The present study had the aim of testing the hexane and methanol extracts of avocado seeds, in order to determine their toxicity towards Artemia salina, evaluate their larvicidal activity towards Aedes aegypti and investigate their in vitro antifungal potential against strains of Candida spp, Cryptococcus neoformans and Malassezia pachydermatis through the microdilution technique. In toxicity tests on Artemia salina, the hexane and methanol extracts from avocado seeds showed LC 50 values of 2.37 and 24.13mg mL -1 respectively. Against Aedes aegypti larvae, the LC 50 results obtained were 16.7mg mL -1 for hexane extract and 8.87mg mL -1 for methanol extract from avocado seeds. The extracts tested were also active against all the yeast strains tested in vitro, with differing results such that the minimum inhibitory concentration of the hexane extract ranged from 0.625 to 1.25mg L-1 , from 0.312 to 0.625mg mL -1 and from 0.031 to 0.625mg mL -1 , for the strains of Candida spp, Cryptococcus neoformans and Malassezia pachydermatis, respectively. The minimal inhibitory concentration for the methanol extract ranged from 0.125 to 0.625mg mL -1 , from 0.08 to 0.156mg mL -1 and from 0.312 to 0.625mg mL -1 , for the strains of Candida spp., Cryptococcus neoformans and Malassezia pachydermatis, respectively. Key-words: Avocado seeds. Artemia salina. Aedes aegypti. Yeasts. RESUMOO presente estudo teve como objetivo testar os extratos hexânico e metanólico das sementes do abacate, a fim de determinar sua toxicidade em Artemia salina, avaliar a atividade larvicida frente ao Aedes aegypti, bem como verificar o potencial antifúngico in vitro contra cepas de Candida spp, Cryptococcus neoformans e Malassezia pachydermatis, através da técnica de microdiluição. Os extratos hexânico e metanólico das sementes de abacate apresentaram no teste de toxicidade frente à Artemia salina, valores de LC 50 2,37 e 24,13mg L -1 , respectivamente; contra as larvas do Aedes aegypti os resultados obtidos foram LC 50 16,7mg L -1 para o extrato hexânico e 8,87mg L -1 para o extrato metanólico das sementes do abacate. Os extratos testados também foram ativos contra todas as cepas de leveduras, testadas in vitro, apresentando diferentes resultados, onde o MIC do extrato hexânico variou de 0,625 a 1,25mg mL -1 , de 0,312 a 0,625mg mL -1 e de 0,031 a 0,625mg mL -1 para as cepas de Candida spp., Cryptococcus neoformans e Malassezia pachydermatis, respectivamente. O intervalo de MIC para o extrato metanólico foi de 0,125 a 0,625mg mL -1 , 0,08 a 0,156mg mL -1 e de 0,312 a 0,625mg mL -1 , para as exemplares de Candida spp., Cryptococcus neoformans e Malassezia pachydermatis, respectivamente. Palavras-chaves: Sementes do abacate. Artemia salina. Aedes aegypti. Leveduras.Persea americana Mill. (Lauraceae) is a plant from Central America (Mexico, Guatemala, Antilles), but it has shown easy adaptation to other tropical regions. Its fruits are commonly known as avocados and have an olive-green peel and thick pale yellow pulp that is rich in vegetable oils...

The objective of this study was to evaluate the antifungal activity of farnesol and its interaction with traditional antifungals against drug-resistant strains of Candida species. To do so, we studied the minimum in vitro inhibitory concentration (MIC) of amphotericin B (AMB), fluconazole (FLC), itraconazole (ITC), caspofungin (CAS) and farnesol against 45 isolates of Candida spp., i.e., 24 C. albicans, 16 C. parapsilosis and 5 C. tropicalis through the use of the broth microdilution method. Then, the isolates were tested with the combination of farnesol plus drugs to which they were previously found to be resistant. Additionally, the strains were pre-incubated at sub-inhibitory farnesol concentrations and their antifungal susceptibilities were re-evaluated. We found the MIC values for farnesol varied from 4.68-150 µM for Candida spp., with 19 isolates having a MIC > 1 mg/l, 18 a MIC ≥ 64 mg/l, 35 having a MIC ≥ 1 mg/l and 6 isolates a MIC ≥ 2 mg/l or were resistant to AMB, FLC, ITC and CAS, respectively. Significant MIC reductions were observed when farnesol and antifungal drugs were combined (P < 0.05) and when Candida strains were incubated with farnesol (P < 0.05). We conclude that the in vitro effects of farnesol improved the activity of traditional antifungals to which the Candida spp. isolates were resistant. These results support further investigation of the role of farnesol in the balance of the sterol biosynthetic pathway and how it interferes with cell viability.

