Triterpenoid saponins from Polaskia chichipe Backbg. and their inhibitory or promotional effects on the melanogenesis of B16 melanoma cells

Abstract

Five new oleanane-type saponins 1-5 together with a known saponin 6 and a steroidal glycoside 7 were isolated from Polaskia chichipe Backbg., and their structures were determined from their 1D and 2D NMR and HRFABMS spectral data. The six isolated saponins 1-6 were tested for their effects on the melanogenesis of B16 melanoma 4A5 cells. Compound 1 exerted an inhibitory effect at 100 μM whereas compound 3 promoted melanogenesis at the same concentration, even though these two compounds contain the same aglycon structure. The dose-dependent activities of compounds 1 and 3 on melanin synthesis were investigated.

Amyloid β aggregation inhibitory activity of triterpene saponins from the cactus Stenocereus pruinosus

“…In contrast, the correlation between H-1′′′ of glucose (δ H 4.33) and C-22 of the aglycone (δ C 77.9) showed that the glucose-1 unit binds at C-22 of the aglycone moiety. Considering the chemical shift of C-22 (δ C 67.4) of chichipenoside C [5], this deshielding of C-22 (δ C 77.9) of the aglycone also supported the binding of the glucose-1 unit at C-22 of the aglycone. In addition, the correlation between H-1′′′′ of the second rhamnose (δ H 4.69) and C-4′′′ of glucose (δ C 76.6) indicated that the rhamnose-1 unit binds at C-4′′′ of the glucose unit.…”

“…glucuronopyranoside, which has already isolated from Polaskia chichipe [5], exhibited Aβ aggregation inhibitory activity at the same level as chichipegenin (chichpenoside C; 43.8%, chichipegenin; 39.2%, respectively, at 25 μM) [6], while chichipenoside D exhibited weaker activity than that of chichipenoside C and chichipegenin. Its SAR suggested that glycosylations at C-22 position of the chichipegenin attenuated Aβ aggregation inhibitory activity.…”

“…Additionally considering ODS HPLC data [25] and comprehensive 2D-NMR analysis including strong three-bond HMBC correlation [27], it was revealed that the presence of two sugars, β-d-glucuronic acid and α-lrhamnose. It could not be performed to measure the 1 J C1-H1 value about the anomeric protons on the rhamnopyranosyl units contained in new saponins (2-5,7) from S. pruinosus, the rhamnopyranosyl units presumably had α-configuration because of our previous reports [5][6][7][8][9][10][11][12], their multiplicity ("br s" or "d" with small coupling constant) and their strong three-bond HMBC correlations [27]. Further analysis confirmed that compound 2 was longispinogenin 3-O-α-lrhamnopyranosyl-(1 → 3)-β-d-glucuronopyranoside and named as longispinoside A (Fig.…”

“…Considering those reports, we had been further investigating triterpene sapogenins from many cacti and discovered that S. pruinosus contained erythrodiol, longispinogenin and 3β-hydroxy-11α,12α-epoxyolean-28,13β-olide in addition to oleanolic acid from hydrolysate of MeOH extract of S. pruinosus [4]. Now, we have been investigating triterpene saponins from cacti for several decades [5][6][7][8][9][10][11][12] and reported the identification of numerous saponins exhibiting bioactivities such as anti-type I allergy activity [7], inhibition or promotion of melanin synthesis [5], inhibition of amyloid β (Aβ) aggregation, and protective effects on SH-SY5Y cells against Aβ-associated toxicity [6].…”

“…The activities of saponins have been well studied and include anti-inflammatory, anti-tumor, anti-obesity, anti-angiogenesis, anti-allergic, anti-microbial, and anti-Alzheimer's disease (AD) [13,14]. In particular, our group found that saponins from cacti have unique structures [5][6][7][8][9][10][11][12] that have not been adequately investigated.…”