Pharmacist-Monks in the Tang Dynasty: A Group of Mahayana Buddhist Followers and their Contributions to Chinese Buddhism

Pharmacist-monks (yaoseng1), a group of Buddhist monks who devote themselves to the production of Chinese herbal medicines, have existed in China for over 1000 years, but are still poorly understood. To provide important insight into the special religious group, this study inspected Poetry of the Tang Dynasty and other historical data in Chinese ancient texts. The results suggest there were numerous pharmacist-monks in the Tang Dynasty. From the samvrti-satya viewpoint, they participated in the entire manufacturing process for Chinese herbal medicines, and sometimes directly carried out medical charity activity. Their contributions to Chinese Buddhism are summarized as: (i) to provide herbal medicines as a form of Buddhist charity, or to express compassionate ideals of Buddhism via direct medical charity; (ii) to provide food for devotees at Buddhist temples; and (iii) to beautify Buddhist temples. However, from the paramartha-satya viewpoint, these pharmacist-monks actually practiced six paramitas (i.e. dana, sila-vinaya, ksanti, virya, dhyana, and prajna) which are the main characteristics of mahayana Buddhism. Therefore, they are considered as mahayana followers. They lived laborious but happy, and were widely respected by the secular society. They inherited mahayanist tradition and accelerated the development of mahayana Buddhism in China

Antioxidant and Cytoprotective Effects of Kukoamines A and B: Comparison and Positional Isomeric Effect

In this study, two natural phenolic polyamines, kukoamine A and B, were comparatively investigated for their antioxidant and cytoprotective effects in Fenton-damaged bone marrow-derived mesenchymal stem cells (bmMSCs). When compared with kukoamine B, kukoamine A consistently demonstrated higher IC50 values in PTIO•-scavenging (pH 7.4), Cu2+-reducing, DPPH•-scavenging, •O2−-scavenging, and •OH-scavenging assays. However, in the PTIO•-scavenging assay, the IC50 values of each kukoamine varied with pH value. In the Fe2+-chelating assay, kukoamine B presented greater UV-Vis absorption and darker color than kukoamine A. In the HPLC–ESI–MS/MS analysis, kukoamine A with DPPH• produced radical-adduct-formation (RAF) peaks (m/z 922 and 713). The 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl (MTT) assay suggested that both kukoamines concentration-dependently increased the viabilities of Fenton-damaged bmMSCs at 56.5–188.4 μM. However, kukoamine A showed lower viability percentages than kukoamine B. In conclusion, the two isomers kukoamine A and B can protect bmMSCs from Fenton-induced damage, possibly through direct or indirect antioxidant pathways, including electron-transfer, proton-transfer, hydrogen atom transfer, RAF, and Fe2+-chelating. Since kukoamine B possesses higher potentials than kukoamine A in these pathways, kukoamine B is thus superior to kukoamine A in terms of cytoprotection. These differences can ultimately be attributed to positional isomeric effects

Comparison of the Antioxidant Effects of Quercitrin and Isoquercitrin: Understanding the Role of the 6″-OH Group

The role of the 6″-OH (ω-OH) group in the antioxidant activity of flavonoid glycosides has been largely overlooked. Herein, we selected quercitrin (quercetin-3-O-rhamnoside) and isoquercitrin (quercetin-3-O-glucoside) as model compounds to investigate the role of the 6″-OH group in several antioxidant pathways, including Fe2+-binding, hydrogen-donating (H-donating), and electron-transfer (ET). The results revealed that quercitrin and isoquercitrin both exhibited dose-dependent antioxidant activities. However, isoquercitrin showed higher levels of activity than quercitrin in the Fe2+-binding, ET-based ferric ion reducing antioxidant power, and multi-pathways-based superoxide anion-scavenging assays. In contrast, quercitrin exhibited greater activity than isoquercitrin in an H-donating-based 1,1-diphenyl-2-picrylhydrazyl radical-scavenging assay. Finally, in a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl assay based on an oxidatively damaged mesenchymal stem cell (MSC) model, isoquercitrin performed more effectively as a cytoprotector than quercitrin. Based on these results, we concluded that (1) quercitrin and isoquercitrin can both indirectly (i.e., Fe2+-chelating or Fe2+-binding) and directly participate in the scavenging of reactive oxygen species (ROS) to protect MSCs against ROS-induced oxidative damage; (2) the 6″-OH group in isoquercitrin enhanced its ET and Fe2+-chelating abilities and lowered its H-donating abilities via steric hindrance or H-bonding compared with quercitrin; and (3) isoquercitrin exhibited higher ROS scavenging activity than quercitrin, allowing it to improve protect MSCs against ROS-induced oxidative damage

