Sterculia and Brachychiton: a comprehensive overview on their ethnopharmacology, biological activities, phytochemistry and the role of their gummy exudates in drug delivery.

OBJECTIVES: Sterculia and Brachychiton are two related genera (Malvaceae) containing more than 300 species. Most of these species are ornamental trees that are native to Australia and widely cultivated in many countries. Different members of the two genera were used by various cultures for medicinal and economical purposes. This review sheds light on the medicinal values and chemical composition of various species of these two genera. KEY FINDINGS: Sterculia and Brachychiton species were used traditionally for the treatment of gastrointestinal disorders, microbial infection, skin diseases, inflammation and many other conditions. The seeds of various species were roasted and eaten by many traditional tribes. Plants from the two genera revealed their anti-inflammatory, antioxidant, antimicrobial, antidiabetic, antiulcer, insecticidal and analgesic activity. These activities may be attributed to the presence of a wide range of secondary metabolites as flavonoids, phenolic acids, coumarins, terpenoids particularly sesquiterpenes and triterpenes in addition to sterols and fatty acids. Moreover, the gummy exudates obtained from some members of these genera played an important role in different pharmaceutical dosage forms and drug-delivery systems. CONCLUSIONS: More research is recommended on other species of Sterculia and Brachychiton to discover new molecular entities with potential biological and economic values.

Chitosan/Sterculia striata polysaccharides nanocomplex as a potential chloroquine drug release device.

Nanoparticles are produced by means of polyelectrolyte complexation (PEC) of oppositely charged polycationic chitosan (CH) with polyanionic polysaccharide extracted from Sterculia striata exudates (rhamnogalacturonoglycan (RG)-type polysaccharide). The nanoparticles formed with low-molar-mass CH are larger than those formed with high-molar-mass CH. This behavior is in contrast with that previously observed for other systems and may be attributed to different mechanisms related to the association of CH with RG of higher persistence length chain than that of CH. Nanoparticles harnessed with a charge ratio (n(+)/n(-)) of <1 are smaller than particles with an excess of polycations. Particles with hydrodynamic sizes smaller than 100nm are achieved using a polyelectrolyte concentration of 10(-4)gmL(-1) and charge ratio (n(+)/n(-)) of <1. The CH/RG nanoparticles are associated with chloroquine (CQ) with an efficiency of 28% and release it for up to ∼60% within ∼10h, whereas in the latter, only ∼40% of the CQ was released after 24h. The main factor that influenced drug release rate is the nanoparticle charge ratio.

Dodecenylsuccinic anhydride derivatives of gum karaya (Sterculia urens): preparation, characterization, and their antibacterial properties.

Esterifications of the tree-based gum, gum karaya (GK), using dodecenylsuccinic anhydride (DDSA) were carried out in aqueous solutions. GK was deacetylated using alkali treatment to obtain deacetylated gum karaya (DGK). The DGK and its DDSA derivative were characterized using gel permeation chromatography/multiangle laser light scattering (GPC/MALLS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), proton nuclear magnetic resonance spectroscopy ((1)H NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) analysis, and rheological studies. The degree of substitution was found to be 10.25% for DGK using (1)H NMR spectroscopy. The critical aggregation concentration of DDSA-DGK was determined using dye solubilization and surface tension methods. The antibacterial activity of the DDSA-DGK derivative was then investigated against Gram-negative Escherichia coli and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. The DDSA-DGK derivative has the potential for use as a stabilizing agent in food and nonfood applications. It can also be developed as an antibacterial agent.

Exudate gums: occurrence, production, and applications.

This paper presents a review of the industrially most relevant exudate gums: gum arabic, gum karya, and gum tragacanth. Exudate gums are obtained as the natural exudates of different tree species and exhibit unique properties in a wide variety of applications. This review covers the chemical structure, occurrence and production of the different gums. It also deals with the size and relative importance of the various players on the world market. Furthermore, it gives an overview of the main application fields of the different gums, both food and non-food.