A customised target capture sequencing tool for molecular identification of Aloe vera and relatives

Plant molecular identification studies have, until recently, been limited to the use of highly conserved markers from plastid and other organellar genomes, compromising resolution in highly diverse plant clades. Due to their higher evolutionary rates and reduced paralogy, low-copy nuclear genes overcome this limitation but are difficult to sequence with conventional methods and require high-quality input DNA. Aloe vera and its relatives in the Alooideae clade (Asphodelaceae, subfamily Asphodeloideae) are of economic interest for food and health products and have horticultural value. However, pressing conservation issues are increasing the need for a molecular identification tool to regulate the trade. With > 600 species and an origin of ± 15 million years ago, this predominantly African succulent plant clade is a diverse and taxonomically complex group for which low-copy nuclear genes would be desirable for accurate species discrimination. Unfortunately, with an average genome size of 16.76 pg, obtaining high coverage sequencing data for these genes would be prohibitively costly and computationally demanding. We used newly generated transcriptome data to design a customised RNA-bait panel targeting 189 low-copy nuclear genes in Alooideae. We demonstrate its efficacy in obtaining high-coverage sequence data for the target loci on Illumina sequencing platforms, including degraded DNA samples from museum specimens, with considerably improved phylogenetic resolution. This customised target capture sequencing protocol has the potential to confidently indicate phylogenetic relationships of Aloe vera and related species, as well as aid molecular identification applications.

Anti-tyrosinase activity of South African Aloe species and isolated compounds plicataloside and aloesin

Tyrosinase is the key enzyme in the production of melanin. Tyrosinase inhibitors have gained interest in the cosmetics industry to prevent hyperpigmentation and skin-related disorders by inhibiting melanin production. It has been reported that several Aloe species exhibit anti-tyrosinase efficacy in vitro. In this study, the exudates of thirty-nine South African Aloe species were screened to identify species and compounds with anti-tyrosinase activity. Qualitative screening revealed that twenty-nine Aloe species exhibited tyrosinase inhibition activity with one to three active bands. Quantitative screening was performed for 29 species and expressed as IC50 values. Three species were further analysed and subsequently, aloesin and aloeresin A was isolated from A. ferox and plicataloside from A. plicatilis and A. chabaudii. Aloeresin A was determined to be a substrate of mushroom tyrosinase. Dose-response assays showed that aloesin (IC50 = 31.5 μM) and plicataloside (IC50 = 84.1 μM) exhibited moderate to weak activity. Molecular docking scores for plicataloside were considerably lower than for aloesin (P < 0.01), confirming its lower IC50. Several Aloe species may have potential for the management of hyperpigmentation or as a skin lightening agent. This is the first report showing that plicataloside, present in A. plicatilis and A. chabaudii, exhibits anti-tyrosinase activity.

Ecological Distribution and Genetic Variations of Some <i>Aloe</i> Species in Taif, KSA

BACKGROUND AND OBJECTIVES

Aloe is a medicinally and economically important genus. Many Aloes seem an endangered species because of over-collection, destruction of plants and destroyed of natural habitats. The objectives of current study was to survey, collect and identification of some Aloe species and to analyze genetic variations between the collected Aloe species.

MATERIALS AND METHODS

Four Aloe species (A. armatissima, A. edentata, A. parvicoma and A. pseudorubroviolacea) and Agave americana (Asperagaceae) were used as plant materials for ecological and genetic studies. In RAPD and ISSR analysis 23 and 16 primers, respectively were screened.

RESULTS

Ecological study showed that the 4 species are endemic: 2 are endangered (A. edentata and A. parvicoma) and the others are not-endangered (A. armatissima and A. pseudorubroviolacea), while A. americana was introduced as ornamental species. Concerning RAPD, a total of 134 reproducible bands of them 131 bands are polymorphic ~ 97.65% polymorphism were produced, which ranged from 9 bands (primer OPC-04) to 18 (primer OPA-03) bands, with an average 13.4 bands/ primer, ranging from ~300-2500 bp. According to ISSR, 113 reproducible bands were totally yielded with an average 12.6 bands/primer, from ~180-1500 bp, of which 107 poly-morphic bands number (PBN) ~94.96% polymorphism ranged from 10 bands (primer UBC-818 and primer UBC-819) to 14 (primer UBC-814) with an average of 11.9 PB/primer.

