Characterization and Evaluation of the In Vitro Antioxidant, α-Glucosidase Inhibitory Activities of Camellia longii Orel and Luu. (Theaceae) Flower Essential Oil and Extracts From Vietnam

Abstract

Objective/Background: Camellia longii Orel and Luu was discovered for the first time in Cat Tien National Park of Lam Dong Province, Southern Vietnam, was determined as a new species. To the best of our knowledge, this is the first report on the phytochemical and bioactivity of this species. Methods: The chemical profile of essential oil (EO) prepared from C. longii flowers was determined by GC/MS analysis and comparison of the recorded retention indices and the corresponding literature values. The total phenolic and flavonoid contents in different flower extracts were estimated by Folin-Ciocalteu and aluminum chloride methods with a spectrophotometer, respectively. The antioxidant activities of the extracts were determined by various bioassays, including DPPH free radical scavenging, ferric reducing power, and cupric reducing antioxidant capacity. The α-glucosidase inhibitory activity of the extracts was evaluated using p-nitrophenyl α-D-glucopyranoside solution as a substrate and acarbose as the positive control. Results: Fifty-seven compounds were identified from the EO of C. longii flowers. Among these, the main components were α-eudesmol (16.1%), followed by ( E)-nerolidol (13.0%), β-eudesmol (8.9%), τ-cadinol (6.5%), and γ-eudesmol (5.8%). The total phenolic and flavonoid contents were found high in ethyl acetate, n-butanol, and ethanol extracts (206.8-378.6 mg gallic acid equivalents/g crude extract and 298.5-390.3 mg rutin equivalents/g crude extract, respectively). These extracts were shown to possess potent antioxidant activities in the examined bioassays. As for the α-glucosidase inhibitory assay, the ethyl acetate, butanol, and ethanol extracts were shown to be more potent than acarbose with IC50 values of 2.16 ± 0.04, 1.95 ± 0.05, and 1.53 ± 0.04 μg/mL, respectively. Conclusion: The findings first provide the phytochemical profiles of Camellia longii Orel and Luu and its bioactivities, indicating moderate potentials in antioxidant activity and strong α-glucosidase inhibition.

Exploring the Therapeutic Potential of Camellia longii Orel & Luu Leaf Extracts for Memory Loss in Alzheimer’s Disease: Novel Findings and Functional Food Applications

“…One of the most recent studies was related to the flowers of C. longii collected from Nam Cat Tien National Park, Lam Dong, Vietnam. 16 This research indicated that the extracts contained high total phenolic content (206.8–378.6 mg of gallic acid equivalents/g of crude extract) and flavonoid content (298.5–390.3 mg of rutin equivalents/g of crude extract) and had moderate potentials in antioxidant activity and potent α-glucosidase inhibition. Once again, the finding provides further evidence of the promising prospects for investigating chemical compositions and biological activities, particularly through comprehensive studies on the leaves of C. longii for supporting and treating memory loss associated with AD.…”

“…The extracts were preliminary investigated functional groups of polyphenols, flavonoids, saponins, coumarins, polysaccharides, amino acids, tannins, alkaloids, terpenoids, organic acids, and carotenoids based on the characteristic reactions of functional groups with reagents. 16 …”

“…One of the most recent studies was related to the flowers of C. longii collected from Nam Cat Tien National Park, Lam Dong, Vietnam . This research indicated that the extracts contained high total phenolic content (206.8–378.6 mg of gallic acid equivalents/g of crude extract) and flavonoid content (298.5–390.3 mg of rutin equivalents/g of crude extract) and had moderate potentials in antioxidant activity and potent α-glucosidase inhibition.…”

Comparative Analysis of Pigments, Phenolics, and Bioactivities of Three Camellia Species Growing in Vietnam

“…This corroborates the previous findings, showing that C. longii and C. quephongensis extracts were not as strong as ascorbic acid with respect to neutralizing DPPH radicals. 9,25 For both tests, increasing concentrations of the extracts considerably scavenged the radicals in a dose-dependent manner.…”

“…There is a considerable body of evidence to show that phenolic compounds, including flavonoids and phenolic acids, are widely distributed in Camellia plants and contribute to various aspects of their bioactivities, particularly antioxidant, antidiabetic, and anti-inflammatory activities. 2,8,9 For instance, rutin reportedly contributed to an inhibitory effect of Camellia japonica leaf extract on xanthine oxidase and had an antigout potential in a mouse model. 10 In another study, rutin and isoquercitrin isolated and characterized in C. sinensis leaves were shown to stimulate insulin release and improve glucose tolerance.…”