A new and simple HPLC method using fluorescence detection was developed to determine 9-methoxycanthin-6-one, an active compound of Eurycoma longifolia Jack in rat and human plasma. The method entailed direct injection of plasma sample after deproteinization using acetonitrile. The mobile phase comprised acetonitrile and distilled water (55 : 45, v/v). Analysis was run at a flow rate of 1.0 ml/min with the detector operating at an excitation wavelength of 371 nm and emission wavelength of 504 nm. The method was specific and sensitive with a detection limit of 0.6 ng/ml and a quantification limit of approximately 1.6 ng/ml. The method was applied in a pilot pharmacokinetic/bioavailability study of the compound in rats. Less than 1 % of the compound was found to be absorbed orally.
Twelve edible plant extracts rich in polyphenols were screened for their potential to inhibit oxidation of low-density lipoprotein (LDL) in vitro and to modulate LDL receptor (LDLr) activity in cultured HepG2 cells. The antioxidant activity (inhibition of LDL oxidation) was determined by measuring the formation of conjugated dienes (lag time) and thiobarbituric acid reagent substances (TBARS). Betel leaf (94%), cashew shoot (63%), Japanese mint (52%), semambu leaf (50%), palm frond (41%), sweet potato shoot, chilli fruit, papaya shoot, roselle calyx, and maman showed significantly increased lag time (>55 min, P < 0.05) and inhibition of TBARS formation (P < 0.05) compared to control. LDLr was significantly up-regulated (P < 0.05) by Japanese mint (67%), semambu (51%), cashew (50%), and noni (49%). Except for noni and betel leaf, most plant extracts studied demonstrated a positive association between antioxidant activity and the ability to up-regulate LDL receptor. Findings suggest that reported protective actions of plant polyphenols on lipoprotein metabolism might be exerted at different biochemical mechanisms.
A further investigation of the leaves and stems of Saprosma scortechinii afforded 13 compounds, of which 10 are new compounds. These were elucidated as the bis-iridoid glucosides, saprosmosides G (1) and H (2), the iridoid glucoside, 6-O-epi-acetylscandoside (3), and the anthraquinones, 1-methoxy-3-hydroxy-2-carbomethoxy-9,10-anthraquinone (4), 1-methoxy-3-hydroxy-2-carbomethoxy-9,10-anthraquinone 3-O-beta-primeveroside (5), 1,3-dihydroxy-2-carbomethoxy-9,10-anthraquinone 3-O-beta-primeveroside (6), 1,3,6-trihydroxy-2-methoxymethyl-9,10-anthraquinone (7), 1-methoxy-3,6-dihydroxy-2-hydroxymethyl-9,10-anthraquinone (8), 1,3,6-trihydroxy-2-hydroxymethyl-9,10-anthraquinone 3-O-beta-primeveroside (9), and 3,6-dihydroxy-2-hydroxymethyl-9,10-anthraquinone (10). Structure assignments for all compounds were established by means of mass and NMR spectroscopies, chemical methods, and comparison with published data. The new anthraquinones were derivatives of munjistin and lucidin.
Goniothalamus scortechinii, Andrographis paniculata and Aralidium pinnatifidum were selected for the study based on their ethnomedicinal values. They were screened for anti-malarial activity towards Plasmodium falciparum in vitro using the lactate dehydrogenase (LDH) assay. The crude extract of G. scortechinii exhibited the most potent schizonticidal activity compared to the other extracts. It is effective against both the chloroquine resistant isolate, Gombak A and the sensitive strain, D10 of Plasmodium falciparum. Furthermore a better IC(50) value was obtained against the resistant strain, (9 microg/ml) compared to the sensitive strain, 40 microg/ml. When the crude extract was fractionated into 3 fractions, the chloroform fraction yielded the best activity, exhibiting equipotency against both strains of parasite used; IC(50) of 23.53 microg/ml against Gombak A and 21.06 microg/ml against D10.
The effects of various fractions of Eurycoma longifolia Jack were studied on the orientation activities of the inbred, adult middle-aged Sprague-Dawley rats, 9 months old and retired breeders towards the receptive females (anogenital sniffing, licking, mounting), the environment (climbing, raring, exploration), themselves (nongenital grooming, genital grooming) and mobility (restricted, unrestricted) after treating these subjects twice daily for 10 days. Results showed that subjects treated with 800 mg/kg of E. longifolia Jack increased orientation activities towards the receptive females (anogenital sniffing, licking and mounting), increased genital grooming towards themselves and restricted movements to a particular area of the cage but decreased interest in the external environment (climbing, raring, exploration) as compared with the controls during the investigation period. In conclusion, this study gives further evidences that different fractions of E. longifolia Jack modified the orientation activities of the middle-aged male rats.