CONCLUSION

The results revealed high genetic variations between 4 bands Aloe species and A. americana species, which will be in concern for improvement, breeding and conservation programs.

Comparative Analysis of Soluble Proteins in Four Medicinal Aloe Species by Two-Dimensional Electrophoresis and MALDI-TOF-MS

Background: Aloe barbadensis Miller 1768, A. vera L. var. chinensis (Haw.) Berger 1908, A. ferox Miller 1768, and A. arborescens Miller 1768 are the most widely cultivated species of Aloe and are used in Asia along with 400 other Aloe species worldwide because of their potent and potential bioactivity. Objective: The objective was to analyze and compare the soluble proteins of four commonly used medicinal Aloe species. Methods: Aloe protein samples were obtained by TCA/acetone-saturated phenol-methanol/ammonium acetate combined extraction (phenol extraction), and then were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis. Finally, the differentially expressed proteins of four Aloe species were identified by matrix-assisted laser desorption ionization-time-of-flight-MS analysis. Results: The phenol extraction method was the most suitable method for the protein extraction of Aloe. Fifty differentially expressed proteins in four Aloe species were successfully identified and divided into eight functional categories. Furthermore, Malate dehydrogenase and ran-binding protein in A. barbadensis, cytoskeletal-related protein tubulin in A. vera var. chinensis and auxin-induced protein PCNT-115 in A. arborescens are closely related to their morphological characteristics. Conclusions: There are differences in the soluble proteins of the four Aloe species. Those proteins, related to the difference of their morphology of Aloe, might be used to identify different species. Highlights: Fifty differentially expressed proteins in four medicinal Aloe species were identified, and these proteins were classified into eight categories according to their biological functions. Four special proteins closely related to the morphological characteristics of Aloe were found and might be used to identify these four Aloe species.

Medicinal Mascarene Aloes: An audit of their phytotherapeutic potential

A phytochemical and biological investigation of the endemic Mascarene Aloes (Aloe spp.), including A. tormentorii (Marais) L.E.Newton & G.D.Rowley, A. purpurea Lam, A. macra Haw., A. lomatophylloides Balf.f and A. vera (synonym A. barbadensis Mill.), which are used in the traditional folk medicine of the Mascarene Islands, was initiated. Methanolic extracts of the Aloes under study were analysed using high resolution LC-UV-MS/MS and compounds belonging to the class of anthraquinones, anthrones, chromones and flavone C-glycosides were detected. The Mascarene Aloes could be distinguished from A. vera by the absence of 2″-O-feruloylaloesin and 7-O-methylaloeresin. GC-MS analysis of monosaccharides revealed the presence of arabinose, fucose, xylose, mannose and galactose in all the Mascarene Aloes and in A. vera. The crude extracts of all Aloes analysed displayed antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Only extracts of A. macra were active against P. aeruginosa and Klebsiella pneumoniae, while none of the Aloe extracts inhibited Propionibacterium acnes. A. macra displayed anti-tyrosinase activity, exhibiting 50% inhibition at 0.95mg/mL, and extracts of A. purpurea (Mauritius) and A. vera displayed activity in a wound healing-scratch assay. In vitro cytotoxicity screening of crude methanolic extracts of the Aloes, using the MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) showed that only A. purpurea (Réunion) elicited a modest toxic effect against HL60 cells, with a percentage toxicity of 8.2% (A. purpurea-Réunion) and none of the Aloe extracts elicited a toxic effect against MRC 5 fibroblast cells at a concentration of 0.1mg/mL. Mascarene Aloe species possess noteworthy pharmacological attributes associated with their rich phytochemical profiles.

The uses of Kenyan aloes: an analysis of implications for names, distribution and conservation

BACKGROUND

The genus Aloe is renowned for its medicinal and cosmetic properties and long history of use. Sixty-three Aloe species occur in Kenya, of which around 50 % are endemic. Several species of aloes are threatened with extinction and knowledge about their use is of major importance for sound conservation strategies. The main aims of this study were to assess the biocultural value of Aloe in Kenya by documenting local uses of aloes and evaluating how the vernacular names reflect the relative importance in different ethnic groups.

