Bioassay-Guided Isolation of Anti-Candida Biofilm Compounds From Methanol Extracts of the Aerial Parts of Salvia officinalis (Annaba, Algeria)

Abstract

Salvia officinalis is frequently used in traditional Algerian medicine to treat diverse microbial infections, including oral and vaginal candidiasis. The aerial parts of S. officinalis collected in Annaba, Algeria were extracted in parallel by maceration with four solvents viz. hexane, acetone, methanol and water. All the extracts were tested in vitro against several Candida species: C. albicans, C. glabrata, and C. parapsilosis. Furthermore, the activity against biofilm-forming C. albicans was investigated using bioassay-guided fractionation. A large-scale extract was prepared via maceration in methanol, followed by fractionation on a silica gel column using increasingly polar mixtures of n-hexane, ethyl acetate, methanol, and acetic acid as mobile phase, to yield a total of 150 fractions. Two major active fractions (F-31 and F-39), were further separated by HPLC, resulting in several active chromatographic peaks. Carnosol and 12-methoxy-trans-carnosic acid were isolated as two major active compounds, and identified by a combination of NMR and mass spectrometry. The biofilm inhibitory concentration showed that 12-methoxy-trans-carnosic acid is more effective than carnosol with BIC50 values of 94 μM (95% confidence interval, 78.9–112.1 μM) and 314 μM (95% confidence interval, 200.7–491.2 μM), respectively. The present study supports the traditional use of sage in the treatment of various fungal infections caused by Candida. Further studies of the bioactive compounds in an in vivo Candida biofilm model are required to validate their clinical potential as antifungals.

Isolation of Antimicrobial Compounds From Cnestis ferruginea Vahl ex. DC (Connaraceae) Leaves Through Bioassay-Guided Fractionation

“…Prior to HPLC injection, samples were filtered through a CHROMAFIL ® Xtra H-PTFI filter (pore size 0.45 μm, filter 13 mm, MACHEREY-NAGEL, Germany). Two mL of sample was injected and run for 41 min at 20°C with flow rate of 4 mL/min (Kerkoub et al, 2018).…”

“…QTOF-MS conditions: ESI mass spectra were acquired in positive and negative mode. The ESI source parameters were set as follows: end plate offset voltage of 500 V, capillary voltage of 4000 V, nebulizer of 2.5 bar and dry gas flow of 8.0 L/min 1 at 200°C (Kerkoub et al, 2018).…”

Antimicrobial Activity of Selected Banana Cultivars Against Important Human Pathogens, Including Candida Biofilm

“…The anti-biofilm activity was determined by following exactly the method described recently [28] on C. albicans SC 5314. A two-fold serial dilution (up to 32-fold) of an extract was prepared in a 96-well conical bottom (V) polystyrene microtiter plate.…”

“…A few additional cultivars were able to inhibit growth of M. luteus, including Namwah Khom-leaf-acetone (31 µg/mL), Mbwazirume-leaf-acetone (33 µg/mL) and Dole-pseudostem-acetone (121 µg/mL). Interestingly, leaf parts of most cultivars extracted with acetone are active against S. faecalis with low IC 50 s (<100 µg/mL): (Kluai tiparot (28), Namwa Khom (31), Saba (37), Pelipita (58), Mbwazirume (83) and Dole (53) ( Table 5).…”

Nematicidal Activity of Holigarna caustica (Dennst.) Oken Fruit Is Due to Linoleic Acid

“…HPLC was performed on a Shimadzu, LC-20AT system (model DGU 20A3) as described earlier [15]. Briefly, 2 mL of sample was injected and separated at a flow rate of 4 mL/min on a reverse-phase HPLC column: Sunfire TM prep C18 (10 mm × 250 mm, 5 µm, Waters).…”