Protective Effects of Dihydromyricetin against •OH-Induced Mesenchymal Stem Cells Damage and Mechanistic Chemistry

As a natural flavonoid in Ampelopsis grossedentata, dihydromyricetin (DHM, 2R,3R-3,5,7,3′,4′,5′-hexahydroxy-2,3-dihydroflavonol) was observed to increase the viability of •OH-treated mesenchymal stem cells using a MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl] assay and flow cytometry analysis. This protective effect indicates DHM may be a beneficial agent for cell transplantation therapy. Mechanistic chemistry studies indicated that compared with myricetin, DHM was less effective at ABTS+• (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid radical) scavenging and reducing Cu2+, and had higher •O2− and DPPH• (1,1-diphenyl-2-picrylhydrazyl radical) scavenging activities. Additionally, DHM could also chelate Fe2+ to give an absorption maximum at 589 nm. Hence, such protective effect of DHM may arise from its antioxidant activities which are thought to occur via direct radical-scavenging and Fe2+-chelation. Direct radical-scavenging involves an electron transfer (ET) pathway. The hydrogenation of the 2,3-double bond is hypothesized to reduce the ET process by blocking the formation of a larger π-π conjugative system. The glycosidation of the 3–OH in myricitrin is assumed to sterically hinder atom transfer in the •O2− and DPPH• radical-scavenging processes. In DHM, the Fe2+-chelating effect can actually be attributed to the 5,3′,4′,5′–OH and 4–C=O groups, and the 3–OH group itself can neither scavenge radicals nor chelate metal

Steric Effect of Antioxidant Diels-Alder-Type Adducts: A Comparison of Sanggenon C with Sanggenon D

Sanggenons C and D are two Diels-Alder-type adducts from Chinese crude drug Sang-bai-pi. Structurally, both sanggenons construct stereoisomers. In the study, they were comparatively determined using four antioxidant assays, including ferric ion reducing antioxidant power (FRAP) assay, Cu2+-reducing assay, 1,1-diphenyl-2-picryl-hydrazl (DPPH•)-scavenging assay, and 2,2′-azino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid radical (ABTS•+)-scavenging assay. Their Fe2+-binding reactions were explored using UV-Vis spectra. Finally, their cytoprotective effects were evaluated using flow cytometry. In electron transfer (ET)-based FRAP and Cu2+-reducing assays, sanggenon D was found to have lower IC50 values than sanggenon C; however, in multi-pathway-based DPPH•-scavenging and ABTS•+-scavenging assays, sanggenon C possessed lower IC50 values than sanggenon D. UV-Vis spectra suggested that sanggenon C generated a bathochromic-shift (286 nm → 302 nm) and displayed stronger UV absorption than sanggenon D. In flow cytometry, sanggenon C and sanggenon D, respectively, exhibited 31.1% and 42.0% early apoptosis-percentages towards oxidative-stressed mesenchymal stem cells (MSCs). In conclusion, both sanggenons may undergo multiple pathways (e.g., ET and Fe2+-binding) to protect MSCs against oxidative stress. In the mere ET aspect, sanggenon D possesses a higher level than sanggenon C, while in multi-pathway-based radical-scavenging, Fe2+-binding, and cytoprotection aspects, sanggenon C is more active than sanggenon D. These discrepancies can conclusively be attributed to the steric effect

3′,8″-Dimerization Enhances the Antioxidant Capacity of Flavonoids: Evidence from Acacetin and Isoginkgetin