In the present study, it was sought to compare yeast microbiota of wild and captive Macrobrachium amazonicum and evaluate the antifungal susceptibility and production of virulence factors by the recovered isolates of Candida spp. Additionally, cultivation water was monitored for the presence of fungi. Overall, 26 yeast isolates belonging to three genera and seven species were obtained, out of which 24 were Candida spp., with Candida famata as the most prevalent species for both wild and captive prawns. From cultivation water, 28 isolates of filamentous fungi were obtained, with Penicillium spp., Cladosporium spp. and Aspergillus spp. as the most frequent genera. Eight out of 24 Candida spp. isolates were resistant to azole derivatives, out of which four were recovered from wild-harvested prawns. As for production of virulence factors, three (12.5%) and eight (33.3%) isolates presented phospholipase and protease activity, respectively. This is the first comparative study between wild and captive prawns and the first report on yeast microbiota of M. amazonicum. The most relevant finding was the high percentage of resistant Candida spp., including from wild individuals, which suggests the occurrence of an environmental imbalance in the area where these prawns were captured.

Coccidioidomycosis is a systemic mycosis caused by the dimorphic fungi Coccidioides spp. The treatment for chronic and/or disseminated coccidioidomycosis can be prolonged and complicated. Therefore, the search for new drugs is necessary. Farnesol is a precursor in the sterol biosynthesis pathway that has been shown to present antifungal activity. Thus, the objective of this study was to evaluate the in vitro antifungal activity of farnesol alone and in combination with antifungal agents against clinical and environmental strains of Coccidioides posadasii as well as to determine their effect on the synthesis of ergosterol and on cell permeability. This study employed the broth macrodilution method to determine the MIC of farnesol against 18 strains of C. posadasii. Quantification of ergosterol was performed with 10 strains of C. posadasii after exposure to subinhibitory concentrations of farnesol. Finally, the activity of farnesol was evaluated in the presence of osmotic stress, induced by the addition of NaCl to the culture medium, during the susceptibility tests. The results showed that farnesol exhibited low MICs (ranging from 0.00171 to 0.01369 mg/liter) against all tested strains. The combination of farnesol with the antifungals showed synergistic effects (fractional inhibitory concentration index [FICI] < 0.5). As for the ergosterol quantification, it was observed that exposure to subinhibitory concentrations of farnesol decreased the amount of ergosterol extracted from the fungal cells. Furthermore, farnesol also showed lower MIC values when the strains were subjected to osmotic stress, indicating the action of this compound on the fungal membrane. Thus, due to the high in vitro antifungal activity, this work brings perspectives for the performance of in vivo studies to further elucidate the effects of farnesol on the host cells.

cThis study aimed to evaluate the in vitro combination of farnesol and ␤-lactams against Burkholderia pseudomallei. A total of 12 ␤-lactamase-positive strains were tested according to CLSI standards. All strains were inhibited by farnesol, with MICs ranging from 75 to 150 M. The combination of this compound with ␤-lactams resulted in statistically significant ␤-lactam MIC reduction (P < 0.05). This study provides new perspectives for the use of farnesol combined with ␤-lactam antibiotics against strains of B. pseudomallei. Burkholderia pseudomallei is a Gram-negative bacillus that causes melioidosis, a severe and potentially fatal disease endemic to Southeast Asia and hyperendemic to Northern Australia (2, 17).Some antibiotics currently recommended for the treatment of melioidosis are ceftazidime, imipenem, meropenem, amoxicillinclavulanate, cefoperazone-sulbactam, trimethoprim-sulfamethoxazole, doxycycline, and chloramphenicol (17). However, B. pseudomallei has developed resistance to these drugs (14,15,17,18); hence, it is necessary to search for new agents that are effective against this microorganism.The sesquiterpene alcohol farnesol is present in many essential oils of plants, such as Pluchea dioscoridis and Pittosporum undulatum, possibly to protect against attack by predators (5, 12). Farnesol has also been detected in the supernatant of Candida albicans broth cultures, as it is a quorum-sensing molecule of this fungal species (11).Moreover, farnesol is able to inhibit some microorganisms, such as Staphylococcus aureus, Streptococcus mutans, and Paracoccidioides brasiliensis, indicating its potential antimicrobial activity (4, 6-9), which has also been demonstrated against bacterial biofilms (16). Some studies have shown the ability of farnesol to increase the susceptibility of microorganisms to antimicrobials, indicating a possible applicability as an adjuvant drug (7). Brehm-Stecher et al. (1) reported increased susceptibility of S. aureus to ciprofloxacin, clindamycin, erythromycin, gentamicin, tetracycline, and vancomycin, as well as of Escherichia coli to polymyxin B, when these drugs were combined with farnesol. Thus, the objective of this study was to evaluate the in vitro activity of farnesol, alone and in combination with ␤-lactams, against strains of B. pseudomallei.We used 12 strains of ␤-lactamase-producing B. pseudomallei, stored in the Laboratory of Emerging and Reemerging Pathogens (LAPERE) of the Federal University of Ceará. Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, methicillinresistant Staphylococcus aureus (MRSA), and ␤-lactamase-negative S. aureus were used as experimental controls. Susceptibility testing was performed by the broth dilution method, as standardized by CLSI, described in document M07-A8 (3). The medium used was Mueller-Hinton broth (Difco, USA), and the concentration ranges were from 0.25 to 128 mg/ml for amoxicillin (Roche, Brazil), from 0.25/0.125 to 128/64 mg/ml for amoxicillin-clavulanate (Roche, Brazil), from 0.0312 to 16 mg/ml for imipenem (Ro...