Rubraxanthone and isocowanol isolated from Garcinia parvifolia Miq. were investigated for their inhibitory effects on platelet-activating factor (PAF) binding to rabbit platelets using 3H-PAF as a ligand. Rubraxanthone showed a strong inhibition with IC 50 value of 18.2 microM. The IC 50 values of macluraxanthone, 6-deoxyjacareubin, 2-(3-methylbut-2-enyl)-1,3,5-trihydroxyxanthone, 2-(3-methylbut-2-enyl)-1,3,5,6-tetrahydroxyxanthone and 1,3,5-trihydroxy-6,6'-dimethylpyrano(2',3':6,7)-4-(1,1-dimethylprop-2-enyl)-xanthone were also determined for comparison. In the course of our study on structure-activity relationship of xanthones, the results revealed that a geranyl group substituted at C-8 was beneficial to the binding while a hydroxylated prenyl group at C-4 resulted in a significant loss in binding to the PAF receptor.
Plant-based polyphenolic compounds have been reported to possess cardiovascular health benefits. Several dietary sources, including herbs and spices, fruits and vegetables, and tea and wine, contain an array of biologically active compounds that have been shown to be effective in retarding oxidation of low-density lipoproteins (LDL) and promoting vascular relaxation. In the present study four different plant sources, both edible and non-edible, were evaluated for potential activity. Organic extracts enriched in polyphenols were prepared from palm fronds (Elaesis guineensis); lemongrass (Cymbopogon citrates); papaya shoots (Carica papaya) and green chilli (Capsicum frutescenes) and tested for their ability to prevent in vitro oxidation of LDL, and for potential vascular relaxation actions. Rings of rat thoracic aorta and isolated perfused mesenteric vascular beds were mounted in organ baths, contracted using a half-maximal dose of noradrenaline and exposed to cumulative additions of test extracts. Palm frond extract resulted in considerable relaxation (>75%) in both preparations and was found to be endothelium-dependent as removal of endothelium or inhibition of endogenous nitric oxide (NO) led to a total loss in relaxant activity. Lemongrass extract caused a greater relaxation action in the mesenteric preparation compared to aortic rings, and appears to be mediated via NO-independent and non-prostanoid mechanisms. Of the extracts tested, palm fronds also demonstrated the highest antioxidant capacity, as determined by the ferric reducing activity/potential assay, and resulted in a significant delay (P < 0.05) in the oxidation of LDL. Collectively, these preliminary findings lend further support to the potential cardiovascular actions of plant polyphenols and also identify oil palm fronds as containing constituents that promote vascular relaxation via endothelium-dependent mechanisms.
The effect of increasing doses of various fractions of Eurycoma longifolia Jack extracts on libido was examined in middle-aged male rats. The results showed that a high dose (800 mg/kg) of all E. longifolia Jack extracts significantly increased mount frequency (MF) (P < 0.05) over that of untreated controls, but had no effect on the frequency of intromission or ejaculation. Methanol, chloroform, water, and butanol fractions exhibited MF of 2.5 +/- 0.1, 2.6 +/- 0.3, 2.5 +/- 0.1 and 2.6 +/- 0.2, respectively, in adult, middle-aged male rats, and retired breeders versus 2.3 +/- 0.1 in untreated controls. This translated to a minor increase in MF of 8.7%, 13.0%, 8.7%, and 13.0% for these fractions, respectively, during the 20-minute observation period. The results of this study show that E. longifolia Jack extracts can increase libido in middle-aged male rats.
Crude ethanol and water extract of leaves and barks from Cassia alata were tested in vitro against fungi, (Aspergillus fumigatus and Microsporum canis), yeast (Candida albicans) and bacteria (Staphylococcus aereus and Escherichia coli). C. albicans showed concentration-dependent susceptibility towards both the ethanol and water extracts from the barks, but resistant towards the extracts of leaves. The degree of susceptibility varied, the water extract from barks showed bigger inhibition zone than the ethanol extracts (12-16 and 10-14 mm, diameter respectively). The growth of Aspergillus fumigatus and Microsporum canis were not affected by all types of the plant extracts. Results were comparable to standard antifungal drug Tioconazole (18 mm diameter) at equivalent concentration. The anti-bacterial activity of C. alata extracts on S. aureus was detected with only the leaves extracts using water and ethanol. The water extract exhibited higher antibacterial activity than the ethanol extract from leaves (inhibition zones of 11-14 and 9-11 mm, respectively). E. coli showed resistance to all types of extracts. Based on the current findings, it can be concluded that this plant has antimicrobial activity, which is as potent as standard antimicrobial drugs against certain microorganisms.
