Biological Activities of a-Pinene and β-Pinene Enantiomers

Abstract

The antimicrobial activities of the isomers and enantiomers of pinene were evaluated against bacterial and fungal cells. The agar diffusion test showed that only the positive enantiomers of the α- and β-isomers of pinene were active. The minimal inhibitory concentration (MIC) and minimal microbicidal concentration (MMC) of these monoterpenes were also determined, confirming that the positive enantiomers exhibited microbicidal activity against all fungi and bacteria tested with MICs ranging from 117 to 4,150 µg/mL. However, no antimicrobial activity was detected with the negative enantiomers up to 20 mg/mL. Time-kill curves showed that (+)-α-pinene and (+)-β-pinene were highly toxic to Candida albicans, killing 100% of inoculum within 60 min. By contrast, the bactericidal effect occurred after 6 h in methicillin-resistant Staphylococcus aureus (MRSA). In combination with commercial antimicrobials, ciprofloxacin plus (+)-α-pinene or (+)-β-pinene presented synergistic activity against MRSA whereas an indifferent effect against all fungi was detected when amphotericin B was combined with the positive enantiomers of pinene. The potential of (+)-α-pinene and (+)-β-pinene to inhibit phospholipase and esterase activities was also evaluated, and the best inhibition results were obtained with Cryptococcusneoformans. C. albicans biofilm formation was prevented with the MIC concentration of (+)-α-pinene and twice the MIC value of (+)-β-pinene. Finally, the cytotoxicity of the positive enantiomers of pinene to murine macrophages was evaluated, and 250 µg/mL of (+)-α-pinene and (+)-β-pinene reduced the cell viability to 66.8% and 57.7%, respectively.

Chemical Composition and Bactericidal Activities of the Leaf Essential Oil of Eucalyptus maculata Hook

“…This result is similar to what was obtained from the leaf essential oil of the plant from Brazil, Iran and Tunisia [30][31][32]. Most of the secondary metabolites present in this essential oil were reported to have good pharmacological properties [33][34][35][36].…”

Antibacterial Potential Of The Alpha-pinene Positive Enantiomer Against The Strain <em>Proteus mirabilis</em>

“…Another research developed to evaluate the antimicrobial effects of the different isomers and enantiomers of the monoterpenes as (+) α-pinene and (+) β-Pinene against the gram-negative bacteria species, Proteus vulgaris and C. albicans fungus, where it was possible to verify that Time-Kill curves showed that (+) -α-pinene and (+) -β-pinene were highly toxic to C. albicans, killing 100% of the inoculum in 1 h. In contrast, the bactericidal effect occurred after 6h. In combination with commercial antimicrobials, ciprofloxacin plus (+) -α-pinene or (+) -β-pinene showed synergistic activity against P. vulgaris strain, whereas an indifferent effect against all fungi was detected when amphotericin B was combined with positive pinene enantiomers [12].…”

Antimicrobial Diterpene from the Brazilian Termite Nasutitermes macrocephalus (Isoptera: Termitidae: Natutitermitinae)

“…32 Candida albicans ATCC 10231 and Aspergillus brasiliensis ATCC 16404 were used in the antifungal assay, since they are responsible for candidiasis and lung infections, respectively. 33 The isolated diterpene showed activity against both MRSA (MIC = 62.5 µg mL -1 ) and C. albicans (MIC = 62.5 µg mL -1 ), and no activity against the Gram-negative bacterium E. coli was observed. It was also inactive against the filamentous fungus A. brasiliensis.…”