belong to the genus Terminalia. Plants of this genus have been extensively used as traditional medicines to treat a variety of illnesses, including pathogen infections. However, we were unable to find any studies that have investigated the antibacterial activity of T. microcarpa. Similarly, whilst some preliminary studies have examined the antimicrobial properties of T. muelleri and T. grandiflora, they did not test the extracts against antibiotic-resistant pathogens. This study screens the antimicrobial activity of T. grandiflora, T. microcarpa, and T. muelleri and compares it to that of T. ferdinandiana extracts prepared from both the fruit and leaves against a range of pathogens, including multi-antibiotic-resistant strains. Solvents with varying polarities were used to extract different phytochemical constituents from the leaves of T. grandiflora, T. microcarpa, and T. muelleri and from the fruit and leaves of T. ferdinandiana. The aqueous and methanolic extracts each displayed significant antimicrobial activity when tested against the bacterial pathogens, including against the multidrug-resistant strains. When these extracts were tested in combination with selected antibiotics, some extracts potentiated the antimicrobial activity. This study identifies twelve synergistic, fifty-eight additive, and sixty non-interactive combinations, as well as thirty antagonistic effects. The extracts were evaluated for toxicity using the Artemia franciscana nauplii lethality assay (ALA) and were each classified as non-toxic, with the exception of the methanolic and aqueous T. ferdinandiana fruit extracts and the aqueous and ethyl acetate T. ferdinandiana leaf extracts. Metabolomic analysis using liquid chromatography-mass spectrometry (LC-MS) highlighted several flavonoids and tannins that may contribute to the antimicrobial activities reported herein. The potential antibacterial mechanism(s) of the T. ferdinandiana extracts are discussed in this study.

Terminalia petiolaris A.Cunn ex Benth. Extracts Have Antibacterial Activity and Potentiate Conventional Antibiotics against ß-Lactam-Drug-Resistant Bacteria.

Terminalia petiolaris A. Cunn. Ex Benth. (genus: Terminalia, family: Combretaceae) is native to Australia. Terminalia spp. have traditionally been used to treat various ailments, including bacterial infections. Solvents of varying polarity were used to extract compounds from leaves of this species, and the extracts were tested against a panel of bacteria, including antibiotic-resistant strains. The methanolic and water extracts showed substantial inhibitory activity against several bacteria, including antibiotic-resistant strains in both disc diffusion and liquid dilution assays. Combining these extracts with selected conventional antibiotics enhanced the inhibition of bacterial growth for some combinations, while others showed no significant interaction. In total, two synergistic, twenty-five additive, twenty-three non-interactive and one antagonistic interaction were observed. The methanolic and ethyl acetate plant extracts were found to be non-toxic in Artemia franciscana nauplii toxicity assays. A liquid chromatography-mass spectrometry metabolomics analysis identified several flavonoid compounds, including miquelianin, trifolin and orientin, which might contribute to the observed activities. The potential modes of these active extracts are further discussed in this study.

Bacterial Foodborne Illness in Malaysia: Terminalia spp. as a Potential Resource for Treating Infections and Countering Antibiotic Resistance.

Acute diarrhoea is becoming a major public health problem in Malaysia, with more than 13.5 million cases reported annually. Foodborne bacterial pathogens are a predominant cause of diarrhoea, with infections causing prolonged illness durations and higher patient mortality rates, placing a tremendous burden on the Malaysian economy. Due to increasing incidences of diarrhoea in Malaysia caused by foodborne pathogens and the increasing levels of resistance towards antibiotics from many different classes, new drugs and/or therapies are urgently required. The evidence for plants as new sources of antibiotics has increased dramatically in recent years and there has been a substantial increase in interest in traditional and herbal medicines. Several Terminalia spp. are native to Malaysia, with previous research demonstrating that Terminalia spp. are rich in therapeutic phytochemicals and possess antibacterial properties. However, limited research has been conducted on the native Malaysian Terminalia spp. for their potential as new antibacterial therapies. The current review discusses the types of bacteria, including antibiotic-resistant strains, that cause food poisoning in Malaysia, and reports the phytochemical content and antibacterial properties of eight of these useful plant species. Future directions pertaining to drug discovery pathways are also suggested.