Anti-complementary activity of Crataegus sinaica.

The 80% and 70% acetone extracts from fruits and leaves of Crataegus sinaica Boiss (Rosaceae) and the ethyl acetate-, butanol-, and water-fractions obtained from these initial extracts as well as the isolated compounds, quercetin (1) (1), hyperoside (quercetin 3-O-galactoside) (2) (2), rutin (quercetin 3-O-rutinoside) (3) (2), vitexin (4) (1), rhamnosylvitexin (5) (3), monoacetylrhamnosylvitexin (6) (3), epicatechin (7) (4), procyanidin B-5 (8) (4), proanthocyanidin A-2 (9) (5), procyanidin B-2 (10) (4), and procyanidin C-1 (11) (4), were tested for their influence on the classical (CP) and alternative (AP) pathways of complement-mediated hemolysis. All extracts and fractions showed a strong anti-complementary effect in a dose-dependent way which was more pronounced on the CP than on the AP. The results indicated that the pure proanthocyanidins were active on the CP. Procyanidin C-1 and proanthocyanidin A-2 were the most active on the CP and also showed activity on AP, whereas the flavonoids isolated were generally less active. However, rutin, showed a strong activity, quercetin and rhamnosylvitexin a moderate activity on the CP. This is the first report on the chemical constituents and complement-modulating activity of C. sinaica and on the occurrence of proanthocyanidin A-2 (9) in hawthorn.

In vitro biological activities of alkaloids from Cryptolepis sanguinolenta.

In our biological screening of higher plants, an aqueous and an 80% EtOH extract from the root bark of Cryptolepis sanguinolenta showed potent antibacterial, anticomplementary, and moderate antiviral activities, but no antifungal effect could be detected. Bioassay-guided fractionation of the 80% EtOH extract led to the isolation of three alkaloids: quindoline (1), hydroxycryptolepine (2), cryptolepine.HCl (3), and the corresponding base cryptolepine (4). All compounds strongly inhibited the growth of Gram-positive bacteria (MIC < or = 100 micrograms/ml) and showed a moderate (MIC = 125 or 250 micrograms/ml), a weak (MIC = 500 micrograms/ml), or no activity (MIC > 500 micrograms/ml) against selected Gram-negative bacteria. They also possessed a bactericidal effect depending on the bacterial strain. Compounds 1, 2 and 3 displayed a dose-dependent inhibitory effect on the classical pathway of the complement system while compounds 2 and 3 activated the alternative pathway, except for compound 1. Compound 3 was found to possess an antiherpetic activity. Compounds 1 and 4 showed no antiviral effect, but were quite cytotoxic in the antiviral test system down to a concentration of 1 microgram/ml.

Antiviral activity of Hawaiian medicinal plants against human immunodeficiency Virus Type-1 (HIV-1).

Hawaiian medicinal plants commonly used for the treatment of a variety of infections were screened for antiviral activity against human immunodeficiency virus type 1 (HIV-1). Sixty-one extracts derived from seventeen plants were tested for selective viral growth inhibition using the LAI (HTLV-IIIB) isolate. The greatest degree of antiviral activity was observed with aqueous extracts made from the bark of Eugenia malaccensis (L.) and the leaves of Pluchea indica (Less.) which had antiviral selectivity indices (50% cytotoxic concentration/50% effective antiviral concentration) of 109 and 94, respectively. These and other extracts conferred 100% cell protection against viral cytopathic effect when compared with control samples. Methanol and water extracts made from the Pipturus albidus (Gray) leaves and bark also achieved a high selective inhibition of virus replication with very low cytotoxicity. Plant extracts made from Aleurites moluccana (Willd.), Psychotria hawaiiensis (Gray), Clermontia aborescens (Mann), and Scaevola sericea (Forst.) also showed antiviral activity. These data provide a rationale for the characterization of antiviral natural products from these plants and related plant species.

Anti-microbial activity and anti-complement activity of extracts obtained from selected Hawaiian medicinal plants.

