Relationship between radical intensity and biological activity of cacao husk extracts.

The relationship between radical intensity and biological activity of cacao husk extracts was investigated. Electron spin resonance (ESR) spectroscopy demonstrated that the radical intensity of hexane, acetone, methanol and 70% methanol extracts increased with water-solubility. Several fractions of these husk extracts, separated by different column chromatographies, significantly inhibited the cytopathic effect of human immunodeficiency virus (HIV) infection in parallel with their radical intensity. However, their cytotoxic activity against human leukemic and carcinoma cell lines is not always correlated with their radical intensity. Water-soluble and lipophilic compounds might induce cytotoxic activity by different mechanisms.

Radical modulation activity of pine cone extracts of Pinus elliottii var. Elliottii.

The radical modulation activity of lignins prepared from the cone of Pinus elliottii var. Elliottii was investigated, using ESR spectroscopy. These lignins produced radical(s) under alkaline conditions, and the radical intensity was increased with increasing pH. Lower concentrations of lignins slightly reduced the radical intensity of sodium ascorbate, whereas higher concentrations of lignins enhanced both the radical intensity and cytotoxic activity of sodium ascorbate. Lignins effectively scavenged superoxide anion, produced by hypoxanthine-xanthine oxidase reaction. Elliottii lignins significantly inhibited the human immunodeficiency virus (HIV)-induced cytopathic effect, in similar fashions to other natural, commercial and synthetic lignins. Pretreatment of mice with lignins significantly protected them from the lethal infection with E. coli. Crude alkaline extracts of Elliottii pine cone displayed similar magnitude of activity with lignins. These data further supports the medicinal efficacy of plant extracts.

Antiviral properties of a mangrove plant, Rhizophora apiculata Blume, against human immunodeficiency virus.

A polysaccharide extracted from the leaf of Rhizophora apiculata (RAP) was assessed in cell culture systems, for its activity against human and simian immunodeficiency viruses. RAP inhibited HIV-1 or HIV-2 or SIV strains in various cell cultures and assay systems. It blocked the expression of HIV-1 antigen in MT-4 cells and abolished the production of HIV-1 p24 antigen in peripheral blood mononuclear cells (PBMC); the 50% effective concentration (EC50) of RAP in HIV-1 infected MT-4 cells and in PBMC was 10.7 and 25.9 microg/ml, respectively. RAP (100 microg/ml) completely blocked the binding of HIV-1 virions to MT-4 cells. RAP also reduced the production of viral mRNA when added before virus adsorption. RAP inhibited syncytium formation in cocultures of MOLT-4 cells and MOLT-4/HIV-1(IIIB) cells. RAP did not prolong activated partial thromboplastin time (APTT) up to 500 microg/ml. These properties may be advantageous should RAP be considered for further development.

Radical modulation activity of lignins from a mangrove plant, Ceriops decandra (Griff.) Ding Hou.

The radical modulation activity of hot water and alkaline extracts from leaf of Ceriops decandra, a mangrove plant, was investigated using ESR spectroscopy. IR and NMR analyses demonstrate that the leaf extracts have a lignin-like polyphenolic structure. All these extracts produced radical(s) under alkaline conditions. The radical intensity of sodium ascorbate was slightly reduced at lower concentrations of the extracts, but it was synergistically enhanced at higher concentrations. All the extracts effectively scavenged superoxide anion, produced by hypoxanthine-xanthine oxidase reaction. Pretreatment of mice with the extracts significantly protected them from the lethal infection by E. coli. Similar activity was found in lignins from pine seed shell of Pinus parviflora Sieb. et Zucc. These data further support the medicinal efficacy of plant extracts.