Antibacterial activities of chemical constituents from the aerial parts of Hedyotis pilulifera

Abstract

Context:Hedyotis pilulifera (Pit.) T.N. Ninh (Rubiaceae) has been used in Vietnamese ethnomedicine; the methanol extract exhibited antibacterial activity in our preliminary screening.Objectives: In this study, compounds from H. pilulifera were isolated and their antibacterial activity in vitro was evaluated.Materials and methods: The aerial parts of H. pilulifera (1.4 kg) were extracted with MeOH, suspended in water and ethyl acetate extract was chromatographed on a silica gel column. The structures of isolated compounds were elucidated by the combination analyses of spectroscopy including 1D-, 2D-NMR, HRMS and in comparison with the reported NMR data in the literature. All isolated compounds were evaluated for inhibitory effect using the microdilution method toward Staphylococcus aureus, Bacillus subtilis and Mycobacterium smegmatis, and MIC values were determined.Results: Twenty compounds were isolated, including five triterpenoids, two steroids, two aromatic compounds, three fatty acids, one quinone derivative, one lignan glycoside, one ceramide and five glycolipids. Among these, oleanolic acid showed significant antibacterial activity against M. smegmatis with the MIC value of 2.5 μg/mL. Remarkably, rotungenic acid showed strong activity against S. aureus, B. subtilis, M. smegmatis with MIC values of 2.5, 2.5 and 1.25 μg/mL, respectively. Rotundic acid exhibited significant antibacterial activity against B. subtilis with the MIC value of 5 μg/mL. To the best of our knowledge, the antibacterial activity of rotungenic acid, stigmast-4-ene-3,6-dione and (2S,3S,4R,2′R)-2-(2′-hydroxytetracosanoylamino) octadecane-1,3,4-triol was reported for the first time.Conclusions: Oleanolic acid, rotungenic acid, and rotundic acid were considered to be useful for developing new antimicrobial therapeutic agents for human.

Antibacterial Activity with Bacterial Growth Kinetics and GC-MS Studies on Leaf and Tuber Extracts of Arisaema tortuosum (Wall.) Schott

“…[22][23] Previous studies on octadecane derivative showed the moderate inhibitory effect against bacterial strains. 24 Another study of oil comprising of hexahydrofarnesyl acetone constituent has reported for its antimicrobial effect. 25 The fatty acid (Methyl ester) reported for moderate antimicrobial activities.…”

Antimicrobial Lipids from Plants and Marine Organisms: An Overview of the Current State-of-the-Art and Future Prospects

“…The lowest MIC against S. aureus were observed for the mixture of lipid classes from the aerial parts of Hedyotis pilulifera (1.25 µg/mL) [83], the artemceramide-B from the roots of A. incisa (0.0313 mg/mL) [73], the linoleate oxylipins isolated from Alternanthera brasiliana (50 µg/mL) [65], and the FAME extracted from the shoots of Salicornia brachiata (60 µg/mL, the same MIC also verified for a MRSA strain) [61]. In the case of artemceramide-B, its high inhibitory potential against S. aureus was assigned to this polar lipid bearing four hydroxyl groups and an amide linkage between two long aliphatic chains [73].…”

“…To identify and/or quantify mixtures of compounds, simpler techniques can be applied as biochemical assays using colorimetric tests, as for instance, for sterols' and steryl glycosides' identification and quantification [68,69,72]. The data obtained for compounds' identification in these studies on antimicrobial plant lipids are normally compared with data reported in the literature, especially for spectroscopic data [72,83].…”

Cytotoxic Evaluation of Compounds Isolated from the Aerial Parts of Hedyotis pilulifera and Methanol Extract of Inonotus obliquus

“…Since the 1940s, the analysis of the sources of new and approved drugs indicated that about 47% of all approved antitumor drugs are either natural products or directly derived therefrom [2]. We have previously reported [3][4] phytochemicals and antibacterial activity of Hedyotis pilulifera (Pit.) T.N.Ninh collected in Vietnam.…”

“…Twenty-one compounds were isolated from the aerial parts of H. pilulifera and identified as follows: oleanolic acid (1), betulinic acid (2), pomolic acid 3β-acetate (3), rotungenic acid (4), rotundic acid (5), daucosterol (6), octadeca-9Z,12Z-dienoic acid (7), (7S*,8R*,7R*,8S*)-icariol A2-9-O-β-xylopyranoside (8), 10-Oacetylborreriagenin (9), asperuloside (10), paederoside (11), asperulosidic acid (12), daphylloside (13), paederosidic acid methyl ester (14), adenosine (15) (21). The isolation processes and structural elucidations of these compounds were reported in our previous publications [3][4][5]11].…”