METHODS

Ethnobotanical and ethnotaxonomical data were collected using field observations and semi-structured interviews. Information was collected by interviewing 63 respondents from nine different ethnic groups, representing different ages, gender and occupations. Statistical analyses were performed using R version 3.1.2.

RESULTS

A total of 19 species of Aloe were found in the study area, of which 16 were used. On the generic level Aloe was easily distinguished. At species level, the local and scientific delimitation were almost identical for frequently used taxa. Aloe secundiflora, with 57 unique use records was the most important species. The two most frequently mentioned Aloe treatments, were malaria and poultry diseases. In our study area neither age nor gender had a significant influence on the level of knowledge of Aloe use. Finally, no correlation was found between extent of use and people's perception of decrease in local aloe populations. The aloes are highly appreciated and are therefore propagated and transported over large areas when people relocate.

CONCLUSION

Biocultural value is reflected in the ethnotaxonomy of Aloe in Kenya. Different ethnic groups recognise their most-valued Aloe at the genus level as "the aloe" and add explanatory names for the other species, such as the "spotted aloe" and the "one-legged aloe". Widespread species of Aloe have the highest number of uses. There is no obvious correlation with high use and decrease in abundance of aloes locally, and we found no compelling evidence for local uses causing devastating damage to populations of the 19 species in use, whereas habitat loss and commercial harvesting appear to be of urgent concern for these important plants.

Evolutionary history and leaf succulence as explanations for medicinal use in aloes and the global popularity of Aloe vera

BACKGROUND

Aloe vera supports a substantial global trade yet its wild origins, and explanations for its popularity over 500 related Aloe species in one of the world's largest succulent groups, have remained uncertain. We developed an explicit phylogenetic framework to explore links between the rich traditions of medicinal use and leaf succulence in aloes.

RESULTS

The phylogenetic hypothesis clarifies the origins of Aloe vera to the Arabian Peninsula at the northernmost limits of the range for aloes. The genus Aloe originated in southern Africa ~16 million years ago and underwent two major radiations driven by different speciation processes, giving rise to the extraordinary diversity known today. Large, succulent leaves typical of medicinal aloes arose during the most recent diversification ~10 million years ago and are strongly correlated to the phylogeny and to the likelihood of a species being used for medicine. A significant, albeit weak, phylogenetic signal is evident in the medicinal uses of aloes, suggesting that the properties for which they are valued do not occur randomly across the branches of the phylogenetic tree.

CONCLUSIONS

Phylogenetic investigation of plant use and leaf succulence among aloes has yielded new explanations for the extraordinary market dominance of Aloe vera. The industry preference for Aloe vera appears to be due to its proximity to important historic trade routes, and early introduction to trade and cultivation. Well-developed succulent leaf mesophyll tissue, an adaptive feature that likely contributed to the ecological success of the genus Aloe, is the main predictor for medicinal use among Aloe species, whereas evolutionary loss of succulence tends to be associated with losses of medicinal use. Phylogenetic analyses of plant use offer potential to understand patterns in the value of global plant diversity.

Identification of Aloe Species by Random Amplified Polymorphic DNA (RAPD) Analysis

Juice and integument of leaves of 3 Aloe species, Aloe vera, A. ferox and A. africana, are not allowed to be used as food according to the Pharmaceutical Affairs Law in Japan. On the other hand, whole leaves of A. arborescens can be used as food. The present study was designed to distinguish Aloe species by random amplified polymorphic DNA (RAPD) analysis. DNA was isolated from fresh and dried leaves of the 4 Aloe species. Five out of 32 different 10-mer primers examined were useful for analysis. By comparison of the characteristic bands of PCR products on agarose gel, it was possible to distinguish the 4 species. Thus, the botanical species of Aloe in commercial food products can be identified by RAPD analysis.

Status of certain additional over-the-counter drug category II and III active ingredients. Final rule

The Food and Drug Administration (FDA) is issuing a final rule stating that the stimulant laxative ingredients aloe (including aloe extract and aloe flower extract) and cascara sagrada (including casanthranol, cascara fluidextract aromatic, cascara sagrada bark, cascara sagrada extract, and cascara sagrada fluidextract) in over-the- counter (OTC) drug products are not generally recognized as safe and effective or are misbranded. This final rule is part of FDA's ongoing OTC drug product review.