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.

Background: Clusia nemorosa, popularly known as pororoca, is used in folk medicine to treat inflammation. Objective: The current study was conducted to isolate and identify bioactive compounds from C. nemorosa fruits and to investigate their antimicrobial and antioxidant activities. Method: The isolation and structural elucidation of the substances were carried out by usual chromatographic techniques and spectroscopic methods, respectively. The antioxidant activity of extracts of C. nemorosa fruits was measured by DPPH assay and antimicrobial activity was evaluated against the microorganisms Staphylococcus aureus, Candida albicans, Cryptococcus neoformans and Rhizopus oryzae. Results: The chemical investigation of the fruit extract of C. nemorosa led to the identification of two phenolic acids, protocatechuic acid (1) and coumaric acid (6), a flavonoid apigenin (7), glycosyl-β-sitosterol (4), glycosyl-stigmasterol (5), citric acid (3), and the trimethyl citrate ester (2). The fraction in AcOET showed the best scavenging activity of the DPPH radical, with IC50 23.50±1.7 µg. mL-1. The extracts were inactive against the tested microorganisms up to 2500 µg. mL-1. Conclusion: With the exception of the steroid glycosyl-β-sitosterol, the substances are being described for the first time in the species and, in addition, we report the promising free radical scavenging activity showing its potential in the treatment of diseases related to oxidative stress.