Phytochemical composition, antioxidant, antibacterial, and enzyme inhibitory activities of organic extracts from flower buds of Cleistocalyx operculatus (Roxb.) Merr. et Perry.

Cleistocalyx operculatus flower buds have been widely used in traditional medicine because of their rich content of bioactive constituents. In this study, we obtained seven solvent extracts from the flower buds and evaluated their total phenolic (TPC), flavonoid (TFC), tannin (TTC), triterpenoid saponin (TSC), and alkaloid (TAC) contents. We assessed antioxidant activities using the DPPH assay and also looked at antimicrobial and enzyme inhibitory effects. The water extract possessed the highest TPC (328.9 mg GAE/g extract), followed by ethanol, methanol, and hexane extracts (85.4-101.5 mg GAE/g extract). Chloroform, butanol, ethyl acetate, and ethanol extracts had high TSCs (245.4-287.2 mg OAE/g extract). The hexane extract was richest in TTC and TFC (32.7 mg CE/g extract and 81.1 mg QE/g extract, respectively). Ethanol and methanol extracts exhibited the strongest antioxidant activities (IC50 values of 25.2 and 30.3 µg/ml, respectively), followed by the water extract (IC50 of 40.2 µg/ml). The hexane extract displayed the most growth-inhibitory activity against Helicobacter pylori ATCC51932 and ATCC43504 strains and Salmonella enterica serovar Typhimurium ATCC13311 (MIC values of 0.06, 0.13, and 0.4 mg/ml, respectively). Moreover, the hexane extract revealed the strongest inhibition of H. pylori urease activity (IC50 of 4.51 µg/ml), whereas the water and methanol extracts had potent inhibitory effects on α-glucosidase activity (IC50 values of 9.9 and 15.1 µg/ml, respectively). These flower bud extracts could be used for health protection, especially in preventing bacterial infections and inhibiting enzymes associated with various human diseases. Further investigation into the application of C. operculatus flower buds in the food and pharmaceutical industries is necessary.

Antiviral activity and possible mechanism of action of constituents identified in Paeonia lactiflora root toward human rhinoviruses.

Human rhinoviruses (HRVs) are responsible for more than half of all cases of the common cold and cost billions of USD annually in medical visits and missed school and work. An assessment was made of the antiviral activities and mechanisms of action of paeonol (PA) and 1,2,3,4,6-penta-O-galloyl-ß-D-glucopyranose (PGG) from Paeonia lactiflora root toward HRV-2 and HRV-4 in MRC5 cells using a tetrazolium method and real-time quantitative reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay. Results were compared with those of a reference control ribavirin. Based on 50% inhibitory concentration values, PGG was 13.4 and 18.0 times more active toward HRV-2 (17.89 µM) and HRV-4 (17.33 µM) in MRC5 cells, respectively, than ribavirin. The constituents had relatively high selective index values (3.3->8.5). The 100 µg/mL PA and 20 µg/mL PGG did not interact with the HRV-4 particles. These constituents inhibited HRV-4 infection only when they were added during the virus inoculation (0 h), the adsorption period of HRVs, but not after 1 h or later. Moreover, the RNA replication levels of HRVs were remarkably reduced in the MRC5 cultures treated with these constituents. These findings suggest that PGG and PA may block or reduce the entry of the viruses into the cells to protect the cells from the virus destruction and abate virus replication, which may play an important role in interfering with expressions of rhinovirus receptors (intercellular adhesion molecule-1 and low-density lipoprotein receptor), inflammatory cytokines (interleukin (IL)-6, IL-8, tumor necrosis factor, interferon beta, and IL-1ß), and Toll-like receptor, which resulted in diminishing symptoms induced by HRV. Global efforts to reduce the level of synthetic drugs justify further studies on P. lactiflora root-derived materials as potential anti-HRV products or lead molecules for the prevention or treatment of HRV.

Growth inhibitory, bactericidal, and morphostructural effects of dehydrocostus lactone from Magnolia sieboldii Leaves on antibiotic-susceptible and -resistant strains of Helicobacter pylori.

