Plants constitute an important source of secondary metabolites in which essential oils are well-known for their use in various domains such as pharmacy, therapeutic, cosmetology and foods. In vitro antimicrobial and antioxidant properties of Ocotea auriculiformis Kost. (Lauraceae) leaves essential oil is demonstrated and its chemical composition is reported in the present study. The essential oil from Ocotea auriculiformis Kost. (Lauraceae) leaves, an endemic plant of Madagascar was extracted by hydrodistillation method. Chemical composition using GC, GC/ MS and NMR 13 C methods showed that the essential oil contained around 47 products in which 93.95% were identified. Known compounds are constituted by 74.7% of hydrocarbons and 19.25% of oxygenated products. The essential oil is rich in sesquiterpene and monoterpene. In vitro antibacterial capacity of the essential oil was assessed by disc method against human and food pathogens. Bacillus cereus and Streptococcus pneumoniae were very sensitive to the essential oil with 11 mm and 25 mm of inhibition zone European Scientific Journal November 2017 edition Vol.13, No.33 ISSN: 1857 -7881 (Print) e -ISSN 1857 365 respectively. The MIC of the essential oil was 1mg/mL for Bacillus cereus and 0.25 mg/mL for Streptococcus pneumoniae. MBC values were 2.5 mg/mL and 0.5 mg/mL, respectively. The ratio MBC/MIC for both strains was inferior to 4 concluding hence that the essential oil has bactericidal effect against the two sensitive strains. In vitro antioxidant capacity of the essential oil was performed according to qualitalive (TLC) and quantitative (measure of DPPH radical scavengening) methods. The essential oil showed antioxidant activity with IC50 value of 0.35 mg/mL

The therapeutic virtues of medicinal plants are known and used in Africa and in Madagascar where natural products form the basis of Traditional Medicine. More than 300 million people worldwide consume dietary supplements and herbal plants. Scientific studies confirm that Aloes contains pharmacologically active ingredients associated with diverse biological activities including fungicidal, antiviral, antibacterial, anti-inflammatory, antimicrobial, laxative, immunomodulating, and anticancer effects. The aim of the present study was to evaluate the effects of orally administered extracts of two Aloe species: A. helenae, A. analavelonensis on mice. Mice were gavaged with crude whole leaves extracts after 24 hours of empty stomach. The extracts administration was found to be not acute toxic at the dose 1200 mg/kg with 100% survival of mice. Since the Aloe helenae is traditionally used against intestinal worms in sheep and goats, it is thus desirable that the plant species could be submitted to phytochemical for the isolation and characterization of new antihelminthic compounds.

The aim of the present study was to evaluate the chemical composition and antioxidant activity of Melicope madagascariensis essential oil from Madagascar East Coast Rainforest. Essential oil from the leaves of this plant species was extracted by hydro-distillation and analyzed by TLC and GC-FID. The extraction revealed a yield is of 0.4% for a mass of 290 g of fresh leaves. Having a bland, pungent taste, the oil has a green-black color, a slightly unpleasant odor with a clear mobile consistency. Its density is 0.8765 and refractive index 1.4956 at 20 °C and is dextrorotatory (+0.1°) at 24 °C for its rotational power. The results of GC/FID analysis revealed that the essential oil contains (Z)-β-ocimene (12.7%) and (E)-β-ocimene (25.7%) as major compounds. The preparative TLC fractionation (using DPPH radical as revelator) and GC-FID analysis of the essential oil revealed the presence of compounds of the sesquiterpene family namely trans-nerolidol (4.32%), phenylpropanoid like methyl eugenol (5.9%), terpene oxide like caryophyllene oxide (3.66%), cinnamic esters like cinnamyl acetate (4.79%) and monoterpene alcohol like linalol (2.81%). The study on M. madagascariensis essential oil is herein reported for the first time. Further studies including cytotoxicity assay in order to evaluate the selectivity/therapeutic index of this essential oil are needed before developing it as novel antioxidant drug.

The World Health Organization reported that at least 80% of populations rely on traditional medicine and medicinal plants for their primary health care. Due to their phytochemical compounds, the plants of the Aloe genus are reported to have high potential antiCovid-19 (and antioxidant properties. The aim of this study is to evaluate the in vitro antioxidant activity of some Malagasy endangered species of Aloe genus. The ethanolic extract of few Aloe of Madagascar leaf extracts was fractionated by liquid-liquid partition using hexane. In total 18 different fractions from 9 species have been used to determine their antioxidant activity through in vitro model by using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay. Both hexanic extract and aqueous extract displayed antioxidant activities in four species. The most evident antioxidant activity was expressed by A. helenae.

The search of new antimicrobial metabolites remains until now an alternative to mitigate concerns caused by antimicrobial resistance. This work aims to demonstrate the ability of actinomycete strain (Streptomyces sp 3400 JX826625) to inhibit pathogen yeast growth (Candida albicans), isolated from a woman infected by recidivate candidiasis and to reveal chemical characteristics of the antifungal metabolites produced. Antifungal test using cylinder agar technique showed that the yeast pathogen was resistant to the nystatin 100.000 and the ketoconazole 50 while Streptomyces sp 3400 displayed activity with 25mm of inhibition zone diameter. The optimization of antifungal production parameters by the strain recapitulates that its culture on sporulation agar medium at a pH=5,13, incubated at 30°C for 7 days promoted the activity of the actinomycete; the butanol was the best solvent for antifungal metabolites extraction. Chemical investigation showed that liquid-liquid fractionation method of crude extract allowed to obtain four fractions (hexane, dichloromethane, butanol and aqueous fractions) in which butanol fraction exhibited the best antifungal activity (19mm) according to antifungal test by disk method. Separation of active compounds from this active fraction by TLC method revealed 10 bands and its bioautography showed two active compounds against the pathogen yeast of which the diameters of inhibition zone were 19mm and 10mm, respectively. Chemical screening of the butanolic fraction revealed the presence of terpenes, alkaloids, coumarins and anthracene derivatives family with colorimetry by TLC method. The recovering of active compounds by TLC preparative gave two methanolic fractions (MF1 and MF2) of which MIC and MFC were respectively 1,562µg/ml and 3,625µg/ml for MF1; 17µg/ml and 34µg/ml for MF2. The two compounds were stable in a range of temperature from 19°C to 46°C; however, a best antifungal activity was recorded at-20°C. UV-visible spectra of the two active compounds revealed that Streptomyces sp 3400 contained non-polyene and heptaene group of polyene molecules.