Chemical Composition of Hexane Extract of Citrus aurantifolia and Anti-Mycobacterium tuberculosis Activity of Some of Its Constituents

Abstract

The main aim of this study was to isolate and characterize the active compounds from the hexane extract of the fruit peels of Citrus aurantiifolia, which showed activity against one sensitive and three monoresistant (isoniazid, streptomycin or ethambutol) strains of Mycobacterium tuberculosis H37Rv. The active extract was fractionated by column chromatography, yielding the following major compounds: 5-geranyloxypsoralen (1); 5-geranyloxy-7-methoxycoumarin (2); 5,7-dimethoxycoumarin (3); 5-methoxypsoralen (4); and 5,8-dimethoxypsoralen (5). The structures of these compounds were elucidated by 1D and 2D NMR spectroscopy. In addition, GC-MS analysis of the hexane extract allowed the identification of 44 volatile compounds, being 5,7-dimethoxycoumarin (15.79%), 3-methyl-1,2-cyclopentanedione (8.27%), 1-methoxy-ciclohexene (8.0%), corylone (6.93%), palmitic acid (6.89%), 5,8-dimethoxypsoralen (6.08%), α-terpineol (5.97%), and umbelliferone (4.36%), the major constituents. Four isolated coumarins and 16 commercial compounds identified by GC-MS were tested against M. tuberculosis H37Rv and three multidrug-resistant M. tuberculosis strains using the Microplate Alamar Blue Assay. The constituents that showed activity against all strains were 5 (MICs = 25–50 μg/mL), 1 (MICs = 50–100 μg/mL), palmitic acid (MICs = 25–50 μg/mL), linoleic acid (MICs = 50–100 μg/mL), oleic acid (MICs = 100 μg/mL), 4-hexen-3-one (MICs = 50–100 μg/mL), and citral (MICs = 50–100 μg/mL). Compound 5 and palmitic acid were the most active ones. The antimycobacterial activity of the hexane extract of C. aurantifolia could be attributed to these compounds.

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“…Among active ingredients contained in the lime extract are flavonoids (polyethoxylated flavones and flavanones), coumarin, and terpenoids, all of which act as antibacterials 32 . Extract prepared from peel, fruit and leaves of lime show promising antibacterial activity against some microbes belong to both gram positive bacteria ( Staphylococcus aureus, S. epidermis and E .…”

Medicinal plants with antimicrobial activities (part 2): Plant based review

“…The saturated fatty acid palmitic acid exhibited higher activity against multidrug-resistant M. tuberculosis strains (MICs = 50 µg/ml) than the unsaturated fatty acids oleic acid and linoleic acid, which showed less activity (MICs = 100 µg/ml) [108].…”

Anticancer activity of key lime, Citrus aurantifolia

“…Mexico: Sandoval-Montemayor et al . [33] reported that C. aurantifolia fruit peels consist of 44 volatile compounds, for example, dimethoxycoumarin (16%), cyclopentanedione (9%), methoxycyclohexane (8%), corylone (7%), palmitic acid (7%), dimethoxypsoralen (6%), α-terpineol (6%), and umbelliferone (5%).…”