Biological and chemo-diverse characterization of Amazonian (Ecuador) Citrus petitgrains

Abstract

S ix Ama z onian petitgrains samples from C. nobilis Lour. , C. aurantium L. , C. limon L. and mixture of Citrus spp. (Rutaceae), named CN, CA, CL1, CL2, C1 and C2, were chemically characterized by GC-MS and 13 C NMR and evaluated for antioxidant acitivity ( DPPH and b -carotene bleaching tests), for antimicrobial properties ( disk diffusion method) and for antifungal capacity ( agar vapour assay) . CN, C1, C2 samples evidenced the most interesting results: CN ( g -terpinene/linalool chemotype: 14.3%/41.6%, with a considerable amount of thymol: 9.0% ), and C1 (linalool, 18.3%; sabinene, 11.6%; thymol, 5.5%), showed relevant antioxidant activity with both DPPH (IC 50 =3.52 and 5.48 mg/ml, respectively) and b -carotene ( IC 50 =0.387and 0.491 mg/ml, respectively). A ntibacterial properties of CN and C1 against P. mirabilis (MIC=0.61 mg/ml for both) and B. subtilis (MIC=0.61 and 0.44 mg/ml, respectively) were most probably due to thymol . C2 (geranial: 34.7%, neral: 33.1%) evidenced a valuable bioactivity against Candida albicans (MIC=0.44 mg/ml). The 50% growth inhibition (IC 50 ) of the dermatophytes T. mentagrophytes and N. cajetani was reached with amounts of C1, C2 and CN less than 4 m l/plate . Bioactivity of Amazonian Citrus spp. CN, C1 and C2 essential oils suggests their potential use as food preservatives or additives in cosmeceuticals as preventive against dermatophytic fungal infections .