Selected plants having a history of use in Polynesian traditional medicine for the treatment of infectious disease were investigated for anti-viral, anti-fungal and anti-bacterial activity in vitro. Extracts from Scaevola sericea, Psychotria hawaiiensis, Pipturus albidus and Eugenia malaccensis showed selective anti-viral activity against Herpes Simplex Virus-1 and 2 and Vesicular Stomatitis Virus. Aleurites moluccana extracts showed anti-bacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, while Pipturus albidus and Eugenia malaccensis extracts showed growth inhibition of Staphylococcus aureus and Streptococcus pyogenes. Psychotria hawaiiensis and Solanum niger inhibited growth of the fungi Microsporum canis, Trichophyton rubrum and Epidermophyton floccosum, while Ipomoea sp., Pipturus albidus, Scaevola sericea, Eugenia malaccensis, Piper methysticum, Barringtonia asiatica and Adansonia digitata extracts showed anti-fungal activity to a lesser extent. Eugenia malaccensis was also found to inhibit the classical pathway of complement suggesting that an immunological basis for its in vivo activity was identified. This study has confirmed some of the ethnobotanical reports of Hawaiian medicinal plants having curative properties against infections using biological assays in vitro.

Screening of hundred Rwandese medicinal plants for antimicrobial and antiviral properties.

A series of 100 Rwandese medicinal plants (267 plant extracts), used by traditional healers to treat infections, were screened for antibacterial, antifungal and antiviral properties. The results of the testing showed that 45% were active against Staphylococcus aureus, 2% against Escherichia coli, 16% against Pseudomonas aeruginosa, 7% against Candida albicans, 80% against Microsporum canis and 60% against Trichophyton mentagrophytes. Not less than 27% of the plant species exhibited prominent antiviral properties against one or more test viruses, more specifically 12% against poliomyelitis, 16% against coxsackie, 3% against Semliki forest, 2% against measles and 8% against herpes simplex virus.

In vitro anticomplementary activity of constituents from Morinda morindoides.

In a screening program for complement classical pathway modulation, an 80% MeOH extract of the leaves of Morinda morindoides showed potent dose-dependent anticomplementary activity. Bioassay-guided chromatographic separation of the active constituents led to the isolation of ten flavonoids of which two were aglycones. The compounds were tested in vitro for their putative complement-inhibiting properties on the classical (CP) and the alternative (AP) pathways of the complement system. The results indicated that quercetin [1], quercetin 3-O-rhamnoside (quercitrin) [5], and quercetin 3-O-rutinoside (rutin) [7] showed similar anticomplementary activities (inhibition) on the CP of complement. A mixture of two kaempferol triglycosides isolated and denoted as M(015), also had a good inhibitory effect. The effects of these compounds were dose-dependent for this pathway. On the AP of complement, quercetin [1] and M(015) had, respectively, more pronounced inhibitory and activatory effects than the other tested flavonoids, but their effects were not dose-dependent for this pathway. The other isolated flavonoids showed weak effects or were inactive for both pathways.

Structure-activity relationship of flavonoids with superoxide scavenging activity.

The superoxide scavenging activities of 12 flavonoids were measured. The superoxide anions were generated by a hypoxanthine-xanthine oxidase system and measured by the nitrite method. The results showed that the scavenging ability enhanced with an increasing number of hydroxyl groups in ring B. Substitution at C3 position with a hydroxyl group increased the activity. Compared to a methoxyl group or a glycoside in this position, a free hydroxyl group showed the highest activity. A saturated C2-C3 bond showed a higher activity than a unsaturated bond. The absence of a carbonyl group at C4 position increased the activity.

Screening of Rwandese plant extracts for their influence on lymphocyte proliferation.

Plants from Rwanda used in traditional medicine have been investigated for their influence on lymphocyte proliferation with and without the presence of the mitogen phytohemagglutinin. Phytolacca dodecandra displayed a significant mitogenic effect. Several plants inhibited the lymphocyte proliferation after prestimulation with the mitogen.