(copied form icmag)
The information on polysaccharides is easily available but let me know.
Aloe vera is a nutrient accumulator like Alfalfa, Kelp, Comfrey, etc. meaning that you get the full panorama of Elements needed by a plant.
What separates any plant material from another are the Secondary Metabolites that they contain. IOW, if you only wanted Elements then it really wouldn't matter which of the accumulators you used. Sure - some plants will have a higher profile on this or that but across the board Alfalfa meal could be used in lieu of kelp meal were it not for their specific compounds.
Alfalfa = Triacontanol or Kelp meal = Alginic acid and the other plants will have their own specific compounds that they manufacture.
In the case of Aloe vera you have two compounds that are important - Saponins and Salicylic acid. You've probably seen references to using Willow shoots to extract a so-called rooting compound - well this is the same one that you can use without climbing trees or whatever.
Saponins are usually promoted as a surfactant or wetting agent which is true. But their role is far more complex as it relates to triggering a plant's innate defense systems - System Acquired Resistance (SAR) and Hormonal Acquired Resistance (HAR).
Saponins in the soil, per se, provide a number of other benefits that you can read about. The problem with trying to do research on the Aloe vera plant in the USA is that the links at Google are loaded with blogs, forum posts and manufacturer's blab sheets. Pretty daunting trying to dig through it.
You'll do much better at the Australian web sites. Australia is the 3rd largest producer of Aloe vera extracts - liquid, spray-dried and freeze dried versions. China & Mexico are bigger than Australia.
Besides these 2 specific compounds (of about 450), there are the enzymes and here you can go back to the Google sites, get the specific enzymes Aloe vera contains and then look over at Google Scholar, SCIRUS, JSTOR or another science-based search engines and figure out how it applies to Botany and soil biology.
But Saponins and Salicylic acid would the main selling points from a sales rep perspective.
HTH
CC