ANTIMICROBIAL, ANTIOXIDANT, CYTOTOXIC ACTIVITIES AND PHYTOCHEMICAL ASSESSMENT OF COLA ACUMINATA USED IN BENIN

Objective: The aim of this study was to make a phytochemical screening and measure some biological activities of Cola acuminata's seeds and leaves extracts.Methods: The secondary metabolite was detected by the method based on coloring and precipitation differential reactions. The antibacterial and antifungal activities were assessed in vitro by the macrodillution and solid medium agar diffusion method. 2,2-diphényl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods were used to evaluate the antioxidant activity of the tested extracts of which larval cytotoxicity was studied.Results: Our data revealed that the seeds contain more polyphenols than the leaves. The seeds extracts displayed a good antibacterial activity against both reference strains and food Staphylococcus strains. The inhibition diameters varied from 7±2.82 to 21.5±4.94 mm. The smallest Minimum Inhibitory Concentrations (MIC) on the food strains (0.08 mg/ml) is twice less than the reference strains one (0.15 mg/ml), this observation is contrary to the Minimum Bactericidal concentrations (MBC). Susceptibility of fungal strains varies according to the extracts (p = 0.0016). The seeds ethyl acetate extracts had the best antioxidant activity with DPPH and ABTS methods. The Lethal Doses (LD50) showed that no extract was toxic.Conclusion: Cola acuminata seeds are richer than the leaves in compounds with biological activities. These two organs have interesting antimicrobial, antifungal and antioxidant activity variables depending to the extracts. The seeds have better biological activity than the leaves.Â

Spasmolytic Effects of Aqueous Extract of Sterculia setigera Delile on Isolated Rat Trachea

The spasmolytic properties of aqueous extract of Sterculia setigera was tested on Rat isolated trachea. Inhibition of the contraction was observed in presence of the aqueous extract (EC50 = 0.91mg/mL ± 0.02) after a pre contraction of the trachea by acetylcholine (10-5M). In the presence of propranolol (10-6M), the spasmolytic activity of the extract was inhibited. The EC50 value was 0.46mg/mL ± 0,11. The aqueous extract of Sterculia setigera also inhibited contraction induced by KCl (4.10-2 M) with EC50 value = 1.9mg/mL ± 0.48).  These results clearly show a relaxing effect of aqueous extract of Sterculia setigera on the trachea isolated from rat. This effect involves at least in part β-adrenergic receptor inhibition

SPASMOLYTIC EFFECTS OF AQUEOUS EXTRACT OF MIXTURE FROM AFRAMOMUMUM MELEGUETA (K SCHUM) – CITRUS AURANTIFOLIA (CHRISTM AND PANZER) ON ISOLATED TRACHEA FROM RAT

The spasmolytic properties of the aqueous extract of Aframomum melegueta (K Schum) and Citrus aurantifolia (Christm and Panzer) (AMCA) mixture were tested on isolated rat trachea. Inhibition of the contraction was observed the in presence of the AMCA (EC 50 = 1.80 ± 0.48 mg/mL) after a pre contraction of the trachea by acetylcholine (10 -5 M). With propranolol (10 -6 M), the spasmolytic activity of the mixture was inhibited and the concentration-response curve shifted to the right. The EC50 value was then 2.60 ± 0.41 mg/mL. AMCA also inhibited contraction induced by KCl (4.10 -2 M) with EC50 value = 1.86 ± 0.65 mg/mL. These results clearly show the relaxing effect of the aqueous extract on the isolated rat trachea. This effect involved some β-adrenergic receptor inhibition

Variation in the phytochemical composition of Chromolaena odorata (L.) King and Robinson (Asteraceae) across climatic zones in Benin (West Africa)

Chromolaena odorata (L.) King and Robinson (Asteraceae) is a tropical shrub with interesting chemical potential widely used in agriculture and medical science and which can be affected by several geographic and climatic conditions. Therefore, we investigated the phytochemical composition of this plant across climatic zones in Benin. The plant material collected from different locations was phytochemically screened by staining and precipitation tests. The total phenolic, flavonoid and tannin contents were determined using, the colorimetric method of Folin-Ciocalteu, the method of aluminum chloride and the method of vanillin, respectively, then the obtained data were subjected to analysis of variance. The phytochemical analysis revealed the presence of the main chemical groups such as alkaloids, free anthracene, coumarins, flavonoids, mucilage, tannins, reducing compounds, saponins, quinone derivatives, steroids. There was a significant difference (P < 0.05) in the phytochemical contents across geographical sites. In comparing the levels of phytochemicals among geographical locations, the raw material collected from the north climatic zone contained the highest phenolic and flavonoid contents, 147.59 ± 3.04 mg/g and 17.17 ±0.31 mg/g, respectively, compared to others. Overall, the study highlighted the potential of C. odorata as source of natural products. There was no difference in the phytochemical markers whereas the phytochemical contents vary across climatic zones. These results can be of use in the development of biopesticides from the raw material of C. odorata

In vitro screening of selected essential oils from medicinal plants acclimated to Benin for their effects on methane production from rumen microbial fermentation

