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Many countries are seeking to expand their use of solid biomass for electricity and heat generation. Nigeria, too, is exploring its own potential energy crops and indigenous residues. The use of this biomass for energy production is, however, limited by factors such as high moisture content, low bulk and low energy density. This study examines the torrefaction and combustion properties of four readily available Nigerian woody biomass, Gmelina arborea, Terminalia superba, Nauclea diderrichii, Lophira alata and a residue, palm kernel expeller (PKE). They are considered for their suitability for use in large scale power stations, especially as pulverized fuels. The Fuels were torrefied at 270 and 290 °C for either 30 or 60 min, and assessed for pyrolysis and combustion characteristics in comparison to their untreated counterparts. Energy densities of the woods improved from 19.2 to 21.2 MJ/kg for the raw fuels to 21.5–24.6 MJ/kg for the torrefied fuels. The milling behaviour of the torrefied fuels improved upon torrefaction, especially for Nauclea; however, torrefaction had very little effect on the grindability of PKE. The apparent first order kinetics for pyrolysis were determined by thermogravimetric analysis (TGA). After torrefaction, the fuels become less reactive; Nauclea and Gmelina were the most reactive fuels, whilst PKE was the least reactive. The combustion behavior of selected fuels was visually examined in a methane air flame. This showed that torrefaction resulted in shorter ignition delay, shorter duration of volatile combustion and longer duration of char burn out.

The aim of this research was to evaluate the natural durability of different wood species against marine organisms in the Messina strait to determine the most durable wood species for the replacement of wooden docks. The wood species tested were Bilinga/Opepe (Nauclea diderrichii Merril), Okan (Cylicodiscus gabunensis Taub (Harms), Demerara Greenheart (Ocota rodiaei Mez) and Azobe (Lophira alata Banks ex Gaertn), the current wood species used for docks. Scots Pine (Pinus sylvestris L.) was used for reference controls. The assessment was performed in accordance with EN 275 combined with a software for image acquisition called Nis D3.22. From the results of this experiment, it can be seen that Bilinga and Okan can well replace the current utilization of Azobe for wooden banking in the Sicilian strait. The Nis D3.22 software distinguished slight differences not perceived by the human eye in the assessment described in EN 275. These differences, which were lost in visual assessment associated with the wide nominal durability classes of EN 275, can contribute to the choice of wood species that are not suitable for their purpose, so the improvement of the assessment due to image analysis might be important even from an economic point of view.

Ethnopharmacological relevance Bark extracts of Nauclea latifolia, Nauclea diderrichii, Nauclea pobeguinii and Nauclea vandergutchii are used in traditional medicine in West and South Africa for the treatment of fevers, diarrhea and malaria. Aim of the study To estimate the possible long-term toxicity and genotoxicity of plant extracts (dichloromethane, methanol, water/methanol, water) and saponins. Materials and methods The clastogenicity of plant extracts and saponins was assessed by the micronucleus assay performed on Chinese Hamster Ovary cells. The DNA-damaging activity of saponin mixture was assessed by the comet assay on Chinese Hamster ovary cells. Results Hydromethanolic extracts from Nauclea latifolia, Nauclea diderrichii and Nauclea pobeguinii exhibited a significant clastogenic/aneugenic activity without S9 mix. The hydromethanolic extract from Nauclea diderrichii was the most clastogenic/aneugenic fraction with a Minimal Active Concentration (MAC) of 23.1 μg mL−1. It was submitted to a separation step leading to six main saponins identified as quinovic acid glycosides (saponins A, D, E, G, J, K). None of the isolated saponins exerted a significant clastogenic/aneugenic activity by the micronucleus assay, however a mixture made with equal quantities of each of the six saponins exhibited a direct genotoxic/clastogenic activity as assessed by both the micronucleus assay and the comet assay on Chinese Hamster Ovary cells. Conclusion Saponins present in the hydromethanolic extracts of Nauclea induced synergistic in vitro DNA-damage and chromosome mutations in mammalian cells. This genotoxic activity was probably due to the capacity of Nauclea saponins to reduce cell defense against oxidative stress through the inhibition of glutathione-S-transferase activity.

Adequate management of forest plantation requires estimation of growth and biomass yield and consequently, the fitting of functions for estimating biomass. Growth, biomass yield and biomass functions for estimating biomass of Nauclea diderrichii plantations in Omo forest reserve, Nigeria are described. Data were obtained from 30 temporary sample plots selected from stands that are 5-30 years old. A total of 81 trees were harvested for biomass estimation. Mean tree diameter at breast height (dbh), total height and stand bole volume ranged from 9.6 to 29.3 cm; 9.0 to 23.6m and 23.27 to 535.52 m(3)ha(-1), respectively while Total Above Ground Biomass (TAGB) varied from 32.5 t ha(-1) to 287.5 t ha(-1) between 5 and 30 years. Biomass allocations to stem, branch and foliage were 84.5%, 13.5% and 3%, respectively. All biomass components could be described precisely by dbh alone (R(adj)(2)>0.97), with very low standard errors of estimates. Little improvement in the precision of the functions was achieved by including total height. In addition, the residuals of regression functions with only dbh were generally more constrained than those that included total height. Consequently, the functions with dbh alone and its derivative as independent variables were recommended for estimating biomass of opepe in Nigeria.

Biomass estimation was carried out for even-aged stands of Gmelina arborea and Nauclea diderrichii in Akure forest reserve. Linear and allometric regression equations for biomass prediction were developed for trees of both species. The yield of each species and total above-ground biomass (TAGB) were estimated and compared. The various equations developed were assessed based on high coefficient of determination (R2), significant F-ratio, and small Furnival index (FI) to select appropriate equation for prediction. The t-test shows a significant difference when the total volume and total dry weight of both species were compared, Gmelina arborea having a greater value than Nauclea diderrichii in both cases. The total volume of Gmelina arborea per hectare was 721.40 m 3 and 265.18 m 3 for Nauclea diderrichii. The TAGB for Gmelina arborea was 264,762 kg / ha and 88,293 kg / ha for Nauclea diderrichii.

Three saponins were isolated from stems of Nauclea diderrichii and their structures established. These saponins are described for the first time in this plant. Two of them are new compounds.

A preliminary laboratory investigation of the effects of opepe timber (Nauclea diderrichii) extractives on biodeterioration of timber was carried out using Pleurotus ostreatus, Gloeophyllum sepiarium and Gloeophyllum sp. as test fungi. The removal of the extractives decreased the decay-resistance of the opepe wood. Impregnation of extracted obeche (Triplochiton scleroxylon) wood with ethanolic opepe wood extractives significantly increased decay-resistance. Synergism was observed in the resistance to deterioration by P. ostreatus in obeche impregnated with a mixture of water and ethanol extractives.

Graphical and mathematical procedures are used to examine stand development in mixed plantations of Lovoa trichilioides , (species tolerant to shade) and Nauclea diderrichii (less tolerant species). The Weibull parameter values for shape and the skewness of the diameter distribution indicate that many stems were below the mean diameter in the L. trichilioides stand up to age 34.6 years. In the N. diderrichii stand the stem diameter distribution appeared to be normal.

The stem bark of Nauclea diderrichii has yielded diderroside, a new secoiridoid glucoside, as well as quinovic acid, 3-oxoquinovic acid and 3- O -glucosylquinovic acid. The hydrocarbon fraction was dominated by n -heptacosane and n -nonacosane, which accords with the predominance of n -octacosanoic acid in the alkanoic acid fraction.

The heartwood of the stems of Nauclea diderrichii yielded as its major alkaloid the parent diacid of desoxycordifoline, which has been named desoxycordifolinic acid.