| Rabdosia serra (Maxim.) Hara is a typical traditional Chinese medicine in South China,which possesses a variety of biological activities and is of great prospect for research anddevelopment. The acitive ingredients of R. serra are complex, which are not comprehensivelyinvestigated. The acitive ingredients of R. serra were purified and identified in terms ofmodern chromatographic and spectroscopic techniques, which illustrated the main activecomponents in R. serra including volatiles, polysaccharides and bioactive compounds. Therelationship between structure of diterpenoids and their antitumor activities were wellillustrated. And the underlying mechanisms of lasiodin-induced inhibitions of humannasopharyngeal carcinoma cells (NPC) proliferation were investigated. The adsorptionkinetics and thermodynamics of adsorption processes by macroporous resin for R. serraphenolics were also studied. The effects of processing methods of R. serra leaf includingblanching and drying on active compounds and their biological activities were illustrated. Thecomprehensive investigation of R. serra could clarify the active ingredients responsible forthe pharmaceutical activities of R. serra and provide theories and methods for thedevelopment of relative products.(1) HS-SPME (headspace solid-phase microextraction) method was optimized forextraction of volatiles of R. serra leaf. A total of56and48compounds including alcohols,aldehydes, hydrocarbons, ketones, carboxylic acid, ester, and aromatics were identified in leafand stem by optimized HS-SPME method (CAR/PDMS fibre; incubation time,10min;extraction temperature,50°C; extraction time,40min), which were seperated and identifiedby gas chromatography-mass spectrometry. The major volatile compounds of leaf were1-octen-3-ol,(2E)-hexenal, and (3E)-1,3-octadiene. The highest diversity of volatiles wasfound in air dried leaf. Furthermore, the volatile diversity of leaf and stem were different.Cluster analysis indicated that there were significant differences between HS-SPME and SDE(simultaneous-distillation extraction) methods. HS-SPME is a useful technique for theanalysis of readily volatile components for the characteristics of R. serra aroma.(2) Twenty compounds were purified from R. serra, which include four phenolicsconsisting of rosmarinic acid (the most abundant compound in R. serra), methyl rosmarinate,pedalitin and rutin; nine diterpenoids consisting of eight7,20-epoxy-ent-kauranes (includingsix known compounds: parvifolin G, lasiodin, effusanin E, rabdosichuanin D,lushanrubescensin F and parvifoliside; and two new compounds: effusanin F and effusanin G)and one6,7-seco-ent-kauranes namely nodosin; five triterpenoids consisting of β-sitosterol, stigmasterol, oleanolic acid, ursolic acid and β-daucosterol; two other compounds consistingof palmitic acid and sucrose. It was the first time that methyl rosmarinate, pedalitin, parvifolinG, effusanin E, rabdosichuanin D, lushanrubescensin F and parvifoliside were found in R.serra. Phenolics are responsible for the good antioxidant capacity of R. serra ethanol extract.Phenolics possessed excellent antioxidant activities, which also exhibited inhibitory effects onboth tyrosinase and α-glucosidase. Diterpenoids are responsible for the good antitumoractivity of R. serra ethanol extract. Effusanin E, lasiodin and effusanin F exhibited stronginhibition against Gram-positive bacteria. Effusanin G and lasiodin exhibited stronginhibitory effects on the HepG-2(human hepatocellular liver carcinoma cell line), MCF-7(human breast adenocarcinoma cell line) and HL-60(human promyelocytic leukemia cell line)cell, and their inhibitory effects were comparable to cisplatin with broad clinical use.(3) The adsorption kinetics and thermodynamics of adsorption processes by HP-20andXAD-7HP resins for R. serra phenolics were studied. The pseudo-second-order kineticsmodel was the most favorable for illustrating the whole exothermic adsorption processes,which were affected by the mutual effects of boundary layer diffusion and intraparticlediffusion kinetics. The adsorption behaviors were of monomolecule layer adsorption. Thenegative enthalpy changes indicated that the adsorption processes were exothermic. From thedynamic adsorption/desorption experiments through column packed with HP-20orXAD-7HP resins, phenolics, antioxidants and rosmarinic acid were enriched in30%ethanolfractions. Total phenolics took up over63%in30%ethanol fractions. And rosmarinic acidaccounted for over93%of total phenolics in30%ethanol fractions.(4) It is the first time that in vitro and in vivo antitumor activity of lasiodin wasinvestigated. Our results provide new insights into the molecular mechanisms oflasiodin-mediated NPC cell suppression. Treatment with lasiodin inhibited cell viability andmigration, mediated cell morphology change, and induced apoptosis in NPC cells. Lasiodinalso significantly suppressed tumor growth with a low toxicity in human NPC tumor-bearingmice. It is the first time that molecular mechanisms of lasiodin-mediated NPC cellsuppression were studied. Lasoidin inhibits NPC tumor growth by simultaneously activatingthe Apaf-1/caspase-dependent apoptotic pathway and suppressing the PI3K/AKT, MAPKsand COX-2/NF-κB signaling.(5) Water-soluble polysaccharides of Rabdosia serra leaf and stem were fractionated byultrafiltration and DEAE-Sepharose fast flow chromatogram to obtain one neutralpolysaccharides and two acidic polysaccharides. The average molecular weights of the neutralpolysaccharides of leaf and stem were estimated to be766and736kDa, respectively. However, acidic polysaccharides possessed lower molecular weights. Glucose, galactose andarabinose constructed the backbone for neutral polysaccharides. Arabinose and galactose werethe major monosaccharides in acidic polysaccharides. The branched neutral polysaccharideswere composed mainly ofâ†'6)-Glcp-(1â†',â†'6)-Galp-(1â†', andâ†'5)-Araf-(1â†'residues.Acidic polysaccharides of leaf were composed mainly of Araf-(1â†'â†'5)-Araf-(1â†'andâ†'6)-Galp-(1â†'residues. Araf-(1â†'andâ†'2,3,6)-Galp-(1â†'residues distributed widely inacidic polysaccharides of stem.(6) Inactivation kinetics of peroxidase and polyphenol oxidase in fresh Rabdosia serraleaf were determined by hot water and steam blanching. Activation energy (52.30kJ·mol-1) ofpolyphenol oxidase inactivation was higher than that (20.15kJ·mol-1) of peroxidaseinactivation. Water blanching at90°C or steam blanching at100°C for90s wasrecommended as the preliminary processing for retention of phenolics. The intact fresh leafafter freeze drying retained the initial quality only. Significant losses of phenolics in Rabdosiaserra leaf after sun-, air-drying were observed. The retention of integrity of fresh leaf wasessential to keep the original quality. |
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