Enteric methane production lowers the efficiency of feed utilization in ruminants and contributes to greenhouse gas emissions which are responsible for global climate change. This study examined the effects of nine essential oils (EO) from Citrus aurantifolia, Cymbopogon citratus, Eucalyptus citriodora, Laurus nobilis, Lippia multiflora, Mentha piperita, Ocimum basilicum, Ocimum gratissimum and Zingiber officinalis on enteric methane production in in vitro batch cultures screening experiments using Andropogon gayanus grass. Two in vitro batch culture incubation runs were conducted independently on separate days at two different ranges of dosages: 0 (control), 150, 300, 600 and 1200 mg/L inoculum and 0 (control), 25, 50, 100 and 150 mg/L inoculum. The effects of EO on in vitro gas production, methane production and apparent dry matter disappearance (DMD) were assessed relative to the control containing no additive. O. basilicum, E. citriodora, O. gratissimum and C. aurantifolia, significantly inhibited (Z’ ˃ 0 and relative decrease ≥ 15%) enteric methane production (g DM incubated) relative to control at dosages of 300-1200 mg/L and L. nobilis, C. citratus and M. piperita significantly decreased it at 600 and 1200 mg/L. A substantial decrease (Z’ ˃ 0 and relative decrease ≥ 15%) in methane production per g DM incubated was apparent for Z. officinalis and L. multiflora at dosage of 1200 mg/L. Most EO had globally negligible effects on methane production (Z’ ≤ 0 and relative decrease &lt; 15%) at dosages of 25 to 150 mg/L. Substantial decrease in apparent DMD together with gas production (g DM) incubated was observed relatively to the control with Z. officinalis and L. multiflora at 1200 mg/L and with the remaining EO at 600 and 1200 mg/L. Overall, this screening investigation demonstrated that addition of assayed EO (except Z. officinalis and L. multiflora) at dosages close to 300 mg/L seem to potentially decrease enteric methane production with limited negative effects on dry matter digestibility of forage grass in vitro.Key words: Essential oil, in vitro, rumen, digestibility, methane production

Allelopathic effects on cowpea ( Vigna unguiculata (L.) Walp) plant and cytotoxic activities of sterols and triterpenes isolated from Justicia anselliana (NEES) T. Anders

Purification of the allelopathic ethanol extract of Justicia anselliana aerial part led to the isolation of three known compounds: two sterols (stigmasterol and β-sitosterol) and one triterpene (lupeol). Their structures were determined by analysis of spectroscopic data and confirmed by GC/MS analysis. All isolated compounds were tested for their allelopathic effects on cowpea (Vigna unguiculata) growth and for their cytotoxic activity on human (HeLa, WI-38 and Mel-43) and mouse (J774) cells. All isolated compounds showed an inhibitory effect on the three parameters measured on cowpea (Vigna unguiculata) germination (rate of germination, shoot length and fresh weight). The highest rate of inhibition of cowpea=s germination was observed with 200 ppm of lupeol (-28.4 % ± 0.7%) whereas all three parameters were inhibited very meaningfully by 200 ppm stigmasterol (-26.6% ± 0.5%; -24.2% ± 0.7% and -21.1% ± 0.7% respectively for germination, shoot length and fresh weight of Vigna unguiculata (L.) Walp). None of the isolated compounds was toxic on J774 (murine macrophages), WI-38 (human lung fibroblasts), human HeLa (human cervix carcinoma cells) and melanoma Mel-43 cell. This is the first report of the allelopathic activities of lupeol, stigmasterol and β-sitosterol on cowpea (Vigna unguiculata)

Anthelmintic flavonoids and other compounds from Combretum glutinosum Perr. ex DC (Combretaceae) leaves

A chemical study of the hydro-ethanol extract of the leaves of Combretum glutinosum resulted in the isolation of nine com­pounds, including 5-de­methyl­sin­en­se­tin (1), umuhengerin (2), (20S,24R)-ocotillone (3), lupeol (4), β-sitosterol (5), oleanolic acid (6), betulinic acid (7), corymbosin (8) and β-sito­sterol glucoside (9). Four com­pounds have been isolated for the first time from the genus Combretum [viz. (1), (2), (3) and (8)]. The crystal structures of flavonoid (2), C20H20O8, Z′ = 2, and triterpene (3), C30H50O3, Z′ = 1, have been determined for the first time; the latter confirmed the absolute configuration of native (20S,24R)-ocotillone previously derived from the crystal structures of related derivatives. The mol­ecules of (3) are linked into supra­molecular chains by inter­molecular O—H⋯O hydrogen bonds. The crude extracts obtained by aqueous decoction and hydro-ethano­lic maceration, as well as the nine isolated com­pounds, were tested for their anthelmintic activity on the larvae and adult worms of Haemonchus contortus, a hematophage that causes parasitic disorders in small ruminants. The evaluated anthelmintic activity showed that the extracts at different doses, as well as all the com­pounds tested at 150 µg ml−1, inhibited the migration of the larvae and the motility of the adult worms of the parasite com­pared with the phosphate buffer solution negative reference control. The best activity was obtained with flavonoids (1), (2) and (8) on both stages of the parasite. The flavones that showed good activity can be used for the further development of other derivatives, which could increase the anthelmintic efficacy