Malaria remains a global problem in the light of chloroquine-resistant strains of Plasmodium falciparum. New compounds are needed for the development of novel antimalarial drugs. Seed, leaf, and fruit skin extracts of Lansium domesticum, a common fruit tree in South-East Asia, are used by indigenous tribes in Sabah, Malaysia for treating malaria. The skin and aqueous leaf extracts of the tree were found to reduce parasite populations of the drug sensitive strain (3D7) and the chloroquine-resistant strain (T9) of P. falciparum equally well. The skin extracts were also found to interrupt the lifecycle of the parasite. The data reported here indicate that extracts of L. domesticum are a potential source for compounds with activity towards chloroquine-resistant strains of P. falciparum.
Two new indole alkaloids with the methyl chanofruticosinate skeletal system viz., methyl 3-oxo-12-methoxy-N1-decarbomethoxy-14,15-didehydrochanofruticosinate (1) and methyl 3-oxo-11,12-methylenedioxy-N-decarbomethoxy-14,15-didehydrochanofruticosinate (2), together with four known compounds, methyl 12-methoxy-N1-decarbomethoxychanofruticosinate, methyl 12-methoxychanofruticosinate, methyl 11,12-dimethoxychanofruticosinate and methyl 11,12-methylenedioxy-N1-decarbomethoxychanofruticosinate, were isolated in continuing studies on the leaves of Kopsia flavida Blume. The structures of the new indole alkaloids were assigned by NMR spectral data using various 2D-techniques.
Enzyme inhibitory activities of 14 iridoids previously obtained from two Malaysian medicinal plants, Saprosma scortechinii and Rothmannia macrophylla, were evaluated in vitro using soybean lipoxygenase and bovine testis hyaluronidase. Most of the iridoids, including asperulosidic acid, paederosidic acid, and an epimeric mixture of gardenogenins A and B, did not show any effect on the enzyme activities, except for the bis-iridoids, which inhibited the lipoxygenase activity with their IC(50) values of approximately 1.3 times that of a known inhibitor, fisetin. Structural modification of asperulosidic acid and paederosidic acid through enzymatic hydrolysis by beta-glucosidase resulted in their inhibition towards the enzyme activities, and these activities were enhanced by the presence of some amino acids (lysine, leucine or glutamic acid) or ammonium acetate. Mixtures of gardenogenins A and B; isomers of non-glucosidic iridoids, incubated with amino acid or ammonium acetate did not show any inhibitory effect on the enzyme activities during the 6 h incubation period, except for lysine where spontaneous reaction between the iridoids and amino acid resulted in the inhibition of lipoxygenase activity. The results from these biomimetic reactions suggested that the iridoid aglycons and the intermediates formed by these reactive species could inhibit the enzyme activities, and thus substantiate previous reports that the formation of iridoidal aglycons is a prerequisite for the iridoid glycosides to demonstrate some of the biological activities. In addition, the results also indicated that it is worthwhile to further explore these intermediates as potential anti-inflammatory agents.
The aqueous extracts of Piper betle and Psidium guajava were prepared and tested for their anti-adherence effect on the adhesion of early plaque settlers (Strep. mitis, Strep. sanguinis and Actinomyces sp.). The saliva-coated glass surfaces were used to simulate the pellicle-coated enamel surface in the oral cavity. Our results showed that the anti-adherence activities of Piper betle and Psidium guajava extracts towards the bacteria were different between the bacterial species. Psidium guajava was shown to have a slightly greater anti-adherence effect on Strep. sanguinis by 5.5% and Actinomyces sp. by 10% and a significantly higher effect on Strep. mitis (70%) compared to Piper betle. The three bacterial species are known to be highly hydrophobic, and that hydrophobic bonding seemed to be an important factor in their adherence activities. It is therefore suggested that the plant extracts, in expressing their anti-adherence activities, could have altered the hydrophobic nature of the bonding between the bacteria and the saliva-coated glass surfaces.
Parasitic nematodes are among the most common and economically important infectious diseases of grazing livestock, especially in small ruminants in the tropics and subtropics in Kenya the control of gastrointestinal nematode infections in sheep and goats is usually made with synthetic anthelmintics but substantial levels of anthelmintic resistance have been recorded. A number of medicinal plants, that may provide possible alternatives, and are used by pastoralists and smallholder farmers in Kenya as deworming agents for their livestock and equines, namely Aframomum sanguineum, Dodonea angustifolia, Hildebrandtia sepalosa, Myrsine africana, Rapanea melanophloeos from Kenya, and Azadirachta indica from Kenya and Malaysia, together with the chemicals embelin and santonin that occur in some of these plants, were evaluated against Heligmosomoides polygyrus in mice. Commercial anthelmintics, namely ivermectin, pyrantel and piperazine, were also investigated, both to validate the mouse model system and to assess efficacy of these drugs against H. polygyrus. Pyrantel and ivermectin were highly effective in reducing the numbers of H. polygyrus worms as well as eggs in faeces of the mice, but piperazine had a lower activity. Application of santonin and M. africana significantly reduced the number of total worm counts (TWC) but not faecal egg counts (FEC). The use of embelin, R. melanophloeos and A. indica reduced FEC but not TWC. In all cases, however, reductions were well below the a priori level of 70% required for biological significance. A. sanguineum, D. angustifolia and H. sepalosa had no effect on either TWC or FEC. In conclusion, none of the plant preparations had any biologically significant anthelmintic effect in this monogastric host-parasite model system.