Helicobacter pylori is associated with various diseases of the upper gastrointestinal tract, such as gastric inflammation and duodenal and gastric ulcers. The aim of the study was to assess anti-H. pylori effects of the sesquiterpene lactone dehydrocostus lactone (DCL) from Magnolia sieboldii leaves, compared to commercial pure DCL, two previously known sesquiterpene lactones (costunolide and parthenolide), (-)-epigallocatechin gallate, and four antibiotics. The antibacterial activity of natural DCL toward antibiotic-susceptible H. pylori ATCC 700392 and H. pylori ATCC 700824 strains (MIC, 4.9 and 4.4 mg/L) was similar to that of commercial DCL and was more effective than costunolide, parthenolide, and EGCG. The activity of DCL was slightly lower than that of metronidazole (MIC, 1.10 and 1.07 mg/L). The antibacterial activity of DCL was virtually identical toward susceptible and resistant strains, even though resistance to amoxicillin (MIC, 11.1 mg/L for PED 503G strain), clarithromycin (49.8 mg/L for PED 3582GA strain), metronidazole (21.6 mg/L for H. pylori ATCC 43504 strain; 71.1 mg/L for 221 strain), or tetracycline (14.2 mg/L for B strain) was observed. This finding indicates that DCL and the antibiotics do not share a common mode of action. The bactericidal activity of DCL toward H. pylori ATCC 43504 was not affected by pH values examined (4.0-7.0). DCL caused considerable conversion to coccoid form (94 versus 49% at 8 and 4 mg/L of DCL for 48 h). The Western blot analysis revealed that urease subunits (UreA and UreB) of H. pylori ATCC 43504 were not affected by 10 mM of DCL, whereas UreA monomer band completely disappeared at 0.1 mM of (-)-epigallocatechin gallate. Global efforts to reduce the level of antibiotics justify further studies on M. sieboldii leaf-derived materials containing DCL as potential antibacterial products or a lead molecule for the prevention or eradication of drug-resistant H. pylori.

Growth-inhibiting, bactericidal, and urease inhibitory effects of Paeonia lactiflora root constituents and related compounds on antibiotic-susceptible and -resistant strains of Helicobacter pylori.

An assessment was made of the growth-inhibiting, bactericidal, and urease inhibitory activities of paeonol (PA), benzoic acid (BA), methyl gallate (MG), and 1,2,3,4,6-penta-O-galloyl-ß-d-glucopyranose (PGG) identified in Paeonia lactiflora root, structurally related compounds, and four antibiotics toward three reference strains and four clinical isolates of Helicobacter pylori using broth dilution bioassay and Western blot. BA and PA showed strong bactericidal effect at pH 4, while MG and PGG were effective at pH 7. These constituents exhibited strong growth-inhibiting and bactericidal activity toward the five strains resistant to amoxicillin (minimal inhibitory concentration (MIC) 12.5 mg/L), clarithromycin (64 mg/L), metronidazole (64 mg/L), or tetracycline (15 mg/L), indicating that these constituents and the antibiotics do not share a common mode of action. Structural characteristics, such as types of functional groups and carbon skeleton, and hydrophobicity appear to play a role in determining the anti- H. pylori activity. H. pylori urease inhibitory activity of PGG was comparable to that of acetohydroxamic acid, while MG was less potent at inhibiting urease than thiourea. The UreB band disappeared at 250 mg/L PGG on Western blot, while the UreA bands were faintly visible at 1000 mg/L PGG. These constituents showed no significant cytotoxicity. Global efforts to reduce the level of antibiotics justify further studies on P. lactiflora root-derived materials containing MG, PA, and PGG as potential antibacterial products or lead molecules for the prevention or eradication from humans from diseases caused by H. pylori .

Growth-inhibiting effects of Paeonia lactiflora root steam distillate constituents and structurally related compounds on human intestinal bacteria.

The growth-inhibiting activities of Paeonia lactiflora (Paeoniaceae) root steam distillate constituents and structurally related compounds against nine harmful intestinal bacteria and eight lactic acid-producing bacteria were compared with those of two antibiotics, amoxicillin and tetracycline. Thymol, α-terpinolene, (-)-perilla alcohol and (1R)-(-)-myrtenol exhibited high to extremely high levels of growth inhibition of all the harmful bacteria, whereas thymol and α-terpinolene (except for Lactobacillus casei ATCC 393) inhibited the growth of all the beneficial bacteria (MIC, both 0.08-0.62 mg mL(-1)). Tetracycline and amoxicillin exhibited extremely high level of growth inhibition of all the test bacteria (MIC, <0.00002-0.001 mg mL(-1)). 1,8-Cineole, geraniol, (-)-borneol, (1S,2S,5S)-(-)-myrtanol, nerol, (S)-(-)-ß-citronellol and (±)-lavandulol also exhibited inhibitory activity but with differing specificity and levels of activity. Structure-activity relationship indicates that structural characteristics, such as geometric isomerism, degrees of saturation, types of functional groups and types of carbon skeleton, appear to play a role in determining the growth-inhibiting activity of monoterpenoids. Global efforts to reduce the level of antibiotics justify further studies on naturally occurring P. lactiflora root-derived materials as potential preventive agents against various diseases caused by harmful intestinal bacteria such as clostridia.