Antioxidation and Melanogenesis Inhibition of Various Dendrobium tosaense Extracts.

This study investigated the polyphenol content, antioxidant activity, and inhibition ability of mushroom tyrosinase and melanogenesis of Dendrobium tosaense (DT) extract. Ground DT was extracted using deionized water (W) or 50% ethanol (50E) at room temperature (RT) or 50 °C (50T) for 20 min. The 50T + 50E extract exhibited the highest total phenol content 47.0 ± 4.0 mg gallic acid equivalent/g DT extract, the highest level of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) free-radical scavenging 66.0 ± 3.0 mg Trolox equivalent/g DT extract, and the highest reducing power 12.00 ± 0.50 mg vitamin C equivalent/g DT extract. The RT + W extract had the highest total flavonoid content 110.0 ± 3.0 mg quercetin equivalent/g DT extract. The RT + 50E extract had the lowest half maximal inhibitory concentration 1.30 ± 0.00 mg/mL for 2,2-diphenyl-1-picrylhydrazyl free-radical scavenging, and the lowest half maximal inhibitory concentration 6.40 ± 0.30 mg/mL for mushroom tyrosinase inhibition activity. DT extracts, especially RT + W and 50T + W, exhibited potent inhibitory effects on melanogenesis of B16/F10 cells. These results demonstrated the application potential of DT extract for skincare.

Characterization and immunomodulatory activity of polysaccharides derived from Dendrobium tosaense.

Dendrobium tosaense is a medicinal Dendrobium species widely used in traditional medicine. This study demonstrated some structural characterizations and immunomodulatory activity of the water-soluble polysaccharides derived from the stem of D. tosaense (DTP). DTP was fractioned using DEAE-650 M anion-exchange gel filtration chromatography, producing one neutral polysaccharide fraction (DTP-N), which was investigated for its structural characteristics, using HPAEC-PAD, HP-SEC, GC-MS, and NMR spectroscopy. DTP and DTP-N consisted of galactose, glucose, and mannose in ratios of 1:9.1:150.7 and 1:12.2:262.5, respectively. DTP-N comprised (1 → 4)Man as its main backbone, and its average molecular weight was 220 kDa. We also investigated the immunomodulatory effects of DTP administered orally to BALB/c mice for 3 weeks. DTP substantially boosted the population of splenic natural killer (NK) cells, NK cytotoxicity, macrophage phagocytosis, and cytokine induction in splenocytes. This is the first study to demonstrate the structural characteristics of an active polysaccharide derived from D. tosaense and its immunopharmacological effects in vivo.

Inhibitory effects of cultured Dendrobium tosaense on atopic dermatitis murine model.

Dendrobium tosaense is one of the most valuable Chinese medicines and well developed health food. Atopic dermatitis (AD) is a chronic skin disease that occurs mainly in childhood. The pathogenesis of atopic dermatitis had been studied in BALB/c mice modeling by skin-inoculated ovalbumin (OVA) with 2,4,6-trinitro-1-chrolobenzene (TNCB). These mice exhibit features of chronic dermatitis, including skin rash, mast cells infiltration, and elevated serum anti-OVA specific IgE and cytokines modulation. In this study, a standardized ethyl acetate extract of D. tosaense (DtE) was used to protect these mice from the OVA/TNCB-induced skin lesions of atopic dermatitis. The results indicated an increased population of natural T regulatory cell was accompanied by immunosuppression in cytokine profiles and anti-OVA IgE level to significantly reduce Th2 polarization. Finally, toluidine blue staining indicated mast cell infiltration and degranulation was reduced in skin lesion. Our results were shed light on the usage of D. tosaense in AD.