Bioactivity profiles of six baobab fruit pulp powders via planar chromatography hyphenated with effect-directed analysis

Baobab (Adansonia digitata) fruit pulp has a high nutrient content and has been traditionally used for medicinal purposes (e.g., as an anti-inflammatory and antioxidant agent) that may help protect against chronic diseases. Six different baobab fruit pulp powders were investigated using three different extractants and analyzed by high-performance thin-layer chromatography (HPTLC) hyphenated with antibacterial bioassays and enzyme inhibition assays. The developed non-target effect-directed screening was performed after extraction with pentyl acetate - ethanol 1:1 (V/V) on the HPTLC plate silica gel 60 using toluene - ethyl acetate - methanol 6:3:1 (V/V/V) as mobile phase system and derivatization via the anisaldehyde sulfuric acid reagent for detection. The physico-chemical profiles of the six baobab fruit pulp powder extracts were comparable, although the intensity of some zones was moderately different. The following effect-directed profiling via tyrosinase, α-glucosidase, and acetylcholinesterase inhibition assays as well as antibacterial Aliivibrio fischeri and Bacillus subtilis bioassays revealed one prominent multipotent bioactive compound zone in common, more or less active in all five studied (bio)assays. Via the recording of high-resolution mass spectra, this compound zone was tentatively assigned to coeluting saturated (palmitic acid 16:0 and stearic acid 18:0), monounsaturated (oleic acid 18:1), and polyunsaturated (linoleic acid 18:2 and linolenic acid 18:3) fatty acids. This finding was confirmed by other studies, which already proved individual activities of fatty acids. The first (bio)activity profiling of baobab fruit pulp powders via HPTLC-effect-directed analysis revealed that the baobab fruit could be considered as a functional food, however, further research is needed to study the impact on health and the influences on the bioactivity arising from different climates, years and soils or regions.

Modeling impacts of climate change on the potential distribution of six endemic baobab species in Madagascar

Madagascar, a globally renowned biodiversity hotspot characterized by high rates of endemism, is one of the few remaining refugia for many plants and animal species. However, global climate change has greatly affected the natural ecosystem and endemic species living in Madagascar, and will likely continue to influence species distribution in the future. Madagascar is home to six endemic baobab (Adansonia spp., Bombacoideae [Malvaceae]) species (Adansonia grandidieri, A. suarezensis, A. madagascariensis, A. perrieri, A. rubrostipa, A. za), which are remarkable and endangered plants. This study aimed to model the current distribution of suitable habitat for each baobab species endemic to Madagascar and determine the effect that climate change will have on suitable baobab habitat by the years 2050 and 2070. The distribution was modeled using MaxEnt based on locality information of 245 occurrence sites of six species from both online database and our own field work. A total of seven climatic variables were used for the modeling process. The present distribution of all six Madagascar's baobabs was largely influenced by temperature-related factors. Although both expansion and contraction of suitable habitat are predicted for all species, loss of original suitable habitat is predicted to be extensive. For the most widespread Madagascar baobab, A. za, more than 40% of its original habitat is predicted to be lost because of climate change. Based on these findings, we recommend that areas predicted to contract in response to climate change should be designated key protection regions for baobab conservation.

Nuclear microsatellite variation in Malagasy baobabs (Adansonia, Bombacoideae, Malvaceae) reveals past hybridization and introgression

BACKGROUND AND AIMS

Adansonia comprises nine species, six of which are endemic to Madagascar. Genetic relationships between the Malagasy species remain unresolved due to conflicting results between nuclear and plastid DNA variation. Morphologically intermediate individuals between distinct species have been identified, indicative of interspecific hybridization. In this paper, microsatellite data are used to identify potential cases of hybridization and to provide insights into the evolutionary history of the genus on Madagascar.

METHODS

Eleven microsatellites amplified with new primers developed for Adansonia rubrostipa were used to analyse 672 individuals collected at 27 sites for the six Malagasy species and morphologically intermediate individuals. Rates of individual admixture were examined using three Bayesian clustering programs, STRUCTURE, BAPS and NewHybrids, with no a priori species assignment.

KEY RESULTS

Population differentiation was coherent, with recognized species boundaries. In the four Malagasy species of section Longitubae, 8·0, 9·0 and 9·5 % of individuals with mixed genotypes were identified by BAPS, NewHybrids and STRUCTURE, respectively. At sites with sympatric populations of A. rubrostipa and A. za, NewHybrids indicated these individuals to be F2 and, predominantly, backcrosses with both parental species. In northern Madagascar, two populations of trees combining A. za and A. perrieri morphology and microsatellite alleles were identified in the current absence of the parental species.

CONCLUSIONS

The clear genetic differentiation observed between the six species may reflect their adaptation to different assortments of climate regimes and habitats during the colonization of the island. Microsatellite variation reveals that hybridization probably occurred in secondary contact between species of section Longitubae. This type of hybridization may also have been involved in the differentiation of a local new stabilized entity showing specific microsatellite alleles and morphological characters, suggesting a potential role of hybridization in the recent history of diversification on Madagascar.