1.Functional characterization and transient expression manipulation of a new sesquiterpene synthase involved in β-caryophyllene accumulation in Ocimum.
Jayaramaiah RH1, Anand A2, Beedkar SD3, Dholakia BB1, Punekar SA4, Kalunke RM1, Gade WN5, Thulasiram HV6, Giri AP7. Biochem Biophys Res Commun. 2016 Mar 19. pii: S0006-291X(16)30401-6. doi: 10.1016/j.bbrc.2016.03.090. [Epub ahead of print]
The genus Ocimum has a unique blend of diverse secondary metabolites, with major proportion of terpenoids including mono- and sesquiterpenes. Although, β-Caryophyllene, bicyclic sesquiterpene, is one of the major terpene found in Ocimum species and known to possess several biological activities, not much is known about its biosynthesis in Ocimum. Here, we describe isolation and characterization of β-caryophyllene synthase gene from Ocimum kilimandscharicum Gürke (OkBCS- GenBank accession no. KP226502). The open reading frame of 1629 bp encoded a protein of 542 amino acids with molecular mass of 63.6 kDa and pI value of 5.66. The deduced amino acid sequence revealed 50-70% similarity with known sesquiterpene synthases from angiosperms. Recombinant OkBCS converted farnesyl diphosphate to β-caryophyllene as a major product (94%) and 6% α-humulene. Expression variation of OkBCS well corroborated with β-caryophyllene levels in different tissues from five Ocimum species.
2.A detailed study of the volatile components of Plectranthus asirensis of Saudi Arabian origin.
Al-Saleem MS1, Khan M2, Alkhathlan HZ2. Nat Prod Res. 2016 Mar 23:1-4. [Epub ahead of print]
Essential oil composition of Plectranthus asirensis grown in Saudi Arabia was chemically analysed for the first time by various gas chromatography techniques (GC-MS, GC-FID, Co-GC, LRI determination and database and literature searches) using two different stationary phase columns (polar and nonpolar). This analysis led to the characterisation of a total of 124 components representing 98.5% of the total oil composition. The results revealed that P. asirensis oil was mainly dominated by monoterpenoids (90.7%) in which most representative constituents were thymol (66.0 ± 0.36%), γ-terpinene (14.0 ± 0.18%), p-cymene (5.2 ± 0.06%) and β-caryophyllene (3.0 ± 0.03%). It is worth mentioning here that this is the first report on the phytochemical constituents of P. asirensis.
3.Characterization of the Migration of Hop Volatiles into Different Crown Cork Liner Polymers and Can Coatings.
Wietstock PC1, Glattfelder R1, Garbe LA2, Methner FJ1. J Agric Food Chem. 2016 Apr 6;64(13):2737-45. doi: 10.1021/acs.jafc.6b00031. Epub 2016 Mar 28.
Absorption of hop volatiles by crown cork liner polymers and can coatings was investigated in beer during storage. All hop volatiles measured were prone to migrate into the closures, and the absorption kinetics was demonstrated to fit Fick's second law of diffusion well for a plane sheet. The extent and rate of diffusion were significantly dissimilar and were greatly dependent upon the nature of the volatile. Diffusion coefficients ranged from 1.32 × 10(-5) cm(2)/day (limonene) to 0.26 × 10(-5) cm(2)/day (α-humulene). The maximum amounts absorbed into the material at equilibrium were in the following order: limonene > α-humulene > trans-caryophyllene > myrcene ≫ linalool > α-terpineol > geraniol. With the application of low-density polyethylene (LDPE) liners with oxygen-scavenging functionality, oxygen-barrier liners made up from high-density polyethylene (HDPE) or liner polymers from a different manufacturer had no significant effect on the composition of hop volatiles in beers after prolonged storage of 55 days; however, significantly higher amounts of myrcene and limonene were found in the oxygen-barrier-type crown cork, while all other closures behaved similarly.
4.Determination of sugars, organic acids, aroma components, and carotenoids in grapefruit pulps.
Zheng H1, Zhang Q1, Quan J2, Zheng Q1, Xi W3. Food Chem. 2016 Aug 15;205:112-21. doi: 10.1016/j.foodchem.2016.03.007. Epub 2016 Mar 3.
The composition and content of sugars, organic acids, volatiles and carotenoids, in the pulps of six grapefruit cultivars, were examined by HPLC and GC-MS. The results showed that sucrose was the dominant sugar in grapefruit, making up 40.08-59.68% of the total sugars, and the ratio of fructose to glucose was almost 1:1. Citric acid was the major organic acid and represented 39.10-63.55% of the total organic acids, followed by quininic acid. The ratios of individual sugars and organic acids play an important role in grapefruit taste determination. Monoterpenes and sesquiterpenes were the predominant volatiles in grapefruit, in particular d-limonene and caryophyllene. Caryophyllene, α-humulene, humulen-(v1), β-linalool and tert-butyl 2-methylpropanoate are the characteristic aroma compounds of grapefruit. Although β-carotene is the primary carotenoid in grapefruit, the pulp color is mainly determined by the ratios of zeaxanthin, β-cryptoxanthin and lycopene.