In vitro approaches for the production of aloin: Advancements and opportunities

Abstract

Aloin, a C-glycosidic derivative of anthraquinone, exhibit immense applications in cosmeceutical industry. It is the main active ingredient of the latex from Aloe vera L., commonly referred as ‘Aloe’ and ‘Ghritkumari’. Aloe is a monocotyledonous, perennial, succulent, herbaceous medicinal plant belonging to the family Liliaceae. Aloe marked its place as a plant of the hour with its versatile uses in pharmaceutical, food, and cosmeceutical industries ensuring a potential economic return. Anthraquinone is the major bioactive component of Aloe and is synthesised via the acetate-polymalonate pathway or shikimic acid-O-succinyl benzoic acid-mevalonic acid pathway. In order to fulfil the industrial demand for enhanced aloin production, methods to complement large-scale Aloe planting techniques must be devised. The conventional method of aloin production is associated with several drawbacks, such as male sterility, insufficient number of planting material, incidence of several diseases and pests of Aloe, ensuing in decline of propagation rate and subsequent aloin accumulation. Hence, biotechnological approaches appear as a better alternative to those conventional systems. The current review focuses on aloin chemistry, its natural biosynthesis, cosmeceutical applications, biotechnological (in vitro) approaches for aloin production as well as highlights the research gaps, unexplored areas, and major obstacles that can be investigated in the near future to ameliorate the production of aloin. To date, reports were emphasized towards direct and indirect regeneration system of Aloe but only a few reports stated the enhancement of aloin production. There is a wide scope for researchers to ameliorate the aloin production via yet-to-be explored synthetic seed technology, elicitation, polyploidization, manipulation of genes involved in aloin biosynthesis pathway, nanotechnology, etc. Hence, this review paves the way forward for Aloe-researchers and scientists associated with research and development at cosmeceutical industries to explore the areas for commercial-scale biotechnological production of aloin.