Potential Biological Applications of Bio-Based Anacardic Acids and Their Derivatives

Abstract

Cashew nut shells (CNS), which are agro wastes from cashew nut processing factories, have proven to be among the most versatile bio-based renewable materials in the search for functional materials and chemicals from renewable resources. CNS are produced in the cashew nut processing process as waste, but they contain cashew nut shell liquid (CNSL) up to about 30–35 wt. % of the nut shell weight depending on the method of extraction. CNSL is a mixture of anacardic acid, cardanol, cardol, and methyl cardol, and the structures of these phenols offer opportunities for the development of diverse products. For anacardic acid, the combination of phenolic, carboxylic, and a 15-carbon alkyl side chain functional group makes it attractive in biological applications or as a synthon for the synthesis of a multitude of bioactive compounds. Anacardic acid, which is about 65% of a CNSL mixture, can be extracted from the agro waste. This shows that CNS waste can be used to extract useful chemicals and thus provide alternative green sources of chemicals, apart from relying only on the otherwise declining petroleum based sources. This paper reviews the potential of anacardic acids and their semi-synthetic derivatives for antibacterial, antitumor, and antioxidant activities. The review focuses on natural anacardic acids from CNS and other plants and their semi-synthetic derivatives as possible lead compounds in medicine. In addition, the use of anacardic acid as a starting material for the synthesis of various biologically active compounds and complexes is reported.

Discovery of Sustainable Drugs for Neglected Tropical Diseases: Cashew Nut Shell Liquid (CNSL)‐Based Hybrids Target Mitochondrial Function and ATP Production in Trypanosoma brucei

“…The pentadecyl alkyl side chain of 1 – 3 may be saturated, mono‐olefinic, di‐olefinic or tri‐olefinic with a high percentage of the components having one or two double bonds (Figure ), depending on the production method . Although CNSL components have been reported to possess a wide range of biological activities, in many cases they are not potent enough to be drug candidates . To overcome this limitation, their use in combination with standard drugs, and the design of new semi‐synthetic derivatives have been exploited …”

“…[12] Al-thoughC NSL components have been reported to possess a wide range of biological activities,i nm any cases they are not potent enough to be drug candidates. [9] To overcome this limi-tation, their use in combination with standard drugs, and the design of new semi-syntheticd erivatives have been exploited. [9] Along these lines, we decided to develop as eries of CNSLbased hybrid compounds.…”

“…[9] To overcome this limi-tation, their use in combination with standard drugs, and the design of new semi-syntheticd erivatives have been exploited. [9] Along these lines, we decided to develop as eries of CNSLbased hybrid compounds. In particular,b uildingo nt he strategy that the combinations of two different fragments into one covalently linked hybrid compound can convey synergy and increasep otency, [13] we combined the chemical features of CNSL derivatives with those of ap reviously developed anti-trypanosomal hit compound (4 in Figure 2).…”

“…Based on the above considerations, as well as on our continuous interest in the NTD field, we explored the possibility of using cashew nut shell liquid (CNSL) as a sustainable, low‐cost starting material for the development of new drugs against trypanosomiases. CNSL, which is obtained as the by‐product of cashew nut processing, has proven to be one of the most versatile food wastes for the production of functional materials and chemicals . However, its potential as a precursor of drugs has been relatively underexplored.…”

“…CNSL, which is obtained as the by-product of cashew nut processing, has provent ob eone of the mostv ersatile food wastes for the production of functional materials and chemicals. [9] However,i ts potential as ap recursor of drugs has been relativelyu nderexplored. Being an inedible waste material, it presents clear environmental, financial and ethical advantages over synthetic drugs and even overn atural products derived from crops grown for that purpose.…”