Enantioselective synthesis of 6-methyloctanal and 8-methyldecanal, the characteristic aroma components in yuzu Citrus junos, and analysis of their enantiomeric compositions in yuzu essential oil

6-Methyloctanal and 8-methyldecanal are the characteristic aroma components of yuzu Citrus junos. However, their absolute configurations and enantiomeric compositions in yuzu essential oil have not been analyzed. A concise enantioselective synthesis of both aldehydes was successfully carried out to determine their absolute configurations and enantiomeric compositions. Both aldehydes in yuzu essential oil were found to be (S)-form with high enantiomeric excess.

Application of integrative physiological approach to evaluate human physiological responses to the inhalation of essential oils of Japanese citrus fruits iyokan (Citrus iyo) and yuzu (Citrus junos)

This study investigated the effects of essential oil odors from Japanese citrus fruits, iyokan (Citrus iyo) and yuzu (Citrus junos), on human psychology and both the autonomic and central nervous systems. The inhalation of both essential oils significantly increased miosis rate and fingertip temperature and could induce parasympathetic dominance by suppressing sympathetic nerve activity. Oxyhemoglobin concentration in the prefrontal cortex increased after the inhalation of yuzu essential oil and decreased after the inhalation of iyokan essential oil. Subjectively, the inhalation of both essential oils reduced the feelings of fatigue and improved the feelings of refreshment, suggesting that the effect of autonomic nervous activity might involve in these psychological changes directly. Moreover, we observed that task performance improved after inhaling yuzu essential oil, which may be due to the increase in oxyhemoglobin concentration in the prefrontal cortex.

A Narrative Review of Human Clinical Trials on the Impact of Phenolic-Rich Plant Extracts on Prediabetes and Its Subgroups

Phenolic-rich plant extracts have been demonstrated to improve glycemic control in individuals with prediabetes. However, there is increasing evidence that people with prediabetes are not a homogeneous group but exhibit different glycemic profiles leading to the existence of prediabetes subgroups. Prediabetes subgroups have been identified as: isolated impaired fasting glucose (IFG), isolated impaired glucose tolerance (IGT), and combined impaired fasting glucose and glucose intolerance (IFG/IGT). The present review investigates human clinical trials examining the hypoglycemic potential of phenolic-rich plant extracts in prediabetes and prediabetes subgroups. Artemisia princeps Pampanini, soy (Glycine max (L.) Merrill) leaf and Citrus junos Tanaka peel have been demonstrated to improve fasting glycemia and thus may be more useful for individuals with IFG with increasing hepatic insulin resistance. In contrast, white mulberry (Morus alba Linn.) leaf, persimmon (Diospyros kaki) leaf and Acacia. Mearnsii bark were shown to improve postprandial glycemia and hence may be preferably beneficial for individuals with IGT with increasing muscle insulin resistance. Elaeis guineensis leaf was observed to improve both fasting and postprandial glycemic measures depending on the dose. Current evidence remains scarce regarding the impact of the plant extracts on glycemic control in prediabetes subgroups and therefore warrants further study.

Different Host Plants Distinctly Influence the Feeding Ability of the Brown Citrus Aphid Toxoptera citricida

Piercing–sucking insects are important crop pests, and an understanding of their feeding behavior and population development plays a crucial role in studying insect population dynamics and crop resistance. In our study, we examined the probing behavior of the brown citrus aphid, Toxoptera citricida, using electropenetrography and assessed its population development after 8 days on seven host plants: Yuzu, Citrus junos Sieb. ex Tanaka; Rough Lemon, C. jambhiri Lush.; ‘Luofu’ kumquat, Fortunella margarita Swingle; ‘Olinda’ valencia orange, C. sinensis (L.) Osbeck; ‘Yanxiwanlu’ Ponkan, C. reticulata Blanco; ‘Rohde Red’ valencia orange, C. sinensis; and ‘Eureka’ lemon, C. limon (L.) Osbeck. The results demonstrated that probing by the brown citrus aphid differed significantly according to the target hosts. Toxoptera citricida produced significantly more pathway activities on Eureka than on Rough Lemon and Yuzu. Toxoptera citricida spent more time from the first probe to first salivation into phloem sieve elements on Eureka compared to Yuzu. In addition, the total duration of ingestion from sieve cells of each aphid in the phloem-feeding phase was shortest on Eureka, and this was significantly shorter than that on Yuzu, Rough Lemon, Luofu, and Olinda. The population number of T. citricida on Eureka after 8 days was significantly lower than that on the other hosts. Overall, Eureka was found to have obvious resistance to T. citricida, whereas Yuzu and Rough Lemon were susceptible host plants. These results provide a theoretical basis for exploring aphid-resistant fruit tree resources using resistant varieties.

Physiological Functions Mediated by Yuzu (Citrus junos) Seed-Derived Nutrients

This section is focused on the physiological functions of yuzu (Citrus junos) to improve health. The modern lifestyle involves number of modern lifestyles involve various factors that may increase the production of active oxygen species. Nutritional supplements and medicines are commonly utilized to maintain health. Yuzu seeds contain >100-fold the limonoid content of grapefruit seeds and are rich in polyamines (PAs), including putrescine, spermidine, and spermine. Limonoid components mediate the antioxidant properties of citrus. Limonoids and PAs convey various bioactivities. PAs are closely associated with maintaining the function of the intestinal mucosal barrier, which might be involved in the metabolic processes of indigenous intestinal bacteria and in the health of the host. After ingestion, food is digested and absorbed in the intestinal tract, which is also responsible for immune responses against food antigens and intestinal bacteria. Detailed investigations of the physiological functions of extracted yuzu seed extracts may help to develop new treatment strategies against diseases associated with inflammatory responses.

Hair Growth-Promoting Activity of Citron Seed Oil: Induction of Premature Telogen-To-Anagen Transition of Hair Follicle in C57BL/6 Mouse Models

Citron (Citrus junos Sieb. Ex Tanaka), a citrus fruit native to Korea, Japan, and China, has been commonly used as a raw material for beverages and herbal medicines. Citron seeds, the by-product of processing industry, contain many bioactive compounds that exhibit several biological properties, such as antioxidative, anti-inflammatory, and antiobesity. However, potential of citron seed oil for hair growth promotion remains unexplored. In the present study, we investigated the hair growth-promoting effect of citron seed oil and its underlying mechanism(s) in a C57BL/6 mouse model. The results show that citron seed oil effectively promotes hair regrowth by early induction of telogen-to-anagen transition and by increasing hair follicle density and hair bulb diameter as well as skin thickness. Citron seed oil treatment increased β-catenin, lymphoid enhancer binding factor 1, sonic hedgehog, cyclin D1 and cyclin E expressions, and alkaline phosphatase activity, compared to the vehicle-treated control mice. Topical administration of citron seed oil upregulated expression of antiapoptotic Bcl-2 protein but did not alter protein level for proapoptotic Bax in mouse skin tissues. Furthermore, insulin-like growth factor 1 and vascular endothelial growth factor were also induced by citron seed oil treatment. These findings suggest the potential of citron seed oil in the prevention and/or treatment of hair loss by inducing hair cycling and regeneration.