Three new diphenylpropanes from Celastrus hindsii

The structure characteristics, biosynthesis and health benefits of naturally occurring rare flavonoids

Rare flavonoids, a special subclass of naturally occurring flavonoids with diverse structures including pterocarpans, aurones, neoflavonoids, homoisoflavones, diphenylpropanes, rotenoids and 2-phenylethyl-chromones. They are mainly found in legumes with numerous health benefits. Rare flavonoids are regarded as minor flavonoids due to their very limited abundance in nature. This review gives an overview of the natural occurrences of rare flavonoids from previous literatures. Recent findings on the biosynthesis of rare flavonoids have been updated by describing their structural characteristics and classifications. Recent findings on the health benefits of rare flavonoids have also been compiled and discussed. Natural rare flavonoids with various characteristics from different subclasses from plant-based food sources are stated. They show a wide range of health benefits, including antibacterial, anticancer, anti-osteoporosis and antiviral activities. Studies reviewed suggest that rare flavonoids possessing different skeletons demonstrate different characteristic bioactivities by discussing their mechanism of actions and structure-activity relationships. Besides, recent advances on the biosynthesis of rare flavonoids, such as pterocarpans, rotenoids and aurones are well-known, while the biosynthesis of other subclasses remain unknown. The perspectives and further applications of rare flavonoids using metabolic engineering strategies also be expected.

α-Amyrin and β-Amyrin Isolated from Celastrus hindsii Leaves and Their Antioxidant, Anti-Xanthine Oxidase, and Anti-Tyrosinase Potentials

Celastrus hindsii is a popular medicinal plant in Vietnam and Southeast Asian countries as well as in South America. In this study, an amount of 12.05 g of an α-amyrin and β-amyrin mixture was isolated from C. hindsii (10.75 g/kg dry weight) by column chromatography applying different solvent systems to obtain maximum efficiency. α-Amyrin and β-amyrin were then confirmed by gas chromatography-mass spectrometry (GC-MS), electrospray ionization-mass spectrometry (ESI-MS), and nuclear magnetic resonance (NMR). The antioxidant activities of the α-amyrin and β-amyrin mixture were determined via 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,20-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays with IC₅₀ of 125.55 and 155.28 µg/mL, respectively. The mixture exhibited a high potential for preventing gout by inhibiting a relevant key enzyme, xanthine oxidase (XO) (IC₅₀ = 258.22 µg/mL). Additionally, an important enzyme in skin hyperpigmentation, tyrosinase, was suppressed by the α-amyrin and β-amyrin mixture (IC₅₀ = 178.85 µg/mL). This study showed that C. hindsii is an abundant source for the isolation of α-amyrin and β-amyrin. Furthermore, this was the first study indicating that α-amyrin and β-amyrin mixture are promising in future therapies for gout and skin hyperpigmentation.

Evaluation of Acute Toxicity and Semi-chronic Toxicity of Extract from <i>Celastrus hindsii</i> Benth

BACKGROUND AND OBJECTIVE

Celastrus hindsii Benth. has been used for generations in Northern Vietnam, for the treatment of disease relating to ulcers, tumors and inflammation without safety evidence. This study's goal is to evaluate the safety of the aqueous extract of leaves of C. hindsii through an acute and semi-chronic toxicity oral administration.

MATERIALS AND METHODS

In the acute study, a single oral dose (1000, 3000, 5000 and 15000 mg kg-1) of the aqueous of C. hindsii extract were administered to mice and observed for seven days. In the semi-chronic study, rabbits were administered daily with 1000 and 3000 mg kg-1 of the extract for 35 days. Hematological and biochemical analyzes were carried out on blood and serum samples collected.

RESULTS

A single oral administration of 15000 mg kg-1 per day for white mice did not determine the LD50 dose. At doses of 1000 and 3000 mg kg-1 for 35 days, the extract from C. hindsii induced neither clinical symptoms of rabbits nor significant changes in hematological parameters such as; total blood cells, hemoglobin concentration, white blood cells and platelets. The quantity of aspartate transaminase (AST or GOT), alanine transaminase (ALT or GPT) of rabbits in the experimental and control group did not differ (p> 0.05). Liver and kidney organizations were also not affected adversely.

CONCLUSION

The results indicate that the oral administration of C. hindsii extract did not produce any significant toxicity in mice, therefore, it is recommended to be used safely for traditional medical practices and modern pharmaceutical applications.

Optimization of Ultrasound-Assisted Extraction of Flavonoids from Celastrus hindsii Leaves Using Response Surface Methodology and Evaluation of Their Antioxidant and Antitumor Activities

Celastrus hindsii is a potential source of flavonoids with biological activities. This study aimed to develop an ultrasound-assisted technique for extracting flavonoids from leaves of C. hindsii. Response surface methodology was employed to optimize the extraction conditions for maximizing the total flavonoid content (TFC). A maximum TFC of 23.6 mg QE/g was obtained under the extraction conditions of ultrasonic power of 130 W, extraction temperature of 40°C, extraction time of 29 min, and ethanol concentration of 65%. The flavonoid-rich extracts were then studied for their antioxidant and anticancer activities. The results showed that the C. hindsii leaf extract exhibited potent radical scavenging activities against DPPH (IC₅₀ of 164.85 μg/mL) and ABTS (IC₅₀ of 89.05 μg/mL). The extract also significantly inhibited the growth of 3 cancer cell lines MCF7, A549, and HeLa with the IC₅₀ values of 88.1 μg/mL, 120.4 μg/mL, and 118.4 μg/mL, respectively. Notably, the extract had no cytotoxicity effect on HK2 normal kidney cell line. This study suggests that flavonoid-rich extract is a promising antioxidant and anticancer agent and that ultrasound-assisted extraction is an efficient method for extracting flavonoids from C. hindsii leaves.

