Objective To evaluate differences in yield and composition of the essential oil and antioxidant contents in Turnera diffusa plants from localities in central region of Tamaulipas. Methods Samples were collected in Tamaulipas, Mexico in the arid zone. Essential oil was obtained through steam distillation and analyzed using GC–MS. Polyphenol contents, antioxidant activities using ABTS and ferric reducing antioxidant power (FRAP) methods also were evaluated. Results A total of 21 compounds were identified in the essential oils; nevertheless, only Eucalyptol, 1,4-Methanocycloocta[d]pyridazine, 1,4,4a,5,6,9,10,10a-octahydro-11,11-dimethyl-, (1à,4à,4aà,10aà) y Ethanone, 1-(1,3-dimethyl-3-cyclohexen-1-yl) were detected in the three sites. Highest contents were registered in the sample from Padrón y Juárez with phenolic content of 33.85 mg GAE/g of dry material and antioxidant activities with ABTS 72.32% and with FRAP 21.33 mg GAE/g of dry material. Statistical differences were observed in essential oil, phenolics and antioxidants contents between populations. Conclusions Results suggest that climatic differences and origin influence the phytochemicals in the medicinal plant Turnera diffusa, and thus, it is worth to consider such effects for industrial and medicinal purposes.

Objective To determinate the recovery of total polyphenolic compounds content, in vitro antioxidant activity and HPLC/ESI/MS characterization of extract from Nephelium lappaceum L. (Mexican rambutan). Methods The rambutan husk extract was obtained by aqueous extraction and a polyphenolic fraction was recovered using Amberlite XAD-16. The total polyphenolic compounds content was determined by the Folin Ciocalteu and butanol-HCI methods. In vitro antioxidant activity was performed using ABTS and ferric reducing antioxidant power methods. Results Mexican rambutan husk showed a total polyphenolic content of 582 mg/g and an evident antioxidant activity by ABTS and ferric reducing antioxidant power analysis. The HPLC/ESI/MS assay allowed the identification of 13 compounds, most of which belong to ellagitannins. Geraniin, corilagin and ellagic acid were present in the sample; the mineral composition was also evaluated. Conclusions Rambutan husk cultivated in Mexico is a promising source for the recovery of added value bioactive compounds with antioxidant activity, which have potential applications as bioactive antioxidant agents for the treatment of diseases.