Trends in Phytochemical Research
Volume:2 Issue: 4, Autumn 2018

Forty traditional medicinal plants from the Cameroonian rain forest belonging to twelve families are reviewed related to botanical description, taxonomy, common names, traditional use, essential oil composition as well as bioactivity and toxicity of their essential oils. A correlation is drawn between traditional use and bioactivity in vitro/in vivo, and structures of seventy-three main oil ingredients are given. Collected data indicate that plant essential oils unfold their biological activity related to functional groups of major and minor compounds, in a complex, fine-tuned interaction, modulated by environmental factors like the vegetation cycle of the plant, the altitude and the presence or absence of plant pathogen microbes, certain crop weevils as well as nematodes, varying with climatic seasons. Comparison of traditional use with laboratory results indicates effectivity of a good number of essential oils received from various plant parts, like leaves, bark, fruit, roots and rhizomes against Plasmodium falciparum, food borne microbes, dermatophytes, the malaria vector Anopheles gambiae, cancer cell lines, river blindness as well as plant pathogen weevils and fungi. However, toxicological studies are needed before any recommendation for application can be given. Importantly, leaf and fruit oil of Cupressus lusitanica (Cupressaceae) displayed strong acute toxicity in animal model, and the bark oil of Cinnamomum verum (Lauraceae) showed high toxicity in a normal cell line, so that preparations should be applied with care. Preformulation and formulation studies will be needed to develop a range of suitable dosage forms to introduce optimized pharmaceuticals (high active, low toxic) as replacement of current crude plant essential oil preparations in Cameroon and other Subsaharan countries.

Theobroma cacao L (sterculiaceae) and Sorghum bicolor (L) Moench, Syn. Sorghum vulgare. Pers (Poaceae) are plants with well-known medicinal properties. Aqueous extracts of the plant blend are being used in the treatment of anaemia caused by the shortage of iron in patients. It is therefore important to investigate the synergetic effects of the blends on their chemical composition. The proximate, phytochemical and mineral composition of the plants and the blend samples containing 50% (w/w) were evaluated using standard procedures. The proximate composition showed that samples contained a high fraction of carbohydrate compared to other parameters; 36.70% for T. cacao, 48.66% for S. bicolor and 73.59% for the blended sample, respectively. The phytochemical composition of the samples showed the presence of medicinally active constituents like alkaloids, tannins, saponins, phlobatannin, flavonoids and cardiac glucosides. The samples showed moderate phytate composition of 18.53 mg/g, 11.74 mg/g and 14.0 mg/g for T. cacao, S. bicolor, and the blended samples, respectively. The study further revealed that the composition of the phytochemicals/antinutrients were temperature dependent. The mineral analysis of the samples showed the presence of Na, K, Ca, Mg, Zn, Fe, Cu, and Mn with a significant amount of Mg (68.20 mg/100g) and Fe (55.10 mg/100g) observed in the blended sample. Our findings support the ethnomedicinal use of the plants in the treatment of anaemia.

Fraxinus excelsior L. (Oleaceae) is used to treat diarrhoea, dysentery, jaundice, joint pain, malaria, sores, swelling and wounds. The leaves of Senna sulfurea (Collad.) H. S. Irwin et Barneby (Leguminosae) are effective to cure blennorrhagia, diabetes, dysentery, gonorrhea and skin diseases. Prosopis cineraria (L.) Druce, (Fabaceae) is taken to alleviate anxiety, asthma, bronchitis, dysentery, dyspepsia, fever, leprosy, leucoderma, muscle tremors, piles, rheumatism and tremors. Our study was planned to isolate chemical constituents of the methanolic extracts obtained from the leaves of F. excelsior, S. sulfurea and P. cineraria and to characterized their structures. The air-dried plant materials were exhaustively extracted with methanol separately in a Soxhlet. The concentrated methanolic extracts were adsorbed on silica gel (60-120 mesh) for the preparation of slurries. The dried slurries were chromatographed over silica gel columns individually packed in petroleum ether. The columns were eluted with petroleum ether, chloroform and methanol successively in order of increasing polarity to isolate a variety of phytoconstituents. Phytochemical investigation of the leaves of F. excelsior afforded (Z,Z,Z)-n-tetratriacont-3,5,15-triene (1), n-hexatriacontane (2), (Z,Z,Z)-n-octatriacont-11,13,20-triene (3), phytanic acid (3,7,11,15-tetramethylhexadecanoic acid, 4), 26-hydroxystigmasterol-18-oic acid (5) and α-L-xylose (6). The leaves of S. sulfurea furnished isoliquiritigenin (7) and 4-methoxy-α-Lxylopyranosyl-(3→1′)-O-α-L-4′-methoxyxylopyranoside (di-4-methoxy-α-L-xyloside, 8). The leaves of P. cineraria on subjection to silica gel column chromatography led to isolate glyceryl-1-oleioyl-2-myristioyl-3-O-hydroxydihydrocinnamate (9), 2,3,4-trihydroxybenzyl n-hexadecanyl ether (10) and salicyloyl O-α-D-glucopyranosyl-2′-oleate (11). Their structures were established on the basis of spectral data analysis and chemical reactions.

Four lupane-type terpenoids, namely lupeol (1), friedelin (2), stigmasterol (3), and stigmasterol-3-O-glucoside (4) were isolated from the ethyl acetate extract of leaves of Lonchocarpus eriocalyx Harms. These compounds were obtained by extensive silica gel chromatography and their structures elucidated by 1D and 2D nuclear magnetic resonance (NMR) as well as comparison with literature data. The ethyl acetate, dichloromethane and methanol extracts (100 mg/Kg) had a pretreatment latency of 3.1±0.15, 3.0±0.01 and 3.5±0.12 at the zero minute. The post latency of 6.4±0.13 was observed for ethyl acetate at 30 minutes which confirmed its effectiveness to halt pain, while compounds 1 and 2 had pretreatment latency of 3.1±0.12 and 3.2±0.12, respectively. The isolated compounds from this medicinal plant along with their analgesic activity have been reported for the first time.

The main objective of the present study was to evaluate preliminary phytochemical screening and in vitro antioxidant properties of leaves, ripe and unripe fruit extracts of Malaysian ‘Kundang (Bouea macrophylla Griffith; Family: Anacardiaceae), by using different solvents like water, ethanol, methanol, and hexane. Phytochemical analysis showed the presence of alkaloids, flavonoids, saponins, sterols and triterpenes, total phenol, tannins, and vitamin C. The prepared extracts from the leaves and fruits of the plant were further investigated for their potential antioxidant activity using radical scavenging DPPH (2,2'-diphenyl-2-picrylhydrazyl) technique, which was compared with ascorbic acid, as standard. This study showed that ripe, unripe fruits and leaves of B. macrophylla have higher amounts of various phytochemicals constituents in methanol and aqueous solvents and possess higher amounts of vitamin C. Moreover, aqueous and methanol extracts of leaves, unripe and ripe fruits of B. macrophylla exhibited a remarkable DPPH radical scavenging activity compared with that of the standard. The results revealed that fruit and leaves extracts are a potential source of antioxidants of natural origin.