Traditional uses, secondary metabolites, and pharmacology of Celastrus species - a review

ETHNOPHARMACOLOGICAL RELEVANCE

Plants of genus Celastrus (Celastraceae) have been widely used in traditional Chinese medicine (TCM) and Indian medicine to treat cognitive dysfunction, epilepsy, insomnia, rheumatism, gout, and dyspepsia for thousands of years.

AIM OF STUDY

We critically summarized the current evidence on the botanic characterization and distribution, ethnopharmacology, secondary metabolites, pharmacological activities, qualitative and quantitative analysis, and toxicology of Celastrus species to provide perspectives for developing more attractive pharmaceuticals of plant origin.

MATERIALS AND METHODS

The relevant information on Celastrus species was gathered from worldwide accepted scientific databases via electronic search (Web of Science, SciFinder, PubMed, Elsevier, SpringerLink, Wiley Online, China Knowledge Resource Integrated, and Google Scholar). Information was also obtained from the literature and books as well as PhD and MSc dissertations. Plant names were validated by "The Plant List" (www.theplantlist.org).

RESULTS

Comprehensive analysis of the above mentioned databases and other sources confirmed that ethnomedical uses of plants of Celastrus genus had been recorded in China, India, and other countries in Southern Asia. The phytochemical investigation revealed the presence of β-dihydroagarofuranoids, diterpenoids, triterpenoids, tetraterpenes, phenylpropanoids, alkaloids, flavonoids, lignans, and others. The crude extracts and isolated constituents have exhibited a wide range of in vitro and in vivo pharmacological effects, including antitumor, cytotoxic, insecticidal, antimicrobial, anti-rheumatoid arthritis (RA), anti-inflammatory, anti-ageing and antioxidative, and neuroprotective activities.

CONCLUSION

Plants of genus Celastrus have been confirmed to show a strong potential for therapeutic and health-maintaining effects, in light of their long traditional use and the phytochemical and pharmacological studies summarized here. Currently, pharmacological studies of this genus mainly focus on Celastrus paniculatus Willd. and Celastrus orbiculatus Thunb. Therefore, more pharmacological investigations should be implemented to support traditional uses of other medicinal plants of the genus Celastrus. Moreover, studies on the toxicity, bioavailability, and pharmacokinetics, in addition to clinical trials, are indispensable for assessing the safety and efficacy of the secondary metabolites or extracts obtained from plants belonging to this genus.

Hindsiipropane B alleviates HIV-1 Tat-induced inflammatory responses by suppressing HDAC6-NADPH oxidase-ROS axis in astrocytes

Human immunodeficiency virus-1 (HIV-1) transactivator of transcription (Tat) is an important viral factor in neuroinflammation. Hindsiipropane B, present in Celastrus hindsii, possesses various biological mechanisms including antiinflammatory activity. In this report, we explored the regulatory activity of hindsiipropane B on HIV-1 Tat-mediated chemokine production and its mode of action in astrocytes. Hindsiipropane B significantly alleviated HIV-1 Tat-mediated production of inflammatory chemokines, CCL2, CXCL8, and CXCL10. Hindsiipropane B inhibited expression of HDAC6, which is important regulator in HIV-1 Tat-mediated chemokine production. Hindsiipropane B diminished HIV-1 Tat-mediated reactive oxygen species (ROS) generation and NADPH oxidase activation/expression. Furthermore, hindsiipropane B inhibited HIV-1 Tat-mediated signaling cascades including MAPK, NF-κB, and AP-1. These data suggest that hindsiipropane B exerts its inhibitory effects on HIV-1 Tat-mediated chemokine production via down-regulating the HDAC6-NADPH oxidase-MAPK-NF-κB/AP-1 signaling axis, and could serve as a therapeutic lead compound against HIV-1 Tat-associated neuroinflammation. [BMB Reports 2018; 51(8): 394-399].

Dihydrostilbenes and diarylpropanes: Synthesis and in vitro pharmacological evaluation as potent nitric oxide production inhibition agents

An efficient synthesis of dihydrostilbenes (1-5) and diarylpropanes (6-10) is achieved from the commercially available starting materials and Wittig-Horner reaction, Claisen-Schmidt condensation and hydrogenation as key steps. Later, their nitric oxide (NO) production inhibition effects were evaluated in lipopolysaccharide (LPS)-induced RAW-264.7 macrophages as an indicator of anti-inflammatory activity. All the tested compounds significantly decreased NO production in a concentration-dependent manner except compounds 2, 6 and 8 and did not show notable cytotoxicity except compound 1. Two compounds i.e., compound 9 (hindsiipropane B) (100%; IC₅₀=1.84μM) possessed the most potent NO inhibitory activity which was even stronger than the positive control, L-NMMA (90.1%; IC₅₀=2.73μM) followed by compound 4 (75.5%; IC₅₀=2.98μM) at 10μM concentration and this finding was also further correlated by suppressed expression of LPS stimulated inducible NO synthase. Our study revealed that compound 9, a 1,3-diarylpropane scaffold with 3″,4″-dimethoxyphenyl and 3',4'-dihydroxy-2'-methoxyphenyl motifs could be considered as potential compound or lead compound for further development of NO production-targeted anti-inflammatory agents.