The effects of Eurycoma longifolia Jack were studied on the sexual qualities of middle aged male rats after dosing them with 0.5 g/kg of various fractions of E. longifolia whilst the control group received 3 ml/kg of normal saline daily for 12 weeks. Results showed than E. longifolia Jack enhanced the sexual qualities of the middle aged male rats by decreasing their hesitation time as compared to controls with various fractions of E. longifolia Jack produced 865-916 (91-96), 860-914 (92-98), 850-904 (93-99), 854-890 (95-99), 844-880 (94-98), 840-875 (94-98), 830-870 (94-98), 825-860 (94-98), 820-850 (96-99), 800-840 (93-98), 750-795 (94-99) and 650-754 sec (82-95%) in contrast to controls which produced 950 (100), 934 (100), 910 (100), 900 (100), 895 (100), 890 (100), 885 (100), 880 (100), 855 (100), 860 (100), 800 (100) and 790 sec (100%) throughout the investigation period. Besides these, there was a transient increase in the % of the male rats responding to the right choice after chronic administration of 0.5 g/kg E. longifolia Jack, with more than 50% of the male rats scored right choice after 2 weeks post-treatment and the effect was more prominent at the dose of the observation period. However, there was no sexual enhancement of the middle aged male rats which consumed normal saline since only 45-55% of the male rats responded to right choice throughout the investigation period. Hence, this study shows that E. longifolia Jack enhanced the sexual qualities of the middle aged male rats, further supports the folkuse of E. longifolia Jack as an aphrodisiac.
Eurycoma longifolia Jack was investigated for sexual motivation activity in adult, middle-aged male mice and in retired breeders, using the modified open field and the modified runway choice methods. Each mouse received 500 mg/kg of one of 4 fractions of E. longifolia Jack, viz. chloroform, methanol, butanol, and water, whereas the mice in the control and yohimbine groups received 3 ml/kg of normal saline and 30 mg/kg of yohimbine daily respectively for 10 d. The results show a transient increase in the percentage of male mice responding to the right choice after chronic consumption of the fractions with 50 percent of the adult middle-aged male mice treated with E. longifolia Jack and yohimbine scoring the right choice after 8 and 5 days post-treatment respectively. In conclusion, this study has shown that E. longifolia Jack continues to enhance sexual motivation in adult, middle-aged male mice and in retired breeders.
Seventy-two extracts (methanol) obtained from the leaves, barks, and roots of 50 plant species used in the traditional medicine of Perak, Peninsular Malaysia, have been screened for antibacterial and antifungal activities. Peristrophe tinctoria, Polyalthia lateriflora, Knema malayana, Solanum torvum, Celosia argentea, Eclipta prostrata, Ancistrocladus tectorius, Dillenia suffruticosa, Piper stylosum and Rafflesia hasseltii displayed the broadest spectrum of activity.
The anti-inflammatory activity of the stem extracts of Sandoricum koetjape was investigated on topical administration using the TPA (tetradecanoylphorbol acetate)-induced mouse ear inflammation model. Bioassay-guided chromatographic fractionation of active fractions led to the isolation 3-oxo-12-oleanen-29-oic acid and katonic acid as the bioactive principles responsible for the anti-inflammatory acitivity. The percentage of inhibition exhibited by 3-oxo-12-oleanen-29-oic acid was almost equivalent to indomethacin.
A new flavonoid, dihydroglychalcone-A, was isolated from the leaves extract of Glycosmis chlorosperma in addition to two known sulphur-containing amides, dambullin and gerambullin. The structure of the new compound was assigned as 2'-hydroxy-4,6'-dimethoxy-3',4'-(2",2"-dimethylpyrano)dihydrochalcone. The extract of the leaves was also found to exhibit antimicrobial and cytotoxic activities.
Six new alkaloids, viz., alstolactone, affinisine oxindole, lagumicine, N(4)-demethylalstonerine, N(4)-demethylalstonerinal, and 10-methoxycathafoline N(4)-oxide, in addition to 36 other known alkaloids, were obtained from the leaf extract of Alstonia angustifolia var. latifolia. The structures of the new alkaloids were determined using NMR and MS analysis.