Tristemma hirtumand Five Other Cameroonian Edible Plants with Weak or No Antibacterial Effects Modulate the Activities of Antibiotics against Gram-Negative Multidrug-Resistant Phenotypes

Abstract

In order to contribute to the fight against infectious diseases, the in vitro antibacterial activity and the antibiotic-potentiating effects of Tristemma hirtum and five other Cameroonian edible plants have been evaluated against Gram-negative multidrug-resistant (MDR) phenotypes. The microdilution method was used to evaluate the bacterial susceptibility of the extracts and their combination to common antibiotics. The phytochemical screening of the extracts was carried out according to standard methods. Phytochemical analysis of the extracts revealed the presence of alkaloids, triterpenes, steroids, and polyphenols, including flavonoids in most of the tested extracts. The entire tested extracts showed moderate (512 μg/mL ≤ MIC ≤ 2048 μg/mL) to weak (MIC > 2048 μg/mL) antibacterial activities against the tested bacteria. Furthermore, extracts of leaf of Tristemma hirtum and pericarps of Raphia hookeri (at their MIC/2 and MIC/4) strongly potentiated the activities of all antibiotics used in the study, especially those of chloramphenicol (CHL), ciprofloxacin (CIP), kanamycin (KAN), and tetracycline (TET) against 70% (7/10) to 100% (10/10) of the tested MDR bacteria, with the modulating factors ranging from 2 to 128. The results of this study suggest that extracts from leaves of Tristemma hirtum and pericarps of Raphia hookeri can be sources of plant-derived products with antibiotic modifying activity.

Antisalmonellal Activities of Extracts, Fractions, Compounds and Semi-synthetic Flavonoid Derivatives from <i>Tristemma hirtum</i> P. Beauv (Melastomataceae)

“…Compounds 1, 4, 5, 9 and 10 are also moderately active (MIC from 16 to 64 µg/mL) and then, could justify the activity shown by the original fraction, suggesting that many of them should proceed by synergism to enable the higher activity of the extract. This potentiating effect of the methanol extract from leaves of T. hirtum against Multi-Drugs Resistant Gram-Negative Bacteria have been reported when it was combined with other antibiotics [16]. Compound 5 as a substrate of prenylation reaction showed moderate activity against three bacteria strains tested while two of its semi-synthetic derivatives, 5a and 5c showed the same activity against four various bacterial strains.…”

“…It is widely found in the West Region of Cameroon where it is used in folk medicine, associated with other plants for the treatment of hemorrhoids, reproductive problems, skin diseases and typhoid fever [14,15]. Previously, researchers have reported antibacterial activities of Tristemma hirtum extracts [16]. As part of our ongoing phytochemical studies of medicinal plants growing in Cameroon, we have previously reported the isolation and characterization of ten compounds including flavonoids, terpenoids, glycerol derivatives and hydrolysable tannins from some fractions of the methanol extract from Tristemma hirtum [17].…”

Bark extract of Cassia sieberiana DC. (Caesalpiniaceae) displayed good antibacterial activity against MDR gram-negative phenotypes in the presence of phenylalanine-arginine β-naphthylamide

“…The search for new molecules to tackle bacterial antibio-resistance has become imperative. Plant kingdom has a great number of bioactive substances, and good numbers of medicinal plants from the flora of Cameroon have proven their ability to inhibit the growth of Gram-negative bacteria, including MDR phenotypes [5][6][7][8][9]. C. sieberiana (Caesalpiniaceae) is widespread in West Africa and is very common in all savannah woodlands or shrubs of the Sudanian zones up to the edge of the Guinean forest in Casamance.…”

Antioxidant and Antibacterial Activity of Alkaloid Fractions of Tristemma hirtum P. Beauv

“…and analgesic properties. [2][3] Also, flavonol glycosides, β-sitosterol glucopyranoside and terpenoid acids have been isolated from the ethyl acetate and n-butanol soluble fractions of the plant methanol extract. 4 In addition, phytocompounds such as alkaloids, triterpenes, steroids, flavonoids and polyphenols were identified in the methanol leaf extract of the plant.…”

“…4 In addition, phytocompounds such as alkaloids, triterpenes, steroids, flavonoids and polyphenols were identified in the methanol leaf extract of the plant. 3 However, numerous biological activities have been reported for other species of this family including antioxidant, antihypertensive, antimicrobial, cytotoxic, hemostatic, antiinflammatory and antihyperglycemic properties. [4][5][6] Also, flavonoids, polyphenols, steroids, fatty acids, etc have been identified from members of this family.…”