Chitin, being the second most abundant biopolymer after cellulose, has been gaining popularity since its initial discovery by Braconot in 1811. However, fundamental knowledge and literature on chitin and its derivatives from insects are difficult to obtain. The most common and sought-after sources of chitin are shellfish (especially crustaceans) and other aquatic invertebrates. The amount of shellfish available is obviously restricted by the amount of food waste that is allowed; hence, it is a limited resource. Therefore, insects are the best choices since, out of 1.3 million species in the world, 900,000 are insects, making them the most abundant species in the world. In this review, a total of 82 samples from shellfish—crustaceans and mollusks (n = 46), insects (n = 23), and others (n = 13)—have been collected and studied for their chemical extraction of chitin and its derivatives. The aim of this paper is to review the extraction method of chitin and chitosan for a comparison of the optimal demineralization and deproteinization processes, with a consideration of insects as alternative sources of chitin. The methods employed in this review are based on comprehensive bibliographic research. Based on previous data, the chitin and chitosan contents of insects in past studies favorably compare and compete with those of commercial chitin and chitosan—for example, 45% in Bombyx eri, 36.6% in Periostracum cicadae (cicada sloughs), and 26.2% in Chyrysomya megacephala. Therefore, according to the data reported by previous researchers, demonstrating comparable yield values to those of crustacean chitin and the great interest in insects as alternative sources, efforts towards comprehensive knowledge in this field are relevant.

A breakthrough in cosmeceuticals by utilizing insects as major ingredients in cosmetic products is gaining popularity. Therefore, the interest in rare sources of ingredients, for instance, from the Oryctes rhinoceros beetle, can bring huge benefits in terms of turning pests into wealth. In this study, curcumin was chosen as the active ingredient loaded into chitosan-gold nanoparticles (CCG-NP). Curcumin is unstable and has poor absorption, a high rate of metabolism, and high sensitivity to light. These are all factors that contribute to the low bioavailability of any substance to reach the target cells. Therefore, chitosan extracted from O. rhinoceros could be used as a drug carrier to overcome these limitations. In order to overcome these limitations, CCG-NPs were synthesized and characterized. Chitosan was isolated from O. rhinoceros and CCG-NPs were successfully synthesized at 70 °C for 60 min under optimal conditions of a reactant ratio of 2:0.5 (0.5 mM HAuCl4: 0.1% curcumin). Characterizations of CCG-NP involved FTIR analysis, zeta potential, morphological properties determination by FE-SEM, particle size analysis, crystallinity study by XRD, and elemental analysis by EDX. The shape of the CCG-NP was round, its size was 128.27 d.nm, and the value of the zeta potential was 20.2 ± 3.81 mV. The IC50 value for cell viability is 58%, indicating a mild toxicity trait. To conclude, CCG-NP is a stable, spherical, nano-sized, non-toxic, and homogeneous solution.

Of many neurodegenerative diseases, Alzheimer’s disease (AD) is the most common cause of dementia globally, which is still incurable even after decades of extensive research to find a definite and permanent cure. Accumulation of free radicals and acetylcholine (ACh) deficiency in the brains of Alzheimer’s patients are considered as the factors leading to dementia and cognitive problems. This is by mechanisms involving disturbance in the balance between the amount of free radicals and the antioxidant defense system along with cholinergic deficit leading to impaired cholinergic neurotransmission. Currently available anti-AD drug therapy carries only the partial benefit of slowing down the progression of disease besides having various side effects and, hence, there is a developing interest to search for new drugs. Plants have always been of special interest in the field of new drug discovery research by virtue of their enormous biological diversity and tremendous potential of bioactive molecules. Many herbs are known to ameliorate the symptoms related to memory and cognitive disorders. Centella asiatica (L.) Urb. is one of the widely used plants claimed by the traditional system of medicine to have its positive effects on memory and brain functioning. The objective of this review is to present a comprehensive account on C. asiatica by summarizing the research until date related to its medicinal potential with a special focus on antioxidant and anti-acetylcholinesterase (antiAChE) properties reflecting their potential therapeutic application for the treatment of AD.

Centella asiatica, Piper sarmentosum and Morinda citrifolia is well-known for their memory enhancement contribution from traditional practices as well as recent researches. However, all three herbs are utilized individually and never mixed together. The nutrient data on the synergistic effect on all three herbs remain scarce. The aims of this research project were to apply Simplex-centroid mixture design in describing the study for the effect of polyherbal formulation on antioxidants properties and its synergistic effects. Based on results obtained, there was a significant difference in antioxidant properties of the polyherbal formulation. The results show the polyherbal formulation 3 and 13 (M. citrifolia only) has the highest antioxidant capacity when being tested with total phenolic content (TPC) (210.10 and 209.12 µg GAE/mL respectively) and 2,2-diphenyl-1- picrylhydrazyl (DPPH) (42.94 and 37.77%) assays. Contradict to this result, the highest in total flavonoid content (TFC) and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) for describing antioxidant properties are formulations 1 and 11 (C. asiatica only). The TPC for formulation 1 and 11 are 479.8 µg RE/mL and 470 µg RE/mL respectively while ABTS radical inhibition for formulation 1 and 11 are 64.53% and 60% respectively. For ferric reducing ability of plasma (FRAP) assay, formulation 7 (2.11 µg FSE/mL) is the highest which have 1:1:1 ratio of each herb. In addition, TPC, TFC, and DPPH assays showed high antioxidant activities when only single herbs were added into the formulation. Meanwhile, ABTS and FRAP are prone to binary polyherbal formulation. Hence, this study showed an antagonism effect instead of synergistic effect since single formulation exhibited the highest for TPC, TFC and DPPH. All tests gave the lowest antioxidant properties when the mix was ternary polyherbal formulation.

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