The search for limonoids started long back when scientists started looking for the factor responsible for bitterness in citrus which has negative impact on citrus fruit and juice industry worldwide. The term limonoids was derived from limonin, the first tetranortriterpenoid obtained from citrus bitter principles. Compounds belonging to this group have exhibited a range of biological activities like insecticidal, insect antifeedant and growth regulating activity on insects as well as antibacterial, antifungal, antimalarial, anticancer, antiviral and a number of other pharmacological activities on humans. Although hundreds of limonoids have been isolated from various plants but, their occurrence in the plant kingdom is confined to only plant families of order Rutales and that too more abundantly in Meliaceae and Rutaceae, and less frequently in Cneoraceae and Harrisonia sp. of Simaroubaceae. Limonoids are highly oxygenated, modified terpenoids with a prototypical structure either containing or derived from a precursor with a 4,4,8-trimethyl-17-furanylsteroid skeleton. All naturally occurring citrus limonoids contain a furan ring attached to the D-ring, at C-17, as well as oxygen containing functional groups at C-3, C-4, C-7, C-16 and C-17. The structural variations of limonoids found in Rutaceae are less than in Meliaceae and are generally limited to the modification of A and B rings, the limonoids of Meliaceae are more complex with very high degree of oxidation and rearrangement exhibited in the parent limonoid structure. To counter the problem of bitterness in citrus juice and products genetic engineering of citrus to maximize the formation of limonoid glucosides for reducing limonoid bitterness is the focus of recent and future research. Regarding the biological activities of limonoids the investigations are to be directed towards detailed characterization, quantification, and designing a simple as well as versatile synthetic route of apparently important limonoids. Extraction methods too should be optimized; evaluation and establishment of pharmaco-dynamic and kinetic principles, and structure activity relationships should be a key goal associated with limonoids so that they can be safely introduced in our arsenal of pharmaceuticals to safeguard the humanity from the wrath of disease and its discomfort.

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Surfactant and polymers are generally used in the controlled drug delivery systems. Surfactant and polymer systems form supra-assemblies, which are extensively exploited as active delivery vehicles. These systems include liquid crystalline aggregates (e.g., liposomes and cubosomes) or cross-linked gel networks (hydrogels) that load, stabilize, and eventually deliver active ingredients. The potential for utilizing a particular active with a vehicle depends on the physicochemical properties of both. To achieve therapeutic effects, it must be possible to load sufficient amounts of the active, which largely depends on the interaction of the vehicle and active. Further, the integrity of the active must be retained through all stages: preparation, storage, and use. The release rate of actives must be controlled to achieve optimal drug release profiles, while ease of preparation and vehicle stability must also be considered. An optimal delivery vehicle must successfully encompass all these properties.Cubosomes are bicontinuous cubic phase liquid crystals have many properties that make them appealing as a universal vehicle for drug delivery. Luzzati et al. 1) first documented its geometric model supplied later by Scriven.2) Which is in the past decade have been examined for drug delivery.3) The surfactant assembles into bilayers that are twisted into a three dimension, periodic, minimal surface forming tightly packed structure, like "honeycombed" with bicontinuous domains of water and lipid.Cubosome particles are first prepared by mechanical fragmentation of the cubic lipid-water phase in a three-phase region containing a liposomal dispersion and to differentiate from liposomes, these particles have been termed as cubosomes. [4][5][6][7][8] Its structure is different from liposomes because its structure can simultaneously accommodate water-soluble, lipid-soluble, and amphiphilic molecules.Three structure of cubosomes have been proposed by Luzzati et al. 9); (i) Pn3m (D-surface) (Diamond surface), (ii) Ia3d (G-surface) (Gyroid surface), and (iii) Im3m (P-surface) (Primitive surface), in terms of nodal surfaces.The structure generally maintains the efficacy; stability of actives such as vitamins 10) and proteins. 11) Cubosomes are thermodynamically stable; lasting indefinitely.12) Colloidal dispersions of cubosomes can be stabilized by the addition of polymers.13) They also possess the potential for controlled delivery of actives, where diffusion is governed by the tortuous diffusion of the active through the "regular" channel structure of the cubic phase.14) Cubosomes possess a sufficient average degree of molecular orientation order to characterize by structural symmetry, and often form in aqueous surfactant system at relatively high ampiphile concentrations.History Luzzati and Husson 15) and Luzzati et al. first recognized the existence of cubic phases in lipid-water system using X-ray scattering measurement. Fontell et al. 16) drew similar conclusions regarding cubic phase in ternary systems of ampiphiles, oils and ...

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