To probe the effect of 3′,8″-dimerization on antioxidant flavonoids, acacetin and its 3′,8″-dimer isoginkgetin were comparatively analyzed using three antioxidant assays, namely, the ·O2− scavenging assay, the Cu2+ reducing assay, and the 2,2′-azino bis(3-ethylbenzothiazolin-6-sulfonic acid) radical scavenging assay. In these assays, acacetin had consistently higher IC50 values than isoginkgetin. Subsequently, the acacetin was incubated with 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxy radicals (4-methoxy-TEMPO) and then analyzed by ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UHPLC−ESI−Q−TOF−MS) technology. The results of the UHPLC−ESI−Q−TOF−MS analysis suggested the presence of a dimer with m/z 565, 550, 413, 389, 374, 345, 330, and 283 peaks. By comparison, standard isoginkgetin yielded peaks at m/z 565, 533, 518, 489, 401, 389, 374, and 151 in the mass spectra. Based on these experimental data, MS interpretation, and the relevant literature, we concluded that isoginkgetin had higher electron transfer potential than its monomer because of the 3′,8″-dimerization. Additionally, acacetin can produce a dimer during its antioxidant process; however, the dimer is not isoginkgetin

Improved Pyrogallol Autoxidation Method: A Reliable and Cheap Superoxide-Scavenging Assay Suitable for All Antioxidants

The original pyrogallol (1,2,3-trihydroxybenzene) method, which was developed specifically for superoxide dismutase, is now widely used for measuring superoxide-scavenging of other antioxidants. However, the strong pH effect has been ignored. In this study, the influencing factors have been systematically investigated for the first time, and a number of experiments have proved that the pH is of major importance. As major antioxidants contain carboxylic acid, ester, or lactone groups, pH 8.2 should be modified to physiological pH 7.4. The improved procedure is as follows. A pyrogallol solution (in 1 M HCl) is thoroughly mixed with pH 7.4 Tris-HCl buffer; <i>A</i>_325 nm is measured every 30 s for 5 min at 37 °C. As the Δ<i>A</i>_{325 nm, control} value reflects the initial concentration of substrate ^•O₂^–, it should be well controlled to guarantee the accuracy of the method. The improved pyrogallol method is a reliable and cheap superoxide-scavenging assay suitable for all types of antioxidants

Improved Pyrogallol Autoxidation Method: A Reliable and Cheap Superoxide-Scavenging Assay Suitable for All Antioxidants

The original pyrogallol (1,2,3-trihydroxybenzene) method, which was developed specifically for superoxide dismutase, is now widely used for measuring superoxide-scavenging of other antioxidants. However, the strong pH effect has been ignored. In this study, the influencing factors have been systematically investigated for the first time, and a number of experiments have proved that the pH is of major importance. As major antioxidants contain carboxylic acid, ester, or lactone groups, pH 8.2 should be modified to physiological pH 7.4. The improved procedure is as follows. A pyrogallol solution (in 1 M HCl) is thoroughly mixed with pH 7.4 Tris-HCl buffer; <i>A</i>_325 nm is measured every 30 s for 5 min at 37 °C. As the Δ<i>A</i>_{325 nm, control} value reflects the initial concentration of substrate ^•O₂^–, it should be well controlled to guarantee the accuracy of the method. The improved pyrogallol method is a reliable and cheap superoxide-scavenging assay suitable for all types of antioxidants

2‑Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3‑Oxide (PTIO^•) Radical Scavenging: A New and Simple Antioxidant Assay <i>In Vitro</i>

Current <i>in vitro</i> antioxidant assays have several limitations, which frequently cause inconsistent results. The study develops a new antioxidant assay using the 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide radical (PTIO^•). After the investigation of various factors, the experimental protocol was briefly recommended as follows: PTIO^• and the sample solution were added to phosphate buffer (pH 7.4, 50 mM), incubated at 37 °C for 2 h, and then spectrophotometrically measured at 557 nm. The validation test based on 20 pure compounds and 30 lyophilized aqueous extracts suggested that PTIO^• scavenging had a good linear relationship, stability, and reproducibility. In the ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry analysis, PTIO^• was observed to give <i>m</i>/<i>z</i> 234 when encountering l-ascorbic acid. As an antioxidant assay, PTIO^• scavenging possesses four advantages, i.e., oxygen-centered radical, physiological aqueous solution, simple and direct measurement, and less interference from the tested sample. It can also satisfactorily analyze the antioxidant structure–activity relationship. PTIO^• scavenging has no stereospecificity and is at least involved in H⁺ transfer