New flav-3-en-3-ol glycosides, kaempferiaosides C and D, and acetophenone glycosides, kaempferiaosides E and F, from the rhizomes of Kaempferia parviflora

Phytochemical constituents from the rhizomes of Kaempferia parviflora Wall. ex Baker and their acetylcholinesterase inhibitory activity

Phytochemical study on the rhizomes of Kaempferia parviflora led to the isolation of twenty-three compounds including six phenolic glycosides (1-6), thirteen flavones (7-19), and five phenolic compounds (20-23). Of these, the new compounds were determined to be 2,4-dihydroxy-6-methoxyacetophenone-2-β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside (1), 2-hydroxy-4-propionyl-phenyl O-β-D-glucopyranoside (2), and 4-hydroxy-3,5-dimethoxyacetophenone 8-O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside (3) and named as kaempanosides A-C, respectively. Their chemical structures were established based on HR-ESI-MS, 1D and 2D NMR spectra. All compounds 1-23 exhibited acetylcholinesterase inhibitory activity with IC50 values ranging from 57.76 to 253.31 µM.

Identification and biosynthesis of plant papanridins, a group of novel oligomeric flavonoids

The discovery of novel flavonoids and elucidation of their biosynthesis are fundamental to understanding their roles in plants and their benefits for human and animal health. Here, we report a new pathway for polymerization of a group of novel oligomeric flavonoids in plants. We engineered red cells for discovering genes of interest involved in the flavonoid pathway and identified a gene encoding a novel flavanol polymerase (FP) localized in the central vacuole. FP catalyzes the polymerization of flavanols, such as epicatechin and catechin, to produce yellowish dimers or oligomers. Structural elucidation shows that these compounds feature a novel oligomeric flaven-flavan (FF) skeleton linked by interflavan-flaven and interflaven bonds, distinguishing them from proanthocyanidins and dehydrodicatechins. Detailed chemical and physical characterizations further confirmed the novel FFs as flavonoids. Mechanistic investigations demonstrated that FP polymerizes flavan-3-ols and flav-2-en-3-ol carbocation, forming dimeric or oligomeric flaven-4→8-flavans, which we term "papanridins." Data from transgenic experiments, mutant analysis, metabolic profiling, and phylogenetic analyses show that the biosynthesis of papanridins is prevalent in cacao, grape, blueberry, corn, rice, Arabidopsis, and other species in the plant kingdom. In summary, our study discoveries a group of novel oligomeric flavonoids, namely papanridins, and reveals that a novel FP-mediated polymerization mechanism for the biosynthesis of papanridins in plants.

Protective Effect of Polymethoxyflavones Isolated from Kaempferia parviflora against TNF-α-Induced Human Dermal Fibroblast Damage

Similar to other organs, the skin undergoes a natural aging process. Moreover, constant direct exposure to environmental stresses, including ultraviolet irradiation, causes the signs of skin aging to appear rather early. Reactive oxygen species (ROS) and inflammatory responses accelerate skin damage in extrinsic aging. In this study, we aimed to investigate the skin protective effects of polymethoxyflavones found in Kaempferia parviflora against oxidative stress and inflammation-induced damage in human dermal fibroblasts (HDFs) stimulated by tumor necrosis factor-α (TNF-α). The experimental data identified 5,7,4' trimethoxyflavone (TMF) as the most potent constituent in preventing TNF-α-induced HDF damage among the tested compounds and it was not only effective in inhibiting matrix metalloproteinase-1 (MMP-1) production but also in stimulating collagen, type I, and alpha 1 (COLIA1) expression. TMF suppressed TNF-α-stimulated generation of ROS and pro-inflammatory mediators, such as cyclooxygenase-2 (COX-2), interleukin (IL)-1β, and IL-6 in HDFs. TMF also inhibited the pathways regulating fibroblast damage, including mitogen-activated protein kinase (MAPK), activator protein 1 (AP-1), and nuclear factor-kappa B (NF-κB). In conclusion, TMF may be a potential agent for preventing skin aging and other dermatological disorders associated with oxidative stress and inflammation.

Suppression of adipocyte hypertrophy by polymethoxyflavonoids isolated from Kaempferia parviflora

We previously demonstrated that ethyl acetate extracts of Kaempferia parviflora Wall. Ex Baker (KPE) improve insulin resistance in TSOD mice and showed that its components induce differentiation and adipogenesis in 3T3-L1 preadipocytes. The present study was undertaken to examine whether KPE and its isolated twelve components suppress further lipid accumulation in 3T3-L1 mature adipocytes. KPE reduced intracellular triglycerides in mature adipocytes, as did two of its components, 3,5,7,3',4'-pentamethoxyflavone and 5,7,4'-trimethoxyflavone. Shrinkage of lipid droplets in mature adipocytes was observed, and mRNA expression levels of adipose tissue triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) were up-regulated by these two polymethoxyflavonoids (PMFs). Furthermore, the protein expression level of ATGL and the release level of glycerol into the cell culture medium increased. In contrast, the peroxisome proliferator-activated receptor γ (PPARγ) agonist, troglitazone, did not decrease intracellular triglycerides in mature adipocytes, and the mRNA expression level of PPARγ was not up-regulated in mature adipocytes treated with the two active PMFs. Therefore, suppression of lipid accumulation in mature adipocytes is unlikely to be enhanced by transcriptional activation of PPARγ. These results suggest that KPE and its active components enhance lipolysis in mature adipocytes by activation of ATGL and HSL independent of PPARγ transcription, thus preventing adipocyte hypertrophy. On the other hand, the full hydroxylated flavonoid quercetin did not show the suppressive effects of lipid accumulation in mature adipocyte in the same conditions. Consequently, methoxy groups in the flavones are important for the activity.

The protective effect of Kaempferia parviflora extract on UVB-induced skin photoaging in hairless mice

BACKGROUND

Chronic skin exposure to ultraviolet (UV) light increases reactive oxygen species (ROS) and stimulates the expression of matrix metalloproteinases (MMPs) through c-Jun and c-Fos activation. These signaling cascades induce the degradation of extracellular matrix (ECM) components, resulting in photoaging.

METHODS

This study evaluated the preventive effect of the ethanol extract of Kaempferia parviflora Wall. ex. Baker (black ginger) on UVB-induced photoaging in vivo. To investigate the antiphotoaging effect of K. parviflora extract (KPE), UVB-irradiated hairless mice administered oral doses of KPE (100 or 200 mg/kg/day) for 13 weeks.

RESULTS

In comparison to the UVB control group, KPE significantly prevented wrinkle formation and the loss of collagen fibers with increased type I, III, and VII collagen genes (COL1A1, COL3A1, and COL7A1). The decrease in wrinkle formation was associated with a significant reduction in the UVB-induced expression of MMP-2, MMP-3, MMP-9, and MMP-13 via the suppression of c-Jun and c-Fos activity. KPE also increased the expression of catalase, which acts as an antioxidant enzyme in skin. In addition, expression of inflammatory mediators, such as nuclear factor kappa B (NF-κB), interleukin-1β (IL-1β), and cyclooxygenase-2 (COX-2), was significantly reduced by KPE treatment.

CONCLUSION

The results show that oral administration of KPE significantly prevents UVB-induced photoaging in hairless mice, suggesting its potential as a natural antiphotoaging material.