Chemical Variability of Peel and Leaf Essential Oils in the Citrus Subgenus Papeda (Swingle) and Few Relatives

Abstract

The Papeda Citrus subgenus includes several species belonging to two genetically distinct groups, containing mostly little-exploited wild forms of citrus. However, little is known about the potentially large and novel aromatic diversity contained in these wild citruses. In this study, we characterized and compared the essential oils obtained from peels and leaves from representatives of both Papeda groups, and three related hybrids. Using a combination of GC, GC-MS, and 13C-NMR spectrometry, we identified a total of 60 compounds in peel oils (PO), and 76 compounds in leaf oils (LO). Limonene was the major component in almost all citrus PO, except for C. micrantha and C. hystrix, where β-pinene dominated (around 35%). LO composition was more variable, with different major compounds among almost all samples, except for two citrus pairs: C. micrantha/C. hystrix and two accessions of C. ichangensis. In hybrid relatives, the profiles were largely consistent with their Citrus/Papeda parental lineage. This high chemical diversity, not only among the sections of the subgenus Papeda, but also between species and even at the intraspecific level, suggests that Papeda may be an important source of aroma diversity for future experimental crosses with field crop species.

Utilization of Pomelo (Citrus maxima) Peel Waste into Bioactive Essential Oils: Chemical Composition and Insecticidal Properties

“…The yield of CMEO reinforces its potential for exploitation as a commercial biopesticide. Essential oil yield obtained from C. maxima peels in the various studies ranges from 0.29–14.25% [ 55 , 56 , 57 ]. This variation can be due to the difference in extraction methods employed and genotypic variations, as well as abiotic factors.…”

Potential Therapeutic Effects of Citrus hystrix DC and Its Bioactive Compounds on Metabolic Disorders

“…It also demonstrates lipase-inhibiting activity which is beneficial for the treatment of obesity, angiotensin-converting enzyme-inhibiting property for the management of hypertension, moderate inhibiting activity against α-amylase and α-glucosidase which could be useful in diabetes, as well as inhibitions against acetylcholinesterase, butyrylcholinesterase, and β-secretase-1 which are favorable in the treatment of Alzheimer's disease [19]. Essential oils extracted from the twigs and leaves contain monoterpenes like citronellal, citronellol, linalool, sabinene, and limonene [35][36][37][38], while the major compounds in the oil from the rind are β-pinene, sabinene, limonene, citronellal, α-pinene, and terpinen-4-ol [38]. The oil from the leaves was noted to be inactive against Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Escherichia coli, and Klebsiella pneumoniae, but was moderately effective in inhibiting the fungal growth of Candida albicans, Saccharomyces cerevisiae, and Cryptococcus neoformans [36].…”

Phylogenetic and taxonomic status of Citrus halimii B.C. Stone determined by genotyping complemented by chemical analysis of leaf and fruit rind essential oils

“…For essential oil extraction of mountain citron, pummelos and trifoliate oranges, fruits (100 g of peel used) and leaves (200 g) were randomly picked all around the tree. For other citrus, the essential oil compositions were from the findings of previous studies conducted by our laboratory on kumquats (Sutour et al, 2016), mandarins (Lota et al, 2001;Fanciullino et al, 2006), citrons (Lota et al, 1999) and papedas (Baccati et al, 2021) sampled from trees of the same citrus collection. The combined use of old and recent data on the composition of essential oils of trees from the same site and grown under the same conditions was possible because the aromatic profiles change very little or not at all over time (Luro et al 2019).…”